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driver.c

/*
 * driver.c - centralized device driver management
 *
 * Copyright (c) 2002-3 Patrick Mochel
 * Copyright (c) 2002-3 Open Source Development Labs
 *
 * This file is released under the GPLv2
 *
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/string.h>
#include "base.h"

#define to_dev(node) container_of(node, struct device, driver_list)
#define to_drv(obj) container_of(obj, struct device_driver, kobj)


static struct device * next_device(struct klist_iter * i)
{
      struct klist_node * n = klist_next(i);
      return n ? container_of(n, struct device, knode_driver) : NULL;
}

/**
 *    driver_for_each_device - Iterator for devices bound to a driver.
 *    @drv: Driver we're iterating.
 *    @start: Device to begin with
 *    @data:      Data to pass to the callback.
 *    @fn:  Function to call for each device.
 *
 *    Iterate over the @drv's list of devices calling @fn for each one.
 */

int driver_for_each_device(struct device_driver * drv, struct device * start, 
                     void * data, int (*fn)(struct device *, void *))
{
      struct klist_iter i;
      struct device * dev;
      int error = 0;

      if (!drv)
            return -EINVAL;

      klist_iter_init_node(&drv->klist_devices, &i,
                       start ? &start->knode_driver : NULL);
      while ((dev = next_device(&i)) && !error)
            error = fn(dev, data);
      klist_iter_exit(&i);
      return error;
}

EXPORT_SYMBOL_GPL(driver_for_each_device);


/**
 * driver_find_device - device iterator for locating a particular device.
 * @drv: The device's driver
 * @start: Device to begin with
 * @data: Data to pass to match function
 * @match: Callback function to check device
 *
 * This is similar to the driver_for_each_device() function above, but
 * it returns a reference to a device that is 'found' for later use, as
 * determined by the @match callback.
 *
 * The callback should return 0 if the device doesn't match and non-zero
 * if it does.  If the callback returns non-zero, this function will
 * return to the caller and not iterate over any more devices.
 */
struct device * driver_find_device(struct device_driver *drv,
                           struct device * start, void * data,
                           int (*match)(struct device *, void *))
{
      struct klist_iter i;
      struct device *dev;

      if (!drv)
            return NULL;

      klist_iter_init_node(&drv->klist_devices, &i,
                       (start ? &start->knode_driver : NULL));
      while ((dev = next_device(&i)))
            if (match(dev, data) && get_device(dev))
                  break;
      klist_iter_exit(&i);
      return dev;
}
EXPORT_SYMBOL_GPL(driver_find_device);

/**
 *    driver_create_file - create sysfs file for driver.
 *    @drv: driver.
 *    @attr:      driver attribute descriptor.
 */

int driver_create_file(struct device_driver * drv, struct driver_attribute * attr)
{
      int error;
      if (get_driver(drv)) {
            error = sysfs_create_file(&drv->kobj, &attr->attr);
            put_driver(drv);
      } else
            error = -EINVAL;
      return error;
}


/**
 *    driver_remove_file - remove sysfs file for driver.
 *    @drv: driver.
 *    @attr:      driver attribute descriptor.
 */

void driver_remove_file(struct device_driver * drv, struct driver_attribute * attr)
{
      if (get_driver(drv)) {
            sysfs_remove_file(&drv->kobj, &attr->attr);
            put_driver(drv);
      }
}


/**
 *    get_driver - increment driver reference count.
 *    @drv: driver.
 */
struct device_driver * get_driver(struct device_driver * drv)
{
      return drv ? to_drv(kobject_get(&drv->kobj)) : NULL;
}


/**
 *    put_driver - decrement driver's refcount.
 *    @drv: driver.
 */
void put_driver(struct device_driver * drv)
{
      kobject_put(&drv->kobj);
}

/**
 *    driver_register - register driver with bus
 *    @drv: driver to register
 *
 *    We pass off most of the work to the bus_add_driver() call,
 *    since most of the things we have to do deal with the bus
 *    structures.
 */
int driver_register(struct device_driver * drv)
{
      if ((drv->bus->probe && drv->probe) ||
          (drv->bus->remove && drv->remove) ||
          (drv->bus->shutdown && drv->shutdown)) {
            printk(KERN_WARNING "Driver '%s' needs updating - please use bus_type methods\n", drv->name);
      }
      klist_init(&drv->klist_devices, NULL, NULL);
      return bus_add_driver(drv);
}

/**
 *    driver_unregister - remove driver from system.
 *    @drv: driver.
 *
 *    Again, we pass off most of the work to the bus-level call.
 */

void driver_unregister(struct device_driver * drv)
{
      bus_remove_driver(drv);
}

/**
 *    driver_find - locate driver on a bus by its name.
 *    @name:      name of the driver.
 *    @bus: bus to scan for the driver.
 *
 *    Call kset_find_obj() to iterate over list of drivers on
 *    a bus to find driver by name. Return driver if found.
 *
 *    Note that kset_find_obj increments driver's reference count.
 */
struct device_driver *driver_find(const char *name, struct bus_type *bus)
{
      struct kobject *k = kset_find_obj(&bus->drivers, name);
      if (k)
            return to_drv(k);
      return NULL;
}

EXPORT_SYMBOL_GPL(driver_register);
EXPORT_SYMBOL_GPL(driver_unregister);
EXPORT_SYMBOL_GPL(get_driver);
EXPORT_SYMBOL_GPL(put_driver);
EXPORT_SYMBOL_GPL(driver_find);

EXPORT_SYMBOL_GPL(driver_create_file);
EXPORT_SYMBOL_GPL(driver_remove_file);

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