sunxi: Use CONFIG_MACH_SUN?I from Kconfig instead of CONFIG_SUN?I
[platform/kernel/u-boot.git] / arch / arm / cpu / armv7 / sunxi / dram.c
index 0f1ceec..dc9fdb9 100644 (file)
 #define CPU_CFG_CHIP_REV_B 0x3
 
 /*
- * Wait up to 1s for mask to be clear in given reg.
+ * Wait up to 1s for value to be set in given part of reg.
  */
-static void await_completion(u32 *reg, u32 mask)
+static void await_completion(u32 *reg, u32 mask, u32 val)
 {
        unsigned long tmo = timer_get_us() + 1000000;
 
-       while (readl(reg) & mask) {
+       while ((readl(reg) & mask) != val) {
                if (timer_get_us() > tmo)
                        panic("Timeout initialising DRAM\n");
        }
 }
 
+/*
+ * Wait up to 1s for mask to be clear in given reg.
+ */
+static inline void await_bits_clear(u32 *reg, u32 mask)
+{
+       await_completion(reg, mask, 0);
+}
+
+/*
+ * Wait up to 1s for mask to be set in given reg.
+ */
+static inline void await_bits_set(u32 *reg, u32 mask)
+{
+       await_completion(reg, mask, mask);
+}
+
+/*
+ * This performs the external DRAM reset by driving the RESET pin low and
+ * then high again. According to the DDR3 spec, the RESET pin needs to be
+ * kept low for at least 200 us.
+ */
 static void mctl_ddr3_reset(void)
 {
        struct sunxi_dram_reg *dram =
                        (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
 
-#ifdef CONFIG_SUN4I
+#ifdef CONFIG_MACH_SUN4I
        struct sunxi_timer_reg *timer =
                        (struct sunxi_timer_reg *)SUNXI_TIMER_BASE;
        u32 reg_val;
@@ -64,22 +85,35 @@ static void mctl_ddr3_reset(void)
        if ((reg_val & CPU_CFG_CHIP_VER_MASK) !=
            CPU_CFG_CHIP_VER(CPU_CFG_CHIP_REV_A)) {
                setbits_le32(&dram->mcr, DRAM_MCR_RESET);
-               udelay(2);
+               udelay(200);
                clrbits_le32(&dram->mcr, DRAM_MCR_RESET);
        } else
 #endif
        {
                clrbits_le32(&dram->mcr, DRAM_MCR_RESET);
-               udelay(2);
+               udelay(200);
                setbits_le32(&dram->mcr, DRAM_MCR_RESET);
        }
+       /* After the RESET pin is de-asserted, the DDR3 spec requires to wait
+        * for additional 500 us before driving the CKE pin (Clock Enable)
+        * high. The duration of this delay can be configured in the SDR_IDCR
+        * (Initialization Delay Configuration Register) and applied
+        * automatically by the DRAM controller during the DDR3 initialization
+        * step. But SDR_IDCR has limited range on sun4i/sun5i hardware and
+        * can't provide sufficient delay at DRAM clock frequencies higher than
+        * 524 MHz (while Allwinner A13 supports DRAM clock frequency up to
+        * 533 MHz according to the datasheet). Additionally, there is no
+        * official documentation for the SDR_IDCR register anywhere, and
+        * there is always a chance that we are interpreting it wrong.
+        * Better be safe than sorry, so add an explicit delay here. */
+       udelay(500);
 }
 
 static void mctl_set_drive(void)
 {
        struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
 
-#ifdef CONFIG_SUN7I
+#ifdef CONFIG_MACH_SUN7I
        clrsetbits_le32(&dram->mcr, DRAM_MCR_MODE_NORM(0x3) | (0x3 << 28),
 #else
        clrsetbits_le32(&dram->mcr, DRAM_MCR_MODE_NORM(0x3),
@@ -102,6 +136,14 @@ static void mctl_itm_enable(void)
        clrbits_le32(&dram->ccr, DRAM_CCR_ITM_OFF);
 }
 
