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firmware_class.c

/*
 * firmware_class.c - Multi purpose firmware loading support
 *
 * Copyright (c) 2003 Manuel Estrada Sainz
 *
 * Please see Documentation/firmware_class/ for more information.
 *
 */

#include <linux/capability.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/vmalloc.h>
#include <linux/interrupt.h>
#include <linux/bitops.h>
#include <linux/mutex.h>
#include <linux/kthread.h>

#include <linux/firmware.h>
#include "base.h"

#define to_dev(obj) container_of(obj, struct device, kobj)

MODULE_AUTHOR("Manuel Estrada Sainz");
MODULE_DESCRIPTION("Multi purpose firmware loading support");
MODULE_LICENSE("GPL");

enum {
      FW_STATUS_LOADING,
      FW_STATUS_DONE,
      FW_STATUS_ABORT,
};

static int loading_timeout = 60;    /* In seconds */

/* fw_lock could be moved to 'struct firmware_priv' but since it is just
 * guarding for corner cases a global lock should be OK */
static DEFINE_MUTEX(fw_lock);

struct firmware_priv {
      char fw_id[FIRMWARE_NAME_MAX];
      struct completion completion;
      struct bin_attribute attr_data;
      struct firmware *fw;
      unsigned long status;
      int alloc_size;
      struct timer_list timeout;
};

static void
fw_load_abort(struct firmware_priv *fw_priv)
{
      set_bit(FW_STATUS_ABORT, &fw_priv->status);
      wmb();
      complete(&fw_priv->completion);
}

static ssize_t
firmware_timeout_show(struct class *class, char *buf)
{
      return sprintf(buf, "%d\n", loading_timeout);
}

/**
 * firmware_timeout_store - set number of seconds to wait for firmware
 * @class: device class pointer
 * @buf: buffer to scan for timeout value
 * @count: number of bytes in @buf
 *
 *    Sets the number of seconds to wait for the firmware.  Once
 *    this expires an error will be returned to the driver and no
 *    firmware will be provided.
 *
 *    Note: zero means 'wait forever'.
 **/
static ssize_t
firmware_timeout_store(struct class *class, const char *buf, size_t count)
{
      loading_timeout = simple_strtol(buf, NULL, 10);
      if (loading_timeout < 0)
            loading_timeout = 0;
      return count;
}

static CLASS_ATTR(timeout, 0644, firmware_timeout_show, firmware_timeout_store);

static void fw_dev_release(struct device *dev);

static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env)
{
      struct firmware_priv *fw_priv = dev_get_drvdata(dev);

      if (add_uevent_var(env, "FIRMWARE=%s", fw_priv->fw_id))
            return -ENOMEM;
      if (add_uevent_var(env, "TIMEOUT=%i", loading_timeout))
            return -ENOMEM;

      return 0;
}

static struct class firmware_class = {
      .name       = "firmware",
      .dev_uevent = firmware_uevent,
      .dev_release      = fw_dev_release,
};

static ssize_t firmware_loading_show(struct device *dev,
                             struct device_attribute *attr, char *buf)
{
      struct firmware_priv *fw_priv = dev_get_drvdata(dev);
      int loading = test_bit(FW_STATUS_LOADING, &fw_priv->status);
      return sprintf(buf, "%d\n", loading);
}

/**
 * firmware_loading_store - set value in the 'loading' control file
 * @dev: device pointer
 * @attr: device attribute pointer
 * @buf: buffer to scan for loading control value
 * @count: number of bytes in @buf
 *
 *    The relevant values are:
 *
 *     1: Start a load, discarding any previous partial load.
 *     0: Conclude the load and hand the data to the driver code.
 *    -1: Conclude the load with an error and discard any written data.
 **/
static ssize_t firmware_loading_store(struct device *dev,
                              struct device_attribute *attr,
                              const char *buf, size_t count)
{
      struct firmware_priv *fw_priv = dev_get_drvdata(dev);
      int loading = simple_strtol(buf, NULL, 10);

