firmware_class.c

	fw_priv = _request_firmware_prepare(firmware_p, name, device, true,
					    false);
	if (IS_ERR_OR_NULL(fw_priv))
		return PTR_RET(fw_priv);

	ret = usermodehelper_read_trylock();
	if (WARN_ON(ret)) {
		dev_err(device, "firmware: %s will not be loaded\n", name);
	} else {
		ret = _request_firmware_load(fw_priv, true,
					firmware_loading_timeout());
		usermodehelper_read_unlock();
	}
	if (ret)
		_request_firmware_cleanup(firmware_p);

	return ret;
}

/**
 * release_firmware: - release the resource associated with a firmware image
 * @fw: firmware resource to release
 **/
void release_firmware(const struct firmware *fw)
{
	if (fw) {
		if (!fw_is_builtin_firmware(fw))
			firmware_free_data(fw);
		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);
	bool uevent;
};

static void request_firmware_work_func(struct work_struct *work)
{
	struct firmware_work *fw_work;
	const struct firmware *fw;
	struct firmware_priv *fw_priv;
	long timeout;
	int ret;

	fw_work = container_of(work, struct firmware_work, work);
	fw_priv = _request_firmware_prepare(&fw, fw_work->name, fw_work->device,
			fw_work->uevent, true);
	if (IS_ERR_OR_NULL(fw_priv)) {
		ret = PTR_RET(fw_priv);
		goto out;
	}

	timeout = usermodehelper_read_lock_wait(firmware_loading_timeout());
	if (timeout) {
		ret = _request_firmware_load(fw_priv, fw_work->uevent, timeout);
		usermodehelper_read_unlock();
	} else {
		dev_dbg(fw_work->device, "firmware: %s loading timed out\n",
			fw_work->name);
		ret = -EAGAIN;
	}
	if (ret)
		_request_firmware_cleanup(&fw);

 out:
	fw_work->cont(fw, fw_work->context);
	put_device(fw_work->device);

	module_put(fw_work->module);
	kfree(fw_work);
}

/**
 * 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
 * @gfp: allocation flags
 * @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.
 *
 *	Caller must hold the reference count of @device.
 *
 *	Asynchronous variant of request_firmware() for user contexts:
 *		- sleep for as small periods as possible since it may
 *		increase kernel boot time of built-in device drivers
 *		requesting firmware in their ->probe() methods, if
 *		@gfp is GFP_KERNEL.
 *
 *		- can't sleep at all if @gfp is GFP_ATOMIC.
 **/
int
request_firmware_nowait(
	struct module *module, bool uevent,
	const char *name, struct device *device, gfp_t gfp, void *context,
	void (*cont)(const struct firmware *fw, void *context))
{
	struct firmware_work *fw_work;

	fw_work = kzalloc(sizeof (struct firmware_work), gfp);
	if (!fw_work)
		return -ENOMEM;

	fw_work->module = module;
	fw_work->name = name;
	fw_work->device = device;
	fw_work->context = context;
	fw_work->cont = cont;
	fw_work->uevent = uevent;

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

	get_device(fw_work->device);
	INIT_WORK(&fw_work->work, request_firmware_work_func);
	schedule_work(&fw_work->work);
	return 0;
}

/**
 * cache_firmware - cache one firmware image in kernel memory space
 * @fw_name: the firmware image name
 *
 * Cache firmware in kernel memory so that drivers can use it when
 * system isn't ready for them to request firmware image from userspace.
 * Once it returns successfully, driver can use request_firmware or its
 * nowait version to get the cached firmware without any interacting
 * with userspace
 *
 * Return 0 if the firmware image has been cached successfully
 * Return !0 otherwise
 *
 */
int cache_firmware(const char *fw_name)
{
	int ret;
	const struct firmware *fw;

	pr_debug("%s: %s\n", __func__, fw_name);

	ret = request_firmware(&fw, fw_name, NULL);
	if (!ret)
		kfree(fw);

	pr_debug("%s: %s ret=%d\n", __func__, fw_name, ret);

	return ret;
}

/**
 * uncache_firmware - remove one cached firmware image
 * @fw_name: the firmware image name
 *
 * Uncache one firmware image which has been cached successfully
 * before.
 *
 * Return 0 if the firmware cache has been removed successfully
 * Return !0 otherwise
 *
 */
int uncache_firmware(const char *fw_name)
{
	struct firmware_buf *buf;
	struct firmware fw;

