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subr_bus.c

/*-
 * Copyright (c) 1997,1998,2003 Doug Rabson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/kern/subr_bus.c,v 1.184.2.6 2007/11/05 11:49:44 phk Exp $");

#include "opt_bus.h"

#include <sys/param.h>
#include <sys/conf.h>
#include <sys/filio.h>
#include <sys/lock.h>
#include <sys/kernel.h>
#include <sys/kobj.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/poll.h>
#include <sys/proc.h>
#include <sys/condvar.h>
#include <sys/queue.h>
#include <machine/bus.h>
#include <sys/rman.h>
#include <sys/selinfo.h>
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/bus.h>

#include <machine/stdarg.h>

#include <vm/uma.h>

SYSCTL_NODE(_hw, OID_AUTO, bus, CTLFLAG_RW, NULL, NULL);
SYSCTL_NODE(, OID_AUTO, dev, CTLFLAG_RW, NULL, NULL);

/*
 * Used to attach drivers to devclasses.
 */
typedef struct driverlink *driverlink_t;
struct driverlink {
      kobj_class_t      driver;
      TAILQ_ENTRY(driverlink) link; /* list of drivers in devclass */
};

/*
 * Forward declarations
 */
typedef TAILQ_HEAD(devclass_list, devclass) devclass_list_t;
typedef TAILQ_HEAD(driver_list, driverlink) driver_list_t;
typedef TAILQ_HEAD(device_list, device) device_list_t;

struct devclass {
      TAILQ_ENTRY(devclass) link;
      devclass_t  parent;           /* parent in devclass hierarchy */
      driver_list_t     drivers;     /* bus devclasses store drivers for bus */
      char        *name;
      device_t    *devices;   /* array of devices indexed by unit */
      int         maxunit;    /* size of devices array */

      struct sysctl_ctx_list sysctl_ctx;
      struct sysctl_oid *sysctl_tree;
};

/**
 * @brief Implementation of device.
 */
00092 struct device {
      /*
       * A device is a kernel object. The first field must be the
       * current ops table for the object.
       */
      KOBJ_FIELDS;

      /*
       * Device hierarchy.
       */
      TAILQ_ENTRY(device)     link; /**< list of devices in parent */
      TAILQ_ENTRY(device)     devlink; /**< global device list membership */
      device_t    parent;           /**< parent of this device  */
      device_list_t     children;   /**< list of child devices */

      /*
       * Details of this device.
       */
      driver_t    *driver;    /**< current driver */
      devclass_t  devclass;   /**< current device class */
      int         unit;       /**< current unit number */
      char*       nameunit;   /**< name+unit e.g. foodev0 */
      char*       desc;       /**< driver specific description */
      int         busy;       /**< count of calls to device_busy() */
      device_state_t    state;            /**< current device state  */
      u_int32_t   devflags;   /**< api level flags for device_get_flags() */
      u_short           flags;            /**< internal device flags  */
#define     DF_ENABLED  1           /* device should be probed/attached */
#define     DF_FIXEDCLASS     2           /* devclass specified at create time */
#define     DF_WILDCARD 4           /* unit was originally wildcard */
#define     DF_DESCMALLOCED   8           /* description was malloced */
#define     DF_QUIET    16          /* don't print verbose attach message */
#define     DF_DONENOMATCH    32          /* don't execute DEVICE_NOMATCH again */
#define     DF_EXTERNALSOFTC 64           /* softc not allocated by us */
#define     DF_REBID    128         /* Can rebid after attach */
      u_char      order;                  /**< order from device_add_child_ordered() */
      u_char      pad;
      void  *ivars;                 /**< instance variables  */
      void  *softc;                 /**< current driver's variables  */

      struct sysctl_ctx_list sysctl_ctx; /**< state for sysctl variables  */
      struct sysctl_oid *sysctl_tree;     /**< state for sysctl variables */
};

static MALLOC_DEFINE(M_BUS, "bus", "Bus data structures");
static MALLOC_DEFINE(M_BUS_SC, "bus-sc", "Bus data structures, softc");

#ifdef BUS_DEBUG

static int bus_debug = 1;
TUNABLE_INT("bus.debug", &bus_debug);
SYSCTL_INT(_debug, OID_AUTO, bus_debug, CTLFLAG_RW, &bus_debug, 0,
    "Debug bus code");

#define PDEBUG(a) if (bus_debug) {printf("%s:%d: ", __func__, __LINE__), printf a; printf("\n");}
#define DEVICENAME(d)   ((d)? device_get_name(d): "no device")
#define DRIVERNAME(d)   ((d)? d->name : "no driver")
#define DEVCLANAME(d)   ((d)? d->name : "no devclass")

/**
 * Produce the indenting, indent*2 spaces plus a '.' ahead of that to
 * prevent syslog from deleting initial spaces
 */
#define indentprintf(p) do { int iJ; printf("."); for (iJ=0; iJ<indent; iJ++) printf("  "); printf p ; } while (0)

static void print_device_short(device_t dev, int indent);
static void print_device(device_t dev, int indent);
void print_device_tree_short(device_t dev, int indent);
void print_device_tree(device_t dev, int indent);
static void print_driver_short(driver_t *driver, int indent);
static void print_driver(driver_t *driver, int indent);
static void print_driver_list(driver_list_t drivers, int indent);
static void print_devclass_short(devclass_t dc, int indent);
static void print_devclass(devclass_t dc, int indent);
void print_devclass_list_short(void);
void print_devclass_list(void);

#else
/* Make the compiler ignore the function calls */
#define PDEBUG(a)             /* nop */
#define DEVICENAME(d)               /* nop */
#define DRIVERNAME(d)               /* nop */
#define DEVCLANAME(d)               /* nop */

#define print_device_short(d,i)           /* nop */
#define print_device(d,i)           /* nop */
#define print_device_tree_short(d,i)      /* nop */
#define print_device_tree(d,i)            /* nop */
#define print_driver_short(d,i)           /* nop */
#define print_driver(d,i)           /* nop */
#define print_driver_list(d,i)            /* nop */
#define print_devclass_short(d,i)   /* nop */
#define print_devclass(d,i)         /* nop */
#define print_devclass_list_short() /* nop */
#define print_devclass_list()       /* nop */
#endif

/*
 * dev sysctl tree
 */

enum {
      DEVCLASS_SYSCTL_PARENT,
};

static int
devclass_sysctl_handler(SYSCTL_HANDLER_ARGS)
{
      devclass_t dc = (devclass_t)arg1;
      const char *value;

      switch (arg2) {
      case DEVCLASS_SYSCTL_PARENT:
            value = dc->parent ? dc->parent->name : "";
            break;
      default:
            return (EINVAL);
      }
      return (SYSCTL_OUT(req, value, strlen(value)));
}

static void
devclass_sysctl_init(devclass_t dc)
{

      if (dc->sysctl_tree != NULL)
            return;
      sysctl_ctx_init(&dc->sysctl_ctx);
      dc->sysctl_tree = SYSCTL_ADD_NODE(&dc->sysctl_ctx,
          SYSCTL_STATIC_CHILDREN(_dev), OID_AUTO, dc->name,
          CTLFLAG_RD, 0, "");
      SYSCTL_ADD_PROC(&dc->sysctl_ctx, SYSCTL_CHILDREN(dc->sysctl_tree),
          OID_AUTO, "%parent", CTLFLAG_RD,
          dc, DEVCLASS_SYSCTL_PARENT, devclass_sysctl_handler, "A",
          "parent class");
}

enum {
      DEVICE_SYSCTL_DESC,
      DEVICE_SYSCTL_DRIVER,
      DEVICE_SYSCTL_LOCATION,
      DEVICE_SYSCTL_PNPINFO,
      DEVICE_SYSCTL_PARENT,
};

static int
device_sysctl_handler(SYSCTL_HANDLER_ARGS)
{
      device_t dev = (device_t)arg1;
      const char *value;
      char *buf;
      int error;

      buf = NULL;
      switch (arg2) {
      case DEVICE_SYSCTL_DESC:
            value = dev->desc ? dev->desc : "";
            break;
      case DEVICE_SYSCTL_DRIVER:
            value = dev->driver ? dev->driver->name : "";
            break;
      case DEVICE_SYSCTL_LOCATION:
            value = buf = malloc(1024, M_BUS, M_WAITOK | M_ZERO);
            bus_child_location_str(dev, buf, 1024);
            break;
      case DEVICE_SYSCTL_PNPINFO:
            value = buf = malloc(1024, M_BUS, M_WAITOK | M_ZERO);
            bus_child_pnpinfo_str(dev, buf, 1024);
            break;
      case DEVICE_SYSCTL_PARENT:
            value = dev->parent ? dev->parent->nameunit : "";
            break;
      default:
            return (EINVAL);
      }
      error = SYSCTL_OUT(req, value, strlen(value));
      if (buf != NULL)
            free(buf, M_BUS);
      return (error);
}

static void
device_sysctl_init(device_t dev)
{
      devclass_t dc = dev->devclass;

      if (dev->sysctl_tree != NULL)
            return;
      devclass_sysctl_init(dc);
      sysctl_ctx_init(&dev->sysctl_ctx);
      dev->sysctl_tree = SYSCTL_ADD_NODE(&dev->sysctl_ctx,
          SYSCTL_CHILDREN(dc->sysctl_tree), OID_AUTO,
          dev->nameunit + strlen(dc->name),
          CTLFLAG_RD, 0, "");
      SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
          OID_AUTO, "%desc", CTLFLAG_RD,
          dev, DEVICE_SYSCTL_DESC, device_sysctl_handler, "A",
          "device description");
      SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
          OID_AUTO, "%driver", CTLFLAG_RD,
          dev, DEVICE_SYSCTL_DRIVER, device_sysctl_handler, "A",
          "device driver name");
      SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
          OID_AUTO, "%location", CTLFLAG_RD,
          dev, DEVICE_SYSCTL_LOCATION, device_sysctl_handler, "A",
          "device location relative to parent");
      SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
          OID_AUTO, "%pnpinfo", CTLFLAG_RD,
          dev, DEVICE_SYSCTL_PNPINFO, device_sysctl_handler, "A",
          "device identification");
      SYSCTL_ADD_PROC(&dev->sysctl_ctx, SYSCTL_CHILDREN(dev->sysctl_tree),
          OID_AUTO, "%parent", CTLFLAG_RD,
          dev, DEVICE_SYSCTL_PARENT, device_sysctl_handler, "A",
          "parent device");
}

static void
device_sysctl_fini(device_t dev)
{
      if (dev->sysctl_tree == NULL)
            return;
      sysctl_ctx_free(&dev->sysctl_ctx);
      dev->sysctl_tree = NULL;
}

/*
 * /dev/devctl implementation
 */

/*
 * This design allows only one reader for /dev/devctl.  This is not desirable
 * in the long run, but will get a lot of hair out of this implementation.
 * Maybe we should make this device a clonable device.
 *
 * Also note: we specifically do not attach a device to the device_t tree
 * to avoid potential chicken and egg problems.  One could argue that all
 * of this belongs to the root node.  One could also further argue that the
 * sysctl interface that we have not might more properly be an ioctl
 * interface, but at this stage of the game, I'm not inclined to rock that
 * boat.
 *
 * I'm also not sure that the SIGIO support is done correctly or not, as
 * I copied it from a driver that had SIGIO support that likely hasn't been
 * tested since 3.4 or 2.2.8!
 */

static int sysctl_devctl_disable(SYSCTL_HANDLER_ARGS);
static int devctl_disable = 0;
TUNABLE_INT("hw.bus.devctl_disable", &devctl_disable);
SYSCTL_PROC(_hw_bus, OID_AUTO, devctl_disable, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
    sysctl_devctl_disable, "I", "devctl disable");

static d_open_t         devopen;
static d_close_t  devclose;
static d_read_t         devread;
static d_ioctl_t  devioctl;
static d_poll_t         devpoll;

static struct cdevsw dev_cdevsw = {
      .d_version =      D_VERSION,
      .d_flags =  D_NEEDGIANT,
      .d_open =   devopen,
      .d_close =  devclose,
      .d_read =   devread,
      .d_ioctl =  devioctl,
      .d_poll =   devpoll,
      .d_name =   "devctl",
};

struct dev_event_info
{
      char *dei_data;
      TAILQ_ENTRY(dev_event_info) dei_link;
};

TAILQ_HEAD(devq, dev_event_info);

static struct dev_softc
{
      int   inuse;
      int   nonblock;
      struct mtx mtx;
      struct cv cv;
      struct selinfo sel;
      struct devq devq;
      struct proc *async_proc;
} devsoftc;

static struct cdev *devctl_dev;

static void
devinit(void)
{
      devctl_dev = make_dev(&dev_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600,
          "devctl");
      mtx_init(&devsoftc.mtx, "dev mtx", "devd", MTX_DEF);
      cv_init(&devsoftc.cv, "dev cv");
      TAILQ_INIT(&devsoftc.devq);
}

static int
devopen(struct cdev *dev, int oflags, int devtype, d_thread_t *td)
{
      if (devsoftc.inuse)
            return (EBUSY);
      /* move to init */
      devsoftc.inuse = 1;
      devsoftc.nonblock = 0;
      devsoftc.async_proc = NULL;
      return (0);
}

static int
devclose(struct cdev *dev, int fflag, int devtype, d_thread_t *td)
{
      devsoftc.inuse = 0;
      mtx_lock(&devsoftc.mtx);
      cv_broadcast(&devsoftc.cv);
      mtx_unlock(&devsoftc.mtx);

      return (0);
}

/*
 * The read channel for this device is used to report changes to
 * userland in realtime.  We are required to free the data as well as
 * the n1 object because we allocate them separately.  Also note that
 * we return one record at a time.  If you try to read this device a
 * character at a time, you will loose the rest of the data.  Listening
 * programs are expected to cope.
 */
static int
devread(struct cdev *dev, struct uio *uio, int ioflag)
{
      struct dev_event_info *n1;
      int rv;

      mtx_lock(&devsoftc.mtx);
      while (TAILQ_EMPTY(&devsoftc.devq)) {
            if (devsoftc.nonblock) {
                  mtx_unlock(&devsoftc.mtx);
                  return (EAGAIN);
            }
            rv = cv_wait_sig(&devsoftc.cv, &devsoftc.mtx);
            if (rv) {
                  /*
                   * Need to translate ERESTART to EINTR here? -- jake
                   */
                  mtx_unlock(&devsoftc.mtx);
                  return (rv);
            }
      }
      n1 = TAILQ_FIRST(&devsoftc.devq);
      TAILQ_REMOVE(&devsoftc.devq, n1, dei_link);
      mtx_unlock(&devsoftc.mtx);
      rv = uiomove(n1->dei_data, strlen(n1->dei_data), uio);
      free(n1->dei_data, M_BUS);
      free(n1, M_BUS);
      return (rv);
}

static      int
devioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag, d_thread_t *td)
{
      switch (cmd) {

      case FIONBIO:
            if (*(int*)data)
                  devsoftc.nonblock = 1;
            else
                  devsoftc.nonblock = 0;
            return (0);
      case FIOASYNC:
            if (*(int*)data)
                  devsoftc.async_proc = td->td_proc;
            else
                  devsoftc.async_proc = NULL;
            return (0);

