firmware_class.c

 * 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 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_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);
	list_for_each_entry(fce, &fwc->fw_names, list) {
		if (!strcmp(fce->name, 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);
	}

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

	wake_up(&fwc->wait_queue);
}

/* 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);
		fwc->cnt++;
		list_add(&fce->list, &fwc->fw_names);
		spin_unlock(&fwc->name_lock);

		async_schedule(__async_dev_cache_fw_image, (void *)fce);
	}
}

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__);

	/*
	 * 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 */
	spin_lock(&fwc->name_lock);
	for (;;) {
		prepare_to_wait(&fwc->wait_queue, &wait,
				TASK_UNINTERRUPTIBLE);
		if (!fwc->cnt)
			break;

		spin_unlock(&fwc->name_lock);

		schedule();

		spin_lock(&fwc->name_lock);
	}
	spin_unlock(&fwc->name_lock);
	finish_wait(&fwc->wait_queue, &wait);

	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);
	fw_cache.cnt = 0;

	init_waitqueue_head(&fw_cache.wait_queue);
	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);