	pr_debug("%s: %s\n", __func__, fw_name);

	if (fw_get_builtin_firmware(&fw, fw_name))
		return 0;

	buf = fw_lookup_buf(fw_name);
	if (buf) {
		fw_free_buf(buf);
		return 0;
	}

	return -EINVAL;
}

#ifdef CONFIG_PM_SLEEP
static ASYNC_DOMAIN_EXCLUSIVE(fw_cache_domain);

static struct fw_cache_entry *alloc_fw_cache_entry(const char *name)
{
	struct fw_cache_entry *fce;

	fce = kzalloc(sizeof(*fce) + strlen(name) + 1, GFP_ATOMIC);
	if (!fce)
		goto exit;

	strcpy(fce->name, name);
exit:
	return fce;
}

static int __fw_entry_found(const char *name)
{
	struct firmware_cache *fwc = &fw_cache;
	struct fw_cache_entry *fce;

	list_for_each_entry(fce, &fwc->fw_names, list) {
		if (!strcmp(fce->name, name))
			return 1;
	}
	return 0;
}

static int fw_cache_piggyback_on_request(const char *name)
{
	struct firmware_cache *fwc = &fw_cache;
	struct fw_cache_entry *fce;
	int ret = 0;

	spin_lock(&fwc->name_lock);
	if (__fw_entry_found(name))
		goto found;

	fce = alloc_fw_cache_entry(name);
	if (fce) {
		ret = 1;
		list_add(&fce->list, &fwc->fw_names);
		pr_debug("%s: fw: %s\n", __func__, name);
	}
found:
	spin_unlock(&fwc->name_lock);
	return ret;
}

static void free_fw_cache_entry(struct fw_cache_entry *fce)
{
	kfree(fce);
}

static void __async_dev_cache_fw_image(void *fw_entry,
				       async_cookie_t cookie)
{
	struct fw_cache_entry *fce = fw_entry;
	struct firmware_cache *fwc = &fw_cache;
	int ret;

	ret = cache_firmware(fce->name);
	if (ret) {
		spin_lock(&fwc->name_lock);
		list_del(&fce->list);
		spin_unlock(&fwc->name_lock);

		free_fw_cache_entry(fce);
	}
}

/* called with dev->devres_lock held */
static void dev_create_fw_entry(struct device *dev, void *res,
				void *data)
{
	struct fw_name_devm *fwn = res;
	const char *fw_name = fwn->name;
	struct list_head *head = data;
	struct fw_cache_entry *fce;

	fce = alloc_fw_cache_entry(fw_name);
	if (fce)
		list_add(&fce->list, head);
}

static int devm_name_match(struct device *dev, void *res,
			   void *match_data)
{
	struct fw_name_devm *fwn = res;
	return (fwn->magic == (unsigned long)match_data);
}

static void dev_cache_fw_image(struct device *dev, void *data)
{
	LIST_HEAD(todo);
	struct fw_cache_entry *fce;
	struct fw_cache_entry *fce_next;
	struct firmware_cache *fwc = &fw_cache;

	devres_for_each_res(dev, fw_name_devm_release,
			    devm_name_match, &fw_cache,
			    dev_create_fw_entry, &todo);

	list_for_each_entry_safe(fce, fce_next, &todo, list) {
		list_del(&fce->list);

		spin_lock(&fwc->name_lock);
		/* only one cache entry for one firmware */
		if (!__fw_entry_found(fce->name)) {
			list_add(&fce->list, &fwc->fw_names);
		} else {
			free_fw_cache_entry(fce);
			fce = NULL;
		}
		spin_unlock(&fwc->name_lock);

		if (fce)
			async_schedule_domain(__async_dev_cache_fw_image,
					      (void *)fce,
					      &fw_cache_domain);
	}
}

static void __device_uncache_fw_images(void)
{
	struct firmware_cache *fwc = &fw_cache;
	struct fw_cache_entry *fce;

	spin_lock(&fwc->name_lock);
	while (!list_empty(&fwc->fw_names)) {
		fce = list_entry(fwc->fw_names.next,
				struct fw_cache_entry, list);
		list_del(&fce->list);
		spin_unlock(&fwc->name_lock);

		uncache_firmware(fce->name);
		free_fw_cache_entry(fce);

		spin_lock(&fwc->name_lock);
	}
	spin_unlock(&fwc->name_lock);
}

/**
 * device_cache_fw_images - cache devices' firmware
 *
 * If one device called request_firmware or its nowait version
 * successfully before, the firmware names are recored into the
 * device's devres link list, so device_cache_fw_images can call
 * cache_firmware() to cache these firmwares for the device,
 * then the device driver can load its firmwares easily at
 * time when system is not ready to complete loading firmware.
 */
static void device_cache_fw_images(void)
{
	struct firmware_cache *fwc = &fw_cache;
	int old_timeout;
	DEFINE_WAIT(wait);

	pr_debug("%s\n", __func__);

