bus.c

Linux Kernel 2.6.9 for OMAP1710

/*
 * bus.c - bus 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/config.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/string.h>
#include "base.h"
#include "power/power.h"

#define to_dev(node) container_of(node, struct device, bus_list)
#define to_drv(node) container_of(node, struct device_driver, kobj.entry)

#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
#define to_bus(obj) container_of(obj, struct bus_type, subsys.kset.kobj)

/*
 * sysfs bindings for drivers
 */

#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
#define to_driver(obj) container_of(obj, struct device_driver, kobj)


static ssize_t
drv_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
{
	struct driver_attribute * drv_attr = to_drv_attr(attr);
	struct device_driver * drv = to_driver(kobj);
	ssize_t ret = 0;

	if (drv_attr->show)
		ret = drv_attr->show(drv, buf);
	return ret;
}

static ssize_t
drv_attr_store(struct kobject * kobj, struct attribute * attr,
	       const char * buf, size_t count)
{
	struct driver_attribute * drv_attr = to_drv_attr(attr);
	struct device_driver * drv = to_driver(kobj);
	ssize_t ret = 0;

	if (drv_attr->store)
		ret = drv_attr->store(drv, buf, count);
	return ret;
}

static struct sysfs_ops driver_sysfs_ops = {
	.show	= drv_attr_show,
	.store	= drv_attr_store,
};


static void driver_release(struct kobject * kobj)
{
	struct device_driver * drv = to_driver(kobj);
	up(&drv->unload_sem);
}

static struct kobj_type ktype_driver = {
	.sysfs_ops	= &driver_sysfs_ops,
	.release	= driver_release,
};


/*
 * sysfs bindings for buses
 */


static ssize_t
bus_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
{
	struct bus_attribute * bus_attr = to_bus_attr(attr);
	struct bus_type * bus = to_bus(kobj);
	ssize_t ret = 0;

	if (bus_attr->show)
		ret = bus_attr->show(bus, buf);
	return ret;
}

static ssize_t
bus_attr_store(struct kobject * kobj, struct attribute * attr,
	       const char * buf, size_t count)
{
	struct bus_attribute * bus_attr = to_bus_attr(attr);
	struct bus_type * bus = to_bus(kobj);
	ssize_t ret = 0;

	if (bus_attr->store)
		ret = bus_attr->store(bus, buf, count);
	return ret;
}

static struct sysfs_ops bus_sysfs_ops = {
	.show	= bus_attr_show,
	.store	= bus_attr_store,
};

int bus_create_file(struct bus_type * bus, struct bus_attribute * attr)
{
	int error;
	if (get_bus(bus)) {
		error = sysfs_create_file(&bus->subsys.kset.kobj, &attr->attr);
		put_bus(bus);
	} else
		error = -EINVAL;
	return error;
}

void bus_remove_file(struct bus_type * bus, struct bus_attribute * attr)
{
	if (get_bus(bus)) {
		sysfs_remove_file(&bus->subsys.kset.kobj, &attr->attr);
		put_bus(bus);
	}
}

static struct kobj_type ktype_bus = {
	.sysfs_ops	= &bus_sysfs_ops,

};

decl_subsys(bus, &ktype_bus, NULL);

/**
 *	bus_for_each_dev - device iterator.
 *	@bus:	bus type.
 *	@start:	device to start iterating from.
 *	@data:	data for the callback.
 *	@fn:	function to be called for each device.
 *
 *	Iterate over @bus's list of devices, and call @fn for each,
 *	passing it @data. If @start is not NULL, we use that device to
 *	begin iterating from.
 *
 *	We check the return of @fn each time. If it returns anything
 *	other than 0, we break out and return that value.
 *
 *	NOTE: The device that returns a non-zero value is not retained
 *	in any way, nor is its refcount incremented. If the caller needs
 *	to retain this data, it should do, and increment the reference
 *	count in the supplied callback.
 */
int bus_for_each_dev(struct bus_type * bus, struct device * start,
		     void * data, int (*fn)(struct device *, void *))
{
	struct device *dev;
	struct list_head * head;
	int error = 0;

	if (!(bus = get_bus(bus)))
		return -EINVAL;

	head = &bus->devices.list;
	dev = list_prepare_entry(start, head, bus_list);

	down_read(&bus->subsys.rwsem);
	list_for_each_entry_continue(dev, head, bus_list) {
		get_device(dev);
		error = fn(dev, data);
		put_device(dev);
		if (error)
			break;
	}
	up_read(&bus->subsys.rwsem);
	put_bus(bus);
	return error;
}

