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/*
 * 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
 *
 */

#undef DEBUG

#include <linuxcomp.h>

#include <linux/device.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/string.h>
#include "base.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 = 0;//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 list_head * head, * entry;
        int error = 0;

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

        head = start ? &start->bus_list : &bus->devices.list;

        //down_read(&bus->subsys.rwsem);
        list_for_each(entry,head) {
                struct device * dev = get_device(to_dev(entry));
                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, * entry;
        int error = 0;

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

        head = start ? &start->kobj.entry : &bus->drivers.list;

        //down_read(&bus->subsys.rwsem);
        list_for_each(entry,head) {
                struct device_driver * drv = get_driver(to_drv(entry));
                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);
                //device_detach_shutdown(dev);
                if (drv->remove)
                        drv->remove(dev);
                dev->driver = NULL;
        }
}


/**
 *      driver_detach - detach driver from all devices it controls.
 *      @drv:   driver.
 */

static void driver_detach(struct device_driver * drv)
{
        struct list_head * entry, * next;
        list_for_each_safe(entry,next,&drv->devices) {
                struct device * dev = container_of(entry,struct device,driver_list);
                device_release_driver(dev);
        }
       
}

/**
 *      bus_add_device - add device to bus
 *      @dev:   device being added
 *
 *      - Add the device to its bus's list of devices.
 *      - Try to attach to driver.
 *      - Create link to device's physical location.
 */
int bus_add_device(struct device * dev)
{
        struct bus_type * bus = get_bus(dev->bus);
        int error = 0;

        if (bus) {
                //down_write(&dev->bus->subsys.rwsem);
                pr_debug("bus %s: add device %s\n",bus->name,dev->bus_id);
                list_add_tail(&dev->bus_list,&dev->bus->devices.list);
                device_attach(dev);
                //up_write(&dev->bus->subsys.rwsem);
                //sysfs_create_link(&bus->devices.kobj,&dev->kobj,dev->bus_id);
        }
        return error;
}

/**
 *      bus_remove_device - remove device from bus
 *      @dev:   device to be removed
 *
 *      - Remove symlink from bus's directory.
 *      - Delete device from bus's list.
 *      - Detach from its driver.
 *      - Drop reference taken in bus_add_device().
 */
void bus_remove_device(struct device * dev)
{
        if (dev->bus) {
                //sysfs_remove_link(&dev->bus->devices.kobj,dev->bus_id);
                //down_write(&dev->bus->subsys.rwsem);
                pr_debug("bus %s: remove device %s\n",dev->bus->name,dev->bus_id);
                device_release_driver(dev);
                list_del_init(&dev->bus_list);
                //up_write(&dev->bus->subsys.rwsem);
                put_bus(dev->bus);
        }
}


/**
 *      bus_add_driver - Add a driver to the bus.
 *      @drv:   driver.
 *
 */
int bus_add_driver(struct device_driver * drv)
{
        struct bus_type * bus = get_bus(drv->bus);
        int error = 0;

        if (bus) {
                pr_debug("bus %s: add driver %s\n",bus->name,drv->name);
                kobject_set_name(&drv->kobj,drv->name);
                drv->kobj.kset = &bus->drivers;
                if ((error = kobject_register(&drv->kobj))) {
                        put_bus(bus);
                        return error;
                }

                //down_write(&bus->subsys.rwsem);
                driver_attach(drv);
                //up_write(&bus->subsys.rwsem);

        }
        return error;
}


/**
 *      bus_remove_driver - delete driver from bus's knowledge.
 *      @drv:   driver.
 *
 *      Detach the driver from the devices it controls, and remove
 *      it from its bus's list of drivers. Finally, we drop the reference
 *      to the bus we took in bus_add_driver().
 */

void bus_remove_driver(struct device_driver * drv)
{
        if (drv->bus) {
                //down_write(&drv->bus->subsys.rwsem);
                pr_debug("bus %s: remove driver %s\n",drv->bus->name,drv->name);
                driver_detach(drv);
                //up_write(&drv->bus->subsys.rwsem);
                kobject_unregister(&drv->kobj);
                put_bus(drv->bus);
        }
}


