fsl-ddr: add the override for write leveling

add the override for write leveling sampling and
start time according to specific board.

Signed-off-by: Dave Liu <daveliu@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

cpu/mpc8xxx/ddr/ctrl_regs.c

@@ -1002,8 +1002,8 @@ static void set_ddr_zq_cntl(fsl_ddr_cfg_regs_t *ddr, unsigned int zq_en)
 }
 
 /* DDR Write Leveling Control (DDR_WRLVL_CNTL) */
-static void set_ddr_wrlvl_cntl(fsl_ddr_cfg_regs_t *ddr,
-			       unsigned int wrlvl_en)
+static void set_ddr_wrlvl_cntl(fsl_ddr_cfg_regs_t *ddr, unsigned int wrlvl_en,
+				const memctl_options_t *popts)
 {
 	/*
 	 * First DQS pulse rising edge after margining mode
@@ -1030,8 +1030,9 @@ static void set_ddr_wrlvl_cntl(fsl_ddr_cfg_regs_t *ddr,
 		/* tWL_DQSEN min = 25 nCK, we set it 32 */
 		wrlvl_dqsen = 0x5;
 		/*
-		 * Write leveling sample time at least need 14 clocks
-		 * due to tWLO = 9, we set it 15 clocks
+		 * Write leveling sample time at least need 6 clocks
+		 * higher than tWLO to allow enough time for progagation
+		 * delay and sampling the prime data bits.
 		 */
 		wrlvl_smpl = 0xf;
 		/*
@@ -1044,9 +1045,16 @@ static void set_ddr_wrlvl_cntl(fsl_ddr_cfg_regs_t *ddr,
 		 * Write leveling start time
 		 * The value use for the DQS_ADJUST for the first sample
 		 * when write leveling is enabled.
-		 * we set it 1 clock delay
 		 */
 		wrlvl_start = 0x8;
+		/*
+		 * Override the write leveling sample and start time
+		 * according to specific board
+		 */
+		if (popts->wrlvl_override) {
+			wrlvl_smpl = popts->wrlvl_sample;
+			wrlvl_start = popts->wrlvl_start;
+		}
 	}
 
 	ddr->ddr_wrlvl_cntl = (0
@@ -1332,7 +1340,7 @@ compute_fsl_memctl_config_regs(const memctl_options_t *popts,
 	set_timing_cfg_5(ddr);
 
 	set_ddr_zq_cntl(ddr, zq_en);
-	set_ddr_wrlvl_cntl(ddr, wrlvl_en);
+	set_ddr_wrlvl_cntl(ddr, wrlvl_en, popts);
 
 	set_ddr_sr_cntr(ddr, sr_it);
 

cpu/mpc8xxx/ddr/options.c

@@ -198,6 +198,7 @@ unsigned int populate_memctl_options(int all_DIMMs_registered,
 	 * meet the tQDSS under different loading.
 	 */
 	popts->wrlvl_en = 1;
+	popts->wrlvl_override = 0;
 #endif
 
 	/*

include/asm-ppc/fsl_ddr_sdram.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2008 Freescale Semiconductor, Inc.
+ * Copyright 2008-2009 Freescale Semiconductor, Inc.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -177,6 +177,11 @@ typedef struct memctl_options_s {
 	unsigned int clk_adjust;		/* */
 	unsigned int cpo_override;
 	unsigned int write_data_delay;		/* DQS adjust */
+
+	unsigned int wrlvl_override;
+	unsigned int wrlvl_sample;		/* Write leveling */
+	unsigned int wrlvl_start;
+
 	unsigned int half_strength_driver_enable;
 	unsigned int twoT_en;
 	unsigned int threeT_en;