driver/ddr/fsl: Add support of overriding chip select write leveling

JEDEC spec allows DRAM vendors to use prime DQ for write leveling. This
is not an issue unless some DQ pins are not connected. If a platform uses
regular DIMMs but with reduced DDR ECC pins, the prime DQ may end up on
those floating pins for the second rank. The workaround is to use a known
good chip select for this purpose.

Signed-off-by: York Sun <yorksun@freescale.com>

drivers/ddr/fsl/ctrl_regs.c

@@ -2276,6 +2276,9 @@ compute_fsl_memctl_config_regs(const memctl_options_t *popts,
 	if (ip_rev > 0x40400)
 		unq_mrs_en = 1;
 
+	if (ip_rev > 0x40700)
+		ddr->debug[18] = popts->cswl_override;
+
 	set_ddr_sdram_cfg_2(ddr, popts, unq_mrs_en);
 	set_ddr_sdram_mode(ddr, popts, common_dimm,
 				cas_latency, additive_latency, unq_mrs_en);

drivers/ddr/fsl/interactive.c

@@ -511,6 +511,7 @@ static void fsl_ddr_options_edit(fsl_ddr_info_t *pinfo,
 		CTRL_OPTIONS(wrlvl_override),
 		CTRL_OPTIONS(wrlvl_sample),
 		CTRL_OPTIONS(wrlvl_start),
+		CTRL_OPTIONS(cswl_override),
 		CTRL_OPTIONS(rcw_override),
 		CTRL_OPTIONS(rcw_1),
 		CTRL_OPTIONS(rcw_2),
@@ -801,6 +802,7 @@ static void print_memctl_options(const memctl_options_t *popts)
 		CTRL_OPTIONS(wrlvl_override),
 		CTRL_OPTIONS(wrlvl_sample),
 		CTRL_OPTIONS(wrlvl_start),
+		CTRL_OPTIONS_HEX(cswl_override),
 		CTRL_OPTIONS(rcw_override),
 		CTRL_OPTIONS(rcw_1),
 		CTRL_OPTIONS(rcw_2),

include/fsl_ddr_sdram.h

@@ -281,6 +281,7 @@ typedef struct memctl_options_partial_s {
 #define DDR_DATA_BUS_WIDTH_64 0
 #define DDR_DATA_BUS_WIDTH_32 1
 #define DDR_DATA_BUS_WIDTH_16 2
+#define DDR_CSWL_CS0	0x04000001
 /*
  * Generalized parameters for memory controller configuration,
  * might be a little specific to the FSL memory controller
@@ -340,6 +341,7 @@ typedef struct memctl_options_s {
 	unsigned int cpo_override;
 	unsigned int write_data_delay;		/* DQS adjust */
 
+	unsigned int cswl_override;
 	unsigned int wrlvl_override;
 	unsigned int wrlvl_sample;		/* Write leveling */
 	unsigned int wrlvl_start;