/* Helper for bus_rescan_devices's iter */
static int bus_rescan_devices_helper(struct device *dev, void *data)
{
        int *count = data;

        if (!dev->driver && device_attach(dev))
                (*count)++;

        return 0;
}


/**
 *      bus_rescan_devices - rescan devices on the bus for possible drivers
 *      @bus:   the bus to scan.
 *
 *      This function will look for devices on the bus with no driver
 *      attached and rescan it against existing drivers to see if it
 *      matches any. Calls device_attach(). Returns the number of devices
 *      that were sucessfully bound to a driver.
 */
int bus_rescan_devices(struct bus_type * bus)
{
        int count = 0;

        bus_for_each_dev(bus, NULL, &count, bus_rescan_devices_helper);

        return count;
}


struct bus_type * get_bus(struct bus_type * bus)
{
        return bus ? container_of(subsys_get(&bus->subsys),struct bus_type,subsys) : NULL;
}

void put_bus(struct bus_type * bus)
{
        subsys_put(&bus->subsys);
}


/**
 *      find_bus - locate bus by name.
 *      @name:  name of bus.
 *
 *      Call kset_find_obj() to iterate over list of buses to
 *      find a bus by name. Return bus if found.
 */

struct bus_type * find_bus(char * name)
{
        struct kobject * k = kset_find_obj(&bus_subsys.kset,name);
        return k ? to_bus(k) : NULL;
}

/**
 *      bus_register - register a bus with the system.
 *      @bus:   bus.
 *
 *      Once we have that, we registered the bus with the kobject
 *      infrastructure, then register the children subsystems it has:
 *      the devices and drivers that belong to the bus.
 */
int bus_register(struct bus_type * bus)
{
        kobject_set_name(&bus->subsys.kset.kobj,bus->name);
        subsys_set_kset(bus,bus_subsys);
        subsystem_register(&bus->subsys);

        kobject_set_name(&bus->devices.kobj, "devices");
        bus->devices.subsys = &bus->subsys;
        kset_register(&bus->devices);

        kobject_set_name(&bus->drivers.kobj, "drivers");
        bus->drivers.subsys = &bus->subsys;
        bus->drivers.ktype = &ktype_driver;
        kset_register(&bus->drivers);
 
        pr_debug("bus type '%s' registered\n",bus->name);
        return 0;
}


/**
 *      bus_unregister - remove a bus from the system
 *      @bus:   bus.
 *
 *      Unregister the child subsystems and the bus itself.
 *      Finally, we call put_bus() to release the refcount
 */
void bus_unregister(struct bus_type * bus)
{
        pr_debug("bus %s: unregistering\n",bus->name);
        kset_unregister(&bus->drivers);
        kset_unregister(&bus->devices);
        subsystem_unregister(&bus->subsys);
}

int __init buses_init(void)
{
        return subsystem_register(&bus_subsys);
}


EXPORT_SYMBOL(bus_for_each_dev);
EXPORT_SYMBOL(bus_for_each_drv);

EXPORT_SYMBOL(device_bind_driver);
EXPORT_SYMBOL(device_release_driver);

EXPORT_SYMBOL(bus_add_device);
EXPORT_SYMBOL(bus_remove_device);
EXPORT_SYMBOL(bus_register);
EXPORT_SYMBOL(bus_unregister);
EXPORT_SYMBOL(bus_rescan_devices);
EXPORT_SYMBOL(get_bus);
EXPORT_SYMBOL(put_bus);
EXPORT_SYMBOL(find_bus);

EXPORT_SYMBOL(bus_create_file);
EXPORT_SYMBOL(bus_remove_file);