            /* (un)Support for other fcntl() calls. */
      case FIOCLEX:
      case FIONCLEX:
      case FIONREAD:
      case FIOSETOWN:
      case FIOGETOWN:
      default:
            break;
      }
      return (ENOTTY);
}

static      int
devpoll(struct cdev *dev, int events, d_thread_t *td)
{
      int   revents = 0;

      mtx_lock(&devsoftc.mtx);
      if (events & (POLLIN | POLLRDNORM)) {
            if (!TAILQ_EMPTY(&devsoftc.devq))
                  revents = events & (POLLIN | POLLRDNORM);
            else
                  selrecord(td, &devsoftc.sel);
      }
      mtx_unlock(&devsoftc.mtx);

      return (revents);
}

/**
 * @brief Queue data to be read from the devctl device
 *
 * Generic interface to queue data to the devctl device.  It is
 * assumed that @p data is properly formatted.  It is further assumed
 * that @p data is allocated using the M_BUS malloc type.
 */
void
devctl_queue_data(char *data)
{
      struct dev_event_info *n1 = NULL;
      struct proc *p;

      n1 = malloc(sizeof(*n1), M_BUS, M_NOWAIT);
      if (n1 == NULL)
            return;
      n1->dei_data = data;
      mtx_lock(&devsoftc.mtx);
      TAILQ_INSERT_TAIL(&devsoftc.devq, n1, dei_link);
      cv_broadcast(&devsoftc.cv);
      mtx_unlock(&devsoftc.mtx);
      selwakeup(&devsoftc.sel);
      p = devsoftc.async_proc;
      if (p != NULL) {
            PROC_LOCK(p);
            psignal(p, SIGIO);
            PROC_UNLOCK(p);
      }
}

/**
 * @brief Send a 'notification' to userland, using standard ways
 */
void
devctl_notify(const char *system, const char *subsystem, const char *type,
    const char *data)
{
      int len = 0;
      char *msg;

      if (system == NULL)
            return;           /* BOGUS!  Must specify system. */
      if (subsystem == NULL)
            return;           /* BOGUS!  Must specify subsystem. */
      if (type == NULL)
            return;           /* BOGUS!  Must specify type. */
      len += strlen(" system=") + strlen(system);
      len += strlen(" subsystem=") + strlen(subsystem);
      len += strlen(" type=") + strlen(type);
      /* add in the data message plus newline. */
      if (data != NULL)
            len += strlen(data);
      len += 3;   /* '!', '\n', and NUL */
      msg = malloc(len, M_BUS, M_NOWAIT);
      if (msg == NULL)
            return;           /* Drop it on the floor */
      if (data != NULL)
            snprintf(msg, len, "!system=%s subsystem=%s type=%s %s\n",
                system, subsystem, type, data);
      else
            snprintf(msg, len, "!system=%s subsystem=%s type=%s\n",
                system, subsystem, type);
      devctl_queue_data(msg);
}

/*
 * Common routine that tries to make sending messages as easy as possible.
 * We allocate memory for the data, copy strings into that, but do not
 * free it unless there's an error.  The dequeue part of the driver should
 * free the data.  We don't send data when the device is disabled.  We do
 * send data, even when we have no listeners, because we wish to avoid
 * races relating to startup and restart of listening applications.
 *
 * devaddq is designed to string together the type of event, with the
 * object of that event, plus the plug and play info and location info
 * for that event.  This is likely most useful for devices, but less
 * useful for other consumers of this interface.  Those should use
 * the devctl_queue_data() interface instead.
 */
static void
devaddq(const char *type, const char *what, device_t dev)
{
      char *data = NULL;
      char *loc = NULL;
      char *pnp = NULL;
      const char *parstr;

      if (devctl_disable)
            return;
      data = malloc(1024, M_BUS, M_NOWAIT);
      if (data == NULL)
            goto bad;

      /* get the bus specific location of this device */
      loc = malloc(1024, M_BUS, M_NOWAIT);
      if (loc == NULL)
            goto bad;
      *loc = '\0';
      bus_child_location_str(dev, loc, 1024);

      /* Get the bus specific pnp info of this device */
      pnp = malloc(1024, M_BUS, M_NOWAIT);
      if (pnp == NULL)
            goto bad;
      *pnp = '\0';
      bus_child_pnpinfo_str(dev, pnp, 1024);

      /* Get the parent of this device, or / if high enough in the tree. */
      if (device_get_parent(dev) == NULL)
            parstr = ".";     /* Or '/' ? */
      else
            parstr = device_get_nameunit(device_get_parent(dev));
      /* String it all together. */
      snprintf(data, 1024, "%s%s at %s %s on %s\n", type, what, loc, pnp,
        parstr);
      free(loc, M_BUS);
      free(pnp, M_BUS);
      devctl_queue_data(data);
      return;
bad:
      free(pnp, M_BUS);
      free(loc, M_BUS);
      free(data, M_BUS);
      return;
}

/*
 * A device was added to the tree.  We are called just after it successfully
 * attaches (that is, probe and attach success for this device).  No call
 * is made if a device is merely parented into the tree.  See devnomatch
 * if probe fails.  If attach fails, no notification is sent (but maybe
 * we should have a different message for this).
 */
static void
devadded(device_t dev)
{
      char *pnp = NULL;
      char *tmp = NULL;

      pnp = malloc(1024, M_BUS, M_NOWAIT);
      if (pnp == NULL)
            goto fail;
      tmp = malloc(1024, M_BUS, M_NOWAIT);
      if (tmp == NULL)
            goto fail;
      *pnp = '\0';
      bus_child_pnpinfo_str(dev, pnp, 1024);
      snprintf(tmp, 1024, "%s %s", device_get_nameunit(dev), pnp);
      devaddq("+", tmp, dev);
fail:
      if (pnp != NULL)
            free(pnp, M_BUS);
      if (tmp != NULL)
            free(tmp, M_BUS);
      return;
}

/*
 * A device was removed from the tree.  We are called just before this
 * happens.
 */
static void
devremoved(device_t dev)
{
      char *pnp = NULL;
      char *tmp = NULL;

      pnp = malloc(1024, M_BUS, M_NOWAIT);
      if (pnp == NULL)
            goto fail;
      tmp = malloc(1024, M_BUS, M_NOWAIT);
      if (tmp == NULL)
            goto fail;
      *pnp = '\0';
      bus_child_pnpinfo_str(dev, pnp, 1024);
      snprintf(tmp, 1024, "%s %s", device_get_nameunit(dev), pnp);
      devaddq("-", tmp, dev);
fail:
      if (pnp != NULL)
            free(pnp, M_BUS);
      if (tmp != NULL)
            free(tmp, M_BUS);
      return;
}

/*
 * Called when there's no match for this device.  This is only called
 * the first time that no match happens, so we don't keep getitng this
 * message.  Should that prove to be undesirable, we can change it.
 * This is called when all drivers that can attach to a given bus
 * decline to accept this device.  Other errrors may not be detected.
 */
static void
devnomatch(device_t dev)
{
      devaddq("?", "", dev);
}

static int
sysctl_devctl_disable(SYSCTL_HANDLER_ARGS)
{
      struct dev_event_info *n1;
      int dis, error;

      dis = devctl_disable;
      error = sysctl_handle_int(oidp, &dis, 0, req);
      if (error || !req->newptr)
            return (error);
      mtx_lock(&devsoftc.mtx);
      devctl_disable = dis;
      if (dis) {
            while (!TAILQ_EMPTY(&devsoftc.devq)) {
                  n1 = TAILQ_FIRST(&devsoftc.devq);
                  TAILQ_REMOVE(&devsoftc.devq, n1, dei_link);
                  free(n1->dei_data, M_BUS);
                  free(n1, M_BUS);
            }
      }
      mtx_unlock(&devsoftc.mtx);
      return (0);
}

/* End of /dev/devctl code */

TAILQ_HEAD(,device)     bus_data_devices;
static int bus_data_generation = 1;

kobj_method_t null_methods[] = {
      { 0, 0 }
};

DEFINE_CLASS(null, null_methods, 0);

/*
 * Devclass implementation
 */

static devclass_list_t devclasses = TAILQ_HEAD_INITIALIZER(devclasses);


/**
 * @internal
 * @brief Find or create a device class
 *
 * If a device class with the name @p classname exists, return it,
 * otherwise if @p create is non-zero create and return a new device
 * class.
 *
 * If @p parentname is non-NULL, the parent of the devclass is set to
 * the devclass of that name.
 *
 * @param classname     the devclass name to find or create
 * @param parentname    the parent devclass name or @c NULL
 * @param create  non-zero to create a devclass
 */
static devclass_t
devclass_find_internal(const char *classname, const char *parentname,
                   int create)
{
      devclass_t dc;

      PDEBUG(("looking for %s", classname));
      if (!classname)
            return (NULL);

      TAILQ_FOREACH(dc, &devclasses, link) {
            if (!strcmp(dc->name, classname))
                  break;
      }

      if (create && !dc) {
            PDEBUG(("creating %s", classname));
            dc = malloc(sizeof(struct devclass) + strlen(classname) + 1,
                M_BUS, M_NOWAIT|M_ZERO);
            if (!dc)
                  return (NULL);
            dc->parent = NULL;
            dc->name = (char*) (dc + 1);
            strcpy(dc->name, classname);
            TAILQ_INIT(&dc->drivers);
            TAILQ_INSERT_TAIL(&devclasses, dc, link);

            bus_data_generation_update();
      }

      /*
       * If a parent class is specified, then set that as our parent so
       * that this devclass will support drivers for the parent class as
       * well.  If the parent class has the same name don't do this though
       * as it creates a cycle that can trigger an infinite loop in
       * device_probe_child() if a device exists for which there is no
       * suitable driver.
       */
      if (parentname && dc && !dc->parent &&
          strcmp(classname, parentname) != 0) {
            dc->parent = devclass_find_internal(parentname, 0, FALSE);
      }

      return (dc);
}

/**
 * @brief Create a device class
 *
 * If a device class with the name @p classname exists, return it,
 * otherwise create and return a new device class.
 *
 * @param classname     the devclass name to find or create
 */
devclass_t
devclass_create(const char *classname)
{
      return (devclass_find_internal(classname, 0, TRUE));
}

/**
 * @brief Find a device class
 *
 * If a device class with the name @p classname exists, return it,
 * otherwise return @c NULL.
 *
 * @param classname     the devclass name to find
 */
devclass_t
devclass_find(const char *classname)
{
      return (devclass_find_internal(classname, 0, FALSE));
}

/**
 * @brief Add a device driver to a device class
 *
 * Add a device driver to a devclass. This is normally called
 * automatically by DRIVER_MODULE(). The BUS_DRIVER_ADDED() method of
 * all devices in the devclass will be called to allow them to attempt
 * to re-probe any unmatched children.
 *
 * @param dc            the devclass to edit
 * @param driver  the driver to register
 */
int
devclass_add_driver(devclass_t dc, driver_t *driver)
{
      driverlink_t dl;
      int i;

      PDEBUG(("%s", DRIVERNAME(driver)));

      dl = malloc(sizeof *dl, M_BUS, M_NOWAIT|M_ZERO);
      if (!dl)
            return (ENOMEM);

      /*
       * Compile the driver's methods. Also increase the reference count
       * so that the class doesn't get freed when the last instance
       * goes. This means we can safely use static methods and avoids a
       * double-free in devclass_delete_driver.
       */
      kobj_class_compile((kobj_class_t) driver);

      /*
       * Make sure the devclass which the driver is implementing exists.
       */
      devclass_find_internal(driver->name, 0, TRUE);

      dl->driver = driver;
      TAILQ_INSERT_TAIL(&dc->drivers, dl, link);
      driver->refs++;         /* XXX: kobj_mtx */

      /*
       * Call BUS_DRIVER_ADDED for any existing busses in this class.
       */
      for (i = 0; i < dc->maxunit; i++)
            if (dc->devices[i])
                  BUS_DRIVER_ADDED(dc->devices[i], driver);

      bus_data_generation_update();
      return (0);
}

/**
 * @brief Delete a device driver from a device class
 *
 * Delete a device driver from a devclass. This is normally called
 * automatically by DRIVER_MODULE().
 *
 * If the driver is currently attached to any devices,
 * devclass_delete_driver() will first attempt to detach from each
 * device. If one of the detach calls fails, the driver will not be
 * deleted.
 *
 * @param dc            the devclass to edit
 * @param driver  the driver to unregister
 */
int
devclass_delete_driver(devclass_t busclass, driver_t *driver)
{
      devclass_t dc = devclass_find(driver->name);
      driverlink_t dl;
      device_t dev;
      int i;
      int error;

      PDEBUG(("%s from devclass %s", driver->name, DEVCLANAME(busclass)));

      if (!dc)
            return (0);

      /*
       * Find the link structure in the bus' list of drivers.
       */
      TAILQ_FOREACH(dl, &busclass->drivers, link) {
            if (dl->driver == driver)
                  break;
      }

      if (!dl) {
            PDEBUG(("%s not found in %s list", driver->name,
                busclass->name));
            return (ENOENT);
      }

