arm: mxs: Add 'Wait for JTAG user' if booted in JTAG mode

When booting in JTAG mode, there is no way to use soft break-points, and
no way of knowing when SPL has finished executing (so the user can issue
a 'halt' command to load u-boot.bin for example)

Add a debug output and simple loop to stop execution at the completion of
the SPL initialisation as a pseudo break-point when booting in JTAG mode

Signed-off-by: Graeme Russ <gruss@tss-engineering.com>

arch/arm/cpu/arm926ejs/mxs/spl_boot.c

@@ -157,6 +157,11 @@ void mxs_common_spl_init(const uint32_t arg, const uint32_t *resptr,
 	data->boot_mode_idx = bootmode;
 
 	mxs_power_wait_pswitch();
+
+	if (mxs_boot_modes[data->boot_mode_idx].boot_pads == MXS_BM_JTAG) {
+		debug("SPL: Waiting for JTAG user\n");
+		asm volatile ("x: b x");
+	}
 }
 
 /* Support aparatus */

arch/arm/include/asm/arch-mxs/sys_proto.h

@@ -74,6 +74,23 @@ static const struct mxs_pair mxs_boot_modes[] = {
 #endif
 };
 
+#define MXS_BM_USB			0x00
+#define MXS_BM_I2C_MASTER_3V3		0x01
+#define MXS_BM_I2C_MASTER_1V8		0x11
+#define MXS_BM_SPI2_MASTER_3V3_NOR	0x02
+#define MXS_BM_SPI2_MASTER_1V8_NOR	0x12
+#define MXS_BM_SPI3_MASTER_3V3_NOR	0x03
+#define MXS_BM_SPI3_MASTER_1V8_NOR	0x13
+#define MXS_BM_NAND_3V3			0x04
+#define MXS_BM_NAND_1V8			0x14
+#define MXS_BM_JTAG			0x06
+#define MXS_BM_SPI3_MASTER_3V3_EEPROM	0x08
+#define MXS_BM_SPI3_MASTER_1V8_EEPROM	0x18
+#define MXS_BM_SDMMC0_3V3		0x09
+#define MXS_BM_SDMMC0_1V8		0x19
+#define MXS_BM_SDMMC1_3V3		0x0a
+#define MXS_BM_SDMMC1_1V8		0x1a
+
 struct mxs_spl_data {
 	uint8_t		boot_mode_idx;
 	uint32_t	mem_dram_size;