[PATCH 13/17] ARM: i.MX6: boot: Move magic numbers into utility functions

[Andrey Smirnov <andrew.smirnov@gmail.com>]

Move magic numbers and algorithm for determining Serial ROM bootsource
and boot instance into utility functions. Add a comment on the logic
behing the latter while at it.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 arch/arm/mach-imx/boot.c | 63 +++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 49 insertions(+), 14 deletions(-)

diff --git a/arch/arm/mach-imx/boot.c b/arch/arm/mach-imx/boot.c
index 3cd79acfc..cdfe3749d 100644
--- a/arch/arm/mach-imx/boot.c
+++ b/arch/arm/mach-imx/boot.c
@@ -269,12 +269,57 @@ static bool imx6_bootsource_serial(uint32_t sbmr2)
 		!(sbmr2 & BT_FUSE_SEL));
 }
 
+static int __imx6_bootsource_serial_rom(uint32_t r)
+{
+	return sbmr(r, 26, 24);	/* BOOT_CFG4[2:0] */
+}
+
+/*
+ * Serial ROM bootsource on i.MX6 are as follows:
+ *
+ *	000 - ECSPI-1
+ *	001 - ECSPI-2
+ *	010 - ECSPI-3
+ *	011 - ECSPI-4
+ *	100 - ECSPI-5
+ *	101 - I2C1
+ *	110 - I2C2
+ *	111 - I2C3
+ *
+ * There's no single bit that would tell us we are booting from I2C or
+ * SPI, so we just have to compare the "source" agains the value for
+ * I2C1 for both: calculating bootsource and boot instance.
+ */
+#define IMX6_BOOTSOURCE_SERIAL_ROM_I2C1	0b101
+
+static enum bootsource imx6_bootsource_serial_rom(uint32_t sbmr)
+{
+	const int source = __imx6_bootsource_serial_rom(sbmr);
+
+	return source < IMX6_BOOTSOURCE_SERIAL_ROM_I2C1 ?
+		BOOTSOURCE_SPI : BOOTSOURCE_I2C;
+}
+
+static int imx6_boot_instance_serial_rom(uint32_t sbmr)
+{
+	const int source = __imx6_bootsource_serial_rom(sbmr);
+
+	if (source < IMX6_BOOTSOURCE_SERIAL_ROM_I2C1)
+		return source;
+
+	return source - IMX6_BOOTSOURCE_SERIAL_ROM_I2C1;
+}
+
+static int imx6_boot_instance_mmc(uint32_t r)
+{
+	return sbmr(r, 13, 11);	/* BOOT_CFG2[4:3] */
+}
+
 void imx6_get_boot_source(enum bootsource *src, int *instance)
 {
 	void __iomem *src_base = IOMEM(MX6_SRC_BASE_ADDR);
 	uint32_t sbmr1 = readl(src_base + IMX6_SRC_SBMR1);
 	uint32_t sbmr2 = readl(src_base + IMX6_SRC_SBMR2);
-	uint32_t boot_cfg_4_2_0;
 
 	if (imx6_bootsource_reserved(sbmr2))
 		return;
@@ -289,25 +334,15 @@ void imx6_get_boot_source(enum bootsource *src, int *instance)
 		*src = BOOTSOURCE_HD;
 		break;
 	case 3:
-		/* BOOT_CFG4[2:0] */
-		boot_cfg_4_2_0 = (sbmr1 >> 24) & 0x7;
-
-		if (boot_cfg_4_2_0 > 4) {
-			*src = BOOTSOURCE_I2C;
-			*instance = boot_cfg_4_2_0 - 5;
-		} else {
-			*src = BOOTSOURCE_SPI;
-			*instance = boot_cfg_4_2_0;
-		}
+		*src = imx6_bootsource_serial_rom(sbmr1);
+		*instance = imx6_boot_instance_serial_rom(sbmr1);
 		break;
 	case 4:
 	case 5:
 	case 6:
 	case 7:
 		*src = BOOTSOURCE_MMC;
-
-		/* BOOT_CFG2[4:3] */
-		*instance = (sbmr1 >> 11) & 0x3;
+		*instance = imx6_boot_instance_mmc(sbmr1);
 		break;
 	default:
 		if (imx53_bootsource_nand(sbmr1))
-- 
2.14.3


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