ARM: stm32: env: Enable scan and start for AB schema on STM32MP15 DHSOM

For the STM32MP15 DHSOM, change the default environment so an AB schema
on a device can be detected.

For this the define "SCAN_DEV_FOR_BOOT_PARTS" is overwritten and
appended.

The detection works by looking for the partitions with specific lables.
The name of those partitions are in the variables and its defaults:
* dh_ab_partname_primary=rootfs-a
* dh_ab_partname_secondary=rootfs-b

To prevent being hanging at bootcmd, enable "CONFIG_BOOT_RETRY" and
"CONFIG_RESET_TO_RETRY", but the timer will only be activated, if the AB
partitions are detected.

Signed-off-by: Pascal Zimmermann <pzimmermann@dh-electronics.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>

configs/stm32mp15_dhsom.config

@@ -10,6 +10,9 @@ CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_BOARD_SIZE_LIMIT=1441792
 CONFIG_BOOTCOUNT_BOOTLIMIT=3
 CONFIG_BOOTDELAY=1
+CONFIG_BOOTRETRY=y
+CONFIG_RESET_TO_RETRY=y
+CONFIG_BOOT_RETRY_TIME=-1
 CONFIG_CMD_ADC=y
 CONFIG_CMD_REMOTEPROC=y
 CONFIG_CMD_STBOARD=y

include/configs/stm32mp15_dh_dhsom.h

@@ -17,7 +17,40 @@
 			" 0x800000\0"
 #endif
 
+/* Add the search for AB partitons */
+#define SCAN_DEV_FOR_BOOT_PARTS						\
+	"run dh_check_if_ab; "						\
+	"if test -z \"${devplist}\"; "					\
+		"then "							\
+		"part list ${devtype} ${devnum} -bootable devplist; "	\
+	"fi; "
+
 #define STM32MP_BOARD_EXTRA_ENV						\
+	"altbootcmd= "							\
+	"setenv dh_ab_get_partnames "					\
+		"'setenv dh_ab_partnames ${dh_ab_partname_secondary} "	\
+			"${dh_ab_partname_primary}' && "		\
+		"run bootcmd\0"						\
+	"dh_check_if_ab= " /* Sets devplist if AB partitions*/		\
+		"echo test for AB on ${devtype} ${devnum} && "		\
+		"run dh_ab_get_partnames && "				\
+		"setenv devplist && "					\
+		"for partname in ${dh_ab_partnames}; do "		\
+			"setenv partnum && "				\
+			"if part number ${devtype} ${devnum} ${partname} partnum; "\
+				"then "					\
+				"setenv devplist \"${devplist} ${partnum}\" && "\
+				"setenv bootretry 60 ;"			\
+			"fi; "						\
+		"done ; "						\
+		"if test -n \"${devplist}\"; "				\
+			"then echo AB partitions found! ; "		\
+		"fi\0"							\
+	"dh_ab_get_partnames= " /* Sets dh_ab_partnames */		\
+		"setenv dh_ab_partnames ${dh_ab_partname_primary} "	\
+			"${dh_ab_partname_secondary}\0"			\
+	"dh_ab_partname_primary=rootfs-a\0" /* Names of AB partitions */\
+	"dh_ab_partname_secondary=rootfs-b\0"				\
 	"dh_preboot="							\
 		"run dh_testbench_backward_compat\0"			\
 	"dh_update_sd_to_emmc=" /* Install U-Boot from SD to eMMC */	\