+static void mctl_itm_reset(void)
+{
+       mctl_itm_disable();
+       udelay(1); /* ITM reset needs a bit of delay */
+       mctl_itm_enable();
+       udelay(1);
+}
+
 static void mctl_enable_dll0(u32 phase)
 {
        struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
@@ -118,23 +160,28 @@ static void mctl_enable_dll0(u32 phase)
        udelay(22);
 }
 
+/* Get the number of DDR byte lanes */
+static u32 mctl_get_number_of_lanes(void)
+{
+       struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
+       if ((readl(&dram->dcr) & DRAM_DCR_BUS_WIDTH_MASK) ==
+                               DRAM_DCR_BUS_WIDTH(DRAM_DCR_BUS_WIDTH_32BIT))
+               return 4;
+       else
+               return 2;
+}
+
 /*
  * Note: This differs from pm/standby in that it checks the bus width
  */
 static void mctl_enable_dllx(u32 phase)
 {
        struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
-       u32 i, n, bus_width;
+       u32 i, number_of_lanes;
 
-       bus_width = readl(&dram->dcr);
+       number_of_lanes = mctl_get_number_of_lanes();
 
-       if ((bus_width & DRAM_DCR_BUS_WIDTH_MASK) ==
-           DRAM_DCR_BUS_WIDTH(DRAM_DCR_BUS_WIDTH_32BIT))
-               n = DRAM_DCR_NR_DLLCR_32BIT;
-       else
-               n = DRAM_DCR_NR_DLLCR_16BIT;
-
-       for (i = 1; i < n; i++) {
+       for (i = 1; i <= number_of_lanes; i++) {
                clrsetbits_le32(&dram->dllcr[i], 0xf << 14,
                                (phase & 0xf) << 14);
                clrsetbits_le32(&dram->dllcr[i], DRAM_DLLCR_NRESET,
@@ -143,19 +190,19 @@ static void mctl_enable_dllx(u32 phase)
        }
        udelay(2);
 
-       for (i = 1; i < n; i++)
+       for (i = 1; i <= number_of_lanes; i++)
                clrbits_le32(&dram->dllcr[i], DRAM_DLLCR_NRESET |
                             DRAM_DLLCR_DISABLE);
        udelay(22);
 
-       for (i = 1; i < n; i++)
+       for (i = 1; i <= number_of_lanes; i++)
                clrsetbits_le32(&dram->dllcr[i], DRAM_DLLCR_DISABLE,
                                DRAM_DLLCR_NRESET);
        udelay(22);
 }
 
 static u32 hpcr_value[32] = {
-#ifdef CONFIG_SUN5I
+#ifdef CONFIG_MACH_SUN5I
        0, 0, 0, 0,
        0, 0, 0, 0,
        0, 0, 0, 0,
@@ -165,7 +212,7 @@ static u32 hpcr_value[32] = {
        0x0301, 0x0301, 0x0301, 0x0301,
        0x0301, 0x0301, 0x0301, 0
 #endif
-#ifdef CONFIG_SUN4I
+#ifdef CONFIG_MACH_SUN4I
        0x0301, 0x0301, 0x0301, 0x0301,
        0x0301, 0x0301, 0, 0,
        0, 0, 0, 0,
@@ -175,7 +222,7 @@ static u32 hpcr_value[32] = {
        0x1035, 0x1031, 0x0731, 0x1035,
        0x1031, 0x0301, 0x0301, 0x0731
 #endif
-#ifdef CONFIG_SUN7I
+#ifdef CONFIG_MACH_SUN7I
        0x0301, 0x0301, 0x0301, 0x0301,
        0x0301, 0x0301, 0x0301, 0x0301,
        0, 0, 0, 0,
@@ -201,10 +248,13 @@ static void mctl_configure_hostport(void)
                writel(hpcr_value[i], &dram->hpcr[i]);
 }
 