      switch (loading) {
      case 1:
            mutex_lock(&fw_lock);
            if (!fw_priv->fw) {
                  mutex_unlock(&fw_lock);
                  break;
            }
            vfree(fw_priv->fw->data);
            fw_priv->fw->data = NULL;
            fw_priv->fw->size = 0;
            fw_priv->alloc_size = 0;
            set_bit(FW_STATUS_LOADING, &fw_priv->status);
            mutex_unlock(&fw_lock);
            break;
      case 0:
            if (test_bit(FW_STATUS_LOADING, &fw_priv->status)) {
                  complete(&fw_priv->completion);
                  clear_bit(FW_STATUS_LOADING, &fw_priv->status);
                  break;
            }
            /* fallthrough */
      default:
            printk(KERN_ERR "%s: unexpected value (%d)\n", __FUNCTION__,
                   loading);
            /* fallthrough */
      case -1:
            fw_load_abort(fw_priv);
            break;
      }

      return count;
}

static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);

static ssize_t
firmware_data_read(struct kobject *kobj, struct bin_attribute *bin_attr,
               char *buffer, loff_t offset, size_t count)
{
      struct device *dev = to_dev(kobj);
      struct firmware_priv *fw_priv = dev_get_drvdata(dev);
      struct firmware *fw;
      ssize_t ret_count = count;

      mutex_lock(&fw_lock);
      fw = fw_priv->fw;
      if (!fw || test_bit(FW_STATUS_DONE, &fw_priv->status)) {
            ret_count = -ENODEV;
            goto out;
      }
      if (offset > fw->size) {
            ret_count = 0;
            goto out;
      }
      if (offset + ret_count > fw->size)
            ret_count = fw->size - offset;

      memcpy(buffer, fw->data + offset, ret_count);
out:
      mutex_unlock(&fw_lock);
      return ret_count;
}

static int
fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size)
{
      u8 *new_data;
      int new_size = fw_priv->alloc_size;

      if (min_size <= fw_priv->alloc_size)
            return 0;

      new_size = ALIGN(min_size, PAGE_SIZE);
      new_data = vmalloc(new_size);
      if (!new_data) {
            printk(KERN_ERR "%s: unable to alloc buffer\n", __FUNCTION__);
            /* Make sure that we don't keep incomplete data */
            fw_load_abort(fw_priv);
            return -ENOMEM;
      }
      fw_priv->alloc_size = new_size;
      if (fw_priv->fw->data) {
            memcpy(new_data, fw_priv->fw->data, fw_priv->fw->size);
            vfree(fw_priv->fw->data);
      }
      fw_priv->fw->data = new_data;
      BUG_ON(min_size > fw_priv->alloc_size);
      return 0;
}

/**
 * firmware_data_write - write method for firmware
 * @kobj: kobject for the device
 * @bin_attr: bin_attr structure
 * @buffer: buffer being written
 * @offset: buffer offset for write in total data store area
 * @count: buffer size
 *
 *    Data written to the 'data' attribute will be later handed to
 *    the driver as a firmware image.
 **/
static ssize_t
firmware_data_write(struct kobject *kobj, struct bin_attribute *bin_attr,
                char *buffer, loff_t offset, size_t count)
{
      struct device *dev = to_dev(kobj);
      struct firmware_priv *fw_priv = dev_get_drvdata(dev);
      struct firmware *fw;
      ssize_t retval;

      if (!capable(CAP_SYS_RAWIO))
            return -EPERM;

      mutex_lock(&fw_lock);
      fw = fw_priv->fw;
      if (!fw || test_bit(FW_STATUS_DONE, &fw_priv->status)) {
            retval = -ENODEV;
            goto out;
      }
      retval = fw_realloc_buffer(fw_priv, offset + count);
      if (retval)
            goto out;

      memcpy(fw->data + offset, buffer, count);

      fw->size = max_t(size_t, offset + count, fw->size);
      retval = count;
out:
      mutex_unlock(&fw_lock);
      return retval;
}

static struct bin_attribute firmware_attr_data_tmpl = {
      .attr = {.name = "data", .mode = 0644},
      .size = 0,
      .read = firmware_data_read,
      .write = firmware_data_write,
};

static void fw_dev_release(struct device *dev)
{
      struct firmware_priv *fw_priv = dev_get_drvdata(dev);

      kfree(fw_priv);
      kfree(dev);

      module_put(THIS_MODULE);
}

static void
firmware_class_timeout(u_long data)
{
      struct firmware_priv *fw_priv = (struct firmware_priv *) data;
      fw_load_abort(fw_priv);
}

static inline void fw_setup_device_id(struct device *f_dev, struct device *dev)
{
      /* XXX warning we should watch out for name collisions */
      strlcpy(f_dev->bus_id, dev->bus_id, BUS_ID_SIZE);
}

static int fw_register_device(struct device **dev_p, const char *fw_name,
                        struct device *device)
{
      int retval;
      struct firmware_priv *fw_priv = kzalloc(sizeof(*fw_priv),
                                    GFP_KERNEL);
      struct device *f_dev = kzalloc(sizeof(*f_dev), GFP_KERNEL);

