[PATCH] Add support for SPL MMC load redundant U-Boot

[Ayrton Leyssens]

>From 99512830410551132e8f7577615b3af4f5f1c137 Mon Sep 17 00:00:00 2001
From: Ayrton Leyssens <ayrton.leyssens at scioteq.com>
Date: Wed, 19 Jul 2023 11:27:19 +0200
Subject: [PATCH Add support for SPL mmc load redundant U-Boot

This patch adds support for loading a redundant / second U-Boot from a MMC.
In some cases you want to update U-Boot, to have a "selectable" bootloader and keep the "old" and "new" one.
In this patch we use the environment for a user-defined variable.
Maybe this could be extended to some other ways as well.

Signed-off-by: Ayrton Leyssens <ayrton.leyssens at scioteq.com>
---

common/spl/Kconfig   | 29 +++++++++++++++++++++++++++++
common/spl/spl_mmc.c | 10 ++++++++++
2 files changed, 39 insertions(+)

diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index bee231b583..2c0ffd4363 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -824,6 +824,25 @@ config SYS_MMCSD_FS_BOOT
                 Enable MMC FS Boot mode. Partition is selected by option
                 SYS_MMCSD_FS_BOOT_PARTITION.
+config SYS_MMCSD_FS_BOOT_PARTITION_FAILSAFE
+             bool "Use MMC Boot Partition Failsafe"
+             depends on SYS_MMCSD_FS_BOOT
+             depends on SPL_ENV_SUPPORT
+             default false
+             help
+               Use a redundant partition to load U-Boot from.
+
+config SYS_MMCSD_FS_BOOT_PARTITION_SELECTOR
+             string "MMC Boot Partition Selector"
+             depends on SYS_MMCSD_FS_BOOT
+             depends on SYS_MMCSD_FS_BOOT_PARTITION_FAILSAFE
+             default ""
+             help
+               Environment variable in U-Boot to use for the partition selection
+               to boot U-Boot from.
+               A 1 selects the "normal" partition, any other value selects the
+               redundant partition.
+
config SYS_MMCSD_FS_BOOT_PARTITION
               int "MMC Boot Partition"
               depends on SYS_MMCSD_FS_BOOT
@@ -833,6 +852,16 @@ config SYS_MMCSD_FS_BOOT_PARTITION
                 used in fs mode.
                 Use -1 as a special value to use the first bootable partition.
+config SYS_MMCSD_FS_BOOT_PARTITION_REDUNDANT
+             int "MMC Boot Partition Redundant"
+             depends on SYS_MMCSD_FS_BOOT
+             depends on SYS_MMCSD_FS_BOOT_PARTITION_FAILSAFE
+             default 2
+             help
+               Redundant Partition on the MMC to load U-Boot from when the MMC is being
+               used in fs mode.
+               Use -1 as a special value to use the first bootable partition.
+
config SPL_MMC_TINY
               bool "Tiny MMC framework in SPL"
               depends on SPL_MMC
diff --git a/common/spl/spl_mmc.c b/common/spl/spl_mmc.c
index a665091b00..bf804fabcc 100644
--- a/common/spl/spl_mmc.c
+++ b/common/spl/spl_mmc.c
@@ -10,6 +10,7 @@
#include <log.h>
#include <part.h>
#include <spl.h>
+#include <env.h>
#include <linux/compiler.h>
#include <errno.h>
#include <asm/u-boot.h>
@@ -281,6 +282,7 @@ static int spl_mmc_do_fs_boot(struct spl_image_info *spl_image,
               int err = -ENOSYS;
                __maybe_unused int partition = CONFIG_SYS_MMCSD_FS_BOOT_PARTITION;
+             __maybe_unused int env_partition_selector = 0;
 #if CONFIG_SYS_MMCSD_FS_BOOT_PARTITION == -1
               {
@@ -303,7 +305,15 @@ static int spl_mmc_do_fs_boot(struct spl_image_info *spl_image,
                               }
               }
#endif
+#ifdef CONFIG_SYS_MMCSD_FS_BOOT_PARTITION_FAILSAFE
+             env_init();
+             env_relocate();
+             env_partition_selector = env_get_ulong(CONFIG_SYS_MMCSD_FS_BOOT_PARTITION_SELECTOR, 10, 0);
+
+             if (env_partition_selector != 1)
+                             partition = CONFIG_SYS_MMCSD_FS_BOOT_PARTITION_REDUNDANT;
+#endif
#ifdef CONFIG_SPL_FS_FAT
               if (!spl_start_uboot()) {
                               err = spl_load_image_fat_os(spl_image, bootdev, mmc_get_blk_desc(mmc),
--
2.25.1