-static void mctl_setup_dram_clock(u32 clk)
+static void mctl_setup_dram_clock(u32 clk, u32 mbus_clk)
 {
        u32 reg_val;
        struct sunxi_ccm_reg *ccm = (struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
+       u32 pll5p_clk, pll6x_clk;
+       u32 pll5p_div, pll6x_div;
+       u32 pll5p_rate, pll6x_rate;
 
        /* setup DRAM PLL */
        reg_val = readl(&ccm->pll5_cfg);
@@ -212,42 +262,40 @@ static void mctl_setup_dram_clock(u32 clk)
        reg_val &= ~CCM_PLL5_CTRL_K_MASK;               /* set K to 0 (x1) */
        reg_val &= ~CCM_PLL5_CTRL_N_MASK;               /* set N to 0 (x0) */
        reg_val &= ~CCM_PLL5_CTRL_P_MASK;               /* set P to 0 (x1) */
+#ifdef CONFIG_OLD_SUNXI_KERNEL_COMPAT
+       /* Old kernels are hardcoded to P=1 (divide by 2) */
+       reg_val |= CCM_PLL5_CTRL_P(1);
+#endif
        if (clk >= 540 && clk < 552) {
-               /* dram = 540MHz, pll5p = 540MHz */
+               /* dram = 540MHz */
                reg_val |= CCM_PLL5_CTRL_M(CCM_PLL5_CTRL_M_X(2));
                reg_val |= CCM_PLL5_CTRL_K(CCM_PLL5_CTRL_K_X(3));
                reg_val |= CCM_PLL5_CTRL_N(CCM_PLL5_CTRL_N_X(15));
-               reg_val |= CCM_PLL5_CTRL_P(1);
        } else if (clk >= 512 && clk < 528) {
-               /* dram = 512MHz, pll5p = 384MHz */
+               /* dram = 512MHz */
                reg_val |= CCM_PLL5_CTRL_M(CCM_PLL5_CTRL_M_X(3));
                reg_val |= CCM_PLL5_CTRL_K(CCM_PLL5_CTRL_K_X(4));
                reg_val |= CCM_PLL5_CTRL_N(CCM_PLL5_CTRL_N_X(16));
-               reg_val |= CCM_PLL5_CTRL_P(2);
        } else if (clk >= 496 && clk < 504) {
-               /* dram = 496MHz, pll5p = 372MHz */
+               /* dram = 496MHz */
                reg_val |= CCM_PLL5_CTRL_M(CCM_PLL5_CTRL_M_X(3));
                reg_val |= CCM_PLL5_CTRL_K(CCM_PLL5_CTRL_K_X(2));
                reg_val |= CCM_PLL5_CTRL_N(CCM_PLL5_CTRL_N_X(31));
-               reg_val |= CCM_PLL5_CTRL_P(2);
        } else if (clk >= 468 && clk < 480) {
-               /* dram = 468MHz, pll5p = 468MHz */
+               /* dram = 468MHz */
                reg_val |= CCM_PLL5_CTRL_M(CCM_PLL5_CTRL_M_X(2));
                reg_val |= CCM_PLL5_CTRL_K(CCM_PLL5_CTRL_K_X(3));
                reg_val |= CCM_PLL5_CTRL_N(CCM_PLL5_CTRL_N_X(13));
-               reg_val |= CCM_PLL5_CTRL_P(1);
        } else if (clk >= 396 && clk < 408) {
-               /* dram = 396MHz, pll5p = 396MHz */
+               /* dram = 396MHz */
                reg_val |= CCM_PLL5_CTRL_M(CCM_PLL5_CTRL_M_X(2));
                reg_val |= CCM_PLL5_CTRL_K(CCM_PLL5_CTRL_K_X(3));
                reg_val |= CCM_PLL5_CTRL_N(CCM_PLL5_CTRL_N_X(11));
-               reg_val |= CCM_PLL5_CTRL_P(1);
        } else  {
                /* any other frequency that is a multiple of 24 */
                reg_val |= CCM_PLL5_CTRL_M(CCM_PLL5_CTRL_M_X(2));
                reg_val |= CCM_PLL5_CTRL_K(CCM_PLL5_CTRL_K_X(2));
                reg_val |= CCM_PLL5_CTRL_N(CCM_PLL5_CTRL_N_X(clk / 24));
-               reg_val |= CCM_PLL5_CTRL_P(CCM_PLL5_CTRL_P_X(2));
        }
        reg_val &= ~CCM_PLL5_CTRL_VCO_GAIN;             /* PLL VCO Gain off */
        reg_val |= CCM_PLL5_CTRL_EN;                    /* PLL On */
@@ -256,7 +304,7 @@ static void mctl_setup_dram_clock(u32 clk)
 
