mips: ath79: add support for QCA953x SOCs

This patch enable work for qca953x SOC.

Signed-off-by: Wills Wang <wills.wang@live.com>

1 files changed, 472 insertions, 0 deletions

diff --git a/arch/mips/mach-ath79/qca953x/ddr.c b/arch/mips/mach-ath79/qca953x/ddr.c
new file mode 100644
index 0000000000..ac0130cff0
--- /dev/null
+++ b/arch/mips/mach-ath79/qca953x/ddr.c
@@ -0,0 +1,472 @@
+/*
+ * Copyright (C) 2015-2016 Wills Wang <wills.wang@live.com>
+ * Based on Atheros LSDK/QSDK
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/addrspace.h>
+#include <asm/types.h>
+#include <mach/ar71xx_regs.h>
+#include <mach/reset.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define DDR_CTRL_UPD_EMR3S      BIT(5)
+#define DDR_CTRL_UPD_EMR2S      BIT(4)
+#define DDR_CTRL_PRECHARGE      BIT(3)
+#define DDR_CTRL_AUTO_REFRESH   BIT(2)
+#define DDR_CTRL_UPD_EMRS       BIT(1)
+#define DDR_CTRL_UPD_MRS        BIT(0)
+
+#define DDR_REFRESH_EN          BIT(14)
+#define DDR_REFRESH_M           0x3ff
+#define DDR_REFRESH(x)          ((x) & DDR_REFRESH_M)
+#define DDR_REFRESH_VAL         (DDR_REFRESH_EN | DDR_REFRESH(312))
+
+#define DDR_TRAS_S              0
+#define DDR_TRAS_M              0x1f
+#define DDR_TRAS(x)             (((x) & DDR_TRAS_M) << DDR_TRAS_S)
+#define DDR_TRCD_M              0xf
+#define DDR_TRCD_S              5
+#define DDR_TRCD(x)             (((x) & DDR_TRCD_M) << DDR_TRCD_S)
+#define DDR_TRP_M               0xf
+#define DDR_TRP_S               9
+#define DDR_TRP(x)              (((x) & DDR_TRP_M) << DDR_TRP_S)
+#define DDR_TRRD_M              0xf
+#define DDR_TRRD_S              13
+#define DDR_TRRD(x)             (((x) & DDR_TRRD_M) << DDR_TRRD_S)
+#define DDR_TRFC_M              0x7f
+#define DDR_TRFC_S              17
+#define DDR_TRFC(x)             (((x) & DDR_TRFC_M) << DDR_TRFC_S)
+#define DDR_TMRD_M              0xf
+#define DDR_TMRD_S              23
+#define DDR_TMRD(x)             (((x) & DDR_TMRD_M) << DDR_TMRD_S)
+#define DDR_CAS_L_M             0x17
+#define DDR_CAS_L_S             27
+#define DDR_CAS_L(x)            (((x) & DDR_CAS_L_M) << DDR_CAS_L_S)
+#define DDR_OPEN                BIT(30)
+#define DDR1_CONF_REG_VAL       (DDR_TRAS(16) | DDR_TRCD(6) | \
+				 DDR_TRP(6) | DDR_TRRD(4) | \
+				 DDR_TRFC(7) | DDR_TMRD(5) | \
+				 DDR_CAS_L(7) | DDR_OPEN)
+#define DDR2_CONF_REG_VAL       (DDR_TRAS(27) | DDR_TRCD(9) | \
+				 DDR_TRP(9) | DDR_TRRD(7) | \
+				 DDR_TRFC(21) | DDR_TMRD(15) | \
+				 DDR_CAS_L(17) | DDR_OPEN)
+
+#define DDR_BURST_LEN_S         0
+#define DDR_BURST_LEN_M         0xf
+#define DDR_BURST_LEN(x)        ((x) << DDR_BURST_LEN_S)
+#define DDR_BURST_TYPE          BIT(4)
