[U-Boot] [PATCH 1/1]: environment in eMMC 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>
---
--- 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


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