[U-Boot] [PATCH v2] Add support for eMMC environment in boot partition

[Sergey Kubushyn]

This allows to place U-Boot environment into eMMC boot partition thus
saving space on user partition for the OS (or whatever.) When booting
off of eMMC many (all?) MCUs can use dedicated boot0/boot1 partitions
to boot so U-Boot (or SPL) is written to one (or both) such partitions.
When such boot configuration is used it makes sense to place environment
in the same partition where the U-Boot itself is so the entire user
partition is available for the OS.

It might be not well polished yet but it is a simple patch that can be
reworked later.

It uses 4 Kconfig variables right now which probably belong to the board
Kconfig. Those are:

CONFIG_ENV_IN_EMMC_BOOT -- tells that environment is in eMMC boot
 partition if defined

CONFIG_EMMC_ENV_PART -- tells which boot partition environment should be
 stored in (either 1 or 2)

CONFIG_EMMC_BOOT_PART -- which boot partition will be used by eMMC to
 read U-Boot/SPL binary for boot protocol (either 1 or 2.) That can be
 different from the environment partition

CONFIG_EMMC_BOOT_ACK -- tells that eMMC should provide boot ACKs if
 defined

Here is an excerpt from actual board Kconfig:

=== Cut ===
config ENV_IN_EMMC_BOOT
        bool "Environment is in eMMC boot partition"
        default y

config EMMC_ENV_PART
        hex "eMMC boot partition used for environment (1 or 2)"
        default 1

config EMMC_BOOT_PART
        hex "eMMC boot partition the board boots off of (1 or 2)"
        default 1

config EMMC_BOOT_ACK
        bool "Enable ACKs from eMMC when booting off of boot partition"
        default n
=== Cut ===

Signed-off-by: Sergey Kubushyn <ksi at koi8.net>
Cc: Tom Rini <trini at konsulko.com>
Cc: Pantelis Antoniou <panto at antoniou-consulting.com>
---
 common/env_mmc.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/common/env_mmc.c b/common/env_mmc.c
index 16f6a17..3b2477c 100644
--- a/common/env_mmc.c
+++ b/common/env_mmc.c
@@ -68,6 +68,45 @@ int env_init(void)
 	return 0;
 }
 
+#ifdef CONFIG_ENV_IN_EMMC_BOOT
+__weak u8 mmc_get_env_part(struct mmc *mmc)
+{
+	return CONFIG_EMMC_ENV_PART;
+}
+
+__weak u8 mmc_get_boot_part(struct mmc *mmc)
+{
+	return CONFIG_EMMC_BOOT_PART;
+}
+
+__weak u8 mmc_get_boot_ack(struct mmc *mmc)
+{
+#ifdef CONFIG_EMMC_BOOT_ACK
+	return 1;
+#else
+	return 0;
+#endif
+}
+
+static int mmc_set_env_part(struct mmc *mmc)
+{
+	int ret = 0;
+	u8 boot_part = 0;
+	u8 boot_ack = 0;
+	u8 env_part = 0;
+
+	boot_part = mmc_get_boot_part(mmc);
+	boot_ack = mmc_get_boot_ack(mmc);
+	env_part = mmc_get_env_part(mmc);
+
+	ret = mmc_set_part_conf(mmc, boot_ack, boot_part, env_part);
+
+	if (ret)
+		puts("MMC switch to boot partition failed\n");
+
+	return ret;
+}
+#else
 #ifdef CONFIG_SYS_MMC_ENV_PART
 __weak uint mmc_get_env_part(struct mmc *mmc)
 {
@@ -96,6 +135,7 @@ static int mmc_set_env_part(struct mmc *mmc)
 #else
 static inline int mmc_set_env_part(struct mmc *mmc) {return 0; };
 #endif
+#endif
 
 static const char *init_mmc_for_env(struct mmc *mmc)
 {
@@ -113,6 +153,15 @@ static const char *init_mmc_for_env(struct mmc *mmc)
 
 static void fini_mmc_for_env(struct mmc *mmc)
 {
+#ifdef CONFIG_ENV_IN_EMMC_BOOT
+	u8 boot_part = 0;
+	u8 boot_ack = 0;
+
+	boot_part = mmc_get_boot_part(mmc);
+	boot_ack = mmc_get_boot_ack(mmc);
+
+	mmc_set_part_conf(mmc, boot_ack, boot_part, 0);
+#else
 #ifdef CONFIG_SYS_MMC_ENV_PART
 	int dev = mmc_get_env_dev();
 
@@ -121,6 +170,7 @@ static void fini_mmc_for_env(struct mmc *mmc)
 #endif
 	blk_select_hwpart_devnum(IF_TYPE_MMC, dev, env_mmc_orig_hwpart);
 #endif
+#endif
 }
 
 #ifdef CONFIG_CMD_SAVEENV
-- 
2.5.5