/*
 * 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
 */
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(global_drivers);

/**
 *      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 global_drivers, and called for
 *      each device.
 */

int sysdev_driver_register(struct sysdev_class * cls,
                           struct sysdev_driver * drv)
{
        down_write(&system_subsys.rwsem);
        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, &global_drivers);
        up_write(&system_subsys.rwsem);
        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_write(&system_subsys.rwsem);
        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_write(&system_subsys.rwsem);
}

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

                /* Notify global drivers */
                list_for_each_entry(drv, &global_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_write(&system_subsys.rwsem);
        }
        return error;
}

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

        down_write(&system_subsys.rwsem);
        list_for_each_entry(drv, &global_drivers, entry) {
                if (drv->remove)
                        drv->remove(sysdev);
        }

        list_for_each_entry(drv, &sysdev->cls->drivers, entry) {
                if (drv->remove)
                        drv->remove(sysdev);
        }
        up_write(&system_subsys.rwsem);

        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_write(&system_subsys.rwsem);
        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, &global_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_write(&system_subsys.rwsem);
}


/**
 *      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, &global_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, &global_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);