driver/ddr/fsl: Add workaround for erratum A-009801

The initial training for the DDRC may provide results that are not
optimized. The workaround provides better read timing margins.

Signed-off-by: Shengzhou Liu <Shengzhou.Liu@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>

arch/arm/include/asm/arch-fsl-layerscape/config.h

@@ -134,6 +134,7 @@
 #define CONFIG_SYS_FSL_ERRATUM_A008751
 #define CONFIG_SYS_FSL_ERRATUM_A009635
 #define CONFIG_SYS_FSL_ERRATUM_A009663
+#define CONFIG_SYS_FSL_ERRATUM_A009801
 #define CONFIG_SYS_FSL_ERRATUM_A009803
 #define CONFIG_SYS_FSL_ERRATUM_A009942
 

drivers/ddr/fsl/fsl_ddr_gen4.c

@@ -251,6 +251,13 @@ void fsl_ddr_set_memctl_regs(const fsl_ddr_cfg_regs_t *regs,
 	}
 #endif
 
+#ifdef CONFIG_SYS_FSL_ERRATUM_A009801
+	temp32 = ddr_in32(&ddr->debug[25]);
+	temp32 &= ~DDR_CAS_TO_PRE_SUB_MASK;
+	temp32 |= 9 << DDR_CAS_TO_PRE_SUB_SHIFT;
+	ddr_out32(&ddr->debug[25], temp32);
+#endif
+
 #ifdef CONFIG_SYS_FSL_ERRATUM_A009942
 	ddr_freq = get_ddr_freq(ctrl_num) / 1000000;
 	tmp = ddr_in32(&ddr->debug[28]);

include/fsl_ddr_sdram.h

@@ -189,6 +189,10 @@ typedef struct ddr4_spd_eeprom_s generic_spd_eeprom_t;
 #define DDR_MR5_CA_PARITY_LAT_4_CLK	0x1 /* for DDR4-1600/1866/2133 */
 #define DDR_MR5_CA_PARITY_LAT_5_CLK	0x2 /* for DDR4-2400 */
 
+/* DEBUG_26 register */
+#define DDR_CAS_TO_PRE_SUB_MASK  0x0000f000 /* CAS to preamble subtract value */
+#define DDR_CAS_TO_PRE_SUB_SHIFT 12
+
 /* DEBUG_29 register */
 #define DDR_TX_BD_DIS	(1 << 10) /* Transmit Bit Deskew Disable */