firmware loader: introduce cache_firmware and uncache_firmware

This patches introduce two kernel APIs of cache_firmware and
uncache_firmware, both of which take the firmware file name
as the only parameter.

So any drivers can call cache_firmware to cache the specified
firmware file into kernel memory, and can use the cached firmware
in situations which can't request firmware from user space.

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>

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 848ad97e8d79be5f87d47f2fec023e9cf01ef1df..fc119ce6fdb8f7d9298fde3e21b607fa1db9ab17 100644 (file)
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -142,6 +142,17 @@ static struct firmware_buf *__allocate_fw_buf(const char *fw_name,
        return buf;
 }
 
+static struct firmware_buf *__fw_lookup_buf(const char *fw_name)
+{
+       struct firmware_buf *tmp;
+       struct firmware_cache *fwc = &fw_cache;
+
+       list_for_each_entry(tmp, &fwc->head, list)
+               if (!strcmp(tmp->fw_id, fw_name))
+                       return tmp;
+       return NULL;
+}
+
 static int fw_lookup_and_allocate_buf(const char *fw_name,
                                      struct firmware_cache *fwc,
                                      struct firmware_buf **buf)
@@ -149,14 +160,13 @@ static int fw_lookup_and_allocate_buf(const char *fw_name,
        struct firmware_buf *tmp;
 
        spin_lock(&fwc->lock);
-       list_for_each_entry(tmp, &fwc->head, list)
-               if (!strcmp(tmp->fw_id, fw_name)) {
-                       kref_get(&tmp->ref);
-                       spin_unlock(&fwc->lock);
-                       *buf = tmp;
-                       return 1;
-               }
-
+       tmp = __fw_lookup_buf(fw_name);
+       if (tmp) {
+               kref_get(&tmp->ref);
+               spin_unlock(&fwc->lock);
+               *buf = tmp;
+               return 1;
+       }
        tmp = __allocate_fw_buf(fw_name, fwc);
        if (tmp)
                list_add(&tmp->list, &fwc->head);
@@ -167,6 +177,18 @@ static int fw_lookup_and_allocate_buf(const char *fw_name,
        return tmp ? 0 : -ENOMEM;
 }
 
+static struct firmware_buf *fw_lookup_buf(const char *fw_name)
+{
+       struct firmware_buf *tmp;
+       struct firmware_cache *fwc = &fw_cache;
+
+       spin_lock(&fwc->lock);
+       tmp = __fw_lookup_buf(fw_name);
+       spin_unlock(&fwc->lock);
+
+       return tmp;
+}
+
 static void __fw_free_buf(struct kref *ref)
 {
        struct firmware_buf *buf = to_fwbuf(ref);
@@ -852,6 +874,66 @@ request_firmware_nowait(
        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;
+}
+
 static int __init firmware_class_init(void)
 {
        fw_cache_init();
@@ -869,3 +951,5 @@ 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);

diff --git a/include/linux/firmware.h b/include/linux/firmware.h
index e85b771f3d8c5d574c7229890e6693793bbb59eb..e4279fedb93a305023059882cca49da35ca7f420 100644 (file)
--- a/include/linux/firmware.h
+++ b/include/linux/firmware.h
@@ -47,6 +47,8 @@ int request_firmware_nowait(
        void (*cont)(const struct firmware *fw, void *context));
 
 void release_firmware(const struct firmware *fw);
+int cache_firmware(const char *name);
+int uncache_firmware(const char *name);
 #else
 static inline int request_firmware(const struct firmware **fw,
                                   const char *name,
@@ -65,6 +67,16 @@ static inline int request_firmware_nowait(
 static inline void release_firmware(const struct firmware *fw)
 {
 }
+
+static inline int cache_firmware(const char *name)
+{
+       return -ENOENT;
+}
+
+static inline int uncache_firmware(const char *name)
+{
+       return -EINVAL;
+}
 #endif
 
 #endif