      /*
       * Disassociate from any devices.  We iterate through all the
       * devices in the devclass of the driver and detach any which are
       * using the driver and which have a parent in the devclass which
       * we are deleting from.
       *
       * Note that since a driver can be in multiple devclasses, we
       * should not detach devices which are not children of devices in
       * the affected devclass.
       */
      for (i = 0; i < dc->maxunit; i++) {
            if (dc->devices[i]) {
                  dev = dc->devices[i];
                  if (dev->driver == driver && dev->parent &&
                      dev->parent->devclass == busclass) {
                        if ((error = device_detach(dev)) != 0)
                              return (error);
                        device_set_driver(dev, NULL);
                  }
            }
      }

      TAILQ_REMOVE(&busclass->drivers, dl, link);
      free(dl, M_BUS);

      /* XXX: kobj_mtx */
      driver->refs--;
      if (driver->refs == 0)
            kobj_class_free((kobj_class_t) driver);

      bus_data_generation_update();
      return (0);
}

/**
 * @brief Quiesces a set of device drivers from a device class
 *
 * Quiesce a device driver from a devclass. This is normally called
 * automatically by DRIVER_MODULE().
 *
 * If the driver is currently attached to any devices,
 * devclass_quiesece_driver() will first attempt to quiesce each
 * device.
 *
 * @param dc            the devclass to edit
 * @param driver  the driver to unregister
 */
int
devclass_quiesce_driver(devclass_t busclass, driver_t *driver)
{
      devclass_t dc = devclass_find(driver->name);
      driverlink_t dl;
      device_t dev;
      int i;
      int error;

      PDEBUG(("%s from devclass %s", driver->name, DEVCLANAME(busclass)));

      if (!dc)
            return (0);

      /*
       * Find the link structure in the bus' list of drivers.
       */
      TAILQ_FOREACH(dl, &busclass->drivers, link) {
            if (dl->driver == driver)
                  break;
      }

      if (!dl) {
            PDEBUG(("%s not found in %s list", driver->name,
                busclass->name));
            return (ENOENT);
      }

      /*
       * Quiesce all devices.  We iterate through all the devices in
       * the devclass of the driver and quiesce any which are using
       * the driver and which have a parent in the devclass which we
       * are quiescing.
       *
       * Note that since a driver can be in multiple devclasses, we
       * should not quiesce devices which are not children of
       * devices in the affected devclass.
       */
      for (i = 0; i < dc->maxunit; i++) {
            if (dc->devices[i]) {
                  dev = dc->devices[i];
                  if (dev->driver == driver && dev->parent &&
                      dev->parent->devclass == busclass) {
                        if ((error = device_quiesce(dev)) != 0)
                              return (error);
                  }
            }
      }

      return (0);
}

/**
 * @internal
 */
static driverlink_t
devclass_find_driver_internal(devclass_t dc, const char *classname)
{
      driverlink_t dl;

      PDEBUG(("%s in devclass %s", classname, DEVCLANAME(dc)));

      TAILQ_FOREACH(dl, &dc->drivers, link) {
            if (!strcmp(dl->driver->name, classname))
                  return (dl);
      }

      PDEBUG(("not found"));
      return (NULL);
}

/**
 * @brief Search a devclass for a driver
 *
 * This function searches the devclass's list of drivers and returns
 * the first driver whose name is @p classname or @c NULL if there is
 * no driver of that name.
 *
 * @param dc            the devclass to search
 * @param classname     the driver name to search for
 */
kobj_class_t
devclass_find_driver(devclass_t dc, const char *classname)
{
      driverlink_t dl;

      dl = devclass_find_driver_internal(dc, classname);
      if (dl)
            return (dl->driver);
      return (NULL);
}

/**
 * @brief Return the name of the devclass
 */
const char *
devclass_get_name(devclass_t dc)
{
      return (dc->name);
}

/**
 * @brief Find a device given a unit number
 *
 * @param dc            the devclass to search
 * @param unit          the unit number to search for
 * 
 * @returns       the device with the given unit number or @c
 *                NULL if there is no such device
 */
device_t
devclass_get_device(devclass_t dc, int unit)
{
      if (dc == NULL || unit < 0 || unit >= dc->maxunit)
            return (NULL);
      return (dc->devices[unit]);
}

/**
 * @brief Find the softc field of a device given a unit number
 *
 * @param dc            the devclass to search
 * @param unit          the unit number to search for
 * 
 * @returns       the softc field of the device with the given
 *                unit number or @c NULL if there is no such
 *                device
 */
void *
devclass_get_softc(devclass_t dc, int unit)
{
      device_t dev;

      dev = devclass_get_device(dc, unit);
      if (!dev)
            return (NULL);

      return (device_get_softc(dev));
}

/**
 * @brief Get a list of devices in the devclass
 *
 * An array containing a list of all the devices in the given devclass
 * is allocated and returned in @p *devlistp. The number of devices
 * in the array is returned in @p *devcountp. The caller should free
 * the array using @c free(p, M_TEMP), even if @p *devcountp is 0.
 *
 * @param dc            the devclass to examine
 * @param devlistp      points at location for array pointer return
 *                value
 * @param devcountp     points at location for array size return value
 *
 * @retval 0            success
 * @retval ENOMEM the array allocation failed
 */
int
devclass_get_devices(devclass_t dc, device_t **devlistp, int *devcountp)
{
      int count, i;
      device_t *list;

      count = devclass_get_count(dc);
      list = malloc(count * sizeof(device_t), M_TEMP, M_NOWAIT|M_ZERO);
      if (!list)
            return (ENOMEM);

      count = 0;
      for (i = 0; i < dc->maxunit; i++) {
            if (dc->devices[i]) {
                  list[count] = dc->devices[i];
                  count++;
            }
      }

      *devlistp = list;
      *devcountp = count;

      return (0);
}

/**
 * @brief Get a list of drivers in the devclass
 *
 * An array containing a list of pointers to all the drivers in the
 * given devclass is allocated and returned in @p *listp.  The number
 * of drivers in the array is returned in @p *countp. The caller should
 * free the array using @c free(p, M_TEMP).
 *
 * @param dc            the devclass to examine
 * @param listp         gives location for array pointer return value
 * @param countp  gives location for number of array elements
 *                return value
 *
 * @retval 0            success
 * @retval ENOMEM the array allocation failed
 */
int
devclass_get_drivers(devclass_t dc, driver_t ***listp, int *countp)
{
      driverlink_t dl;
      driver_t **list;
      int count;

      count = 0;
      TAILQ_FOREACH(dl, &dc->drivers, link)
            count++;
      list = malloc(count * sizeof(driver_t *), M_TEMP, M_NOWAIT);
      if (list == NULL)
            return (ENOMEM);

      count = 0;
      TAILQ_FOREACH(dl, &dc->drivers, link) {
            list[count] = dl->driver;
            count++;
      }
      *listp = list;
      *countp = count;

      return (0);
}

/**
 * @brief Get the number of devices in a devclass
 *
 * @param dc            the devclass to examine
 */
int
devclass_get_count(devclass_t dc)
{
      int count, i;

      count = 0;
      for (i = 0; i < dc->maxunit; i++)
            if (dc->devices[i])
                  count++;
      return (count);
}

/**
 * @brief Get the maximum unit number used in a devclass
 *
 * Note that this is one greater than the highest currently-allocated
 * unit.
 *
 * @param dc            the devclass to examine
 */
int
devclass_get_maxunit(devclass_t dc)
{
      return (dc->maxunit);
}

/**
 * @brief Find a free unit number in a devclass
 *
 * This function searches for the first unused unit number greater
 * that or equal to @p unit.
 *
 * @param dc            the devclass to examine
 * @param unit          the first unit number to check
 */
int
devclass_find_free_unit(devclass_t dc, int unit)
{
      if (dc == NULL)
            return (unit);
      while (unit < dc->maxunit && dc->devices[unit] != NULL)
            unit++;
      return (unit);
}

/**
 * @brief Set the parent of a devclass
 *
 * The parent class is normally initialised automatically by
 * DRIVER_MODULE().
 *
 * @param dc            the devclass to edit
 * @param pdc           the new parent devclass
 */
void
devclass_set_parent(devclass_t dc, devclass_t pdc)
{
      dc->parent = pdc;
}

/**
 * @brief Get the parent of a devclass
 *
 * @param dc            the devclass to examine
 */
devclass_t
devclass_get_parent(devclass_t dc)
{
      return (dc->parent);
}

struct sysctl_ctx_list *
devclass_get_sysctl_ctx(devclass_t dc)
{
      return (&dc->sysctl_ctx);
}

struct sysctl_oid *
devclass_get_sysctl_tree(devclass_t dc)
{
      return (dc->sysctl_tree);
}

/**
 * @internal
 * @brief Allocate a unit number
 *
 * On entry, @p *unitp is the desired unit number (or @c -1 if any
 * will do). The allocated unit number is returned in @p *unitp.

 * @param dc            the devclass to allocate from
 * @param unitp         points at the location for the allocated unit
 *                number
 *
 * @retval 0            success
 * @retval EEXIST the requested unit number is already allocated
 * @retval ENOMEM memory allocation failure
 */
static int
devclass_alloc_unit(devclass_t dc, int *unitp)
{
      int unit = *unitp;

      PDEBUG(("unit %d in devclass %s", unit, DEVCLANAME(dc)));

      /* If we were given a wired unit number, check for existing device */
      /* XXX imp XXX */
      if (unit != -1) {
            if (unit >= 0 && unit < dc->maxunit &&
                dc->devices[unit] != NULL) {
                  if (bootverbose)
                        printf("%s: %s%d already exists; skipping it\n",
                            dc->name, dc->name, *unitp);
                  return (EEXIST);
            }
      } else {
            /* Unwired device, find the next available slot for it */
            unit = 0;
            while (unit < dc->maxunit && dc->devices[unit] != NULL)
                  unit++;
      }

      /*
       * We've selected a unit beyond the length of the table, so let's
       * extend the table to make room for all units up to and including
       * this one.
       */
      if (unit >= dc->maxunit) {
            device_t *newlist;
            int newsize;

            newsize = roundup((unit + 1), MINALLOCSIZE / sizeof(device_t));
            newlist = malloc(sizeof(device_t) * newsize, M_BUS, M_NOWAIT);
            if (!newlist)
                  return (ENOMEM);
            bcopy(dc->devices, newlist, sizeof(device_t) * dc->maxunit);
            bzero(newlist + dc->maxunit,
                sizeof(device_t) * (newsize - dc->maxunit));
            if (dc->devices)
                  free(dc->devices, M_BUS);
            dc->devices = newlist;
            dc->maxunit = newsize;
      }
      PDEBUG(("now: unit %d in devclass %s", unit, DEVCLANAME(dc)));

      *unitp = unit;
      return (0);
}

/**
 * @internal
 * @brief Add a device to a devclass
 *
 * A unit number is allocated for the device (using the device's
 * preferred unit number if any) and the device is registered in the
 * devclass. This allows the device to be looked up by its unit
 * number, e.g. by decoding a dev_t minor number.
 *
 * @param dc            the devclass to add to
 * @param dev           the device to add
 *
 * @retval 0            success
 * @retval EEXIST the requested unit number is already allocated
 * @retval ENOMEM memory allocation failure
 */
static int
devclass_add_device(devclass_t dc, device_t dev)
{
      int buflen, error;

      PDEBUG(("%s in devclass %s", DEVICENAME(dev), DEVCLANAME(dc)));

      buflen = snprintf(NULL, 0, "%s%d$", dc->name, dev->unit);
      if (buflen < 0)
            return (ENOMEM);
      dev->nameunit = malloc(buflen, M_BUS, M_NOWAIT|M_ZERO);
      if (!dev->nameunit)
            return (ENOMEM);

      if ((error = devclass_alloc_unit(dc, &dev->unit)) != 0) {
            free(dev->nameunit, M_BUS);
            dev->nameunit = NULL;
            return (error);
      }
      dc->devices[dev->unit] = dev;
      dev->devclass = dc;
      snprintf(dev->nameunit, buflen, "%s%d", dc->name, dev->unit);

      return (0);
}

/**
 * @internal
 * @brief Delete a device from a devclass
 *
 * The device is removed from the devclass's device list and its unit
 * number is freed.