        setbits_le32(&ccm->pll5_cfg, CCM_PLL5_CTRL_DDR_CLK);
 
-#if defined(CONFIG_SUN4I) || defined(CONFIG_SUN7I)
+#if defined(CONFIG_MACH_SUN4I) || defined(CONFIG_MACH_SUN7I)
        /* reset GPS */
        clrbits_le32(&ccm->gps_clk_cfg, CCM_GPS_CTRL_RESET | CCM_GPS_CTRL_GATE);
        setbits_le32(&ccm->ahb_gate0, CCM_AHB_GATE_GPS);
@@ -264,26 +312,43 @@ static void mctl_setup_dram_clock(u32 clk)
        clrbits_le32(&ccm->ahb_gate0, CCM_AHB_GATE_GPS);
 #endif
 
-#if defined(CONFIG_SUN5I) || defined(CONFIG_SUN7I)
        /* setup MBUS clock */
-       reg_val = CCM_MBUS_CTRL_GATE |
-#ifdef CONFIG_SUN7I
-                 CCM_MBUS_CTRL_CLK_SRC(CCM_MBUS_CTRL_CLK_SRC_PLL6) |
-                 CCM_MBUS_CTRL_N(CCM_MBUS_CTRL_N_X(2)) |
-                 CCM_MBUS_CTRL_M(CCM_MBUS_CTRL_M_X(2));
-#else /* defined(CONFIG_SUN5I) */
-                 CCM_MBUS_CTRL_CLK_SRC(CCM_MBUS_CTRL_CLK_SRC_PLL5) |
-                 CCM_MBUS_CTRL_N(CCM_MBUS_CTRL_N_X(1)) |
-                 CCM_MBUS_CTRL_M(CCM_MBUS_CTRL_M_X(2));
+       if (!mbus_clk)
+               mbus_clk = 300;
+
+       /* PLL5P and PLL6 are the potential clock sources for MBUS */
+       pll6x_clk = clock_get_pll6() / 1000000;
+#ifdef CONFIG_MACH_SUN7I
+       pll6x_clk *= 2; /* sun7i uses PLL6*2, sun5i uses just PLL6 */
 #endif
+       pll5p_clk = clock_get_pll5p() / 1000000;
+       pll6x_div = DIV_ROUND_UP(pll6x_clk, mbus_clk);
+       pll5p_div = DIV_ROUND_UP(pll5p_clk, mbus_clk);
+       pll6x_rate = pll6x_clk / pll6x_div;
+       pll5p_rate = pll5p_clk / pll5p_div;
+
+       if (pll6x_div <= 16 && pll6x_rate > pll5p_rate) {
+               /* use PLL6 as the MBUS clock source */
+               reg_val = CCM_MBUS_CTRL_GATE |
+                         CCM_MBUS_CTRL_CLK_SRC(CCM_MBUS_CTRL_CLK_SRC_PLL6) |
+                         CCM_MBUS_CTRL_N(CCM_MBUS_CTRL_N_X(1)) |
+                         CCM_MBUS_CTRL_M(CCM_MBUS_CTRL_M_X(pll6x_div));
+       } else if (pll5p_div <= 16) {
+               /* use PLL5P as the MBUS clock source */
+               reg_val = CCM_MBUS_CTRL_GATE |
+                         CCM_MBUS_CTRL_CLK_SRC(CCM_MBUS_CTRL_CLK_SRC_PLL5) |
+                         CCM_MBUS_CTRL_N(CCM_MBUS_CTRL_N_X(1)) |
+                         CCM_MBUS_CTRL_M(CCM_MBUS_CTRL_M_X(pll5p_div));
+       } else {
+               panic("Bad mbus_clk\n");
+       }
        writel(reg_val, &ccm->mbus_clk_cfg);
-#endif
 