+#define DDR_CNTL_OE_EN          BIT(5)
+#define DDR_PHASE_SEL           BIT(6)
+#define DDR_CKE                 BIT(7)
+#define DDR_TWR_S               8
+#define DDR_TWR_M               0xf
+#define DDR_TWR(x)              (((x) & DDR_TWR_M) << DDR_TWR_S)
+#define DDR_TRTW_S              12
+#define DDR_TRTW_M              0x1f
+#define DDR_TRTW(x)             (((x) & DDR_TRTW_M) << DDR_TRTW_S)
+#define DDR_TRTP_S              17
+#define DDR_TRTP_M              0xf
+#define DDR_TRTP(x)             (((x) & DDR_TRTP_M) << DDR_TRTP_S)
+#define DDR_TWTR_S              21
+#define DDR_TWTR_M              0x1f
+#define DDR_TWTR(x)             (((x) & DDR_TWTR_M) << DDR_TWTR_S)
+#define DDR_G_OPEN_L_S          26
+#define DDR_G_OPEN_L_M          0xf
+#define DDR_G_OPEN_L(x)         ((x) << DDR_G_OPEN_L_S)
+#define DDR_HALF_WIDTH_LOW      BIT(31)
+#define DDR1_CONF2_REG_VAL      (DDR_BURST_LEN(8) | DDR_CNTL_OE_EN | \
+				 DDR_CKE | DDR_TWR(13) | DDR_TRTW(14) | \
+				 DDR_TRTP(8) | DDR_TWTR(14) | \
+				 DDR_G_OPEN_L(6) | DDR_HALF_WIDTH_LOW)
+#define DDR2_CONF2_REG_VAL      (DDR_BURST_LEN(8) | DDR_CNTL_OE_EN | \
+				 DDR_CKE | DDR_TWR(1) | DDR_TRTW(14) | \
+				 DDR_TRTP(9) | DDR_TWTR(21) | \
+				 DDR_G_OPEN_L(8) | DDR_HALF_WIDTH_LOW)
+
+#define DDR_TWR_MSB             BIT(3)
+#define DDR_TRAS_MSB            BIT(2)
+#define DDR_TRFC_MSB_M          0x3
+#define DDR_TRFC_MSB(x)         (x)
+#define DDR1_CONF3_REG_VAL      0
+#define DDR2_CONF3_REG_VAL      (DDR_TWR_MSB | DDR_TRFC_MSB(2))
+
+#define DDR_CTL_SRAM_TSEL       BIT(30)
+#define DDR_CTL_SRAM_GE0_SYNC   BIT(20)
+#define DDR_CTL_SRAM_GE1_SYNC   BIT(19)
+#define DDR_CTL_SRAM_USB_SYNC   BIT(18)
+#define DDR_CTL_SRAM_PCIE_SYNC  BIT(17)
+#define DDR_CTL_SRAM_WMAC_SYNC  BIT(16)
+#define DDR_CTL_SRAM_MISC1_SYNC BIT(15)
+#define DDR_CTL_SRAM_MISC2_SYNC BIT(14)
+#define DDR_CTL_PAD_DDR2_SEL    BIT(6)
+#define DDR_CTL_HALF_WIDTH      BIT(1)
+#define DDR_CTL_CONFIG_VAL      (DDR_CTL_SRAM_TSEL | \
+				 DDR_CTL_SRAM_GE0_SYNC | \
+				 DDR_CTL_SRAM_GE1_SYNC | \
+				 DDR_CTL_SRAM_USB_SYNC | \
+				 DDR_CTL_SRAM_PCIE_SYNC | \
+				 DDR_CTL_SRAM_WMAC_SYNC | \
+				 DDR_CTL_HALF_WIDTH)
+
+#define DDR_BURST_GE0_MAX_BL_S  0
+#define DDR_BURST_GE0_MAX_BL_M  0xf
+#define DDR_BURST_GE0_MAX_BL(x) \
+	(((x) & DDR_BURST_GE0_MAX_BL_M) << DDR_BURST_GE0_MAX_BL_S)
+#define DDR_BURST_GE1_MAX_BL_S  4
+#define DDR_BURST_GE1_MAX_BL_M  0xf
+#define DDR_BURST_GE1_MAX_BL(x) \
+	(((x) & DDR_BURST_GE1_MAX_BL_M) << DDR_BURST_GE1_MAX_BL_S)
+#define DDR_BURST_PCIE_MAX_BL_S 8
+#define DDR_BURST_PCIE_MAX_BL_M 0xf
+#define DDR_BURST_PCIE_MAX_BL(x) \
+	(((x) & DDR_BURST_PCIE_MAX_BL_M) << DDR_BURST_PCIE_MAX_BL_S)