 * @param dc            the devclass to delete from
 * @param dev           the device to delete
 *
 * @retval 0            success
 */
static int
devclass_delete_device(devclass_t dc, device_t dev)
{
      if (!dc || !dev)
            return (0);

      PDEBUG(("%s in devclass %s", DEVICENAME(dev), DEVCLANAME(dc)));

      if (dev->devclass != dc || dc->devices[dev->unit] != dev)
            panic("devclass_delete_device: inconsistent device class");
      dc->devices[dev->unit] = NULL;
      if (dev->flags & DF_WILDCARD)
            dev->unit = -1;
      dev->devclass = NULL;
      free(dev->nameunit, M_BUS);
      dev->nameunit = NULL;

      return (0);
}

/**
 * @internal
 * @brief Make a new device and add it as a child of @p parent
 *
 * @param parent  the parent of the new device
 * @param name          the devclass name of the new device or @c NULL
 *                to leave the devclass unspecified
 * @parem unit          the unit number of the new device of @c -1 to
 *                leave the unit number unspecified
 *
 * @returns the new device
 */
static device_t
make_device(device_t parent, const char *name, int unit)
{
      device_t dev;
      devclass_t dc;

      PDEBUG(("%s at %s as unit %d", name, DEVICENAME(parent), unit));

      if (name) {
            dc = devclass_find_internal(name, 0, TRUE);
            if (!dc) {
                  printf("make_device: can't find device class %s\n",
                      name);
                  return (NULL);
            }
      } else {
            dc = NULL;
      }

      dev = malloc(sizeof(struct device), M_BUS, M_NOWAIT|M_ZERO);
      if (!dev)
            return (NULL);

      dev->parent = parent;
      TAILQ_INIT(&dev->children);
      kobj_init((kobj_t) dev, &null_class);
      dev->driver = NULL;
      dev->devclass = NULL;
      dev->unit = unit;
      dev->nameunit = NULL;
      dev->desc = NULL;
      dev->busy = 0;
      dev->devflags = 0;
      dev->flags = DF_ENABLED;
      dev->order = 0;
      if (unit == -1)
            dev->flags |= DF_WILDCARD;
      if (name) {
            dev->flags |= DF_FIXEDCLASS;
            if (devclass_add_device(dc, dev)) {
                  kobj_delete((kobj_t) dev, M_BUS);
                  return (NULL);
            }
      }
      dev->ivars = NULL;
      dev->softc = NULL;

      dev->state = DS_NOTPRESENT;

      TAILQ_INSERT_TAIL(&bus_data_devices, dev, devlink);
      bus_data_generation_update();

      return (dev);
}

/**
 * @internal
 * @brief Print a description of a device.
 */
static int
device_print_child(device_t dev, device_t child)
{
      int retval = 0;

      if (device_is_alive(child))
            retval += BUS_PRINT_CHILD(dev, child);
      else
            retval += device_printf(child, " not found\n");

      return (retval);
}

/**
 * @brief Create a new device
 *
 * This creates a new device and adds it as a child of an existing
 * parent device. The new device will be added after the last existing
 * child with order zero.
 * 
 * @param dev           the device which will be the parent of the
 *                new child device
 * @param name          devclass name for new device or @c NULL if not
 *                specified
 * @param unit          unit number for new device or @c -1 if not
 *                specified
 * 
 * @returns       the new device
 */
device_t
device_add_child(device_t dev, const char *name, int unit)
{
      return (device_add_child_ordered(dev, 0, name, unit));
}

/**
 * @brief Create a new device
 *
 * This creates a new device and adds it as a child of an existing
 * parent device. The new device will be added after the last existing
 * child with the same order.
 * 
 * @param dev           the device which will be the parent of the
 *                new child device
 * @param order         a value which is used to partially sort the
 *                children of @p dev - devices created using
 *                lower values of @p order appear first in @p
 *                dev's list of children
 * @param name          devclass name for new device or @c NULL if not
 *                specified
 * @param unit          unit number for new device or @c -1 if not
 *                specified
 * 
 * @returns       the new device
 */
device_t
device_add_child_ordered(device_t dev, int order, const char *name, int unit)
{
      device_t child;
      device_t place;

      PDEBUG(("%s at %s with order %d as unit %d",
          name, DEVICENAME(dev), order, unit));

      child = make_device(dev, name, unit);
      if (child == NULL)
            return (child);
      child->order = order;

      TAILQ_FOREACH(place, &dev->children, link) {
            if (place->order > order)
                  break;
      }

      if (place) {
            /*
             * The device 'place' is the first device whose order is
             * greater than the new child.
             */
            TAILQ_INSERT_BEFORE(place, child, link);
      } else {
            /*
             * The new child's order is greater or equal to the order of
             * any existing device. Add the child to the tail of the list.
             */
            TAILQ_INSERT_TAIL(&dev->children, child, link);
      }

      bus_data_generation_update();
      return (child);
}

/**
 * @brief Delete a device
 *
 * This function deletes a device along with all of its children. If
 * the device currently has a driver attached to it, the device is
 * detached first using device_detach().
 * 
 * @param dev           the parent device
 * @param child         the device to delete
 *
 * @retval 0            success
 * @retval non-zero     a unit error code describing the error
 */
int
device_delete_child(device_t dev, device_t child)
{
      int error;
      device_t grandchild;

      PDEBUG(("%s from %s", DEVICENAME(child), DEVICENAME(dev)));

      /* remove children first */
      while ( (grandchild = TAILQ_FIRST(&child->children)) ) {
            error = device_delete_child(child, grandchild);
            if (error)
                  return (error);
      }

      if ((error = device_detach(child)) != 0)
            return (error);
      if (child->devclass)
            devclass_delete_device(child->devclass, child);
      TAILQ_REMOVE(&dev->children, child, link);
      TAILQ_REMOVE(&bus_data_devices, child, devlink);
      kobj_delete((kobj_t) child, M_BUS);

      bus_data_generation_update();
      return (0);
}

/**
 * @brief Find a device given a unit number
 *
 * This is similar to devclass_get_devices() but only searches for
 * devices which have @p dev as a parent.
 *
 * @param dev           the parent device to search
 * @param unit          the unit number to search for.  If the unit is -1,
 *                return the first child of @p dev which has name
 *                @p classname (that is, the one with the lowest unit.)
 *
 * @returns       the device with the given unit number or @c
 *                NULL if there is no such device
 */
device_t
device_find_child(device_t dev, const char *classname, int unit)
{
      devclass_t dc;
      device_t child;

      dc = devclass_find(classname);
      if (!dc)
            return (NULL);

      if (unit != -1) {
            child = devclass_get_device(dc, unit);
            if (child && child->parent == dev)
                  return (child);
      } else {
            for (unit = 0; unit < devclass_get_maxunit(dc); unit++) {
                  child = devclass_get_device(dc, unit);
                  if (child && child->parent == dev)
                        return (child);
            }
      }
      return (NULL);
}

/**
 * @internal
 */
static driverlink_t
first_matching_driver(devclass_t dc, device_t dev)
{
      if (dev->devclass)
            return (devclass_find_driver_internal(dc, dev->devclass->name));
      return (TAILQ_FIRST(&dc->drivers));
}

/**
 * @internal
 */
static driverlink_t
next_matching_driver(devclass_t dc, device_t dev, driverlink_t last)
{
      if (dev->devclass) {
            driverlink_t dl;
            for (dl = TAILQ_NEXT(last, link); dl; dl = TAILQ_NEXT(dl, link))
                  if (!strcmp(dev->devclass->name, dl->driver->name))
                        return (dl);
            return (NULL);
      }
      return (TAILQ_NEXT(last, link));
}

/**
 * @internal
 */
static int
device_probe_child(device_t dev, device_t child)
{
      devclass_t dc;
      driverlink_t best = 0;
      driverlink_t dl;
      int result, pri = 0;
      int hasclass = (child->devclass != 0);

      GIANT_REQUIRED;

      dc = dev->devclass;
      if (!dc)
            panic("device_probe_child: parent device has no devclass");

      /*
       * If the state is already probed, then return.  However, don't
       * return if we can rebid this object.
       */
      if (child->state == DS_ALIVE && (child->flags & DF_REBID) == 0)
            return (0);

      for (; dc; dc = dc->parent) {
            for (dl = first_matching_driver(dc, child);
                 dl;
                 dl = next_matching_driver(dc, child, dl)) {
                  PDEBUG(("Trying %s", DRIVERNAME(dl->driver)));
                  device_set_driver(child, dl->driver);
                  if (!hasclass)
                        device_set_devclass(child, dl->driver->name);

                  /* Fetch any flags for the device before probing. */
                  resource_int_value(dl->driver->name, child->unit,
                      "flags", &child->devflags);

                  result = DEVICE_PROBE(child);

                  /* Reset flags and devclass before the next probe. */
                  child->devflags = 0;
                  if (!hasclass)
                        device_set_devclass(child, 0);

                  /*
                   * If the driver returns SUCCESS, there can be
                   * no higher match for this device.
                   */
                  if (result == 0) {
                        best = dl;
                        pri = 0;
                        break;
                  }

                  /*
                   * The driver returned an error so it
                   * certainly doesn't match.
                   */
                  if (result > 0) {
                        device_set_driver(child, 0);
                        continue;
                  }

                  /*
                   * A priority lower than SUCCESS, remember the
                   * best matching driver. Initialise the value
                   * of pri for the first match.
                   */
                  if (best == 0 || result > pri) {
                        best = dl;
                        pri = result;
                        continue;
                  }
            }
            /*
             * If we have an unambiguous match in this devclass,
             * don't look in the parent.
             */
            if (best && pri == 0)
                  break;
      }

      /*
       * If we found a driver, change state and initialise the devclass.
       */
      /* XXX What happens if we rebid and got no best? */
      if (best) {
            /*
             * If this device was atached, and we were asked to
             * rescan, and it is a different driver, then we have
             * to detach the old driver and reattach this new one.
             * Note, we don't have to check for DF_REBID here
             * because if the state is > DS_ALIVE, we know it must
             * be.
             *
             * This assumes that all DF_REBID drivers can have
             * their probe routine called at any time and that
             * they are idempotent as well as completely benign in
             * normal operations.
             *
             * We also have to make sure that the detach
             * succeeded, otherwise we fail the operation (or
             * maybe it should just fail silently?  I'm torn).
             */
            if (child->state > DS_ALIVE && best->driver != child->driver)
                  if ((result = device_detach(dev)) != 0)
                        return (result);

            /* Set the winning driver, devclass, and flags. */
            if (!child->devclass)
                  device_set_devclass(child, best->driver->name);
            device_set_driver(child, best->driver);
            resource_int_value(best->driver->name, child->unit,
                "flags", &child->devflags);

            if (pri < 0) {
                  /*
                   * A bit bogus. Call the probe method again to make
                   * sure that we have the right description.
                   */
                  DEVICE_PROBE(child);
#if 0
                  child->flags |= DF_REBID;
#endif
            } else
                  child->flags &= ~DF_REBID;
            child->state = DS_ALIVE;

            bus_data_generation_update();
            return (0);
      }

      return (ENXIO);
}

/**
 * @brief Return the parent of a device
 */
device_t
device_get_parent(device_t dev)
{
      return (dev->parent);
}

/**
 * @brief Get a list of children of a device
 *
 * An array containing a list of all the children of the given device
 * is allocated and returned in @p *devlistp. The number of devices
 * in the array is returned in @p *devcountp. The caller should free
 * the array using @c free(p, M_TEMP).
 *
 * @param dev           the device to examine
 * @param devlistp      points at location for array pointer return
 *                value
 * @param devcountp     points at location for array size return value
 *
 * @retval 0            success
 * @retval ENOMEM the array allocation failed
 */
int
device_get_children(device_t dev, device_t **devlistp, int *devcountp)
{
      int count;
      device_t child;
      device_t *list;

      count = 0;
      TAILQ_FOREACH(child, &dev->children, link) {
            count++;
      }

      list = malloc(count * sizeof(device_t), M_TEMP, M_NOWAIT|M_ZERO);
      if (!list)
            return (ENOMEM);

      count = 0;
      TAILQ_FOREACH(child, &dev->children, link) {
            list[count] = child;
            count++;
      }

      *devlistp = list;
      *devcountp = count;

      return (0);
}

/**
 * @brief Return the current driver for the device or @c NULL if there
 * is no driver currently attached
 */
driver_t *
device_get_driver(device_t dev)
{
      return (dev->driver);
}

/**
 * @brief Return the current devclass for the device or @c NULL if
 * there is none.
 */
devclass_t
device_get_devclass(device_t dev)
{
      return (dev->devclass);
}

/**
 * @brief Return the name of the device's devclass or @c NULL if there
 * is none.
 */
const char *
device_get_name(device_t dev)
{
      if (dev != NULL && dev->devclass)
            return (devclass_get_name(dev->devclass));
      return (NULL);
}

/**
 * @brief Return a string containing the device's devclass name
 * followed by an ascii representation of the device's unit number
 * (e.g. @c "foo2").
 */
const char *
device_get_nameunit(device_t dev)
{
      return (dev->nameunit);
}

/**
 * @brief Return the device's unit number.
 */
int
device_get_unit(device_t dev)
{
      return (dev->unit);
}

/**
 * @brief Return the device's description string
 */
const char *
device_get_desc(device_t dev)
{
      return (dev->desc);
}

/**
 * @brief Return the device's flags
 */
u_int32_t
device_get_flags(device_t dev)
{
      return (dev->devflags);
}

struct sysctl_ctx_list *
device_get_sysctl_ctx(device_t dev)
{
      return (&dev->sysctl_ctx);
}

struct sysctl_oid *
device_get_sysctl_tree(device_t dev)
{
      return (dev->sysctl_tree);
}

/**
 * @brief Print the name of the device followed by a colon and a space
 *
 * @returns the number of characters printed
 */
int
device_print_prettyname(device_t dev)
{
      const char *name = device_get_name(dev);

      if (name == 0)
            return (printf("unknown: "));
      return (printf("%s%d: ", name, device_get_unit(dev)));
}

/**
 * @brief Print the name of the device followed by a colon, a space
 * and the result of calling vprintf() with the value of @p fmt and
 * the following arguments.
 *
 * @returns the number of characters printed
 */
int
device_printf(device_t dev, const char * fmt, ...)
{
      va_list ap;
      int retval;

      retval = device_print_prettyname(dev);
      va_start(ap, fmt);
      retval += vprintf(fmt, ap);
      va_end(ap);
      return (retval);
}

/**
 * @internal
 */
static void
device_set_desc_internal(device_t dev, const char* desc, int copy)
{
      if (dev->desc && (dev->flags & DF_DESCMALLOCED)) {
            free(dev->desc, M_BUS);
            dev->flags &= ~DF_DESCMALLOCED;
            dev->desc = NULL;
      }

      if (copy && desc) {
            dev->desc = malloc(strlen(desc) + 1, M_BUS, M_NOWAIT);
            if (dev->desc) {
                  strcpy(dev->desc, desc);
                  dev->flags |= DF_DESCMALLOCED;
            }
      } else {
            /* Avoid a -Wcast-qual warning */
            dev->desc = (char *)(uintptr_t) desc;
      }

      bus_data_generation_update();
}

/**
 * @brief Set the device's description
 *
 * The value of @c desc should be a string constant that will not
 * change (at least until the description is changed in a subsequent
 * call to device_set_desc() or device_set_desc_copy()).
 */
void
device_set_desc(device_t dev, const char* desc)
{
      device_set_desc_internal(dev, desc, FALSE);
}

/**
 * @brief Set the device's description
 *
 * The string pointed to by @c desc is copied. Use this function if
 * the device description is generated, (e.g. with sprintf()).
 */
void
device_set_desc_copy(device_t dev, const char* desc)
{
      device_set_desc_internal(dev, desc, TRUE);
}