        /*
         * open DRAMC AHB & DLL register clock
         * close it first
         */
-#if defined(CONFIG_SUN5I) || defined(CONFIG_SUN7I)
+#if defined(CONFIG_MACH_SUN5I) || defined(CONFIG_MACH_SUN7I)
        clrbits_le32(&ccm->ahb_gate0, CCM_AHB_GATE_SDRAM | CCM_AHB_GATE_DLL);
 #else
        clrbits_le32(&ccm->ahb_gate0, CCM_AHB_GATE_SDRAM);
@@ -291,7 +356,7 @@ static void mctl_setup_dram_clock(u32 clk)
        udelay(22);
 
        /* then open it */
-#if defined(CONFIG_SUN5I) || defined(CONFIG_SUN7I)
+#if defined(CONFIG_MACH_SUN5I) || defined(CONFIG_MACH_SUN7I)
        setbits_le32(&ccm->ahb_gate0, CCM_AHB_GATE_SDRAM | CCM_AHB_GATE_DLL);
 #else
        setbits_le32(&ccm->ahb_gate0, CCM_AHB_GATE_SDRAM);
@@ -299,19 +364,48 @@ static void mctl_setup_dram_clock(u32 clk)
        udelay(22);
 }
 
+/*
+ * The data from rslrX and rdgrX registers (X=rank) is stored
+ * in a single 32-bit value using the following format:
+ *   bits [31:26] - DQS gating system latency for byte lane 3
+ *   bits [25:24] - DQS gating phase select for byte lane 3
+ *   bits [23:18] - DQS gating system latency for byte lane 2
+ *   bits [17:16] - DQS gating phase select for byte lane 2
+ *   bits [15:10] - DQS gating system latency for byte lane 1
+ *   bits [ 9:8 ] - DQS gating phase select for byte lane 1
+ *   bits [ 7:2 ] - DQS gating system latency for byte lane 0
+ *   bits [ 1:0 ] - DQS gating phase select for byte lane 0
+ */
+static void mctl_set_dqs_gating_delay(int rank, u32 dqs_gating_delay)
+{
+       struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
+       u32 lane, number_of_lanes = mctl_get_number_of_lanes();
+       /* rank0 gating system latency (3 bits per lane: cycles) */
+       u32 slr = readl(rank == 0 ? &dram->rslr0 : &dram->rslr1);
+       /* rank0 gating phase select (2 bits per lane: 90, 180, 270, 360) */
+       u32 dgr = readl(rank == 0 ? &dram->rdgr0 : &dram->rdgr1);
+       for (lane = 0; lane < number_of_lanes; lane++) {
+               u32 tmp = dqs_gating_delay >> (lane * 8);
+               slr &= ~(7 << (lane * 3));
+               slr |= ((tmp >> 2) & 7) << (lane * 3);
+               dgr &= ~(3 << (lane * 2));
+               dgr |= (tmp & 3) << (lane * 2);
+       }
+       writel(slr, rank == 0 ? &dram->rslr0 : &dram->rslr1);
+       writel(dgr, rank == 0 ? &dram->rdgr0 : &dram->rdgr1);
+}
+
 static int dramc_scan_readpipe(void)
 {
        struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
        u32 reg_val;
 
        /* data training trigger */
-#ifdef CONFIG_SUN7I
        clrbits_le32(&dram->csr, DRAM_CSR_FAILED);
-#endif
        setbits_le32(&dram->ccr, DRAM_CCR_DATA_TRAINING);
 
