firmware loader: introduce module parameter to customize(v4) fw search path
This patch introduces one module parameter of 'path' in firmware_class
to support customizing firmware image search path, so that people can
use its own firmware path if the default built-in paths can't meet their
demand[1], and the typical usage is passing the below from kernel command
parameter when 'firmware_class' is built in kernel:
firmware_class.path=$CUSTOMIZED_PATH
[1], https://lkml.org/lkml/2012/10/11/337
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>
diff --git a/Documentation/firmware_class/README b/Documentation/firmware_class/README
index 815b711..e9fce78 100644
--- a/Documentation/firmware_class/README
+++ b/Documentation/firmware_class/README
@@ -22,12 +22,17 @@
- calls request_firmware(&fw_entry, $FIRMWARE, device)
- kernel searchs the fimware image with name $FIRMWARE directly
in the below search path of root filesystem:
+ User customized search path by module parameter 'path'[1]
"/lib/firmware/updates/" UTS_RELEASE,
"/lib/firmware/updates",
"/lib/firmware/" UTS_RELEASE,
"/lib/firmware"
- If found, goto 7), else goto 2)
+ [1], the 'path' is a string parameter which length should be less
+ than 256, user should pass 'firmware_class.path=$CUSTOMIZED_PATH'
+ if firmware_class is built in kernel(the general situation)
+
2), userspace:
- /sys/class/firmware/xxx/{loading,data} appear.
- hotplug gets called with a firmware identifier in $FIRMWARE
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 4b04ec4..7888af7 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -269,13 +269,23 @@
}
/* direct firmware loading support */
-static const char *fw_path[] = {
+static char fw_path_para[256];
+static const char * const fw_path[] = {
+ fw_path_para,
"/lib/firmware/updates/" UTS_RELEASE,
"/lib/firmware/updates",
"/lib/firmware/" UTS_RELEASE,
"/lib/firmware"
};
+/*
+ * Typical usage is that passing 'firmware_class.path=$CUSTOMIZED_PATH'
+ * from kernel command line because firmware_class is generally built in
+ * kernel instead of module.
+ */
+module_param_string(path, fw_path_para, sizeof(fw_path_para), 0644);
+MODULE_PARM_DESC(path, "customized firmware image search path with a higher priority than default path");
+
/* Don't inline this: 'struct kstat' is biggish */
static noinline_for_stack long fw_file_size(struct file *file)
{
@@ -317,6 +327,11 @@
for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
struct file *file;
+
+ /* skip the unset customized path */
+ if (!fw_path[i][0])
+ continue;
+
snprintf(path, PATH_MAX, "%s/%s", fw_path[i], buf->fw_id);
file = filp_open(path, O_RDONLY, 0);