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/*
 * drivers/base/core.c - core driver model code (device registration, etc)
 *
 * Copyright (c) 2002-3 Patrick Mochel
 * Copyright (c) 2002-3 Open Source Development Labs
 *
 * This file is released under the GPLv2
 *
 */

#undef DEBUG

#include <linuxcomp.h>

#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>

#include <asm/semaphore.h>

#include "base.h"

int (*platform_notify)(struct device * dev) = NULL;
int (*platform_notify_remove)(struct device * dev) = NULL;

/*
 * sysfs bindings for devices.
 */

#define to_dev(obj) container_of(obj,struct device,kobj)
#define to_dev_attr(_attr) container_of(_attr,struct device_attribute,attr)

extern struct attribute * dev_default_attrs[];

static ssize_t
dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
{
        struct device_attribute * dev_attr = to_dev_attr(attr);
        struct device * dev = to_dev(kobj);
        ssize_t ret = 0;

        if (dev_attr->show)
                ret = dev_attr->show(dev,buf);
        return ret;
}

static ssize_t
dev_attr_store(struct kobject * kobj, struct attribute * attr,
               const char * buf, size_t count)
{
        struct device_attribute * dev_attr = to_dev_attr(attr);
        struct device * dev = to_dev(kobj);
        ssize_t ret = 0;

        if (dev_attr->store)
                ret = dev_attr->store(dev,buf,count);
        return ret;
}

static struct sysfs_ops dev_sysfs_ops = {
        .show   = dev_attr_show,
        .store  = dev_attr_store,
};


/**
 *      device_release - free device structure.
 *      @kobj:  device's kobject.
 *
 *      This is called once the reference count for the object
 *      reaches 0. We forward the call to the device's release
 *      method, which should handle actually freeing the structure.
 */
static void device_release(struct kobject * kobj)
{
        struct device * dev = to_dev(kobj);
        //struct completion * c = dev->complete;

        if (dev->release)
                dev->release(dev);
        else {
                printk(KERN_ERR "Device '%s' does not have a release() function, "
                        "it is broken and must be fixed.\n",
                        dev->bus_id);
        }
        //if (c)
        //      complete(c);
}

static struct kobj_type ktype_device = {
        .release        = device_release,
        .sysfs_ops      = &dev_sysfs_ops,
        .default_attrs  = dev_default_attrs,
};


static int dev_hotplug_filter(struct kset *kset, struct kobject *kobj)
{
        struct kobj_type *ktype = get_ktype(kobj);

        if (ktype == &ktype_device) {
                struct device *dev = to_dev(kobj);
                if (dev->bus)
                        return 1;
        }
        return 0;
}

static char *dev_hotplug_name(struct kset *kset, struct kobject *kobj)
{
        struct device *dev = to_dev(kobj);

        return dev->bus->name;
}

static int dev_hotplug(struct kset *kset, struct kobject *kobj, char **envp,
                        int num_envp, char *buffer, int buffer_size)
{
        struct device *dev = to_dev(kobj);
        int retval = 0;

        if (dev->bus->hotplug) {
                /* have the bus specific function add its stuff */
                retval = dev->bus->hotplug (dev, envp, num_envp, buffer, buffer_size);
                        if (retval) {
                        pr_debug ("%s - hotplug() returned %d\n",
                                  __FUNCTION__, retval);
                }
        }

        return retval;
}

static struct kset_hotplug_ops device_hotplug_ops = {
        .filter =       dev_hotplug_filter,
        .name =         dev_hotplug_name,
        .hotplug =      dev_hotplug,
};

/**
 *      device_subsys - structure to be registered with kobject core.
 */

decl_subsys(devices, &ktype_device, &device_hotplug_ops);


/**
 *      device_create_file - create sysfs attribute file for device.
 *      @dev:   device.
 *      @attr:  device attribute descriptor.
 */

int device_create_file(struct device * dev, struct device_attribute * attr)
{
        int error = 0;
        if (get_device(dev)) {
                error = 0;//sysfs_create_file(&dev->kobj,&attr->attr);
                put_device(dev);
        }
        return error;
}

/**
 *      device_remove_file - remove sysfs attribute file.
 *      @dev:   device.
 *      @attr:  device attribute descriptor.
 */

void device_remove_file(struct device * dev, struct device_attribute * attr)
{
        if (get_device(dev)) {
                //sysfs_remove_file(&dev->kobj,&attr->attr);
                put_device(dev);
        }
}


/**
 *      device_initialize - init device structure.
 *      @dev:   device.
 *
 *      This prepares the device for use by other layers,
 *      including adding it to the device hierarchy.
 *      It is the first half of device_register(), if called by
 *      that, though it can also be called separately, so one
 *      may use @dev's fields (e.g. the refcount).
 */

void device_initialize(struct device *dev)
{
        kobj_set_kset_s(dev,devices_subsys);
        kobject_init(&dev->kobj);
        INIT_LIST_HEAD(&dev->node);
        INIT_LIST_HEAD(&dev->children);
        INIT_LIST_HEAD(&dev->driver_list);
        INIT_LIST_HEAD(&dev->bus_list);
}

/**
 *      device_add - add device to device hierarchy.
 *      @dev:   device.
 *
 *      This is part 2 of device_register(), though may be called
 *      separately _iff_ device_initialize() has been called separately.
 *
 *      This adds it to the kobject hierarchy via kobject_add(), adds it
 *      to the global and sibling lists for the device, then
 *      adds it to the other relevant subsystems of the driver model.
 */
int device_add(struct device *dev)
{
        struct device * parent;
        int error;

        dev = get_device(dev);

        if (!dev || !strlen(dev->bus_id))
                return -EINVAL;

        parent = get_device(dev->parent);

        pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);

