[U-Boot] [PATCH v2 04/11] drivers:dfu: new feature: separated bootloader alt setting

[Przemyslaw Marczak]

This patch introduces new feature: initialization of the dfu
bootloader entity from a separate environmental variable which
can be set on a boot time.

By default, DFU always check environmental variable: $dfu_alt_info.

Changes:
- DFU will also look for environmental variable: $dfu_alt_bootloader
- if any of dfu_alt_* variable is properly defined, then function
  dfu_init_env_entities() will return success.

Use case:
Some devices can boot from various media type (SD, eMMC, NAND, etc.)
or some board configs are common for more than one board type.
In a such case, bootloader is probably placed on a different
devices or even offsets. So such DFU feature is welcome.

Signed-off-by: Przemyslaw Marczak <p.marczak at samsung.com>

---
Changes v2:
- new commit
---
 drivers/dfu/dfu.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/dfu/dfu.c b/drivers/dfu/dfu.c
index a938109..8848624 100644
--- a/drivers/dfu/dfu.c
+++ b/drivers/dfu/dfu.c
@@ -44,24 +44,32 @@ static int dfu_find_alt_num(const char *s)
 
 int dfu_init_env_entities(char *interface, int dev)
 {
+	const char *alt_info[] = {"dfu_alt_info", "dfu_alt_bootloader"};
 	const char *str_env;
 	char *env_bkp;
-	int ret;
+	int ret, i;
+	int alt_init_cnt = 0;
+
+	for (i = 0; i < ARRAY_SIZE(alt_info); i++) {
+		str_env = getenv(alt_info[i]);
+		if (!str_env)
+			continue;
 
-	str_env = getenv("dfu_alt_info");
-	if (!str_env) {
-		error("\"dfu_alt_info\" env variable not defined!\n");
-		return -EINVAL;
+		env_bkp = strdup(str_env);
+		ret = dfu_config_entities(env_bkp, interface, dev);
+		free(env_bkp);
+
+		if (ret)
+			continue;
+
+		alt_init_cnt++;
 	}
 
-	env_bkp = strdup(str_env);
-	ret = dfu_config_entities(env_bkp, interface, dev);
-	if (ret) {
+	if (!alt_init_cnt) {
 		error("DFU entities configuration failed!\n");
-		return ret;
+		return -1;
 	}
 
-	free(env_bkp);
 	return 0;
 }
 
-- 
1.9.1