add support for firmware loading

diff --git a/util-linux/Config.in b/util-linux/Config.in
index 2184df153349b9035e8efdf24e896cc27926c77c..1040ce282f8f716ecd6aa874bc81d9382816c092 100644 (file)
--- a/util-linux/Config.in
+++ b/util-linux/Config.in
@@ -294,6 +294,17 @@ config FEATURE_MDEV_EXEC
 
          For more information, please see docs/mdev.txt
 
+config FEATURE_MDEV_LOAD_FIRMWARE
+       bool "Support loading of firmwares"
+       default n
+       depends on MDEV
+       help
+         Some devices need to load firmware before they can be usable.
+
+         These devices will request userspace look up the files in
+         /lib/firmware/ and if it exists, send it to the kernel for
+         loading into the hardware.
+
 config MKSWAP
        bool "mkswap"
        default n

diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index d1b2684bc60698ac19715cb5d2dee0e4eec01b6c..8e5b8a94b66bd5002226b153220ef29591e3769a 100644 (file)
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -226,6 +226,71 @@ static void find_dev(char *path)
        closedir(dir);
 }
 
+/* For the full gory details, see linux/Documentation/firmware_class/README
+ *
+ * Firmware loading works like this:
+ * - kernel sets FIRMWARE env var
+ * - userspace checks /lib/firmware/$FIRMWARE
+ * - userspace waits for /sys/$DEVPATH/loading to appear
+ * - userspace writes "1" to /sys/$DEVPATH/loading
+ * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
+ * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
+ * - kernel loads firmware into device
+ */
+static inline void load_firmware(const char * const firmware, const char * const sysfs_path)
+{
+       int cnt;
+       int firmware_fd, loading_fd, data_fd;
+
+       /* check for $FIRMWARE from kernel */
+       /* XXX: dont bother: open(NULL) works same as open("no-such-file")
+        * if (!firmware)
+        *      return;
+        */
+
+       /* check for /lib/firmware/$FIRMWARE */
+       xchdir("/lib/firmware");
+       firmware_fd = xopen(firmware, O_WRONLY);
+
+       /* in case we goto out ... */
+       data_fd = -1;
+
+       /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
+       xchdir(sysfs_path);
+       for (cnt = 0; cnt < 30; ++cnt) {
+               loading_fd = open("loading", O_WRONLY);
+               if (loading_fd == -1)
+                       sleep(1);
+               else
+                       break;
+       }
+       if (loading_fd == -1)
+               goto out;
+
+       /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
+       if (write(loading_fd, "1", 1) != 1)
+               goto out;
+
+       /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
+       data_fd = open("data", O_WRONLY);
+       if (data_fd == -1)
+               goto out;
+       cnt = bb_copyfd_eof(firmware_fd, data_fd);
+
+       /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
+       if (cnt > 0)
+               write(loading_fd, "0", 1);
+       else
+               write(loading_fd, "-1", 2);
+
+ out:
+       if (ENABLE_FEATURE_CLEAN_UP) {
+               close(firmware_fd);
+               close(loading_fd);
+               close(data_fd);
+       }
+}
+
 int mdev_main(int argc, char **argv);
 int mdev_main(int argc, char **argv)
 {
@@ -257,8 +322,14 @@ int mdev_main(int argc, char **argv)
                        bb_show_usage();
 
                sprintf(temp, "/sys%s", env_path);
-               if (!strcmp(action, "add")) make_device(temp,0);
-               else if (!strcmp(action, "remove")) make_device(temp,1);
+               if (!strcmp(action, "remove"))
+                       make_device(temp, 1);
+               else if (!strcmp(action, "add")) {
+                       make_device(temp, 0);
+
+                       if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE)
+                               load_firmware(getenv("FIRMWARE"), temp);
+               }
        }
 
        if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);