+#define DDR_BURST_USB_MAX_BL_S  12
+#define DDR_BURST_USB_MAX_BL_M  0xf
+#define DDR_BURST_USB_MAX_BL(x) \
+	(((x) & DDR_BURST_USB_MAX_BL_M) << DDR_BURST_USB_MAX_BL_S)
+#define DDR_BURST_CPU_MAX_BL_S  16
+#define DDR_BURST_CPU_MAX_BL_M  0xf
+#define DDR_BURST_CPU_MAX_BL(x) \
+	(((x) & DDR_BURST_CPU_MAX_BL_M) << DDR_BURST_CPU_MAX_BL_S)
+#define DDR_BURST_RD_MAX_BL_S   20
+#define DDR_BURST_RD_MAX_BL_M   0xf
+#define DDR_BURST_RD_MAX_BL(x) \
+	(((x) & DDR_BURST_RD_MAX_BL_M) << DDR_BURST_RD_MAX_BL_S)
+#define DDR_BURST_WR_MAX_BL_S   24
+#define DDR_BURST_WR_MAX_BL_M   0xf
+#define DDR_BURST_WR_MAX_BL(x) \
+	(((x) & DDR_BURST_WR_MAX_BL_M) << DDR_BURST_WR_MAX_BL_S)
+#define DDR_BURST_RWP_MASK_EN_S 28
+#define DDR_BURST_RWP_MASK_EN_M 0x3
+#define DDR_BURST_RWP_MASK_EN(x) \
+	(((x) & DDR_BURST_RWP_MASK_EN_M) << DDR_BURST_RWP_MASK_EN_S)
+#define DDR_BURST_CPU_PRI_BE    BIT(30)
+#define DDR_BURST_CPU_PRI       BIT(31)
+#define DDR_BURST_VAL           (DDR_BURST_CPU_PRI_BE | \
+				 DDR_BURST_RWP_MASK_EN(3) | \
+				 DDR_BURST_WR_MAX_BL(4) | \
+				 DDR_BURST_RD_MAX_BL(4) | \
+				 DDR_BURST_CPU_MAX_BL(4) | \
+				 DDR_BURST_USB_MAX_BL(4) | \
+				 DDR_BURST_PCIE_MAX_BL(4) | \
+				 DDR_BURST_GE1_MAX_BL(4) | \
+				 DDR_BURST_GE0_MAX_BL(4))
+
+#define DDR_BURST_WMAC_MAX_BL_S 0
+#define DDR_BURST_WMAC_MAX_BL_M 0xf
+#define DDR_BURST_WMAC_MAX_BL(x) \
+	(((x) & DDR_BURST_WMAC_MAX_BL_M) << DDR_BURST_WMAC_MAX_BL_S)
+#define DDR_BURST2_VAL          DDR_BURST_WMAC_MAX_BL(4)
+
+#define DDR2_CONF_TWL_S         10
+#define DDR2_CONF_TWL_M         0xf
+#define DDR2_CONF_TWL(x) \
+	(((x) & DDR2_CONF_TWL_M) << DDR2_CONF_TWL_S)
+#define DDR2_CONF_ODT           BIT(9)
+#define DDR2_CONF_TFAW_S        2
+#define DDR2_CONF_TFAW_M        0x3f
+#define DDR2_CONF_TFAW(x) \
+	(((x) & DDR2_CONF_TFAW_M) << DDR2_CONF_TFAW_S)
+#define DDR2_CONF_EN            BIT(0)
+#define DDR2_CONF_VAL           (DDR2_CONF_TWL(5) | \
+				 DDR2_CONF_TFAW(31) | \
+				 DDR2_CONF_ODT | \
+				 DDR2_CONF_EN)
+
+#define DDR1_EXT_MODE_VAL       0
+#define DDR2_EXT_MODE_VAL       0x402
+#define DDR2_EXT_MODE_OCD_VAL   0x782
+#define DDR1_MODE_DLL_VAL       0x133
+#define DDR2_MODE_DLL_VAL       0x143
+#define DDR1_MODE_VAL           0x33
+#define DDR2_MODE_VAL           0x43
+#define DDR1_TAP_VAL            0x20
+#define DDR2_TAP_VAL            0x10
+
+#define DDR_REG_BIST_MASK_ADDR_0        0x2c
+#define DDR_REG_BIST_MASK_ADDR_1        0x30
+#define DDR_REG_BIST_MASK_AHB_GE0_0     0x34
+#define DDR_REG_BIST_COMP_AHB_GE0_0     0x38
+#define DDR_REG_BIST_MASK_AHB_GE1_0     0x3c
+#define DDR_REG_BIST_COMP_AHB_GE1_0     0x40
+#define DDR_REG_BIST_COMP_ADDR_0        0x64
