sunxi: When we've both mmc0 and mmc2, detect from which one we're booting

sunxi SOCs can boot from both mmc0 and mmc2, detect from which one we're
booting, and make that one "mmc dev 0" so that a single u-boot binary can
be used for both the onboard eMMC and for external sdcards.

When we're booting from mmc2, we make it dev 0 because that is where the SPL
will load the tertiary payload (the actual u-boot binary in our case) from,
see: common/spl/spl_mmc.c, which has dev 0 hardcoded everywhere.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

arch/arm/include/asm/arch-sunxi/mmc.h

@@ -123,5 +123,5 @@ struct sunxi_mmc {
 #define SUNXI_MMC_IDIE_TXIRQ		(0x1 << 0)
 #define SUNXI_MMC_IDIE_RXIRQ		(0x1 << 1)
 
-int sunxi_mmc_init(int sdc_no);
+struct mmc *sunxi_mmc_init(int sdc_no);
 #endif /* _SUNXI_MMC_H */

board/sunxi/board.c

@@ -12,6 +12,7 @@
  */
 
 #include <common.h>
+#include <mmc.h>
 #ifdef CONFIG_AXP152_POWER
 #include <axp152.h>
 #endif
@@ -104,11 +105,36 @@ static void mmc_pinmux_setup(int sdc)
 
 int board_mmc_init(bd_t *bis)
 {
+	__maybe_unused struct mmc *mmc0, *mmc1;
+	__maybe_unused char buf[512];
+
 	mmc_pinmux_setup(CONFIG_MMC_SUNXI_SLOT);
-	sunxi_mmc_init(CONFIG_MMC_SUNXI_SLOT);
+	mmc0 = sunxi_mmc_init(CONFIG_MMC_SUNXI_SLOT);
+	if (!mmc0)
+		return -1;
+
 #if CONFIG_MMC_SUNXI_SLOT_EXTRA != -1
 	mmc_pinmux_setup(CONFIG_MMC_SUNXI_SLOT_EXTRA);
-	sunxi_mmc_init(CONFIG_MMC_SUNXI_SLOT_EXTRA);
+	mmc1 = sunxi_mmc_init(CONFIG_MMC_SUNXI_SLOT_EXTRA);
+	if (!mmc1)
+		return -1;
+#endif
+
+#if CONFIG_MMC_SUNXI_SLOT == 0 && CONFIG_MMC_SUNXI_SLOT_EXTRA == 2
+	/*
+	 * Both mmc0 and mmc2 are bootable, figure out where we're booting
+	 * from. Try mmc0 first, just like the brom does.
+	 */
+	if (mmc_getcd(mmc0) && mmc_init(mmc0) == 0 &&
+	    mmc0->block_dev.block_read(0, 16, 1, buf) == 1) {
+		buf[12] = 0;
+		if (strcmp(&buf[4], "eGON.BT0") == 0)
+			return 0;
+	}
+
+	/* no bootable card in mmc0, so we must be booting from mmc2, swap */
+	mmc0->block_dev.dev = 1;
+	mmc1->block_dev.dev = 0;
 #endif
 
 	return 0;

drivers/mmc/sunxi_mmc.c

@@ -373,7 +373,7 @@ static const struct mmc_ops sunxi_mmc_ops = {
 	.getcd		= sunxi_mmc_getcd,
 };
 
-int sunxi_mmc_init(int sdc_no)
+struct mmc *sunxi_mmc_init(int sdc_no)
 {
 	struct mmc_config *cfg = &mmc_host[sdc_no].cfg;
 
@@ -396,8 +396,5 @@ int sunxi_mmc_init(int sdc_no)
 	mmc_resource_init(sdc_no);
 	mmc_clk_io_on(sdc_no);
 
-	if (mmc_create(cfg, &mmc_host[sdc_no]) == NULL)
-		return -1;
-
-	return 0;
+	return mmc_create(cfg, &mmc_host[sdc_no]);
 }