learning uboot how to set ddr parameter in qca4531 cpu

DDR工作频率  在600MHZ.

include/configs/board953x.h

#define CFG_PLL_FREQ            CFG_PLL_650_600_200

#define  CFG_DDR_REFRESH_VAL            0x4138   (default 12c)

0x0100 0001 0011 1000

./board/atheros/common/init-953x.c:59:#define CFG_DDR2_SCORPION_CAS_LATENCY    4

#if CFG_DDR2_SCORPION_CAS_LATENCY == 4

#define CFG_DDR2_CONFIG_VAL                     DDR_CONFIG_CAS_LATENCY_MSB_SET(0x1) | \ c

DRAM CAS latency parameter MSB rounded up in memory core clock cycles

DDR_CONFIG_OPEN_PAGE_SET(0x1) | \

DDR_CONFIG_CAS_LATENCY_SET(0x1) | \

DRAM CAS latency  parameter(first 3 bit)      (?)  我认为应该是4；

DDR_CONFIG_TMRD_SET(0xf) | \

TMRD 最小为两个时钟周期： 取值范围： 0x2 -  0xf

DDR_CONFIG_TRFC_SET(0x15) | \

TRFC最小为105/5=21 = 0x15个时钟周期：

DDR_CONFIG_TRRD_SET(0x7) | \

TRRD最小为10/5=2 = 0x2个时钟周期

DDR_CONFIG_TRP_SET(0x9) | \

TRP最小为15/5=2 = 0x3个时钟周期

DDR_CONFIG_TRCD_SET(0x9) | \

TRCD最小为15/5=3 = 0x3个时钟周期

DDR_CONFIG_TRAS_SET(0x1b)

TRAS 最小为9个时钟周期

TRAS=max(Tras_min,tRcd+CL)  =  MAX(45,15+4)  = 45 /5  =9

#define CFG_DDR2_CONFIG2_VAL                    DDR_CONFIG2_HALF_WIDTH_LOW_SET(0x1) | \

DDR_CONFIG2_SWAP_A26_A27_SET(DDR_CONFIG2_SWAP_A26_A27_VAL) \

DDR_CONFIG2_GATE_OPEN_LATENCY_SET(0x8) | \

DDR_CONFIG2_TWTR_SET(0x15) | \

TWTR=[1+BL/2+tWTR/tCK]*2  = [1+8/2+ROUND_UP(7.5/5) ] *2  = [1+4+2 ]  * 2 = 14  =  0xE

DDR_CONFIG2_TRTP_SET(0x9) | \

TRTP= BL/2 +max(tRTP,2)-2 =  8/2 + max(2,2) -2 =  4;

DDR_CONFIG2_TRTW_SET(0xe) | \

TRTW =  (CL+BL/2)  *2  =  (3+8/2)*2  =  14

DDR_CONFIG2_TWR_SET(0x1) | \

TWR= [BL/2  +  tWR/tCK ]  * 2 -1  =  [8/2 + 15/5] *2-1  = [4+3]*2-1=13  (?)

DRAM CKE bit

DDR_CONFIG2_CKE_SET(0x1) | \

Control bit to allow the memory control to tri-state the address/control outputs;

DDR_CONFIG2_CNTL_OE_EN_SET(0x1) | \

DRAM burst type Sequential;

DDR_CONFIG2_BURST_LENGTH_SET(0x8)

DRAM burst length setting,Only 8 is supported

#define CFG_DDR2_CONFIG3_VAL                    0x0000000a

#define CFG_DDR2_EXT_MODE_VAL                   0x402

#define CFG_DDR2_MODE_VAL_INIT                  0x143

#define CFG_DDR2_MODE_VAL                       0x43

#define CFG_DDR2_TAP_VAL                        0x10

#define CFG_DDR2_EN_TWL_VAL                     0x0000167d

#define CFG_DDR2_RD_DATA_THIS_CYCLE_VAL_16      0xffff

#define CFG_DDR2_RD_DATA_THIS_CYCLE_VAL_32      0xff