[U-Boot] [PATCH] env_mmc: support overriding mmc dev from board code

[Clemens Gruber]

This enables boards to choose where to/from the environment should be
saved/loaded. They can then for example support using the same device
(dynamically) from which the bootloader was launched to load and save
env data and do not have to define CONFIG_SYS_MMC_ENV_DEV statically.

In my use case, the environment needs to be on the same device I
booted from. It can be the eMMC or an optional SD card.
I therefore would override mmc_get_env_dev in the board code, read the
CPU registers to determine where we booted from and return the
corresponding device index.

Cc: Tom Rini <trini at konsulko.com>
Cc: Stephen Warren <swarren at nvidia.com>
Cc: Tim Harvey <tharvey at gateworks.com>
Cc: Simon Glass <sjg at chromium.org>
Cc: Hans de Goede <hdegoede at redhat.com>

Signed-off-by: Clemens Gruber <clemens.gruber at pqgruber.com>

---
 common/env_mmc.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/common/env_mmc.c b/common/env_mmc.c
index 15aa43d..bdb452e 100644
--- a/common/env_mmc.c
+++ b/common/env_mmc.c
@@ -54,6 +54,11 @@ __weak int mmc_get_env_addr(struct mmc *mmc, int copy, u32 *env_addr)
 	return 0;
 }
 
+__weak int mmc_get_env_dev(void)
+{
+	return CONFIG_SYS_MMC_ENV_DEV;
+}
+
 int env_init(void)
 {
 	/* use default */
@@ -74,7 +79,7 @@ static unsigned char env_mmc_orig_hwpart;
 static int mmc_set_env_part(struct mmc *mmc)
 {
 	uint part = mmc_get_env_part(mmc);
-	int dev = CONFIG_SYS_MMC_ENV_DEV;
+	int dev = mmc_get_env_dev();
 	int ret = 0;
 
 #ifdef CONFIG_SPL_BUILD
@@ -109,7 +114,7 @@ static const char *init_mmc_for_env(struct mmc *mmc)
 static void fini_mmc_for_env(struct mmc *mmc)
 {
 #ifdef CONFIG_SYS_MMC_ENV_PART
-	int dev = CONFIG_SYS_MMC_ENV_DEV;
+	int dev = mmc_get_env_dev();
 
 #ifdef CONFIG_SPL_BUILD
 	dev = 0;
@@ -140,7 +145,8 @@ static unsigned char env_flags;
 int saveenv(void)
 {
 	ALLOC_CACHE_ALIGN_BUFFER(env_t, env_new, 1);
-	struct mmc *mmc = find_mmc_device(CONFIG_SYS_MMC_ENV_DEV);
+	int dev = mmc_get_env_dev();
+	struct mmc *mmc = find_mmc_device(dev);
 	u32	offset;
 	int	ret, copy = 0;
 	const char *errmsg;
@@ -167,8 +173,7 @@ int saveenv(void)
 		goto fini;
 	}
 
-	printf("Writing to %sMMC(%d)... ", copy ? "redundant " : "",
-	       CONFIG_SYS_MMC_ENV_DEV);
+	printf("Writing to %sMMC(%d)... ", copy ? "redundant " : "", dev);
 	if (write_env(mmc, CONFIG_ENV_SIZE, offset, (u_char *)env_new)) {
 		puts("failed\n");
 		ret = 1;
@@ -212,7 +217,7 @@ void env_relocate_spec(void)
 	int crc1_ok = 0, crc2_ok = 0;
 	env_t *ep;
 	int ret;
-	int dev = CONFIG_SYS_MMC_ENV_DEV;
+	int dev = mmc_get_env_dev();
 	const char *errmsg = NULL;
 
 	ALLOC_CACHE_ALIGN_BUFFER(env_t, tmp_env1, 1);
@@ -298,7 +303,7 @@ void env_relocate_spec(void)
 	struct mmc *mmc;
 	u32 offset;
 	int ret;
-	int dev = CONFIG_SYS_MMC_ENV_DEV;
+	int dev = mmc_get_env_dev();
 	const char *errmsg;
 
 #ifdef CONFIG_SPL_BUILD
-- 
2.7.0