diff options
| author | Ming Lei <ming.lei@canonical.com> | 2012-10-24 10:49:33 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-10-25 11:53:36 -0700 |
| commit | 10bd4c7572b6c6eb97f1c15dedd2d36c63907f91 (patch) | |
| tree | 01c09c3f0cc9e8dbd351ae34580f5cd873272b11 /Documentation | |
| parent | 66081a72517a131430dcf986775f3268aafcb546 (diff) | |
firmware loader: document kernel direct loading
This patch adds description on recently introduced direct firmware
loading by Linus.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/firmware_class/README | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/Documentation/firmware_class/README b/Documentation/firmware_class/README index 7eceaff63f5..815b711bcd8 100644 --- a/Documentation/firmware_class/README +++ b/Documentation/firmware_class/README @@ -18,32 +18,40 @@ High level behavior (mixed): ============================ - kernel(driver): calls request_firmware(&fw_entry, $FIRMWARE, device) - - userspace: + 1), kernel(driver): + - calls request_firmware(&fw_entry, $FIRMWARE, device) + - kernel searchs the fimware image with name $FIRMWARE directly + in the below search path of root filesystem: + "/lib/firmware/updates/" UTS_RELEASE, + "/lib/firmware/updates", + "/lib/firmware/" UTS_RELEASE, + "/lib/firmware" + - If found, goto 7), else goto 2) + + 2), userspace: - /sys/class/firmware/xxx/{loading,data} appear. - hotplug gets called with a firmware identifier in $FIRMWARE and the usual hotplug environment. - hotplug: echo 1 > /sys/class/firmware/xxx/loading - kernel: Discard any previous partial load. + 3), kernel: Discard any previous partial load. - userspace: + 4), userspace: - hotplug: cat appropriate_firmware_image > \ /sys/class/firmware/xxx/data - kernel: grows a buffer in PAGE_SIZE increments to hold the image as it + 5), kernel: grows a buffer in PAGE_SIZE increments to hold the image as it comes in. - userspace: + 6), userspace: - hotplug: echo 0 > /sys/class/firmware/xxx/loading - kernel: request_firmware() returns and the driver has the firmware + 7), kernel: request_firmware() returns and the driver has the firmware image in fw_entry->{data,size}. If something went wrong request_firmware() returns non-zero and fw_entry is set to NULL. - kernel(driver): Driver code calls release_firmware(fw_entry) releasing + 8), kernel(driver): Driver code calls release_firmware(fw_entry) releasing the firmware image and any related resource. High level behavior (driver code): |