[PATCH 3/3] ARM: i.MX bootsource: adapt boot device detection for imx8mp

[Sascha Hauer]

imx8mp uses sbmr2[27..24] for encoding the bootmode while existing
code reads only sbmr2[25..24].

This can detect BOOTSOURCE_SERIAL for the wrong mode.

Based on:
https://lore.barebox.org/barebox/20221014115354.4072202-1-enrico.scholz@sigma-chemnitz.de/T/#u

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 arch/arm/mach-imx/boot.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-imx/boot.c b/arch/arm/mach-imx/boot.c
index 7b3334d5e2..c0193cfa43 100644
--- a/arch/arm/mach-imx/boot.c
+++ b/arch/arm/mach-imx/boot.c
@@ -202,7 +202,8 @@ void imx51_boot_save_loc(void)
 }
 
 #define IMX53_SRC_SBMR	0x4
-#define SRC_SBMR_BMOD	GENMASK(25, 24)
+#define IMX53_SRC_SBMR_BMOD	GENMASK(25, 24)
+#define IMX8MP_SRC_SBMR_BMOD	GENMASK(27, 24)
 #define IMX53_BMOD_SERIAL	0b11
 
 #define __BOOT_CFG(n, m, l)	GENMASK((m) + ((n) - 1) * 8, \
@@ -234,7 +235,12 @@ __MAKE_BOOT_CFG_BITS(4)
 
 static unsigned int imx53_get_bmod(uint32_t r)
 {
-	return FIELD_GET(SRC_SBMR_BMOD, r);
+	return FIELD_GET(IMX53_SRC_SBMR_BMOD, r);
+}
+
+static unsigned int imx8mp_get_bmod(uint32_t r)
+{
+	return FIELD_GET(IMX8MP_SRC_SBMR_BMOD, r);
 }
 
 static int imx53_bootsource_internal(uint32_t r)
@@ -317,6 +323,8 @@ void imx53_boot_save_loc(void)
 #define IMX6_SRC_GPR10	0x44
 #define IMX6_BMOD_SERIAL	0b01
 #define IMX6_BMOD_RESERVED	0b11
+#define IMX8MP_BMOD_FUSES	0b0000
+#define IMX8MP_BMOD_SERIAL	0b0001
 #define IMX6_BMOD_FUSES		0b00
 #define BT_FUSE_SEL		BIT(4)
 #define GPR10_BOOT_FROM_GPR9	BIT(28)
@@ -338,6 +346,18 @@ static bool imx6_bootsource_serial(uint32_t sbmr2)
 		!(sbmr2 & BT_FUSE_SEL));
 }
 
+static bool imx8mp_bootsource_serial(uint32_t sbmr2)
+{
+	return imx8mp_get_bmod(sbmr2) == IMX8MP_BMOD_SERIAL ||
+		/*
+		 * If boot from fuses is selected and fuses are not
+		 * programmed by setting BT_FUSE_SEL, ROM code will
+		 * fallback to serial mode
+		 */
+		(imx8mp_get_bmod(sbmr2) == IMX8MP_BMOD_FUSES &&
+		 !(sbmr2 & BT_FUSE_SEL));
+}
+
 static bool imx6_bootsource_serial_forced(uint32_t bootmode)
 {
 	if (cpu_mx6_is_mx6ul() || cpu_mx6_is_mx6ull())
@@ -694,7 +714,7 @@ void imx8mp_get_boot_source(enum bootsource *src, int *instance)
 	void __iomem *src_base = IOMEM(MX8MP_SRC_BASE_ADDR);
 	uint32_t sbmr2 = readl(src_base + 0x70);
 
-	if (imx6_bootsource_serial(sbmr2)) {
+	if (imx8mp_bootsource_serial(sbmr2)) {
 		*src = BOOTSOURCE_SERIAL;
 		return;
 	}
-- 
2.30.2