[PATCH 2/2] firmware loader: introduce kernel parameter to customize fw search path

From: Ming Lei
Date: Tue Oct 23 2012 - 22:50:02 EST


This patch introduces one kernel parameter of 'fw_path' 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].

[1], https://lkml.org/lkml/2012/10/11/337

Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
---
Documentation/firmware_class/README | 1 +
Documentation/kernel-parameters.txt | 9 +++++++++
drivers/base/firmware_class.c | 24 ++++++++++++++++++++++--
3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/Documentation/firmware_class/README b/Documentation/firmware_class/README
index 815b711..af63ad3 100644
--- a/Documentation/firmware_class/README
+++ b/Documentation/firmware_class/README
@@ -22,6 +22,7 @@
- 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 kernel parameter of 'fw_path'
"/lib/firmware/updates/" UTS_RELEASE,
"/lib/firmware/updates",
"/lib/firmware/" UTS_RELEASE,
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9776f06..d1125c5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -52,6 +52,7 @@ parameter is applicable:
EVM Extended Verification Module
FB The frame buffer device is enabled.
FTRACE Function tracing enabled.
+ FW The firmware loader is enabled.
GCOV GCOV profiling is enabled.
HW Appropriate hardware is enabled.
IA-64 IA-64 architecture is enabled.
@@ -843,6 +844,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Format: <interval>,<probability>,<space>,<times>
See also Documentation/fault-injection/.

+ fw_path= [FW]
+ Customized firmware image search path for kernel
+ direct loading, which has higher priority than
+ built-in default search path.
+ Format: <string>, length < 256
+ direcory path, such as /lib/firmware.
+ See Documentation/firmware_class/README.
+
floppy= [HW]
See Documentation/blockdev/floppy.txt.

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 8945f4e..e7db931 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -274,6 +274,17 @@ static const char *fw_path[] = {
"/lib/firmware"
};

+static char fw_path_para[256];
+static int __init customized_path(char *str)
+{
+ if (strlen(str) < 256)
+ strlcpy(fw_path_para, str, sizeof(fw_path_para));
+ return 1;
+}
+__setup("fw_path=", customized_path);
+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 long fw_file_size(struct file *file)
{
@@ -313,9 +324,18 @@ static bool fw_get_filesystem_firmware(struct firmware_buf *buf)
bool success = false;
char *path = __getname();

- for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
+ for (i = -1; i < ARRAY_SIZE(fw_path); i++) {
struct file *file;
- snprintf(path, PATH_MAX, "%s/%s", fw_path[i], buf->fw_id);
+
+ if (i < 0) {
+ if (!fw_path_para[0]) /* No customized path */
+ continue;
+ snprintf(path, PATH_MAX, "%s/%s", fw_path_para,
+ buf->fw_id);
+ } else {
+ snprintf(path, PATH_MAX, "%s/%s", fw_path[i],
+ buf->fw_id);
+ }

file = filp_open(path, O_RDONLY, 0);
if (IS_ERR(file))
--
1.7.9.5

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