/**
 * @brief Set the device's flags
 */
void
device_set_flags(device_t dev, u_int32_t flags)
{
      dev->devflags = flags;
}

/**
 * @brief Return the device's softc field
 *
 * The softc is allocated and zeroed when a driver is attached, based
 * on the size field of the driver.
 */
void *
device_get_softc(device_t dev)
{
      return (dev->softc);
}

/**
 * @brief Set the device's softc field
 *
 * Most drivers do not need to use this since the softc is allocated
 * automatically when the driver is attached.
 */
void
device_set_softc(device_t dev, void *softc)
{
      if (dev->softc && !(dev->flags & DF_EXTERNALSOFTC))
            free(dev->softc, M_BUS_SC);
      dev->softc = softc;
      if (dev->softc)
            dev->flags |= DF_EXTERNALSOFTC;
      else
            dev->flags &= ~DF_EXTERNALSOFTC;
}

/**
 * @brief Get the device's ivars field
 *
 * The ivars field is used by the parent device to store per-device
 * state (e.g. the physical location of the device or a list of
 * resources).
 */
void *
device_get_ivars(device_t dev)
{

      KASSERT(dev != NULL, ("device_get_ivars(NULL, ...)"));
      return (dev->ivars);
}

/**
 * @brief Set the device's ivars field
 */
void
device_set_ivars(device_t dev, void * ivars)
{

      KASSERT(dev != NULL, ("device_set_ivars(NULL, ...)"));
      dev->ivars = ivars;
}

/**
 * @brief Return the device's state
 */
device_state_t
device_get_state(device_t dev)
{
      return (dev->state);
}

/**
 * @brief Set the DF_ENABLED flag for the device
 */
void
device_enable(device_t dev)
{
      dev->flags |= DF_ENABLED;
}

/**
 * @brief Clear the DF_ENABLED flag for the device
 */
void
device_disable(device_t dev)
{
      dev->flags &= ~DF_ENABLED;
}

/**
 * @brief Increment the busy counter for the device
 */
void
device_busy(device_t dev)
{
      if (dev->state < DS_ATTACHED)
            panic("device_busy: called for unattached device");
      if (dev->busy == 0 && dev->parent)
            device_busy(dev->parent);
      dev->busy++;
      dev->state = DS_BUSY;
}

/**
 * @brief Decrement the busy counter for the device
 */
void
device_unbusy(device_t dev)
{
      if (dev->state != DS_BUSY)
            panic("device_unbusy: called for non-busy device %s",
                device_get_nameunit(dev));
      dev->busy--;
      if (dev->busy == 0) {
            if (dev->parent)
                  device_unbusy(dev->parent);
            dev->state = DS_ATTACHED;
      }
}

/**
 * @brief Set the DF_QUIET flag for the device
 */
void
device_quiet(device_t dev)
{
      dev->flags |= DF_QUIET;
}

/**
 * @brief Clear the DF_QUIET flag for the device
 */
void
device_verbose(device_t dev)
{
      dev->flags &= ~DF_QUIET;
}

/**
 * @brief Return non-zero if the DF_QUIET flag is set on the device
 */
int
device_is_quiet(device_t dev)
{
      return ((dev->flags & DF_QUIET) != 0);
}

/**
 * @brief Return non-zero if the DF_ENABLED flag is set on the device
 */
int
device_is_enabled(device_t dev)
{
      return ((dev->flags & DF_ENABLED) != 0);
}

/**
 * @brief Return non-zero if the device was successfully probed
 */
int
device_is_alive(device_t dev)
{
      return (dev->state >= DS_ALIVE);
}

/**
 * @brief Return non-zero if the device currently has a driver
 * attached to it
 */
int
device_is_attached(device_t dev)
{
      return (dev->state >= DS_ATTACHED);
}

/**
 * @brief Set the devclass of a device
 * @see devclass_add_device().
 */
int
device_set_devclass(device_t dev, const char *classname)
{
      devclass_t dc;
      int error;

      if (!classname) {
            if (dev->devclass)
                  devclass_delete_device(dev->devclass, dev);
            return (0);
      }

      if (dev->devclass) {
            printf("device_set_devclass: device class already set\n");
            return (EINVAL);
      }

      dc = devclass_find_internal(classname, 0, TRUE);
      if (!dc)
            return (ENOMEM);

      error = devclass_add_device(dc, dev);

      bus_data_generation_update();
      return (error);
}

/**
 * @brief Set the driver of a device
 *
 * @retval 0            success
 * @retval EBUSY  the device already has a driver attached
 * @retval ENOMEM a memory allocation failure occurred
 */
int
device_set_driver(device_t dev, driver_t *driver)
{
      if (dev->state >= DS_ATTACHED)
            return (EBUSY);

      if (dev->driver == driver)
            return (0);

      if (dev->softc && !(dev->flags & DF_EXTERNALSOFTC)) {
            free(dev->softc, M_BUS_SC);
            dev->softc = NULL;
      }
      kobj_delete((kobj_t) dev, 0);
      dev->driver = driver;
      if (driver) {
            kobj_init((kobj_t) dev, (kobj_class_t) driver);
            if (!(dev->flags & DF_EXTERNALSOFTC) && driver->size > 0) {
                  dev->softc = malloc(driver->size, M_BUS_SC,
                      M_NOWAIT | M_ZERO);
                  if (!dev->softc) {
                        kobj_delete((kobj_t) dev, 0);
                        kobj_init((kobj_t) dev, &null_class);
                        dev->driver = NULL;
                        return (ENOMEM);
                  }
            }
      } else {
            kobj_init((kobj_t) dev, &null_class);
      }

      bus_data_generation_update();
      return (0);
}

/**
 * @brief Probe a device and attach a driver if possible
 *
 * This function is the core of the device autoconfiguration
 * system. Its purpose is to select a suitable driver for a device and
 * then call that driver to initialise the hardware appropriately. The
 * driver is selected by calling the DEVICE_PROBE() method of a set of
 * candidate drivers and then choosing the driver which returned the
 * best value. This driver is then attached to the device using
 * device_attach().
 *
 * The set of suitable drivers is taken from the list of drivers in
 * the parent device's devclass. If the device was originally created
 * with a specific class name (see device_add_child()), only drivers
 * with that name are probed, otherwise all drivers in the devclass
 * are probed. If no drivers return successful probe values in the
 * parent devclass, the search continues in the parent of that
 * devclass (see devclass_get_parent()) if any.
 *
 * @param dev           the device to initialise
 *
 * @retval 0            success
 * @retval ENXIO  no driver was found
 * @retval ENOMEM memory allocation failure
 * @retval non-zero     some other unix error code
 */
int
device_probe_and_attach(device_t dev)
{
      int error;

      GIANT_REQUIRED;

      if (dev->state >= DS_ALIVE && (dev->flags & DF_REBID) == 0)
            return (0);

      if (!(dev->flags & DF_ENABLED)) {
            if (bootverbose && device_get_name(dev) != NULL) {
                  device_print_prettyname(dev);
                  printf("not probed (disabled)\n");
            }
            return (0);
      }
      if ((error = device_probe_child(dev->parent, dev)) != 0) {
            if (!(dev->flags & DF_DONENOMATCH)) {
                  BUS_PROBE_NOMATCH(dev->parent, dev);
                  devnomatch(dev);
                  dev->flags |= DF_DONENOMATCH;
            }
            return (error);
      }
      error = device_attach(dev);

      return (error);
}

/**
 * @brief Attach a device driver to a device
 *
 * This function is a wrapper around the DEVICE_ATTACH() driver
 * method. In addition to calling DEVICE_ATTACH(), it initialises the
 * device's sysctl tree, optionally prints a description of the device
 * and queues a notification event for user-based device management
 * services.
 *
 * Normally this function is only called internally from
 * device_probe_and_attach().
 *
 * @param dev           the device to initialise
 *
 * @retval 0            success
 * @retval ENXIO  no driver was found
 * @retval ENOMEM memory allocation failure
 * @retval non-zero     some other unix error code
 */
int
device_attach(device_t dev)
{
      int error;

      device_sysctl_init(dev);
      if (!device_is_quiet(dev))
            device_print_child(dev->parent, dev);
      if ((error = DEVICE_ATTACH(dev)) != 0) {
            printf("device_attach: %s%d attach returned %d\n",
                dev->driver->name, dev->unit, error);
            /* Unset the class; set in device_probe_child */
            if (dev->devclass == 0)
                  device_set_devclass(dev, 0);
            device_set_driver(dev, NULL);
            device_sysctl_fini(dev);
            dev->state = DS_NOTPRESENT;
            return (error);
      }
      dev->state = DS_ATTACHED;
      devadded(dev);
      return (0);
}

/**
 * @brief Detach a driver from a device
 *
 * This function is a wrapper around the DEVICE_DETACH() driver
 * method. If the call to DEVICE_DETACH() succeeds, it calls
 * BUS_CHILD_DETACHED() for the parent of @p dev, queues a
 * notification event for user-based device management services and
 * cleans up the device's sysctl tree.
 *
 * @param dev           the device to un-initialise
 *
 * @retval 0            success
 * @retval ENXIO  no driver was found
 * @retval ENOMEM memory allocation failure
 * @retval non-zero     some other unix error code
 */
int
device_detach(device_t dev)
{
      int error;

      GIANT_REQUIRED;

      PDEBUG(("%s", DEVICENAME(dev)));
      if (dev->state == DS_BUSY)
            return (EBUSY);
      if (dev->state != DS_ATTACHED)
            return (0);

      if ((error = DEVICE_DETACH(dev)) != 0)
            return (error);
      devremoved(dev);
      device_printf(dev, "detached\n");
      if (dev->parent)
            BUS_CHILD_DETACHED(dev->parent, dev);

      if (!(dev->flags & DF_FIXEDCLASS))
            devclass_delete_device(dev->devclass, dev);

      dev->state = DS_NOTPRESENT;
      device_set_driver(dev, NULL);
      device_set_desc(dev, NULL);
      device_sysctl_fini(dev);

      return (0);
}

/**
 * @brief Tells a driver to quiesce itself.
 *
 * This function is a wrapper around the DEVICE_QUIESCE() driver
 * method. If the call to DEVICE_QUIESCE() succeeds.
 *
 * @param dev           the device to quiesce
 *
 * @retval 0            success
 * @retval ENXIO  no driver was found
 * @retval ENOMEM memory allocation failure
 * @retval non-zero     some other unix error code
 */
int
device_quiesce(device_t dev)
{

      PDEBUG(("%s", DEVICENAME(dev)));
      if (dev->state == DS_BUSY)
            return (EBUSY);
      if (dev->state != DS_ATTACHED)
            return (0);

      return (DEVICE_QUIESCE(dev));
}

/**
 * @brief Notify a device of system shutdown
 *
 * This function calls the DEVICE_SHUTDOWN() driver method if the
 * device currently has an attached driver.
 *
 * @returns the value returned by DEVICE_SHUTDOWN()
 */
int
device_shutdown(device_t dev)
{
      if (dev->state < DS_ATTACHED)
            return (0);
      return (DEVICE_SHUTDOWN(dev));
}

/**
 * @brief Set the unit number of a device
 *
 * This function can be used to override the unit number used for a
 * device (e.g. to wire a device to a pre-configured unit number).
 */
int
device_set_unit(device_t dev, int unit)
{
      devclass_t dc;
      int err;

      dc = device_get_devclass(dev);
      if (unit < dc->maxunit && dc->devices[unit])
            return (EBUSY);
      err = devclass_delete_device(dc, dev);
      if (err)
            return (err);
      dev->unit = unit;
      err = devclass_add_device(dc, dev);
      if (err)
            return (err);

      bus_data_generation_update();
      return (0);
}

/*======================================*/
/*
 * Some useful method implementations to make life easier for bus drivers.
 */

/**
 * @brief Initialise a resource list.
 *
 * @param rl            the resource list to initialise
 */
void
resource_list_init(struct resource_list *rl)
{
      STAILQ_INIT(rl);
}

/**
 * @brief Reclaim memory used by a resource list.
 *
 * This function frees the memory for all resource entries on the list
 * (if any).
 *
 * @param rl            the resource list to free           
 */
void
resource_list_free(struct resource_list *rl)
{
      struct resource_list_entry *rle;

      while ((rle = STAILQ_FIRST(rl)) != NULL) {
            if (rle->res)
                  panic("resource_list_free: resource entry is busy");
            STAILQ_REMOVE_HEAD(rl, link);
            free(rle, M_BUS);
      }
}

/**
 * @brief Add a resource entry.
 *
 * This function adds a resource entry using the given @p type, @p
 * start, @p end and @p count values. A rid value is chosen by
 * searching sequentially for the first unused rid starting at zero.
 *
 * @param rl            the resource list to edit
 * @param type          the resource entry type (e.g. SYS_RES_MEMORY)
 * @param start         the start address of the resource
 * @param end           the end address of the resource
 * @param count         XXX end-start+1
 */
int
resource_list_add_next(struct resource_list *rl, int type, u_long start,
    u_long end, u_long count)
{
      int rid;

      rid = 0;
      while (resource_list_find(rl, type, rid) != NULL)
            rid++;
      resource_list_add(rl, type, rid, start, end, count);
      return (rid);
}

/**
 * @brief Add or modify a resource entry.
 *
 * If an existing entry exists with the same type and rid, it will be
 * modified using the given values of @p start, @p end and @p
 * count. If no entry exists, a new one will be created using the
 * given values.  The resource list entry that matches is then returned.
 *
 * @param rl            the resource list to edit
 * @param type          the resource entry type (e.g. SYS_RES_MEMORY)
 * @param rid           the resource identifier
 * @param start         the start address of the resource
 * @param end           the end address of the resource
 * @param count         XXX end-start+1
 */
struct resource_list_entry *
resource_list_add(struct resource_list *rl, int type, int rid,
    u_long start, u_long end, u_long count)
{
      struct resource_list_entry *rle;

      rle = resource_list_find(rl, type, rid);
      if (!rle) {
            rle = malloc(sizeof(struct resource_list_entry), M_BUS,
                M_NOWAIT);
            if (!rle)
                  panic("resource_list_add: can't record entry");
            STAILQ_INSERT_TAIL(rl, rle, link);
            rle->type = type;
            rle->rid = rid;
            rle->res = NULL;
      }

      if (rle->res)
            panic("resource_list_add: resource entry is busy");

      rle->start = start;
      rle->end = end;
      rle->count = count;
      return (rle);
}