+#define DDR_REG_BIST_COMP_ADDR_1        0x68
+#define DDR_REG_BIST_MASK_AHB_GE0_1     0x6c
+#define DDR_REG_BIST_COMP_AHB_GE0_1     0x70
+#define DDR_REG_BIST_MASK_AHB_GE1_1     0x74
+#define DDR_REG_BIST_COMP_AHB_GE1_1     0x78
+#define DDR_REG_BIST                    0x11c
+#define DDR_REG_BIST_STATUS             0x120
+
+#define DDR_BIST_COMP_CNT_S     1
+#define DDR_BIST_COMP_CNT_M     0xff
+#define DDR_BIST_COMP_CNT(x) \
+	(((x) & DDR_BIST_COMP_CNT_M) << DDR_BIST_COMP_CNT_S)
+#define DDR_BIST_COMP_CNT_MASK \
+	(DDR_BIST_COMP_CNT_M << DDR_BIST_COMP_CNT_S)
+#define DDR_BIST_TEST_START     BIT(0)
+#define DDR_BIST_STATUS_DONE    BIT(0)
+
+/* 4 Row Address Bits, 4 Column Address Bits, 2 BA bits */
+#define DDR_BIST_MASK_ADDR_VAL  0xfa5de83f
+
+#define DDR_TAP_MAGIC_VAL       0xaa55aa55
+#define DDR_TAP_MAX_VAL         0x40
+
+void ddr_init(void)
+{
+	void __iomem *regs;
+	u32 val;
+
+	regs = map_physmem(AR71XX_DDR_CTRL_BASE, AR71XX_DDR_CTRL_SIZE,
+			   MAP_NOCACHE);
+	val = get_bootstrap();
+	if (val & QCA953X_BOOTSTRAP_DDR1) {
+		writel(DDR_CTL_CONFIG_VAL, regs + QCA953X_DDR_REG_CTL_CONF);
+		udelay(10);
+
+		/* For 16-bit DDR */
+		writel(0xffff, regs + AR71XX_DDR_REG_RD_CYCLE);
+		udelay(100);
+
+		/* Burst size */
+		writel(DDR_BURST_VAL, regs + QCA953X_DDR_REG_BURST);
+		udelay(100);
+		writel(DDR_BURST2_VAL, regs + QCA953X_DDR_REG_BURST2);
+		udelay(100);
+
+		/* AHB maximum timeout */
+		writel(0xfffff, regs + QCA953X_DDR_REG_TIMEOUT_MAX);
+		udelay(100);
+
+		/* DRAM timing */
+		writel(DDR1_CONF_REG_VAL, regs + AR71XX_DDR_REG_CONFIG);
+		udelay(100);
+		writel(DDR1_CONF2_REG_VAL, regs + AR71XX_DDR_REG_CONFIG2);
+		udelay(100);
+		writel(DDR1_CONF3_REG_VAL, regs + QCA953X_DDR_REG_CONFIG3);
+		udelay(100);
+
+		/* Precharge All */
+		writel(DDR_CTRL_PRECHARGE, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* ODT disable, Full strength, Enable DLL */
+		writel(DDR1_EXT_MODE_VAL, regs + AR71XX_DDR_REG_EMR);
+		udelay(100);
+
+		/* Update Extended Mode Register Set (EMRS) */
+		writel(DDR_CTRL_UPD_EMRS, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Reset DLL, CAS Latency 3, Burst Length 8 */
+		writel(DDR1_MODE_DLL_VAL, regs + AR71XX_DDR_REG_MODE);
+		udelay(100);
+
+		/* Update Mode Register Set (MRS) */
+		writel(DDR_CTRL_UPD_MRS, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Precharge All */
+		writel(DDR_CTRL_PRECHARGE, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Auto Refresh */
+		writel(DDR_CTRL_AUTO_REFRESH, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+		writel(DDR_CTRL_AUTO_REFRESH, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Normal DLL, CAS Latency 3, Burst Length 8 */
