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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);