imx: imx6ul: kontron-sl-mx6ul: Select correct boot and env device

Instead of checking both, SPI NOR and MMC for loading U-Boot proper
and the environment, implement a way to detect the actual boot
device even if the BootROM doesn't report it and we can't rely
solely on the fuse settings, as by default we use MMC as primary
boot device and boot from SPI NOR via the secondary fallback device
(EEPROM Recovery Mode).

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>

board/kontron/sl-mx6ul/Makefile

@@ -6,3 +6,5 @@ obj-y := spl.o
 else
 obj-y := sl-mx6ul.o
 endif
+
+obj-y += sl-mx6ul-common.o

board/kontron/sl-mx6ul/sl-mx6ul-common.c

@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2022 Kontron Electronics GmbH
+ */
+
+#include <asm/types.h>
+#include <asm/arch/sys_proto.h>
+
+#include <sl-mx6ul-common.h>
+
+bool sl_mx6ul_is_spi_nor_boot(void)
+{
+	u32 bmode = imx6_src_get_boot_mode();
+
+	/*
+	 * Check if "EEPROM Recovery" enabled and ECSPI2_CONREG not 0x0.
+	 * If this is the case and U-Boot didn't initialize the SPI bus
+	 * yet, we can safely assume that we are booting from SPI NOR.
+	 */
+	if ((bmode & 0x40000000) && readl(0x0200c008))
+		return true;
+
+	return false;
+}

board/kontron/sl-mx6ul/sl-mx6ul-common.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2022 Kontron Electronics GmbH
+ */
+
+#ifndef __SL_MX6UL_COMMON_H
+#define __SL_MX6UL_COMMON_H
+
+bool sl_mx6ul_is_spi_nor_boot(void);
+
+#endif // __SL_MX6UL_COMMON_H

board/kontron/sl-mx6ul/sl-mx6ul.c

@@ -6,8 +6,10 @@
 #include <asm/arch/clock.h>
 #include <asm/arch/sys_proto.h>
 #include <asm/global_data.h>
+#include <env_internal.h>
 #include <fdt_support.h>
 #include <phy.h>
+#include <sl-mx6ul-common.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -83,3 +85,16 @@ int board_init(void)
 
 	return 0;
 }
+
+enum env_location env_get_location(enum env_operation op, int prio)
+{
+	if (prio)
+		return ENVL_UNKNOWN;
+
+	if (sl_mx6ul_is_spi_nor_boot() && CONFIG_IS_ENABLED(ENV_IS_IN_SPI_FLASH))
+		return ENVL_SPI_FLASH;
+	else if (CONFIG_IS_ENABLED(ENV_IS_IN_MMC))
+		return ENVL_MMC;
+
+	return ENVL_NOWHERE;
+}

board/kontron/sl-mx6ul/spl.c

@@ -17,6 +17,7 @@
 #include <linux/sizes.h>
 #include <linux/errno.h>
 #include <mmc.h>
+#include <sl-mx6ul-common.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -339,26 +340,30 @@ void board_boot_order(u32 *spl_boot_list)
 
 	/*
 	 * The default boot fuse settings use the SD card (MMC1) as primary
-	 * boot device, but allow SPI NOR as a fallback boot device.
-	 * We can't detect the fallback case and spl_boot_device() will return
-	 * BOOT_DEVICE_MMC1 despite the actual boot device being SPI NOR.
-	 * Therefore we try to load U-Boot proper vom SPI NOR after loading
-	 * from MMC has failed.
+	 * boot device, but allow SPI NOR as a fallback boot device. There
+	 * is no proper way to detect if the fallback was used. Therefore
+	 * we read the ECSPI2_CONREG register and see if it differs from the
+	 * reset value 0x0. If that's the case we can assume that the BootROM
+	 * has successfully probed the SPI NOR.
 	 */
-	spl_boot_list[0] = bootdev;
-
 	switch (bootdev) {
 	case BOOT_DEVICE_MMC1:
 	case BOOT_DEVICE_MMC2:
-		spl_boot_list[1] = BOOT_DEVICE_SPI;
+		if (sl_mx6ul_is_spi_nor_boot()) {
+			spl_boot_list[0] = BOOT_DEVICE_SPI;
+			return;
+		}
 		break;
 	}
+
+	spl_boot_list[0] = bootdev;
 }
 
 int board_early_init_f(void)
 {
 	setup_iomux_uart();
-	setup_spi();
+	if (sl_mx6ul_is_spi_nor_boot())
+		setup_spi();
 
 	return 0;
 }