      *dev_p = NULL;

      if (!fw_priv || !f_dev) {
            printk(KERN_ERR "%s: kmalloc failed\n", __FUNCTION__);
            retval = -ENOMEM;
            goto error_kfree;
      }

      init_completion(&fw_priv->completion);
      fw_priv->attr_data = firmware_attr_data_tmpl;
      strlcpy(fw_priv->fw_id, fw_name, FIRMWARE_NAME_MAX);

      fw_priv->timeout.function = firmware_class_timeout;
      fw_priv->timeout.data = (u_long) fw_priv;
      init_timer(&fw_priv->timeout);

      fw_setup_device_id(f_dev, device);
      f_dev->parent = device;
      f_dev->class = &firmware_class;
      dev_set_drvdata(f_dev, fw_priv);
      f_dev->uevent_suppress = 1;
      retval = device_register(f_dev);
      if (retval) {
            printk(KERN_ERR "%s: device_register failed\n",
                   __FUNCTION__);
            goto error_kfree;
      }
      *dev_p = f_dev;
      return 0;

error_kfree:
      kfree(fw_priv);
      kfree(f_dev);
      return retval;
}

static int fw_setup_device(struct firmware *fw, struct device **dev_p,
                     const char *fw_name, struct device *device,
                     int uevent)
{
      struct device *f_dev;
      struct firmware_priv *fw_priv;
      int retval;

      *dev_p = NULL;
      retval = fw_register_device(&f_dev, fw_name, device);
      if (retval)
            goto out;

      /* Need to pin this module until class device is destroyed */
      __module_get(THIS_MODULE);

      fw_priv = dev_get_drvdata(f_dev);

      fw_priv->fw = fw;
      retval = sysfs_create_bin_file(&f_dev->kobj, &fw_priv->attr_data);
      if (retval) {
            printk(KERN_ERR "%s: sysfs_create_bin_file failed\n",
                   __FUNCTION__);
            goto error_unreg;
      }

      retval = device_create_file(f_dev, &dev_attr_loading);
      if (retval) {
            printk(KERN_ERR "%s: device_create_file failed\n",
                   __FUNCTION__);
            goto error_unreg;
      }

      if (uevent)
            f_dev->uevent_suppress = 0;
      *dev_p = f_dev;
      goto out;

error_unreg:
      device_unregister(f_dev);
out:
      return retval;
}

static int
_request_firmware(const struct firmware **firmware_p, const char *name,
             struct device *device, int uevent)
{
      struct device *f_dev;
      struct firmware_priv *fw_priv;
      struct firmware *firmware;
      int retval;

      if (!firmware_p)
            return -EINVAL;

      *firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_KERNEL);
      if (!firmware) {
            printk(KERN_ERR "%s: kmalloc(struct firmware) failed\n",
                   __FUNCTION__);
            retval = -ENOMEM;
            goto out;
      }

      retval = fw_setup_device(firmware, &f_dev, name, device, uevent);
      if (retval)
            goto error_kfree_fw;

      fw_priv = dev_get_drvdata(f_dev);

      if (uevent) {
            if (loading_timeout > 0) {
                  fw_priv->timeout.expires = jiffies + loading_timeout * HZ;
                  add_timer(&fw_priv->timeout);
            }

            kobject_uevent(&f_dev->kobj, KOBJ_ADD);
            wait_for_completion(&fw_priv->completion);
            set_bit(FW_STATUS_DONE, &fw_priv->status);
            del_timer_sync(&fw_priv->timeout);
      } else
            wait_for_completion(&fw_priv->completion);

      mutex_lock(&fw_lock);
      if (!fw_priv->fw->size || test_bit(FW_STATUS_ABORT, &fw_priv->status)) {
            retval = -ENOENT;
            release_firmware(fw_priv->fw);
            *firmware_p = NULL;
      }
      fw_priv->fw = NULL;
      mutex_unlock(&fw_lock);
      device_unregister(f_dev);
      goto out;

error_kfree_fw:
      kfree(firmware);
      *firmware_p = NULL;
out:
      return retval;
}