	/* cancel uncache work */
	cancel_delayed_work_sync(&fwc->work);

	/*
	 * use small loading timeout for caching devices' firmware
	 * because all these firmware images have been loaded
	 * successfully at lease once, also system is ready for
	 * completing firmware loading now. The maximum size of
	 * firmware in current distributions is about 2M bytes,
	 * so 10 secs should be enough.
	 */
	old_timeout = loading_timeout;
	loading_timeout = 10;

	mutex_lock(&fw_lock);
	fwc->state = FW_LOADER_START_CACHE;
	dpm_for_each_dev(NULL, dev_cache_fw_image);
	mutex_unlock(&fw_lock);

	/* wait for completion of caching firmware for all devices */
	async_synchronize_full_domain(&fw_cache_domain);

	loading_timeout = old_timeout;
}

/**
 * device_uncache_fw_images - uncache devices' firmware
 *
 * uncache all firmwares which have been cached successfully
 * by device_uncache_fw_images earlier
 */
static void device_uncache_fw_images(void)
{
	pr_debug("%s\n", __func__);
	__device_uncache_fw_images();
}

static void device_uncache_fw_images_work(struct work_struct *work)
{
	device_uncache_fw_images();
}

/**
 * device_uncache_fw_images_delay - uncache devices firmwares
 * @delay: number of milliseconds to delay uncache device firmwares
 *
 * uncache all devices's firmwares which has been cached successfully
 * by device_cache_fw_images after @delay milliseconds.
 */
static void device_uncache_fw_images_delay(unsigned long delay)
{
	schedule_delayed_work(&fw_cache.work,
			msecs_to_jiffies(delay));
}

static int fw_pm_notify(struct notifier_block *notify_block,
			unsigned long mode, void *unused)
{
	switch (mode) {
	case PM_HIBERNATION_PREPARE:
	case PM_SUSPEND_PREPARE:
		device_cache_fw_images();
		break;

	case PM_POST_SUSPEND:
	case PM_POST_HIBERNATION:
	case PM_POST_RESTORE:
		/*
		 * In case that system sleep failed and syscore_suspend is
		 * not called.
		 */
		mutex_lock(&fw_lock);
		fw_cache.state = FW_LOADER_NO_CACHE;
		mutex_unlock(&fw_lock);

		device_uncache_fw_images_delay(10 * MSEC_PER_SEC);
		break;
	}

	return 0;
}

/* stop caching firmware once syscore_suspend is reached */
static int fw_suspend(void)
{
	fw_cache.state = FW_LOADER_NO_CACHE;
	return 0;
}

static struct syscore_ops fw_syscore_ops = {
	.suspend = fw_suspend,
};
#else
static int fw_cache_piggyback_on_request(const char *name)
{
	return 0;
}
#endif

static void __init fw_cache_init(void)
{
	spin_lock_init(&fw_cache.lock);
	INIT_LIST_HEAD(&fw_cache.head);
	fw_cache.state = FW_LOADER_NO_CACHE;

#ifdef CONFIG_PM_SLEEP
	spin_lock_init(&fw_cache.name_lock);
	INIT_LIST_HEAD(&fw_cache.fw_names);

	INIT_DELAYED_WORK(&fw_cache.work,
			  device_uncache_fw_images_work);

	fw_cache.pm_notify.notifier_call = fw_pm_notify;
	register_pm_notifier(&fw_cache.pm_notify);

	register_syscore_ops(&fw_syscore_ops);
#endif
}

static int __init firmware_class_init(void)
{
	fw_cache_init();
	return class_register(&firmware_class);
}

static void __exit firmware_class_exit(void)
{
#ifdef CONFIG_PM_SLEEP
	unregister_syscore_ops(&fw_syscore_ops);
	unregister_pm_notifier(&fw_cache.pm_notify);
#endif
	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);
EXPORT_SYMBOL_GPL(cache_firmware);
EXPORT_SYMBOL_GPL(uncache_firmware);