[PATCH 2/3] arm: mvebu: Espressobin: Set default value for $fdtfile env variable

[Pali Rohár]

On Espressobin board value for $fdtfile cannot be determined at compile
time and is calculated at board runtime code. This change uses a new option
DEFAULT_ENV_IS_RW to allow modifying default_environment[] array at runtime
and set into it correct value.

This change also ensure that 'env default -a' set correct value to $fdtfile.

Signed-off-by: Pali Rohár <pali at kernel.org>
---
 board/Marvell/mvebu_armada-37xx/board.c | 22 +++++++++++++++-------
 include/configs/mvebu_armada-37xx.h     | 13 ++++++++++++-
 2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/board/Marvell/mvebu_armada-37xx/board.c b/board/Marvell/mvebu_armada-37xx/board.c
index f67b04b78c..9297ea0f90 100644
--- a/board/Marvell/mvebu_armada-37xx/board.c
+++ b/board/Marvell/mvebu_armada-37xx/board.c
@@ -6,6 +6,7 @@
 #include <common.h>
 #include <dm.h>
 #include <env.h>
+#include <env_internal.h>
 #include <i2c.h>
 #include <init.h>
 #include <mmc.h>
@@ -84,15 +85,17 @@ int board_init(void)
 #ifdef CONFIG_BOARD_LATE_INIT
 int board_late_init(void)
 {
+	char *ptr = (char *)&default_environment[0];
 	struct mmc *mmc_dev;
 	bool ddr4, emmc;
 
-	if (env_get("fdtfile"))
-		return 0;
-
 	if (!of_machine_is_compatible("globalscale,espressobin"))
 		return 0;
 
+	/* Find free buffer in default_environment[] for new variables */
+	while (*ptr != '\0' && *(ptr+1) != '\0') ptr++;
+	ptr += 2;
+
 	/* If the memory controller has been configured for DDR4, we're running on v7 */
 	ddr4 = ((readl(A3700_CH0_MC_CTRL2_REG) >> A3700_MC_CTRL2_SDRAM_TYPE_OFFS)
 		& A3700_MC_CTRL2_SDRAM_TYPE_MASK) == A3700_MC_CTRL2_SDRAM_TYPE_DDR4;
@@ -101,14 +104,19 @@ int board_late_init(void)
 	mmc_dev = find_mmc_device(1);
 	emmc = (mmc_dev && mmc_init(mmc_dev) == 0);
 
+	/* Ensure that 'env default -a' set correct value to $fdtfile */
 	if (ddr4 && emmc)
-		env_set("fdtfile", "marvell/armada-3720-espressobin-v7-emmc.dtb");
+		strcpy(ptr, "fdtfile=marvell/armada-3720-espressobin-v7-emmc.dtb");
 	else if (ddr4)
-		env_set("fdtfile", "marvell/armada-3720-espressobin-v7.dtb");
+		strcpy(ptr, "fdtfile=marvell/armada-3720-espressobin-v7.dtb");
 	else if (emmc)
-		env_set("fdtfile", "marvell/armada-3720-espressobin-emmc.dtb");
+		strcpy(ptr, "fdtfile=marvell/armada-3720-espressobin-emmc.dtb");
 	else
-		env_set("fdtfile", "marvell/armada-3720-espressobin.dtb");
+		strcpy(ptr, "fdtfile=marvell/armada-3720-espressobin.dtb");
+
+	/* If $fdtfile was not set explicitly by user then set default value */
+	if (!env_get("fdtfile"))
+		env_set("fdtfile", ptr + sizeof("fdtfile="));
 
 	return 0;
 }
diff --git a/include/configs/mvebu_armada-37xx.h b/include/configs/mvebu_armada-37xx.h
index 0d585606a7..6df702367c 100644
--- a/include/configs/mvebu_armada-37xx.h
+++ b/include/configs/mvebu_armada-37xx.h
@@ -57,6 +57,11 @@
  */
 #define CONFIG_MTD_PARTITIONS		/* required for UBI partition support */
 
+/*
+ * Environment
+ */
+#define DEFAULT_ENV_IS_RW		/* required for configuring default fdtfile= */
+
 /*
  * Ethernet Driver configuration
  */
@@ -87,6 +92,11 @@
 
 #include <config_distro_bootcmd.h>
 
+/* filler for default values filled by board_early_init_f() */
+#define ENV_RW_FILLER \
+	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" /* for fdtfile= */ \
+	""
+
 /* fdt_addr and kernel_addr are needed for existing distribution boot scripts */
 #define CONFIG_EXTRA_ENV_SETTINGS	\
 	"scriptaddr=0x6d00000\0"	\
@@ -96,6 +106,7 @@
 	"kernel_addr=0x7000000\0"	\
 	"kernel_addr_r=0x7000000\0"	\
 	"ramdisk_addr_r=0xa000000\0"	\
-	BOOTENV
+	BOOTENV \
+	ENV_RW_FILLER
 
 #endif /* _CONFIG_MVEBU_ARMADA_37XX_H */
-- 
2.20.1