/**
 * request_firmware: - send firmware request and wait for it
 * @firmware_p: pointer to firmware image
 * @name: name of firmware file
 * @device: device for which firmware is being loaded
 *
 *      @firmware_p will be used to return a firmware image by the name
 *      of @name for device @device.
 *
 *      Should be called from user context where sleeping is allowed.
 *
 *      @name will be used as $FIRMWARE in the uevent environment and
 *      should be distinctive enough not to be confused with any other
 *      firmware image for this or any other device.
 **/
int
request_firmware(const struct firmware **firmware_p, const char *name,
                 struct device *device)
{
        int uevent = 1;
        return _request_firmware(firmware_p, name, device, uevent);
}

/**
 * release_firmware: - release the resource associated with a firmware image
 * @fw: firmware resource to release
 **/
void
release_firmware(const struct firmware *fw)
{
      if (fw) {
            vfree(fw->data);
            kfree(fw);
      }
}

/* Async support */
struct firmware_work {
      struct work_struct work;
      struct module *module;
      const char *name;
      struct device *device;
      void *context;
      void (*cont)(const struct firmware *fw, void *context);
      int uevent;
};

static int
request_firmware_work_func(void *arg)
{
      struct firmware_work *fw_work = arg;
      const struct firmware *fw;
      int ret;
      if (!arg) {
            WARN_ON(1);
            return 0;
      }
      ret = _request_firmware(&fw, fw_work->name, fw_work->device,
            fw_work->uevent);
      if (ret < 0)
            fw_work->cont(NULL, fw_work->context);
      else {
            fw_work->cont(fw, fw_work->context);
            release_firmware(fw);
      }
      module_put(fw_work->module);
      kfree(fw_work);
      return ret;
}

/**
 * request_firmware_nowait: asynchronous version of request_firmware
 * @module: module requesting the firmware
 * @uevent: sends uevent to copy the firmware image if this flag
 *    is non-zero else the firmware copy must be done manually.
 * @name: name of firmware file
 * @device: device for which firmware is being loaded
 * @context: will be passed over to @cont, and
 *    @fw may be %NULL if firmware request fails.
 * @cont: function will be called asynchronously when the firmware
 *    request is over.
 *
 *    Asynchronous variant of request_firmware() for contexts where
 *    it is not possible to sleep.
 **/
int
request_firmware_nowait(
      struct module *module, int uevent,
      const char *name, struct device *device, void *context,
      void (*cont)(const struct firmware *fw, void *context))
{
      struct task_struct *task;
      struct firmware_work *fw_work = kmalloc(sizeof (struct firmware_work),
                                    GFP_ATOMIC);

      if (!fw_work)
            return -ENOMEM;
      if (!try_module_get(module)) {
            kfree(fw_work);
            return -EFAULT;
      }

      *fw_work = (struct firmware_work) {
            .module = module,
            .name = name,
            .device = device,
            .context = context,
            .cont = cont,
            .uevent = uevent,
      };

      task = kthread_run(request_firmware_work_func, fw_work,
                      "firmware/%s", name);

      if (IS_ERR(task)) {
            fw_work->cont(NULL, fw_work->context);
            module_put(fw_work->module);
            kfree(fw_work);
            return PTR_ERR(task);
      }
      return 0;
}

static int __init
firmware_class_init(void)
{
      int error;
      error = class_register(&firmware_class);
      if (error) {
            printk(KERN_ERR "%s: class_register failed\n", __FUNCTION__);
            return error;
      }
      error = class_create_file(&firmware_class, &class_attr_timeout);
      if (error) {
            printk(KERN_ERR "%s: class_create_file failed\n",
                   __FUNCTION__);
            class_unregister(&firmware_class);
      }
      return error;

}
static void __exit
firmware_class_exit(void)
{
      class_unregister(&firmware_class);
}

fs_initcall(firmware_class_init);
module_exit(firmware_class_exit);

EXPORT_SYMBOL(release_firmware);
EXPORT_SYMBOL(request_firmware);
EXPORT_SYMBOL(request_firmware_nowait);

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