        /* check whether data training process has completed */
-       await_completion(&dram->ccr, DRAM_CCR_DATA_TRAINING);
+       await_bits_clear(&dram->ccr, DRAM_CCR_DATA_TRAINING);
 
        /* check data training result */
        reg_val = readl(&dram->csr);
@@ -321,120 +415,9 @@ static int dramc_scan_readpipe(void)
        return 0;
 }
 
-static int dramc_scan_dll_para(void)
-{
-       struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
-       const u32 dqs_dly[7] = {0x3, 0x2, 0x1, 0x0, 0xe, 0xd, 0xc};
-       const u32 clk_dly[15] = {0x07, 0x06, 0x05, 0x04, 0x03,
-                                0x02, 0x01, 0x00, 0x08, 0x10,
-                                0x18, 0x20, 0x28, 0x30, 0x38};
-       u32 clk_dqs_count[15];
-       u32 dqs_i, clk_i, cr_i;
-       u32 max_val, min_val;
-       u32 dqs_index, clk_index;
-
-       /* Find DQS_DLY Pass Count for every CLK_DLY */
-       for (clk_i = 0; clk_i < 15; clk_i++) {
-               clk_dqs_count[clk_i] = 0;
-               clrsetbits_le32(&dram->dllcr[0], 0x3f << 6,
-                               (clk_dly[clk_i] & 0x3f) << 6);
-               for (dqs_i = 0; dqs_i < 7; dqs_i++) {
-                       for (cr_i = 1; cr_i < 5; cr_i++) {
-                               clrsetbits_le32(&dram->dllcr[cr_i],
-                                               0x4f << 14,
-                                               (dqs_dly[dqs_i] & 0x4f) << 14);
-                       }
-                       udelay(2);
-                       if (dramc_scan_readpipe() == 0)
-                               clk_dqs_count[clk_i]++;
-               }
-       }
-       /* Test DQS_DLY Pass Count for every CLK_DLY from up to down */
-       for (dqs_i = 15; dqs_i > 0; dqs_i--) {
-               max_val = 15;
-               min_val = 15;
-               for (clk_i = 0; clk_i < 15; clk_i++) {
-                       if (clk_dqs_count[clk_i] == dqs_i) {
-                               max_val = clk_i;
-                               if (min_val == 15)
-                                       min_val = clk_i;
-                       }
-               }
-               if (max_val < 15)
-                       break;
-       }
-
-       /* Check if Find a CLK_DLY failed */
-       if (!dqs_i)
-               goto fail;
-
-       /* Find the middle index of CLK_DLY */
-       clk_index = (max_val + min_val) >> 1;
-       if ((max_val == (15 - 1)) && (min_val > 0))
-               /* if CLK_DLY[MCTL_CLK_DLY_COUNT] is very good, then the middle
-                * value can be more close to the max_val
-                */
-               clk_index = (15 + clk_index) >> 1;
-       else if ((max_val < (15 - 1)) && (min_val == 0))
-               /* if CLK_DLY[0] is very good, then the middle value can be more
-                * close to the min_val
-                */
-               clk_index >>= 1;
-       if (clk_dqs_count[clk_index] < dqs_i)
-               clk_index = min_val;
-
-       /* Find the middle index of DQS_DLY for the CLK_DLY got above, and Scan
-        * read pipe again
-        */
-       clrsetbits_le32(&dram->dllcr[0], 0x3f << 6,
-                       (clk_dly[clk_index] & 0x3f) << 6);
-       max_val = 7;
-       min_val = 7;
-       for (dqs_i = 0; dqs_i < 7; dqs_i++) {
-               clk_dqs_count[dqs_i] = 0;
-               for (cr_i = 1; cr_i < 5; cr_i++) {
-                       clrsetbits_le32(&dram->dllcr[cr_i],
-                                       0x4f << 14,
-                                       (dqs_dly[dqs_i] & 0x4f) << 14);
-               }
-               udelay(2);
-               if (dramc_scan_readpipe() == 0) {
-                       clk_dqs_count[dqs_i] = 1;
-                       max_val = dqs_i;
-                       if (min_val == 7)
-                               min_val = dqs_i;
-               }
-       }
-
-       if (max_val < 7) {
-               dqs_index = (max_val + min_val) >> 1;
-               if ((max_val == (7-1)) && (min_val > 0))
-                       dqs_index = (7 + dqs_index) >> 1;
-               else if ((max_val < (7-1)) && (min_val == 0))
-                       dqs_index >>= 1;
-               if (!clk_dqs_count[dqs_index])
-                       dqs_index = min_val;
-               for (cr_i = 1; cr_i < 5; cr_i++) {
-                       clrsetbits_le32(&dram->dllcr[cr_i],
-                                       0x4f << 14,
-                                       (dqs_dly[dqs_index] & 0x4f) << 14);
-               }
-               udelay(2);
-               return dramc_scan_readpipe();
-       }
-
-fail:
-       clrbits_le32(&dram->dllcr[0], 0x3f << 6);
-       for (cr_i = 1; cr_i < 5; cr_i++)
-               clrbits_le32(&dram->dllcr[cr_i], 0x4f << 14);
-       udelay(2);
-
-       return dramc_scan_readpipe();
-}
-
 static void dramc_clock_output_en(u32 on)
 {
-#if defined(CONFIG_SUN5I) || defined(CONFIG_SUN7I)
+#if defined(CONFIG_MACH_SUN5I) || defined(CONFIG_MACH_SUN7I)
        struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
 