/**
 * @brief Find a resource entry by type and rid.
 *
 * @param rl            the resource list to search
 * @param type          the resource entry type (e.g. SYS_RES_MEMORY)
 * @param rid           the resource identifier
 *
 * @returns the resource entry pointer or NULL if there is no such
 * entry.
 */
struct resource_list_entry *
resource_list_find(struct resource_list *rl, int type, int rid)
{
      struct resource_list_entry *rle;

      STAILQ_FOREACH(rle, rl, link) {
            if (rle->type == type && rle->rid == rid)
                  return (rle);
      }
      return (NULL);
}

/**
 * @brief Delete a resource entry.
 *
 * @param rl            the resource list to edit
 * @param type          the resource entry type (e.g. SYS_RES_MEMORY)
 * @param rid           the resource identifier
 */
void
resource_list_delete(struct resource_list *rl, int type, int rid)
{
      struct resource_list_entry *rle = resource_list_find(rl, type, rid);

      if (rle) {
            if (rle->res != NULL)
                  panic("resource_list_delete: resource has not been released");
            STAILQ_REMOVE(rl, rle, resource_list_entry, link);
            free(rle, M_BUS);
      }
}

/**
 * @brief Helper function for implementing BUS_ALLOC_RESOURCE()
 *
 * Implement BUS_ALLOC_RESOURCE() by looking up a resource from the list
 * and passing the allocation up to the parent of @p bus. This assumes
 * that the first entry of @c device_get_ivars(child) is a struct
 * resource_list. This also handles 'passthrough' allocations where a
 * child is a remote descendant of bus by passing the allocation up to
 * the parent of bus.
 *
 * Typically, a bus driver would store a list of child resources
 * somewhere in the child device's ivars (see device_get_ivars()) and
 * its implementation of BUS_ALLOC_RESOURCE() would find that list and
 * then call resource_list_alloc() to perform the allocation.
 *
 * @param rl            the resource list to allocate from
 * @param bus           the parent device of @p child
 * @param child         the device which is requesting an allocation
 * @param type          the type of resource to allocate
 * @param rid           a pointer to the resource identifier
 * @param start         hint at the start of the resource range - pass
 *                @c 0UL for any start address
 * @param end           hint at the end of the resource range - pass
 *                @c ~0UL for any end address
 * @param count         hint at the size of range required - pass @c 1
 *                for any size
 * @param flags         any extra flags to control the resource
 *                allocation - see @c RF_XXX flags in
 *                <sys/rman.h> for details
 * 
 * @returns       the resource which was allocated or @c NULL if no
 *                resource could be allocated
 */
struct resource *
resource_list_alloc(struct resource_list *rl, device_t bus, device_t child,
    int type, int *rid, u_long start, u_long end, u_long count, u_int flags)
{
      struct resource_list_entry *rle = 0;
      int passthrough = (device_get_parent(child) != bus);
      int isdefault = (start == 0UL && end == ~0UL);

      if (passthrough) {
            return (BUS_ALLOC_RESOURCE(device_get_parent(bus), child,
                type, rid, start, end, count, flags));
      }

      rle = resource_list_find(rl, type, *rid);

      if (!rle)
            return (NULL);          /* no resource of that type/rid */

      if (rle->res)
            panic("resource_list_alloc: resource entry is busy");

      if (isdefault) {
            start = rle->start;
            count = ulmax(count, rle->count);
            end = ulmax(rle->end, start + count - 1);
      }

      rle->res = BUS_ALLOC_RESOURCE(device_get_parent(bus), child,
          type, rid, start, end, count, flags);

      /*
       * Record the new range.
       */
      if (rle->res) {
            rle->start = rman_get_start(rle->res);
            rle->end = rman_get_end(rle->res);
            rle->count = count;
      }

      return (rle->res);
}

/**
 * @brief Helper function for implementing BUS_RELEASE_RESOURCE()
 * 
 * Implement BUS_RELEASE_RESOURCE() using a resource list. Normally
 * used with resource_list_alloc().
 * 
 * @param rl            the resource list which was allocated from
 * @param bus           the parent device of @p child
 * @param child         the device which is requesting a release
 * @param type          the type of resource to allocate
 * @param rid           the resource identifier
 * @param res           the resource to release
 * 
 * @retval 0            success
 * @retval non-zero     a standard unix error code indicating what
 *                error condition prevented the operation
 */
int
resource_list_release(struct resource_list *rl, device_t bus, device_t child,
    int type, int rid, struct resource *res)
{
      struct resource_list_entry *rle = 0;
      int passthrough = (device_get_parent(child) != bus);
      int error;

      if (passthrough) {
            return (BUS_RELEASE_RESOURCE(device_get_parent(bus), child,
                type, rid, res));
      }

      rle = resource_list_find(rl, type, rid);

      if (!rle)
            panic("resource_list_release: can't find resource");
      if (!rle->res)
            panic("resource_list_release: resource entry is not busy");

      error = BUS_RELEASE_RESOURCE(device_get_parent(bus), child,
          type, rid, res);
      if (error)
            return (error);

      rle->res = NULL;
      return (0);
}

/**
 * @brief Print a description of resources in a resource list
 *
 * Print all resources of a specified type, for use in BUS_PRINT_CHILD().
 * The name is printed if at least one resource of the given type is available.
 * The format is used to print resource start and end.
 *
 * @param rl            the resource list to print
 * @param name          the name of @p type, e.g. @c "memory"
 * @param type          type type of resource entry to print
 * @param format  printf(9) format string to print resource
 *                start and end values
 * 
 * @returns       the number of characters printed
 */
int
resource_list_print_type(struct resource_list *rl, const char *name, int type,
    const char *format)
{
      struct resource_list_entry *rle;
      int printed, retval;

      printed = 0;
      retval = 0;
      /* Yes, this is kinda cheating */
      STAILQ_FOREACH(rle, rl, link) {
            if (rle->type == type) {
                  if (printed == 0)
                        retval += printf(" %s ", name);
                  else
                        retval += printf(",");
                  printed++;
                  retval += printf(format, rle->start);
                  if (rle->count > 1) {
                        retval += printf("-");
                        retval += printf(format, rle->start +
                                     rle->count - 1);
                  }
            }
      }
      return (retval);
}

/**
 * @brief Releases all the resources in a list.
 *
 * @param rl            The resource list to purge.
 * 
 * @returns       nothing
 */
void
resource_list_purge(struct resource_list *rl)
{
      struct resource_list_entry *rle;

      STAILQ_FOREACH(rle, rl, link) {
            if (rle->res)
                  bus_release_resource(rman_get_device(rle->res),
                      rle->type, rle->rid, rle->res);
            STAILQ_REMOVE_HEAD(rl, link);
            free(rle, M_BUS);
      }
}

device_t
bus_generic_add_child(device_t dev, int order, const char *name, int unit)
{

      return (device_add_child_ordered(dev, order, name, unit));
}

/**
 * @brief Helper function for implementing DEVICE_PROBE()
 *
 * This function can be used to help implement the DEVICE_PROBE() for
 * a bus (i.e. a device which has other devices attached to it). It
 * calls the DEVICE_IDENTIFY() method of each driver in the device's
 * devclass.
 */
int
bus_generic_probe(device_t dev)
{
      devclass_t dc = dev->devclass;
      driverlink_t dl;

      TAILQ_FOREACH(dl, &dc->drivers, link) {
            DEVICE_IDENTIFY(dl->driver, dev);
      }

      return (0);
}

/**
 * @brief Helper function for implementing DEVICE_ATTACH()
 *
 * This function can be used to help implement the DEVICE_ATTACH() for
 * a bus. It calls device_probe_and_attach() for each of the device's
 * children.
 */
int
bus_generic_attach(device_t dev)
{
      device_t child;

      TAILQ_FOREACH(child, &dev->children, link) {
            device_probe_and_attach(child);
      }

      return (0);
}

/**
 * @brief Helper function for implementing DEVICE_DETACH()
 *
 * This function can be used to help implement the DEVICE_DETACH() for
 * a bus. It calls device_detach() for each of the device's
 * children.
 */
int
bus_generic_detach(device_t dev)
{
      device_t child;
      int error;

      if (dev->state != DS_ATTACHED)
            return (EBUSY);

      TAILQ_FOREACH(child, &dev->children, link) {
            if ((error = device_detach(child)) != 0)
                  return (error);
      }

      return (0);
}

/**
 * @brief Helper function for implementing DEVICE_SHUTDOWN()
 *
 * This function can be used to help implement the DEVICE_SHUTDOWN()
 * for a bus. It calls device_shutdown() for each of the device's
 * children.
 */
int
bus_generic_shutdown(device_t dev)
{
      device_t child;

      TAILQ_FOREACH(child, &dev->children, link) {
            device_shutdown(child);
      }

      return (0);
}

/**
 * @brief Helper function for implementing DEVICE_SUSPEND()
 *
 * This function can be used to help implement the DEVICE_SUSPEND()
 * for a bus. It calls DEVICE_SUSPEND() for each of the device's
 * children. If any call to DEVICE_SUSPEND() fails, the suspend
 * operation is aborted and any devices which were suspended are
 * resumed immediately by calling their DEVICE_RESUME() methods.
 */
int
bus_generic_suspend(device_t dev)
{
      int         error;
      device_t    child, child2;

      TAILQ_FOREACH(child, &dev->children, link) {
            error = DEVICE_SUSPEND(child);
            if (error) {
                  for (child2 = TAILQ_FIRST(&dev->children);
                       child2 && child2 != child;
                       child2 = TAILQ_NEXT(child2, link))
                        DEVICE_RESUME(child2);
                  return (error);
            }
      }
      return (0);
}

/**
 * @brief Helper function for implementing DEVICE_RESUME()
 *
 * This function can be used to help implement the DEVICE_RESUME() for
 * a bus. It calls DEVICE_RESUME() on each of the device's children.
 */
int
bus_generic_resume(device_t dev)
{
      device_t    child;

      TAILQ_FOREACH(child, &dev->children, link) {
            DEVICE_RESUME(child);
            /* if resume fails, there's nothing we can usefully do... */
      }
      return (0);
}

/**
 * @brief Helper function for implementing BUS_PRINT_CHILD().
 *
 * This function prints the first part of the ascii representation of
 * @p child, including its name, unit and description (if any - see
 * device_set_desc()).
 *
 * @returns the number of characters printed
 */
int
bus_print_child_header(device_t dev, device_t child)
{
      int   retval = 0;

      if (device_get_desc(child)) {
            retval += device_printf(child, "<%s>", device_get_desc(child));
      } else {
            retval += printf("%s", device_get_nameunit(child));
      }

      return (retval);
}

/**
 * @brief Helper function for implementing BUS_PRINT_CHILD().
 *
 * This function prints the last part of the ascii representation of
 * @p child, which consists of the string @c " on " followed by the
 * name and unit of the @p dev.
 *
 * @returns the number of characters printed
 */
int
bus_print_child_footer(device_t dev, device_t child)
{
      return (printf(" on %s\n", device_get_nameunit(dev)));
}

/**
 * @brief Helper function for implementing BUS_PRINT_CHILD().
 *
 * This function simply calls bus_print_child_header() followed by
 * bus_print_child_footer().
 *
 * @returns the number of characters printed
 */
int
bus_generic_print_child(device_t dev, device_t child)
{
      int   retval = 0;

      retval += bus_print_child_header(dev, child);
      retval += bus_print_child_footer(dev, child);

      return (retval);
}

/**
 * @brief Stub function for implementing BUS_READ_IVAR().
 * 
 * @returns ENOENT
 */
int
bus_generic_read_ivar(device_t dev, device_t child, int index,
    uintptr_t * result)
{
      return (ENOENT);
}

/**
 * @brief Stub function for implementing BUS_WRITE_IVAR().
 * 
 * @returns ENOENT
 */
int
bus_generic_write_ivar(device_t dev, device_t child, int index,
    uintptr_t value)
{
      return (ENOENT);
}

/**
 * @brief Stub function for implementing BUS_GET_RESOURCE_LIST().
 * 
 * @returns NULL
 */
struct resource_list *
bus_generic_get_resource_list(device_t dev, device_t child)
{
      return (NULL);
}

/**
 * @brief Helper function for implementing BUS_DRIVER_ADDED().
 *
 * This implementation of BUS_DRIVER_ADDED() simply calls the driver's
 * DEVICE_IDENTIFY() method to allow it to add new children to the bus
 * and then calls device_probe_and_attach() for each unattached child.
 */
void
bus_generic_driver_added(device_t dev, driver_t *driver)
{
      device_t child;

      DEVICE_IDENTIFY(driver, dev);
      TAILQ_FOREACH(child, &dev->children, link) {
            if (child->state == DS_NOTPRESENT ||
                (child->flags & DF_REBID))
                  device_probe_and_attach(child);
      }
}

/**
 * @brief Helper function for implementing BUS_SETUP_INTR().
 *
 * This simple implementation of BUS_SETUP_INTR() simply calls the
 * BUS_SETUP_INTR() method of the parent of @p dev.
 */
int
bus_generic_setup_intr(device_t dev, device_t child, struct resource *irq,
    int flags, driver_intr_t *intr, void *arg, void **cookiep)
{
      /* Propagate up the bus hierarchy until someone handles it. */
      if (dev->parent)
            return (BUS_SETUP_INTR(dev->parent, child, irq, flags,
                intr, arg, cookiep));
      return (EINVAL);
}