+		writel(DDR1_MODE_VAL, regs + AR71XX_DDR_REG_MODE);
+		udelay(100);
+
+		/* Update Mode Register Set (MRS) */
+		writel(DDR_CTRL_UPD_MRS, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Refresh time control */
+		writel(DDR_REFRESH_VAL, regs + AR71XX_DDR_REG_REFRESH);
+		udelay(100);
+
+		/* DQS 0 Tap Control */
+		writel(DDR1_TAP_VAL, regs + AR71XX_DDR_REG_TAP_CTRL0);
+
+		/* DQS 1 Tap Control */
+		writel(DDR1_TAP_VAL, regs + AR71XX_DDR_REG_TAP_CTRL1);
+	} else {
+		writel(DDR_CTRL_UPD_EMR2S, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(10);
+		writel(DDR_CTRL_UPD_EMR3S, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(10);
+		writel(DDR_CTL_CONFIG_VAL | DDR_CTL_PAD_DDR2_SEL,
+		       regs + QCA953X_DDR_REG_CTL_CONF);
+		udelay(10);
+
+		/* For 16-bit DDR */
+		writel(0xffff, regs + AR71XX_DDR_REG_RD_CYCLE);
+		udelay(100);
+
+		/* Burst size */
+		writel(DDR_BURST_VAL, regs + QCA953X_DDR_REG_BURST);
+		udelay(100);
+		writel(DDR_BURST2_VAL, regs + QCA953X_DDR_REG_BURST2);
+		udelay(100);
+
+		/* AHB maximum timeout */
+		writel(0xfffff, regs + QCA953X_DDR_REG_TIMEOUT_MAX);
+		udelay(100);
+
+		/* DRAM timing */
+		writel(DDR2_CONF_REG_VAL, regs + AR71XX_DDR_REG_CONFIG);
+		udelay(100);
+		writel(DDR2_CONF2_REG_VAL, regs + AR71XX_DDR_REG_CONFIG2);
+		udelay(100);
+		writel(DDR2_CONF3_REG_VAL, regs + QCA953X_DDR_REG_CONFIG3);
+		udelay(100);
+
+		/* Enable DDR2 */
+		writel(DDR2_CONF_VAL, regs + QCA953X_DDR_REG_DDR2_CONFIG);
+		udelay(100);
+
+		/* Precharge All */
+		writel(DDR_CTRL_PRECHARGE, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Update Extended Mode Register 2 Set (EMR2S) */
+		writel(DDR_CTRL_UPD_EMR2S, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Update Extended Mode Register 3 Set (EMR3S) */
+		writel(DDR_CTRL_UPD_EMR3S, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* 150 ohm, Reduced strength, Enable DLL */
+		writel(DDR2_EXT_MODE_VAL, regs + AR71XX_DDR_REG_EMR);
+		udelay(100);
+
+		/* Update Extended Mode Register Set (EMRS) */
+		writel(DDR_CTRL_UPD_EMRS, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Reset DLL, CAS Latency 4, Burst Length 8 */
+		writel(DDR2_MODE_DLL_VAL, regs + AR71XX_DDR_REG_MODE);
+		udelay(100);
+
+		/* Update Mode Register Set (MRS) */
+		writel(DDR_CTRL_UPD_MRS, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Precharge All */
+		writel(DDR_CTRL_PRECHARGE, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Auto Refresh */
+		writel(DDR_CTRL_AUTO_REFRESH, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+		writel(DDR_CTRL_AUTO_REFRESH, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Normal DLL, CAS Latency 4, Burst Length 8 */