        /* first, register with generic layer. */
        kobject_set_name(&dev->kobj,dev->bus_id);
       
        if (parent)
                dev->kobj.parent = &parent->kobj;

        if ((error = kobject_add(&dev->kobj)))
                goto Error;
        //if ((error = device_pm_add(dev)))
        //      goto PMError;

        if ((error = bus_add_device(dev)))
                goto BusError;

        //down_write(&devices_subsys.rwsem);
        if (parent)
                list_add_tail(&dev->node,&parent->children);
        //up_write(&devices_subsys.rwsem);

        /* notify platform of device entry */
        if (platform_notify)
                platform_notify(dev);
 Done:
        put_device(dev);
        return error;
 BusError:
        //device_pm_remove(dev);
 //PMError:
        kobject_unregister(&dev->kobj);
 Error:
        if (parent)
                put_device(parent);
        goto Done;
}


/**
 *      device_register - register a device with the system.
 *      @dev:   pointer to the device structure
 *
 *      This happens in two clean steps - initialize the device
 *      and add it to the system. The two steps can be called
 *      separately, but this is the easiest and most common.
 *      I.e. you should only call the two helpers separately if
 *      have a clearly defined need to use and refcount the device
 *      before it is added to the hierarchy.
 */

int device_register(struct device *dev)
{
        device_initialize(dev);
        return device_add(dev);
}


/**
 *      get_device - increment reference count for device.
 *      @dev:   device.
 *
 *      This simply forwards the call to kobject_get(), though
 *      we do take care to provide for the case that we get a NULL
 *      pointer passed in.
 */

struct device * get_device(struct device * dev)
{
        return dev ? to_dev(kobject_get(&dev->kobj)) : NULL;
}


/**
 *      put_device - decrement reference count.
 *      @dev:   device in question.
 */
void put_device(struct device * dev)
{
        kobject_put(&dev->kobj);
}


/**
 *      device_del - delete device from system.
 *      @dev:   device.
 *
 *      This is the first part of the device unregistration
 *      sequence. This removes the device from the lists we control
 *      from here, has it removed from the other driver model
 *      subsystems it was added to in device_add(), and removes it
 *      from the kobject hierarchy.
 *
 *      NOTE: this should be called manually _iff_ device_add() was
 *      also called manually.
 */

void device_del(struct device * dev)
{
        struct device * parent = dev->parent;

        //down_write(&devices_subsys.rwsem);
        if (parent)
                list_del_init(&dev->node);
        //up_write(&devices_subsys.rwsem);

        /* Notify the platform of the removal, in case they
         * need to do anything...
         */
        if (platform_notify_remove)
                platform_notify_remove(dev);
        bus_remove_device(dev);
        //device_pm_remove(dev);
        kobject_del(&dev->kobj);
        if (parent)
                put_device(parent);
}

/**
 *      device_unregister - unregister device from system.
 *      @dev:   device going away.
 *
 *      We do this in two parts, like we do device_register(). First,
 *      we remove it from all the subsystems with device_del(), then
 *      we decrement the reference count via put_device(). If that
 *      is the final reference count, the device will be cleaned up
 *      via device_release() above. Otherwise, the structure will
 *      stick around until the final reference to the device is dropped.
 */
void device_unregister(struct device * dev)
{
        pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id);
        device_del(dev);
        put_device(dev);
}


/**
 *      device_unregister_wait - Unregister device and wait for it to be freed.
 *      @dev: Device to unregister.
 *
 *      For the cases where the caller needs to wait for all references to
 *      be dropped from the device before continuing (e.g. modules with
 *      statically allocated devices), this function uses a completion struct
 *      to wait, along with a matching complete() in device_release() above.
 */

void device_unregister_wait(struct device * dev)
{
        struct completion c;
        init_completion(&c);
        dev->complete = &c;
        device_unregister(dev);
        //wait_for_completion(&c);
}

/**
 *      device_for_each_child - device child iterator.
 *      @dev:   parent struct device.
 *      @data:  data for the callback.
 *      @fn:    function to be called for each device.
 *
 *      Iterate over @dev's child devices, and call @fn for each,
 *      passing it @data.
 *
 *      We check the return of @fn each time. If it returns anything
 *      other than 0, we break out and return that value.
 */
int device_for_each_child(struct device * dev, void * data,
                     int (*fn)(struct device *, void *))
{
        struct device * child;
        int error = 0;

        //down_read(&devices_subsys.rwsem);
        list_for_each_entry(child,&dev->children,node) {
                if((error = fn(child,data)))
                        break;
        }
        //up_read(&devices_subsys.rwsem);
        return error;
}

int __init devices_init(void)
{
        return subsystem_register(&devices_subsys);
}

EXPORT_SYMBOL(device_for_each_child);

EXPORT_SYMBOL(device_initialize);
EXPORT_SYMBOL(device_add);
EXPORT_SYMBOL(device_register);

EXPORT_SYMBOL(device_del);
EXPORT_SYMBOL(device_unregister);
EXPORT_SYMBOL(device_unregister_wait);
EXPORT_SYMBOL(get_device);
EXPORT_SYMBOL(put_device);

EXPORT_SYMBOL(device_create_file);
EXPORT_SYMBOL(device_remove_file);