[PATCH v3 1/6] sifive: fu540: Add runtime boot mode detection

[Jagan Teki <jagan@amarulasolutions.com>]

Add support to detect boot mode at runtime for
SiFive FU540 boards.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
---
Changes for v3:
- new patch

 board/sifive/fu540/fu540.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/board/sifive/fu540/fu540.c b/board/sifive/fu540/fu540.c
index fa705dea71..a35b79ace3 100644
--- a/board/sifive/fu540/fu540.c
+++ b/board/sifive/fu540/fu540.c
@@ -10,6 +10,7 @@
 #include <env.h>
 #include <init.h>
 #include <log.h>
+#include <linux/bitops.h>
 #include <linux/bug.h>
 #include <linux/delay.h>
 #include <linux/io.h>
@@ -120,14 +121,26 @@ int board_init(void)
 }
 
 #ifdef CONFIG_SPL
+#define MODE_SELECT_REG		0x1000
+#define MODE_SELECT_QSPI	0x6
+#define MODE_SELECT_SD		0xb
+#define MODE_SELECT_MASK	GENMASK(3, 0)
+
 u32 spl_boot_device(void)
 {
-#ifdef CONFIG_SPL_MMC_SUPPORT
-	return BOOT_DEVICE_MMC1;
-#else
-	puts("Unknown boot device\n");
-	hang();
-#endif
+	u32 mode_select = readl((void *)MODE_SELECT_REG);
+	u32 boot_device = mode_select & MODE_SELECT_MASK;
+
+	switch (boot_device) {
+	case MODE_SELECT_QSPI:
+		return BOOT_DEVICE_SPI;
+	case MODE_SELECT_SD:
+		return BOOT_DEVICE_MMC1;
+	default:
+		debug("Unsupported boot device 0x%x but trying MMC1\n",
+		      boot_device);
+		return BOOT_DEVICE_MMC1;
+	}
 }
 #endif
 
-- 
2.25.1