/**
 * @brief Helper function for implementing BUS_TEARDOWN_INTR().
 *
 * This simple implementation of BUS_TEARDOWN_INTR() simply calls the
 * BUS_TEARDOWN_INTR() method of the parent of @p dev.
 */
int
bus_generic_teardown_intr(device_t dev, device_t child, struct resource *irq,
    void *cookie)
{
      /* Propagate up the bus hierarchy until someone handles it. */
      if (dev->parent)
            return (BUS_TEARDOWN_INTR(dev->parent, child, irq, cookie));
      return (EINVAL);
}

/**
 * @brief Helper function for implementing BUS_ALLOC_RESOURCE().
 *
 * This simple implementation of BUS_ALLOC_RESOURCE() simply calls the
 * BUS_ALLOC_RESOURCE() method of the parent of @p dev.
 */
struct resource *
bus_generic_alloc_resource(device_t dev, device_t child, int type, int *rid,
    u_long start, u_long end, u_long count, u_int flags)
{
      /* Propagate up the bus hierarchy until someone handles it. */
      if (dev->parent)
            return (BUS_ALLOC_RESOURCE(dev->parent, child, type, rid,
                start, end, count, flags));
      return (NULL);
}

/**
 * @brief Helper function for implementing BUS_RELEASE_RESOURCE().
 *
 * This simple implementation of BUS_RELEASE_RESOURCE() simply calls the
 * BUS_RELEASE_RESOURCE() method of the parent of @p dev.
 */
int
bus_generic_release_resource(device_t dev, device_t child, int type, int rid,
    struct resource *r)
{
      /* Propagate up the bus hierarchy until someone handles it. */
      if (dev->parent)
            return (BUS_RELEASE_RESOURCE(dev->parent, child, type, rid,
                r));
      return (EINVAL);
}

/**
 * @brief Helper function for implementing BUS_ACTIVATE_RESOURCE().
 *
 * This simple implementation of BUS_ACTIVATE_RESOURCE() simply calls the
 * BUS_ACTIVATE_RESOURCE() method of the parent of @p dev.
 */
int
bus_generic_activate_resource(device_t dev, device_t child, int type, int rid,
    struct resource *r)
{
      /* Propagate up the bus hierarchy until someone handles it. */
      if (dev->parent)
            return (BUS_ACTIVATE_RESOURCE(dev->parent, child, type, rid,
                r));
      return (EINVAL);
}

/**
 * @brief Helper function for implementing BUS_DEACTIVATE_RESOURCE().
 *
 * This simple implementation of BUS_DEACTIVATE_RESOURCE() simply calls the
 * BUS_DEACTIVATE_RESOURCE() method of the parent of @p dev.
 */
int
bus_generic_deactivate_resource(device_t dev, device_t child, int type,
    int rid, struct resource *r)
{
      /* Propagate up the bus hierarchy until someone handles it. */
      if (dev->parent)
            return (BUS_DEACTIVATE_RESOURCE(dev->parent, child, type, rid,
                r));
      return (EINVAL);
}

/**
 * @brief Helper function for implementing BUS_CONFIG_INTR().
 *
 * This simple implementation of BUS_CONFIG_INTR() simply calls the
 * BUS_CONFIG_INTR() method of the parent of @p dev.
 */
int
bus_generic_config_intr(device_t dev, int irq, enum intr_trigger trig,
    enum intr_polarity pol)
{

      /* Propagate up the bus hierarchy until someone handles it. */
      if (dev->parent)
            return (BUS_CONFIG_INTR(dev->parent, irq, trig, pol));
      return (EINVAL);
}

/**
 * @brief Helper function for implementing BUS_GET_RESOURCE().
 *
 * This implementation of BUS_GET_RESOURCE() uses the
 * resource_list_find() function to do most of the work. It calls
 * BUS_GET_RESOURCE_LIST() to find a suitable resource list to
 * search.
 */
int
bus_generic_rl_get_resource(device_t dev, device_t child, int type, int rid,
    u_long *startp, u_long *countp)
{
      struct resource_list *        rl = NULL;
      struct resource_list_entry *  rle = NULL;

      rl = BUS_GET_RESOURCE_LIST(dev, child);
      if (!rl)
            return (EINVAL);

      rle = resource_list_find(rl, type, rid);
      if (!rle)
            return (ENOENT);

      if (startp)
            *startp = rle->start;
      if (countp)
            *countp = rle->count;

      return (0);
}

/**
 * @brief Helper function for implementing BUS_SET_RESOURCE().
 *
 * This implementation of BUS_SET_RESOURCE() uses the
 * resource_list_add() function to do most of the work. It calls
 * BUS_GET_RESOURCE_LIST() to find a suitable resource list to
 * edit.
 */
int
bus_generic_rl_set_resource(device_t dev, device_t child, int type, int rid,
    u_long start, u_long count)
{
      struct resource_list *        rl = NULL;

      rl = BUS_GET_RESOURCE_LIST(dev, child);
      if (!rl)
            return (EINVAL);

      resource_list_add(rl, type, rid, start, (start + count - 1), count);

      return (0);
}

/**
 * @brief Helper function for implementing BUS_DELETE_RESOURCE().
 *
 * This implementation of BUS_DELETE_RESOURCE() uses the
 * resource_list_delete() function to do most of the work. It calls
 * BUS_GET_RESOURCE_LIST() to find a suitable resource list to
 * edit.
 */
void
bus_generic_rl_delete_resource(device_t dev, device_t child, int type, int rid)
{
      struct resource_list *        rl = NULL;

      rl = BUS_GET_RESOURCE_LIST(dev, child);
      if (!rl)
            return;

      resource_list_delete(rl, type, rid);

      return;
}

/**
 * @brief Helper function for implementing BUS_RELEASE_RESOURCE().
 *
 * This implementation of BUS_RELEASE_RESOURCE() uses the
 * resource_list_release() function to do most of the work. It calls
 * BUS_GET_RESOURCE_LIST() to find a suitable resource list.
 */
int
bus_generic_rl_release_resource(device_t dev, device_t child, int type,
    int rid, struct resource *r)
{
      struct resource_list *        rl = NULL;

      rl = BUS_GET_RESOURCE_LIST(dev, child);
      if (!rl)
            return (EINVAL);

      return (resource_list_release(rl, dev, child, type, rid, r));
}

/**
 * @brief Helper function for implementing BUS_ALLOC_RESOURCE().
 *
 * This implementation of BUS_ALLOC_RESOURCE() uses the
 * resource_list_alloc() function to do most of the work. It calls
 * BUS_GET_RESOURCE_LIST() to find a suitable resource list.
 */
struct resource *
bus_generic_rl_alloc_resource(device_t dev, device_t child, int type,
    int *rid, u_long start, u_long end, u_long count, u_int flags)
{
      struct resource_list *        rl = NULL;

      rl = BUS_GET_RESOURCE_LIST(dev, child);
      if (!rl)
            return (NULL);

      return (resource_list_alloc(rl, dev, child, type, rid,
          start, end, count, flags));
}

/**
 * @brief Helper function for implementing BUS_CHILD_PRESENT().
 *
 * This simple implementation of BUS_CHILD_PRESENT() simply calls the
 * BUS_CHILD_PRESENT() method of the parent of @p dev.
 */
int
bus_generic_child_present(device_t dev, device_t child)
{
      return (BUS_CHILD_PRESENT(device_get_parent(dev), dev));
}

/*
 * Some convenience functions to make it easier for drivers to use the
 * resource-management functions.  All these really do is hide the
 * indirection through the parent's method table, making for slightly
 * less-wordy code.  In the future, it might make sense for this code
 * to maintain some sort of a list of resources allocated by each device.
 */

int
bus_alloc_resources(device_t dev, struct resource_spec *rs,
    struct resource **res)
{
      int i;

      for (i = 0; rs[i].type != -1; i++)
            res[i] = NULL;
      for (i = 0; rs[i].type != -1; i++) {
            res[i] = bus_alloc_resource_any(dev,
                rs[i].type, &rs[i].rid, rs[i].flags);
            if (res[i] == NULL && !(rs[i].flags & RF_OPTIONAL)) {
                  bus_release_resources(dev, rs, res);
                  return (ENXIO);
            }
      }
      return (0);
}

void
bus_release_resources(device_t dev, const struct resource_spec *rs,
    struct resource **res)
{
      int i;

      for (i = 0; rs[i].type != -1; i++)
            if (res[i] != NULL) {
                  bus_release_resource(
                      dev, rs[i].type, rs[i].rid, res[i]);
                  res[i] = NULL;
            }
}

/**
 * @brief Wrapper function for BUS_ALLOC_RESOURCE().
 *
 * This function simply calls the BUS_ALLOC_RESOURCE() method of the
 * parent of @p dev.
 */
struct resource *
bus_alloc_resource(device_t dev, int type, int *rid, u_long start, u_long end,
    u_long count, u_int flags)
{
      if (dev->parent == 0)
            return (0);
      return (BUS_ALLOC_RESOURCE(dev->parent, dev, type, rid, start, end,
          count, flags));
}

/**
 * @brief Wrapper function for BUS_ACTIVATE_RESOURCE().
 *
 * This function simply calls the BUS_ACTIVATE_RESOURCE() method of the
 * parent of @p dev.
 */
int
bus_activate_resource(device_t dev, int type, int rid, struct resource *r)
{
      if (dev->parent == 0)
            return (EINVAL);
      return (BUS_ACTIVATE_RESOURCE(dev->parent, dev, type, rid, r));
}

/**
 * @brief Wrapper function for BUS_DEACTIVATE_RESOURCE().
 *
 * This function simply calls the BUS_DEACTIVATE_RESOURCE() method of the
 * parent of @p dev.
 */
int
bus_deactivate_resource(device_t dev, int type, int rid, struct resource *r)
{
      if (dev->parent == 0)
            return (EINVAL);
      return (BUS_DEACTIVATE_RESOURCE(dev->parent, dev, type, rid, r));
}

/**
 * @brief Wrapper function for BUS_RELEASE_RESOURCE().
 *
 * This function simply calls the BUS_RELEASE_RESOURCE() method of the
 * parent of @p dev.
 */
int
bus_release_resource(device_t dev, int type, int rid, struct resource *r)
{
      if (dev->parent == 0)
            return (EINVAL);
      return (BUS_RELEASE_RESOURCE(dev->parent, dev, type, rid, r));
}

/**
 * @brief Wrapper function for BUS_SETUP_INTR().
 *
 * This function simply calls the BUS_SETUP_INTR() method of the
 * parent of @p dev.
 */
int
bus_setup_intr(device_t dev, struct resource *r, int flags,
    driver_intr_t handler, void *arg, void **cookiep)
{
      int error;

      if (dev->parent != 0) {
            if ((flags &~ INTR_ENTROPY) == (INTR_TYPE_NET | INTR_MPSAFE) &&
                !debug_mpsafenet)
                  flags &= ~INTR_MPSAFE;
            error = BUS_SETUP_INTR(dev->parent, dev, r, flags,
                handler, arg, cookiep);
            if (error == 0) {
                  if (!(flags & (INTR_MPSAFE | INTR_FAST)))
                        device_printf(dev, "[GIANT-LOCKED]\n");
                  if (bootverbose && (flags & INTR_MPSAFE))
                        device_printf(dev, "[MPSAFE]\n");
                  if (flags & INTR_FAST)
                        device_printf(dev, "[FAST]\n");
            }
      } else
            error = EINVAL;
      return (error);
}

/**
 * @brief Wrapper function for BUS_TEARDOWN_INTR().
 *
 * This function simply calls the BUS_TEARDOWN_INTR() method of the
 * parent of @p dev.
 */
int
bus_teardown_intr(device_t dev, struct resource *r, void *cookie)
{
      if (dev->parent == 0)
            return (EINVAL);
      return (BUS_TEARDOWN_INTR(dev->parent, dev, r, cookie));
}

/**
 * @brief Wrapper function for BUS_SET_RESOURCE().
 *
 * This function simply calls the BUS_SET_RESOURCE() method of the
 * parent of @p dev.
 */
int
bus_set_resource(device_t dev, int type, int rid,
    u_long start, u_long count)
{
      return (BUS_SET_RESOURCE(device_get_parent(dev), dev, type, rid,
          start, count));
}

/**
 * @brief Wrapper function for BUS_GET_RESOURCE().
 *
 * This function simply calls the BUS_GET_RESOURCE() method of the
 * parent of @p dev.
 */
int
bus_get_resource(device_t dev, int type, int rid,
    u_long *startp, u_long *countp)
{
      return (BUS_GET_RESOURCE(device_get_parent(dev), dev, type, rid,
          startp, countp));
}

/**
 * @brief Wrapper function for BUS_GET_RESOURCE().
 *
 * This function simply calls the BUS_GET_RESOURCE() method of the
 * parent of @p dev and returns the start value.
 */
u_long
bus_get_resource_start(device_t dev, int type, int rid)
{
      u_long start, count;
      int error;

      error = BUS_GET_RESOURCE(device_get_parent(dev), dev, type, rid,
          &start, &count);
      if (error)
            return (0);
      return (start);
}

/**
 * @brief Wrapper function for BUS_GET_RESOURCE().
 *
 * This function simply calls the BUS_GET_RESOURCE() method of the
 * parent of @p dev and returns the count value.
 */
u_long
bus_get_resource_count(device_t dev, int type, int rid)
{
      u_long start, count;
      int error;

      error = BUS_GET_RESOURCE(device_get_parent(dev), dev, type, rid,
          &start, &count);
      if (error)
            return (0);
      return (count);
}

/**
 * @brief Wrapper function for BUS_DELETE_RESOURCE().
 *
 * This function simply calls the BUS_DELETE_RESOURCE() method of the
 * parent of @p dev.
 */
void
bus_delete_resource(device_t dev, int type, int rid)
{
      BUS_DELETE_RESOURCE(device_get_parent(dev), dev, type, rid);
}

/**
 * @brief Wrapper function for BUS_CHILD_PRESENT().
 *
 * This function simply calls the BUS_CHILD_PRESENT() method of the
 * parent of @p dev.
 */
int
bus_child_present(device_t child)
{
      return (BUS_CHILD_PRESENT(device_get_parent(child), child));
}