/**
 *	bus_for_each_drv - driver iterator
 *	@bus:	bus we're dealing with.
 *	@start:	driver to start iterating on.
 *	@data:	data to pass to the callback.
 *	@fn:	function to call for each driver.
 *
 *	This is nearly identical to the device iterator above.
 *	We iterate over each driver that belongs to @bus, and call
 *	@fn for each. If @fn returns anything but 0, we break out
 *	and return it. If @start is not NULL, we use it as the head
 *	of the list.
 *
 *	NOTE: we don't return the driver that returns a non-zero
 *	value, nor do we leave the reference count incremented for that
 *	driver. If the caller needs to know that info, it must set it
 *	in the callback. It must also be sure to increment the refcount
 *	so it doesn't disappear before returning to the caller.
 */

int bus_for_each_drv(struct bus_type * bus, struct device_driver * start,
		     void * data, int (*fn)(struct device_driver *, void *))
{
	struct list_head * head;
	struct device_driver *drv;
	int error = 0;

	if(!(bus = get_bus(bus)))
		return -EINVAL;

	head = &bus->drivers.list;
	drv = list_prepare_entry(start, head, kobj.entry);

	down_read(&bus->subsys.rwsem);
	list_for_each_entry_continue(drv, head, kobj.entry) {
		get_driver(drv);
		error = fn(drv, data);
		put_driver(drv);
		if(error)
			break;
	}
	up_read(&bus->subsys.rwsem);
	put_bus(bus);
	return error;
}

/**
 *	device_bind_driver - bind a driver to one device.
 *	@dev:	device.
 *
 *	Allow manual attachment of a driver to a deivce.
 *	Caller must have already set @dev->driver.
 *
 *	Note that this does not modify the bus reference count
 *	nor take the bus's rwsem. Please verify those are accounted
 *	for before calling this. (It is ok to call with no other effort
 *	from a driver's probe() method.)
 */

void device_bind_driver(struct device * dev)
{
	pr_debug("bound device '%s' to driver '%s'\n",
		 dev->bus_id, dev->driver->name);
	list_add_tail(&dev->driver_list, &dev->driver->devices);
	sysfs_create_link(&dev->driver->kobj, &dev->kobj,
			  kobject_name(&dev->kobj));
}


/**
 *	bus_match - check compatibility between device & driver.
 *	@dev:	device.
 *	@drv:	driver.
 *
 *	First, we call the bus's match function, which should compare
 *	the device IDs the driver supports with the device IDs of the
 *	device. Note we don't do this ourselves because we don't know
 *	the format of the ID structures, nor what is to be considered
 *	a match and what is not.
 *
 *	If we find a match, we call @drv->probe(@dev) if it exists, and
 *	call attach() above.
 */
static int bus_match(struct device * dev, struct device_driver * drv)
{
	int error = -ENODEV;
	if (dev->bus->match(dev, drv)) {
		dev->driver = drv;
		if (drv->probe) {
			if ((error = drv->probe(dev))) {
				dev->driver = NULL;
				return error;
			}
		}
		device_bind_driver(dev);
		error = 0;
	}
	return error;
}


/**
 *	device_attach - try to attach device to a driver.
 *	@dev:	device.
 *
 *	Walk the list of drivers that the bus has and call bus_match()
 *	for each pair. If a compatible pair is found, break out and return.
 */
static int device_attach(struct device * dev)
{
 	struct bus_type * bus = dev->bus;
	struct list_head * entry;
	int error;

	if (dev->driver) {
		device_bind_driver(dev);
		return 1;
	}

	if (bus->match) {
		list_for_each(entry, &bus->drivers.list) {
			struct device_driver * drv = to_drv(entry);
			error = bus_match(dev, drv);
			if (!error)
				/* success, driver matched */
				return 1;
			if (error != -ENODEV)
				/* driver matched but the probe failed */
				printk(KERN_WARNING
				    "%s: probe of %s failed with error %d\n",
				    drv->name, dev->bus_id, error);
		}
	}

	return 0;
}


/**
 *	driver_attach - try to bind driver to devices.
 *	@drv:	driver.
 *
 *	Walk the list of devices that the bus has on it and try to match
 *	the driver with each one.
 *	If bus_match() returns 0 and the @dev->driver is set, we've found
 *	a compatible pair.
 *
 *	Note that we ignore the -ENODEV error from bus_match(), since it's
 *	perfectly valid for a driver not to bind to any devices.
 */
void driver_attach(struct device_driver * drv)
{
	struct bus_type * bus = drv->bus;
	struct list_head * entry;
	int error;

	if (!bus->match)
		return;

	list_for_each(entry, &bus->devices.list) {
		struct device * dev = container_of(entry, struct device, bus_list);
		if (!dev->driver) {
			error = bus_match(dev, drv);
			if (error && (error != -ENODEV))
				/* driver matched but the probe failed */
				printk(KERN_WARNING
				    "%s: probe of %s failed with error %d\n",
				    drv->name, dev->bus_id, error);
		}
	}
}


/**
 *	device_release_driver - manually detach device from driver.
 *	@dev:	device.
 *
 *	Manually detach device from driver.
 *	Note that this is called without incrementing the bus
 *	reference count nor taking the bus's rwsem. Be sure that
 *	those are accounted for before calling this function.
 */

void device_release_driver(struct device * dev)
{
	struct device_driver * drv = dev->driver;
	if (drv) {
		sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
		list_del_init(&dev->driver_list);