ANDROID: firmware_loader: Add support for customer firmware paths

Currently firmware_class.patch commandline can take a single path for
loading firmwares on custom paths. SoC vendors and oems can have
firmwares in multiple file system paths. So add support for paassing
multiple paths through command line for firmware loader.
Add a getter function to read the class path.

For example - firmware_class.path="/vendor,/vendor/firmware_mnt,
/oem/firmware". firmware_class.path can take upto 10 file system
paths with ',' separation.

Bug: 259298396
Change-Id: I31d1470d7dd0255c7aefd856f3c129bdb4b7f2e8
Signed-off-by: Prasad Sodagudi <quic_psodagud@quicinc.com>
Signed-off-by: Vamsi Krishna Lanka <quic_vamslank@quicinc.com>
(cherry picked from commit ce17e299)

drivers/base/firmware_loader/main.c

@@ -467,21 +467,85 @@ static int fw_decompress_xz(struct device *dev, struct fw_priv *fw_priv,
 #endif /* CONFIG_FW_LOADER_COMPRESS_XZ */
 
 /* direct firmware loading support */
-static char fw_path_para[256];
+#define CUSTOM_FW_PATH_COUNT	10
+#define PATH_SIZE		255
+static char fw_path_para[CUSTOM_FW_PATH_COUNT][PATH_SIZE];
 static const char * const fw_path[] = {
-	fw_path_para,
+	fw_path_para[0],
+	fw_path_para[1],
+	fw_path_para[2],
+	fw_path_para[3],
+	fw_path_para[4],
+	fw_path_para[5],
+	fw_path_para[6],
+	fw_path_para[7],
+	fw_path_para[8],
+	fw_path_para[9],
 	"/lib/firmware/updates/" UTS_RELEASE,
 	"/lib/firmware/updates",
 	"/lib/firmware/" UTS_RELEASE,
 	"/lib/firmware"
 };
 
+static char strpath[PATH_SIZE * CUSTOM_FW_PATH_COUNT];
+static int firmware_param_path_set(const char *val, const struct kernel_param *kp)
+{
+	int i;
+	char *path, *end;
+
+	strscpy(strpath, val, sizeof(strpath));
+	/* Remove leading and trailing spaces from path */
+	path = strim(strpath);
+	for (i = 0; path && i < CUSTOM_FW_PATH_COUNT; i++) {
+		end = strchr(path, ',');
+
+		/* Skip continuous token case, for example ',,,' */
+		if (end == path) {
+			i--;
+			path = ++end;
+			continue;
+		}
+
+		if (end != NULL)
+			*end = '\0';
+		else {
+			/* end of the string reached and no other tockens ','  */
+			strscpy(fw_path_para[i], path, PATH_SIZE);
+			break;
+		}
+
+		strscpy(fw_path_para[i], path, PATH_SIZE);
+		path = ++end;
+	}
+
+	return 0;
+}
+
+static int firmware_param_path_get(char *buffer, const struct kernel_param *kp)
+{
+	int count = 0, i;
+
+	for (i = 0; i < CUSTOM_FW_PATH_COUNT; i++) {
+		if (strlen(fw_path_para[i]) != 0)
+			count += scnprintf(buffer + count, PATH_SIZE, "%s%s", fw_path_para[i], ",");
+	}
+
+	buffer[count - 1] = '\0';
+
+	return count - 1;
+}
 /*
- * Typical usage is that passing 'firmware_class.path=$CUSTOMIZED_PATH'
+ * Typical usage is that passing 'firmware_class.path=/vendor,/firwmare_mnt'
  * from kernel command line because firmware_class is generally built in
- * kernel instead of module.
+ * kernel instead of module. ',' is used as delimiter for setting 10
+ * custom paths for firmware loader.
  */
-module_param_string(path, fw_path_para, sizeof(fw_path_para), 0644);
+
+static const struct kernel_param_ops firmware_param_ops = {
+	.set = firmware_param_path_set,
+	.get = firmware_param_path_get,
+};
+module_param_cb(path, &firmware_param_ops, NULL, 0644);
 MODULE_PARM_DESC(path, "customized firmware image search path with a higher priority than default path");
 
 static int