+		writel(DDR2_MODE_VAL, regs + AR71XX_DDR_REG_MODE);
+		udelay(100);
+
+		/* Mode Register Set (MRS) */
+		writel(DDR_CTRL_UPD_MRS, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Enable OCD, Enable DLL, Reduced Drive Strength */
+		writel(DDR2_EXT_MODE_OCD_VAL, regs + AR71XX_DDR_REG_EMR);
+		udelay(100);
+
+		/* Update Extended Mode Register Set (EMRS) */
+		writel(DDR_CTRL_UPD_EMRS, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* OCD diable, Enable DLL, Reduced Drive Strength */
+		writel(DDR2_EXT_MODE_VAL, regs + AR71XX_DDR_REG_EMR);
+		udelay(100);
+
+		/* Update Extended Mode Register Set (EMRS) */
+		writel(DDR_CTRL_UPD_EMRS, regs + AR71XX_DDR_REG_CONTROL);
+		udelay(100);
+
+		/* Refresh time control */
+		writel(DDR_REFRESH_VAL, regs + AR71XX_DDR_REG_REFRESH);
+		udelay(100);
+
+		/* DQS 0 Tap Control */
+		writel(DDR2_TAP_VAL, regs + AR71XX_DDR_REG_TAP_CTRL0);
+
+		/* DQS 1 Tap Control */
+		writel(DDR2_TAP_VAL, regs + AR71XX_DDR_REG_TAP_CTRL1);
+	}
+}
+
+void ddr_tap_tuning(void)
+{
+	void __iomem *regs;
+	u32 val, pass, tap, cnt, tap_val, last, first;
+
+	regs = map_physmem(AR71XX_DDR_CTRL_BASE, AR71XX_DDR_CTRL_SIZE,
+			   MAP_NOCACHE);
+
+	tap_val = readl(regs + AR71XX_DDR_REG_TAP_CTRL0);
+	first = DDR_TAP_MAGIC_VAL;
+	last = 0;
+	cnt = 0;
+	tap = 0;
+
+	do {
+		writel(tap, regs + AR71XX_DDR_REG_TAP_CTRL0);
+		writel(tap, regs + AR71XX_DDR_REG_TAP_CTRL1);
+
+		writel(DDR_BIST_COMP_CNT(8), regs + DDR_REG_BIST_COMP_ADDR_1);
+		writel(DDR_BIST_MASK_ADDR_VAL, regs + DDR_REG_BIST_MASK_ADDR_0);
+		writel(0xffff, regs + DDR_REG_BIST_COMP_AHB_GE0_1);
+		writel(0xffff, regs + DDR_REG_BIST_COMP_AHB_GE1_0);
+		writel(0xffff, regs + DDR_REG_BIST_COMP_AHB_GE1_1);
+		writel(0xffff, regs + DDR_REG_BIST_MASK_AHB_GE0_0);
+		writel(0xffff, regs + DDR_REG_BIST_MASK_AHB_GE0_1);
+		writel(0xffff, regs + DDR_REG_BIST_MASK_AHB_GE1_0);
+		writel(0xffff, regs + DDR_REG_BIST_MASK_AHB_GE1_1);
+		writel(0xffff, regs + DDR_REG_BIST_COMP_AHB_GE0_0);
+
+		/* Start BIST test */
+		writel(DDR_BIST_TEST_START, regs + DDR_REG_BIST);
+
+		do {
+			val = readl(regs + DDR_REG_BIST_STATUS);
+		} while (!(val & DDR_BIST_STATUS_DONE));
+
+		/* Stop BIST test */
+		writel(0, regs + DDR_REG_BIST);
+
+		pass = val & DDR_BIST_COMP_CNT_MASK;
+		pass ^= DDR_BIST_COMP_CNT(8);
+		if (!pass) {
+			if (first != DDR_TAP_MAGIC_VAL) {
+				last = tap;
+			} else  {
+				first = tap;
+				last = tap;
+			}
+			cnt++;
+		}
+		tap++;
+	} while (tap < DDR_TAP_MAX_VAL);
+
+	if (cnt) {
+		tap_val = (first + last) / 2;
+		tap_val %= DDR_TAP_MAX_VAL;
+	}
+
+	writel(tap_val, regs + AR71XX_DDR_REG_TAP_CTRL0);
+	writel(tap_val, regs + AR71XX_DDR_REG_TAP_CTRL1);
+}