arm: mxs: Add debug outputs and comments to mxs SPL source files

It is difficult to track down fail to boot issues in the mxs SPL.
Implement the following to make it easier:
 - Add debug outputs to allow tracing of SPL progress in order to track
where failure to boot occurs. DEUBUG and CONFIG_SPL_SERIAL_SUPPORT must
be defined to enable debug output in SPL
 - Add TODO comments where it is not clear if the code is doing what it
is meant to be doing, even tough the board boots properly (these comments
refer to existing code, not to any code added by this patch)

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

1 files changed, 18 insertions, 0 deletions

diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
index 97ef67d8c5..a744e5d499 100644
--- a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
+++ b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
@@ -92,6 +92,7 @@ static uint32_t dram_vals[] = {
 
 __weak void mxs_adjust_memory_params(uint32_t *dram_vals)
 {
+	debug("SPL: Using default SDRAM parameters\n");
 }
 
 #ifdef CONFIG_MX28
@@ -99,8 +100,10 @@ static void initialize_dram_values(void)
 {
 	int i;
 
+	debug("SPL: Setting mx28 board specific SDRAM parameters\n");
 	mxs_adjust_memory_params(dram_vals);
 
+	debug("SPL: Applying SDRAM parameters\n");
 	for (i = 0; i < ARRAY_SIZE(dram_vals); i++)
 		writel(dram_vals[i], MXS_DRAM_BASE + (4 * i));
 }
@@ -109,6 +112,7 @@ static void initialize_dram_values(void)
 {
 	int i;
 
+	debug("SPL: Setting mx23 board specific SDRAM parameters\n");
 	mxs_adjust_memory_params(dram_vals);
 
 	/*
@@ -120,6 +124,7 @@ static void initialize_dram_values(void)
 	 * HW_DRAM_CTL8 is setup as the last element.
 	 * So skip the initialization of these HW_DRAM_CTL registers.
 	 */
+	debug("SPL: Applying SDRAM parameters\n");
 	for (i = 0; i < ARRAY_SIZE(dram_vals); i++) {
 		if (i == 8 || i == 27 || i == 28 || i == 35)
 			continue;
@@ -146,6 +151,8 @@ static void mxs_mem_init_clock(void)
 	const unsigned char divider = 21;
 #endif
 
+	debug("SPL: Initialising FRAC0\n");
+
 	/* Gate EMI clock */
 	writeb(CLKCTRL_FRAC_CLKGATE,
 		&clkctrl_regs->hw_clkctrl_frac0_set[CLKCTRL_FRAC0_EMI]);
@@ -170,6 +177,7 @@ static void mxs_mem_init_clock(void)
 		&clkctrl_regs->hw_clkctrl_clkseq_clr);
 
 	early_delay(10000);
+	debug("SPL: FRAC0 Initialised\n");
 }
 
 static void mxs_mem_setup_cpu_and_hbus(void)
@@ -177,6 +185,8 @@ static void mxs_mem_setup_cpu_and_hbus(void)
 	struct mxs_clkctrl_regs *clkctrl_regs =
 		(struct mxs_clkctrl_regs *)MXS_CLKCTRL_BASE;
 
+	debug("SPL: Setting CPU and HBUS clock frequencies\n");
+
 	/* Set fractional divider for ref_cpu to 480 * 18 / 19 = 454MHz
 	 * and ungate CPU clock */
 	writeb(19 & CLKCTRL_FRAC_FRAC_MASK,
@@ -209,6 +219,8 @@ static void mxs_mem_setup_vdda(void)
 	struct mxs_power_regs *power_regs =
 		(struct mxs_power_regs *)MXS_POWER_BASE;
 
+	debug("SPL: Configuring VDDA\n");
+
 	writel((0xc << POWER_VDDACTRL_TRG_OFFSET) |
 		(0x7 << POWER_VDDACTRL_BO_OFFSET_OFFSET) |
 		POWER_VDDACTRL_LINREG_OFFSET_1STEPS_BELOW,
@@ -240,6 +252,8 @@ static void mx23_mem_setup_vddmem(void)
 	struct mxs_power_regs *power_regs =
 		(struct mxs_power_regs *)MXS_POWER_BASE;
 
+	debug("SPL: Setting mx23 VDDMEM\n");
+
 	/* We must wait before and after disabling the current limiter! */
 	early_delay(10000);
 
@@ -252,6 +266,8 @@ static void mx23_mem_setup_vddmem(void)
 
 static void mx23_mem_init(void)
 {
+	debug("SPL: Initialising mx23 SDRAM Controller\n");
+
 	/*
 	 * Reset/ungate the EMI block. This is essential, otherwise the system
 	 * suffers from memory instability. This thing is mx23 specific and is
@@ -297,6 +313,8 @@ static void mx28_mem_init(void)
 	struct mxs_pinctrl_regs *pinctrl_regs =
 		(struct mxs_pinctrl_regs *)MXS_PINCTRL_BASE;
 
+	debug("SPL: Initialising mx28 SDRAM Controller\n");
+
 	/* Set DDR2 mode */
 	writel(PINCTRL_EMI_DS_CTRL_DDR_MODE_DDR2,
 		&pinctrl_regs->hw_pinctrl_emi_ds_ctrl_set);