linux_kernel/drivers/base/sys.c

/*
 * sys.c - pseudo-bus for system 'devices' (cpus, PICs, timers, etc)
 *
 * Copyright (c) 2002-3 Patrick Mochel
 *               2002-3 Open Source Development Lab
 *
 * This file is released under the GPLv2
 *
 * This exports a 'system' bus type.
 * By default, a 'sys' bus gets added to the root of the system. There will
 * always be core system devices. Devices can use sysdev_register() to
 * add themselves as children of the system bus.
 */

#include <linux/config.h>
#include <linux/sysdev.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/string.h>


extern struct subsystem devices_subsys;

#define to_sysdev(k) container_of(k, struct sys_device, kobj)
#define to_sysdev_attr(a) container_of(a, struct sysdev_attribute, attr)


static ssize_t
sysdev_show(struct kobject * kobj, struct attribute * attr, char * buffer)
{
	struct sys_device * sysdev = to_sysdev(kobj);
	struct sysdev_attribute * sysdev_attr = to_sysdev_attr(attr);

	if (sysdev_attr->show)
		return sysdev_attr->show(sysdev, buffer);
	return 0;
}


static ssize_t
sysdev_store(struct kobject * kobj, struct attribute * attr,
	     const char * buffer, size_t count)
{
	struct sys_device * sysdev = to_sysdev(kobj);
	struct sysdev_attribute * sysdev_attr = to_sysdev_attr(attr);

	if (sysdev_attr->store)
		return sysdev_attr->store(sysdev, buffer, count);
	return 0;
}

static struct sysfs_ops sysfs_ops = {
	.show	= sysdev_show,
	.store	= sysdev_store,
};

static struct kobj_type ktype_sysdev = {
	.sysfs_ops	= &sysfs_ops,
};


int sysdev_create_file(struct sys_device * s, struct sysdev_attribute * a)
{
	return sysfs_create_file(&s->kobj, &a->attr);
}


void sysdev_remove_file(struct sys_device * s, struct sysdev_attribute * a)
{
	sysfs_remove_file(&s->kobj, &a->attr);
}

EXPORT_SYMBOL_GPL(sysdev_create_file);
EXPORT_SYMBOL_GPL(sysdev_remove_file);

/*
 * declare system_subsys
 */
static decl_subsys(system, &ktype_sysdev, NULL);

int sysdev_class_register(struct sysdev_class * cls)
{
	pr_debug("Registering sysdev class '%s'\n",
		 kobject_name(&cls->kset.kobj));
	INIT_LIST_HEAD(&cls->drivers);
	cls->kset.subsys = &system_subsys;
	kset_set_kset_s(cls, system_subsys);
	return kset_register(&cls->kset);
}

void sysdev_class_unregister(struct sysdev_class * cls)
{
	pr_debug("Unregistering sysdev class '%s'\n",
		 kobject_name(&cls->kset.kobj));
	kset_unregister(&cls->kset);
}

EXPORT_SYMBOL_GPL(sysdev_class_register);
EXPORT_SYMBOL_GPL(sysdev_class_unregister);


static LIST_HEAD(sysdev_drivers);
static DECLARE_MUTEX(sysdev_drivers_lock);

/**
 *	sysdev_driver_register - Register auxillary driver
 * 	@cls:	Device class driver belongs to.
 *	@drv:	Driver.
 *
 *	If @cls is valid, then @drv is inserted into @cls->drivers to be
 *	called on each operation on devices of that class. The refcount
 *	of @cls is incremented.
 *	Otherwise, @drv is inserted into sysdev_drivers, and called for
 *	each device.
 */

int sysdev_driver_register(struct sysdev_class * cls,
			   struct sysdev_driver * drv)
{
	down(&sysdev_drivers_lock);
	if (cls && kset_get(&cls->kset)) {
		list_add_tail(&drv->entry, &cls->drivers);

		/* If devices of this class already exist, tell the driver */
		if (drv->add) {
			struct sys_device *dev;
			list_for_each_entry(dev, &cls->kset.list, kobj.entry)
				drv->add(dev);
		}
	} else
		list_add_tail(&drv->entry, &sysdev_drivers);
	up(&sysdev_drivers_lock);
	return 0;
}


/**
 *	sysdev_driver_unregister - Remove an auxillary driver.
 *	@cls:	Class driver belongs to.
 *	@drv:	Driver.
 */
void sysdev_driver_unregister(struct sysdev_class * cls,
			      struct sysdev_driver * drv)
{
	down(&sysdev_drivers_lock);
	list_del_init(&drv->entry);
	if (cls) {
		if (drv->remove) {
			struct sys_device *dev;
			list_for_each_entry(dev, &cls->kset.list, kobj.entry)
				drv->remove(dev);
		}
		kset_put(&cls->kset);
	}
	up(&sysdev_drivers_lock);
}

EXPORT_SYMBOL_GPL(sysdev_driver_register);
EXPORT_SYMBOL_GPL(sysdev_driver_unregister);



/**
 *	sysdev_register - add a system device to the tree
 *	@sysdev:	device in question
 *
 */
int sysdev_register(struct sys_device * sysdev)
{
	int error;
	struct sysdev_class * cls = sysdev->cls;

	if (!cls)
		return -EINVAL;

	/* Make sure the kset is set */
	sysdev->kobj.kset = &cls->kset;

	/* But make sure we point to the right type for sysfs translation */
	sysdev->kobj.ktype = &ktype_sysdev;
	error = kobject_set_name(&sysdev->kobj, "%s%d",
			 kobject_name(&cls->kset.kobj), sysdev->id);
	if (error)
		return error;

	pr_debug("Registering sys device '%s'\n", kobject_name(&sysdev->kobj));