/**
 * @brief Wrapper function for BUS_CHILD_PNPINFO_STR().
 *
 * This function simply calls the BUS_CHILD_PNPINFO_STR() method of the
 * parent of @p dev.
 */
int
bus_child_pnpinfo_str(device_t child, char *buf, size_t buflen)
{
      device_t parent;

      parent = device_get_parent(child);
      if (parent == NULL) {
            *buf = '\0';
            return (0);
      }
      return (BUS_CHILD_PNPINFO_STR(parent, child, buf, buflen));
}

/**
 * @brief Wrapper function for BUS_CHILD_LOCATION_STR().
 *
 * This function simply calls the BUS_CHILD_LOCATION_STR() method of the
 * parent of @p dev.
 */
int
bus_child_location_str(device_t child, char *buf, size_t buflen)
{
      device_t parent;

      parent = device_get_parent(child);
      if (parent == NULL) {
            *buf = '\0';
            return (0);
      }
      return (BUS_CHILD_LOCATION_STR(parent, child, buf, buflen));
}

/* Resume all devices and then notify userland that we're up again. */
static int
root_resume(device_t dev)
{
      int error;

      error = bus_generic_resume(dev);
      if (error == 0)
            devctl_notify("kern", "power", "resume", NULL);
      return (error);
}

static int
root_print_child(device_t dev, device_t child)
{
      int   retval = 0;

      retval += bus_print_child_header(dev, child);
      retval += printf("\n");

      return (retval);
}

static int
root_setup_intr(device_t dev, device_t child, driver_intr_t *intr, void *arg,
    void **cookiep)
{
      /*
       * If an interrupt mapping gets to here something bad has happened.
       */
      panic("root_setup_intr");
}

/*
 * If we get here, assume that the device is permanant and really is
 * present in the system.  Removable bus drivers are expected to intercept
 * this call long before it gets here.  We return -1 so that drivers that
 * really care can check vs -1 or some ERRNO returned higher in the food
 * chain.
 */
static int
root_child_present(device_t dev, device_t child)
{
      return (-1);
}

static kobj_method_t root_methods[] = {
      /* Device interface */
      KOBJMETHOD(device_shutdown,   bus_generic_shutdown),
      KOBJMETHOD(device_suspend,    bus_generic_suspend),
      KOBJMETHOD(device_resume,     root_resume),

      /* Bus interface */
      KOBJMETHOD(bus_print_child,   root_print_child),
      KOBJMETHOD(bus_read_ivar,     bus_generic_read_ivar),
      KOBJMETHOD(bus_write_ivar,    bus_generic_write_ivar),
      KOBJMETHOD(bus_setup_intr,    root_setup_intr),
      KOBJMETHOD(bus_child_present, root_child_present),

      { 0, 0 }
};

static driver_t root_driver = {
      "root",
      root_methods,
      1,                /* no softc */
};

device_t    root_bus;
devclass_t  root_devclass;

static int
root_bus_module_handler(module_t mod, int what, void* arg)
{
      switch (what) {
      case MOD_LOAD:
            TAILQ_INIT(&bus_data_devices);
            kobj_class_compile((kobj_class_t) &root_driver);
            root_bus = make_device(NULL, "root", 0);
            root_bus->desc = "System root bus";
            kobj_init((kobj_t) root_bus, (kobj_class_t) &root_driver);
            root_bus->driver = &root_driver;
            root_bus->state = DS_ATTACHED;
            root_devclass = devclass_find_internal("root", 0, FALSE);
            devinit();
            return (0);

      case MOD_SHUTDOWN:
            device_shutdown(root_bus);
            return (0);
      default:
            return (EOPNOTSUPP);
      }

      return (0);
}

static moduledata_t root_bus_mod = {
      "rootbus",
      root_bus_module_handler,
      0
};
DECLARE_MODULE(rootbus, root_bus_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);

/**
 * @brief Automatically configure devices
 *
 * This function begins the autoconfiguration process by calling
 * device_probe_and_attach() for each child of the @c root0 device.
 */ 
void
root_bus_configure(void)
{
      device_t dev;

      PDEBUG(("."));

      TAILQ_FOREACH(dev, &root_bus->children, link) {
            device_probe_and_attach(dev);
      }
}

/**
 * @brief Module handler for registering device drivers
 *
 * This module handler is used to automatically register device
 * drivers when modules are loaded. If @p what is MOD_LOAD, it calls
 * devclass_add_driver() for the driver described by the
 * driver_module_data structure pointed to by @p arg
 */
int
driver_module_handler(module_t mod, int what, void *arg)
{
      int error;
      struct driver_module_data *dmd;
      devclass_t bus_devclass;
      kobj_class_t driver;

      dmd = (struct driver_module_data *)arg;
      bus_devclass = devclass_find_internal(dmd->dmd_busname, 0, TRUE);
      error = 0;

      switch (what) {
      case MOD_LOAD:
            if (dmd->dmd_chainevh)
                  error = dmd->dmd_chainevh(mod,what,dmd->dmd_chainarg);

            driver = dmd->dmd_driver;
            PDEBUG(("Loading module: driver %s on bus %s",
                DRIVERNAME(driver), dmd->dmd_busname));
            error = devclass_add_driver(bus_devclass, driver);
            if (error)
                  break;

            /*
             * If the driver has any base classes, make the
             * devclass inherit from the devclass of the driver's
             * first base class. This will allow the system to
             * search for drivers in both devclasses for children
             * of a device using this driver.
             */
            if (driver->baseclasses) {
                  const char *parentname;
                  parentname = driver->baseclasses[0]->name;
                  *dmd->dmd_devclass =
                        devclass_find_internal(driver->name,
                            parentname, TRUE);
            } else {
                  *dmd->dmd_devclass =
                        devclass_find_internal(driver->name, 0, TRUE);
            }
            break;

      case MOD_UNLOAD:
            PDEBUG(("Unloading module: driver %s from bus %s",
                DRIVERNAME(dmd->dmd_driver),
                dmd->dmd_busname));
            error = devclass_delete_driver(bus_devclass,
                dmd->dmd_driver);

            if (!error && dmd->dmd_chainevh)
                  error = dmd->dmd_chainevh(mod,what,dmd->dmd_chainarg);
            break;
      case MOD_QUIESCE:
            PDEBUG(("Quiesce module: driver %s from bus %s",
                DRIVERNAME(dmd->dmd_driver),
                dmd->dmd_busname));
            error = devclass_quiesce_driver(bus_devclass,
                dmd->dmd_driver);

            if (!error && dmd->dmd_chainevh)
                  error = dmd->dmd_chainevh(mod,what,dmd->dmd_chainarg);
            break;
      default:
            error = EOPNOTSUPP;
            break;
      }

      return (error);
}

/**
 * @brief Enumerate all hinted devices for this bus.
 *
 * Walks throught he hints for this bus and calls the bus_hinted_child
 * routine for each one it fines.  It searches first for the specific
 * bus that's being probed for hinted children (eg isa0), and then for
 * generic children (eg isa).
 *
 * @param   dev   bus device to enumerate
 */
void
bus_enumerate_hinted_children(device_t bus)
{
      int i;
      const char *dname, *busname;
      int dunit;

      /*
       * enumerate all devices on the specific bus
       */
      busname = device_get_nameunit(bus);
      i = 0;
      while (resource_find_match(&i, &dname, &dunit, "at", busname) == 0)
            BUS_HINTED_CHILD(bus, dname, dunit);

      /*
       * and all the generic ones.
       */
      busname = device_get_name(bus);
      i = 0;
      while (resource_find_match(&i, &dname, &dunit, "at", busname) == 0)
            BUS_HINTED_CHILD(bus, dname, dunit);
}

#ifdef BUS_DEBUG

/* the _short versions avoid iteration by not calling anything that prints
 * more than oneliners. I love oneliners.
 */

static void
print_device_short(device_t dev, int indent)
{
      if (!dev)
            return;

      indentprintf(("device %d: <%s> %sparent,%schildren,%s%s%s%s%s,%sivars,%ssoftc,busy=%d\n",
          dev->unit, dev->desc,
          (dev->parent? "":"no "),
          (TAILQ_EMPTY(&dev->children)? "no ":""),
          (dev->flags&DF_ENABLED? "enabled,":"disabled,"),
          (dev->flags&DF_FIXEDCLASS? "fixed,":""),
          (dev->flags&DF_WILDCARD? "wildcard,":""),
          (dev->flags&DF_DESCMALLOCED? "descmalloced,":""),
          (dev->flags&DF_REBID? "rebiddable,":""),
          (dev->ivars? "":"no "),
          (dev->softc? "":"no "),
          dev->busy));
}

static void
print_device(device_t dev, int indent)
{
      if (!dev)
            return;

      print_device_short(dev, indent);

      indentprintf(("Parent:\n"));
      print_device_short(dev->parent, indent+1);
      indentprintf(("Driver:\n"));
      print_driver_short(dev->driver, indent+1);
      indentprintf(("Devclass:\n"));
      print_devclass_short(dev->devclass, indent+1);
}

void
print_device_tree_short(device_t dev, int indent)
/* print the device and all its children (indented) */
{
      device_t child;

      if (!dev)
            return;

      print_device_short(dev, indent);

      TAILQ_FOREACH(child, &dev->children, link) {
            print_device_tree_short(child, indent+1);
      }
}

void
print_device_tree(device_t dev, int indent)
/* print the device and all its children (indented) */
{
      device_t child;

      if (!dev)
            return;

      print_device(dev, indent);

      TAILQ_FOREACH(child, &dev->children, link) {
            print_device_tree(child, indent+1);
      }
}

static void
print_driver_short(driver_t *driver, int indent)
{
      if (!driver)
            return;

      indentprintf(("driver %s: softc size = %zd\n",
          driver->name, driver->size));
}

static void
print_driver(driver_t *driver, int indent)
{
      if (!driver)
            return;

      print_driver_short(driver, indent);
}


static void
print_driver_list(driver_list_t drivers, int indent)
{
      driverlink_t driver;

      TAILQ_FOREACH(driver, &drivers, link) {
            print_driver(driver->driver, indent);
      }
}

static void
print_devclass_short(devclass_t dc, int indent)
{
      if ( !dc )
            return;

      indentprintf(("devclass %s: max units = %d\n", dc->name, dc->maxunit));
}

static void
print_devclass(devclass_t dc, int indent)
{
      int i;

      if ( !dc )
            return;

      print_devclass_short(dc, indent);
      indentprintf(("Drivers:\n"));
      print_driver_list(dc->drivers, indent+1);

      indentprintf(("Devices:\n"));
      for (i = 0; i < dc->maxunit; i++)
            if (dc->devices[i])
                  print_device(dc->devices[i], indent+1);
}

void
print_devclass_list_short(void)
{
      devclass_t dc;

      printf("Short listing of devclasses, drivers & devices:\n");
      TAILQ_FOREACH(dc, &devclasses, link) {
            print_devclass_short(dc, 0);
      }
}

void
print_devclass_list(void)
{
      devclass_t dc;

      printf("Full listing of devclasses, drivers & devices:\n");
      TAILQ_FOREACH(dc, &devclasses, link) {
            print_devclass(dc, 0);
      }
}

#endif

/*
 * User-space access to the device tree.
 *
 * We implement a small set of nodes:
 *
 * hw.bus               Single integer read method to obtain the
 *                      current generation count.
 * hw.bus.devices       Reads the entire device tree in flat space.
 * hw.bus.rman                Resource manager interface
 *
 * We might like to add the ability to scan devclasses and/or drivers to
 * determine what else is currently loaded/available.
 */

static int
sysctl_bus(SYSCTL_HANDLER_ARGS)
{
      struct u_businfo  ubus;

      ubus.ub_version = BUS_USER_VERSION;
      ubus.ub_generation = bus_data_generation;

      return (SYSCTL_OUT(req, &ubus, sizeof(ubus)));
}
SYSCTL_NODE(_hw_bus, OID_AUTO, info, CTLFLAG_RW, sysctl_bus,
    "bus-related data");

static int
sysctl_devices(SYSCTL_HANDLER_ARGS)
{
      int               *name = (int *)arg1;
      u_int             namelen = arg2;
      int               index;
      struct device           *dev;
      struct u_device         udev; /* XXX this is a bit big */
      int               error;

      if (namelen != 2)
            return (EINVAL);

      if (bus_data_generation_check(name[0]))
            return (EINVAL);

      index = name[1];

      /*
       * Scan the list of devices, looking for the requested index.
       */
      TAILQ_FOREACH(dev, &bus_data_devices, devlink) {
            if (index-- == 0)
                  break;
      }
      if (dev == NULL)
            return (ENOENT);

      /*
       * Populate the return array.
       */
      bzero(&udev, sizeof(udev));
      udev.dv_handle = (uintptr_t)dev;
      udev.dv_parent = (uintptr_t)dev->parent;
      if (dev->nameunit != NULL)
            strlcpy(udev.dv_name, dev->nameunit, sizeof(udev.dv_name));
      if (dev->desc != NULL)
            strlcpy(udev.dv_desc, dev->desc, sizeof(udev.dv_desc));
      if (dev->driver != NULL && dev->driver->name != NULL)
            strlcpy(udev.dv_drivername, dev->driver->name,
                sizeof(udev.dv_drivername));
      bus_child_pnpinfo_str(dev, udev.dv_pnpinfo, sizeof(udev.dv_pnpinfo));
      bus_child_location_str(dev, udev.dv_location, sizeof(udev.dv_location));
      udev.dv_devflags = dev->devflags;
      udev.dv_flags = dev->flags;
      udev.dv_state = dev->state;
      error = SYSCTL_OUT(req, &udev, sizeof(udev));
      return (error);
}

SYSCTL_NODE(_hw_bus, OID_AUTO, devices, CTLFLAG_RD, sysctl_devices,
    "system device tree");

int
bus_data_generation_check(int generation)
{
      if (generation != bus_data_generation)
            return (1);

      /* XXX generate optimised lists here? */
      return (0);
}

void
bus_data_generation_update(void)
{
      bus_data_generation++;
}

int
bus_free_resource(device_t dev, int type, struct resource *r)
{
      if (r == NULL)
            return (0);
      return (bus_release_resource(dev, type, rman_get_rid(r), r));
}

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