firmware: Add support for loading compressed files

This patch adds the support for loading compressed firmware files.
The primary motivation is to reduce the storage size; e.g. currently
the files in /lib/firmware on my machine counts up to 419MB, while
they can be reduced to 130MB by file compression.

The patch introduces a new kconfig option CONFIG_FW_LOADER_COMPRESS.
Even with this option set, the firmware loader still tries to load the
original firmware file as-is at first, but then falls back to the file
with ".xz" extension when it's not found, and the decompressed file
content is returned to the caller of request_firmware().  So, no
change is needed for the rest.

Currently only XZ format is supported.  A caveat is that the kernel XZ
helper code supports only CRC32 (or none) integrity check type, so
you'll have to compress the files via xz -C crc32 option.

Since we can't determine the expanded size immediately from an XZ
file, the patch re-uses the paged buffer that was used for the
user-mode fallback; it puts the decompressed content page, which are
vmapped at the end.  The paged buffer code is conditionally built with
a new Kconfig that is selected automatically.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/base/firmware_loader/firmware.h b/drivers/base/firmware_loader/firmware.h
index 35f4e58b2d98..7048a41973ed 100644
--- a/drivers/base/firmware_loader/firmware.h
+++ b/drivers/base/firmware_loader/firmware.h
@@ -64,12 +64,14 @@ struct fw_priv {
 	void *data;
 	size_t size;
 	size_t allocated_size;
-#ifdef CONFIG_FW_LOADER_USER_HELPER
+#ifdef CONFIG_FW_LOADER_PAGED_BUF
 	bool is_paged_buf;
-	bool need_uevent;
 	struct page **pages;
 	int nr_pages;
 	int page_array_size;
+#endif
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+	bool need_uevent;
 	struct list_head pending_list;
 #endif
 	const char *fw_name;
@@ -133,7 +135,7 @@ static inline void fw_state_done(struct fw_priv *fw_priv)
 int assign_fw(struct firmware *fw, struct device *device,
 	      enum fw_opt opt_flags);
 
-#ifdef CONFIG_FW_LOADER_USER_HELPER
+#ifdef CONFIG_FW_LOADER_PAGED_BUF
 void fw_free_paged_buf(struct fw_priv *fw_priv);
 int fw_grow_paged_buf(struct fw_priv *fw_priv, int pages_needed);
 int fw_map_paged_buf(struct fw_priv *fw_priv);