[PATCH v5] misc: fs-loader: Use fw_storage_interface instead of storage_interface

[MD Danish Anwar]

The fs-loader driver reads env storage_interface and uses it to load
firmware file into memory using the medium set by env. Update the driver
to use env fw_storage_interface as this variable is only used to load
firmwares. This is to keep all variables used by fs-loader driver with
'fw_' prefix. All other variables have 'fw_' prefix except for
storage_interface.

The env storage_interface will act as fallback so that the
existing implementations do not break.

Also update the FS Loader documentation accordingly.

Signed-off-by: MD Danish Anwar <danishanwar at ti.com>
---
Cc: Sean Anderson <seanga2 at gmail.com>
Changes from v4 to v5:
*) Modified commit message to make the motive cleared for this commit.
*) Added RB tag of Ravi.
*) Rebased on the latest u-boot/master [commit
   a4650bf65e4b7d3ef04c90ba8031374428e4a682]

v4: https://lore.kernel.org/all/20240130062627.2344282-1-danishanwar@ti.com/

 doc/develop/driver-model/fs_firmware_loader.rst | 5 ++++-
 drivers/misc/fs_loader.c                        | 5 ++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/doc/develop/driver-model/fs_firmware_loader.rst b/doc/develop/driver-model/fs_firmware_loader.rst
index 149b8b436e..410cc1442d 100644
--- a/doc/develop/driver-model/fs_firmware_loader.rst
+++ b/doc/develop/driver-model/fs_firmware_loader.rst
@@ -98,8 +98,11 @@ through the U-Boot environment variable during run time.
 
 For examples:
 
+fw_storage_interface:
+  Firmware storage interface, it can be "mmc", "usb", "sata" or "ubi".
 storage_interface:
-  Storage interface, it can be "mmc", "usb", "sata" or "ubi".
+  Storage interface, it can be "mmc", "usb", "sata" or "ubi". This acts
+  as a fallback if fw_storage_interface is not set.
 fw_dev_part:
   Block device number and its partition, it can be "0:1".
 fw_ubi_mtdpart:
diff --git a/drivers/misc/fs_loader.c b/drivers/misc/fs_loader.c
index 1ffc199ba1..3798dab5b6 100644
--- a/drivers/misc/fs_loader.c
+++ b/drivers/misc/fs_loader.c
@@ -153,7 +153,10 @@ static int fw_get_filesystem_firmware(struct udevice *dev)
 	char *storage_interface, *dev_part, *ubi_mtdpart, *ubi_volume;
 	int ret;
 
-	storage_interface = env_get("storage_interface");
+	storage_interface = env_get("fw_storage_interface");
+	if (!storage_interface)
+		storage_interface = env_get("storage_interface");
+
 	dev_part = env_get("fw_dev_part");
 	ubi_mtdpart = env_get("fw_ubi_mtdpart");
 	ubi_volume = env_get("fw_ubi_volume");
-- 
2.34.1