firmware: introduce device_cache/uncache_fw_images

This patch introduces the three helpers below:

	void device_cache_fw_images(void)
	void device_uncache_fw_images(void)
	void device_uncache_fw_images_delay(unsigned long)

so we can use device_cache_fw_images() to cache firmware for
all devices which need firmware to work, and the device driver
can get the firmware easily from kernel memory when system isn't
ready for completing requests of loading firmware.

After system is ready for completing firmware loading, driver core
will call device_uncache_fw_images() or its delay version to free
the cached firmware.

The above helpers will be used to cache device firmware during
system suspend/resume cycle in the following patches.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/firmware_class.c

@@ -22,6 +22,11 @@
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/list.h>
+#include <linux/async.h>
+#include <linux/pm.h>
+
+#include "base.h"
+#include "power/power.h"
 
 MODULE_AUTHOR("Manuel Estrada Sainz");
 MODULE_DESCRIPTION("Multi purpose firmware loading support");
@@ -90,6 +95,19 @@ struct firmware_cache {
 	/* firmware_buf instance will be added into the below list */
 	spinlock_t lock;
 	struct list_head head;
+
+	/*
+	 * Names of firmware images which have been cached successfully
+	 * will be added into the below list so that device uncache
+	 * helper can trace which firmware images have been cached
+	 * before.
+	 */
+	spinlock_t name_lock;
+	struct list_head fw_names;
+
+	wait_queue_head_t wait_queue;
+	int cnt;
+	struct delayed_work work;
 };
 
 struct firmware_buf {
@@ -106,6 +124,11 @@ struct firmware_buf {
 	char fw_id[];
 };
 
+struct fw_cache_entry {
+	struct list_head list;
+	char name[];
+};
+
 struct firmware_priv {
 	struct timer_list timeout;
 	bool nowait;
@@ -220,12 +243,6 @@ static void fw_free_buf(struct firmware_buf *buf)
 	kref_put(&buf->ref, __fw_free_buf);
 }
 
-static void __init fw_cache_init(void)
-{
-	spin_lock_init(&fw_cache.lock);
-	INIT_LIST_HEAD(&fw_cache.head);
-}
-
 static struct firmware_priv *to_firmware_priv(struct device *dev)
 {
 	return container_of(dev, struct firmware_priv, dev);
@@ -1008,6 +1025,198 @@ int uncache_firmware(const char *fw_name)
 	return -EINVAL;
 }
 
+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 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)
+		goto free;
+
+	spin_lock(&fwc->name_lock);
+	list_add(&fce->list, &fwc->fw_names);
+	spin_unlock(&fwc->name_lock);
+	goto drop_ref;
+
+free:
+	free_fw_cache_entry(fce);
+drop_ref:
+	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)
+{
+	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++;
+		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;
+	struct device *dev;
+	DEFINE_WAIT(wait);
+
+	pr_debug("%s\n", __func__);
+
+	device_pm_lock();
+	list_for_each_entry(dev, &dpm_list, power.entry)
+		dev_cache_fw_image(dev);
+	device_pm_unlock();
+
+	/* 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);
+}
+
+/**
+ * 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 void __init fw_cache_init(void)
+{
+	spin_lock_init(&fw_cache.lock);
+	INIT_LIST_HEAD(&fw_cache.head);
+
+	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);
+}
+
 static int __init firmware_class_init(void)
 {
 	fw_cache_init();