	/* Register the object */
	error = kobject_register(&sysdev->kobj);

	if (!error) {
		struct sysdev_driver * drv;

		down(&sysdev_drivers_lock);
		/* Generic notification is implicit, because it's that
		 * code that should have called us.
		 */

		/* Notify global drivers */
		list_for_each_entry(drv, &sysdev_drivers, entry) {
			if (drv->add)
				drv->add(sysdev);
		}

		/* Notify class auxillary drivers */
		list_for_each_entry(drv, &cls->drivers, entry) {
			if (drv->add)
				drv->add(sysdev);
		}
		up(&sysdev_drivers_lock);
	}
	return error;
}

void sysdev_unregister(struct sys_device * sysdev)
{
	struct sysdev_driver * drv;

	down(&sysdev_drivers_lock);
	list_for_each_entry(drv, &sysdev_drivers, entry) {
		if (drv->remove)
			drv->remove(sysdev);
	}

	list_for_each_entry(drv, &sysdev->cls->drivers, entry) {
		if (drv->remove)
			drv->remove(sysdev);
	}
	up(&sysdev_drivers_lock);

	kobject_unregister(&sysdev->kobj);
}



/**
 *	sysdev_shutdown - Shut down all system devices.
 *
 *	Loop over each class of system devices, and the devices in each
 *	of those classes. For each device, we call the shutdown method for
 *	each driver registered for the device - the globals, the auxillaries,
 *	and the class driver.
 *
 *	Note: The list is iterated in reverse order, so that we shut down
 *	child devices before we shut down thier parents. The list ordering
 *	is guaranteed by virtue of the fact that child devices are registered
 *	after their parents.
 */

void sysdev_shutdown(void)
{
	struct sysdev_class * cls;

	pr_debug("Shutting Down System Devices\n");

	down(&sysdev_drivers_lock);
	list_for_each_entry_reverse(cls, &system_subsys.kset.list,
				    kset.kobj.entry) {
		struct sys_device * sysdev;

		pr_debug("Shutting down type '%s':\n",
			 kobject_name(&cls->kset.kobj));

		list_for_each_entry(sysdev, &cls->kset.list, kobj.entry) {
			struct sysdev_driver * drv;
			pr_debug(" %s\n", kobject_name(&sysdev->kobj));

			/* Call global drivers first. */
			list_for_each_entry(drv, &sysdev_drivers, entry) {
				if (drv->shutdown)
					drv->shutdown(sysdev);
			}

			/* Call auxillary drivers next. */
			list_for_each_entry(drv, &cls->drivers, entry) {
				if (drv->shutdown)
					drv->shutdown(sysdev);
			}

			/* Now call the generic one */
			if (cls->shutdown)
				cls->shutdown(sysdev);
		}
	}
	up(&sysdev_drivers_lock);
}


/**
 *	sysdev_suspend - Suspend all system devices.
 *	@state:		Power state to enter.
 *
 *	We perform an almost identical operation as sys_device_shutdown()
 *	above, though calling ->suspend() instead. Interrupts are disabled
 *	when this called. Devices are responsible for both saving state and
 *	quiescing or powering down the device.
 *
 *	This is only called by the device PM core, so we let them handle
 *	all synchronization.
 */

int sysdev_suspend(u32 state)
{
	struct sysdev_class * cls;

	pr_debug("Suspending System Devices\n");

	list_for_each_entry_reverse(cls, &system_subsys.kset.list,
				    kset.kobj.entry) {
		struct sys_device * sysdev;

		pr_debug("Suspending type '%s':\n",
			 kobject_name(&cls->kset.kobj));

		list_for_each_entry(sysdev, &cls->kset.list, kobj.entry) {
			struct sysdev_driver * drv;
			pr_debug(" %s\n", kobject_name(&sysdev->kobj));

			/* Call global drivers first. */
			list_for_each_entry(drv, &sysdev_drivers, entry) {
				if (drv->suspend)
					drv->suspend(sysdev, state);
			}

			/* Call auxillary drivers next. */
			list_for_each_entry(drv, &cls->drivers, entry) {
				if (drv->suspend)
					drv->suspend(sysdev, state);
			}

			/* Now call the generic one */
			if (cls->suspend)
				cls->suspend(sysdev, state);
		}
	}
	return 0;
}


/**
 *	sysdev_resume - Bring system devices back to life.
 *
 *	Similar to sys_device_suspend(), but we iterate the list forwards
 *	to guarantee that parent devices are resumed before their children.
 *
 *	Note: Interrupts are disabled when called.
 */

int sysdev_resume(void)
{
	struct sysdev_class * cls;

	pr_debug("Resuming System Devices\n");

	list_for_each_entry(cls, &system_subsys.kset.list, kset.kobj.entry) {
		struct sys_device * sysdev;

		pr_debug("Resuming type '%s':\n",
			 kobject_name(&cls->kset.kobj));

		list_for_each_entry(sysdev, &cls->kset.list, kobj.entry) {
			struct sysdev_driver * drv;
			pr_debug(" %s\n", kobject_name(&sysdev->kobj));

			/* First, call the class-specific one */
			if (cls->resume)
				cls->resume(sysdev);

			/* Call auxillary drivers next. */
			list_for_each_entry(drv, &cls->drivers, entry) {
				if (drv->resume)
					drv->resume(sysdev);
			}

			/* Call global drivers. */
			list_for_each_entry(drv, &sysdev_drivers, entry) {
				if (drv->resume)
					drv->resume(sysdev);
			}

		}
	}
	return 0;
}


int __init system_bus_init(void)
{
	system_subsys.kset.kobj.parent = &devices_subsys.kset.kobj;
	return subsystem_register(&system_subsys);
}

EXPORT_SYMBOL_GPL(sysdev_register);
EXPORT_SYMBOL_GPL(sysdev_unregister);