        if (on)
@@ -442,7 +425,7 @@ static void dramc_clock_output_en(u32 on)
        else
                clrbits_le32(&dram->mcr, DRAM_MCR_DCLK_OUT);
 #endif
-#ifdef CONFIG_SUN4I
+#ifdef CONFIG_MACH_SUN4I
        struct sunxi_ccm_reg *ccm = (struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
        if (on)
                setbits_le32(&ccm->dram_clk_cfg, CCM_DRAM_CTRL_DCLK_OUT);
@@ -451,54 +434,170 @@ static void dramc_clock_output_en(u32 on)
 #endif
 }
 
-static const u16 tRFC_table[2][6] = {
-       /*       256Mb    512Mb    1Gb      2Gb      4Gb      8Gb      */
-       /* DDR2  75ns     105ns    127.5ns  195ns    327.5ns  invalid  */
-       {        77,      108,     131,     200,     336,     336 },
-       /* DDR3  invalid  90ns     110ns    160ns    300ns    350ns    */
-       {        93,      93,      113,     164,     308,     359 }
+/* tRFC in nanoseconds for different densities (from the DDR3 spec) */
+static const u16 tRFC_DDR3_table[6] = {
+       /* 256Mb    512Mb    1Gb      2Gb      4Gb      8Gb */
+          90,      90,      110,     160,     300,     350
 };
 
-static void dramc_set_autorefresh_cycle(u32 clk, u32 type, u32 density)
+static void dramc_set_autorefresh_cycle(u32 clk, u32 density)
 {
        struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
        u32 tRFC, tREFI;
 
-       tRFC = (tRFC_table[type][density] * clk + 1023) >> 10;
+       tRFC = (tRFC_DDR3_table[density] * clk + 999) / 1000;
        tREFI = (7987 * clk) >> 10;     /* <= 7.8us */
 
        writel(DRAM_DRR_TREFI(tREFI) | DRAM_DRR_TRFC(tRFC), &dram->drr);
 }
 
-unsigned long dramc_init(struct dram_para *para)
+/* Calculate the value for A11, A10, A9 bits in MR0 (write recovery) */
+static u32 ddr3_write_recovery(u32 clk)
+{
+       u32 twr_ns = 15; /* DDR3 spec says that it is 15ns for all speed bins */
+       u32 twr_ck = (twr_ns * clk + 999) / 1000;
+       if (twr_ck < 5)
+               return 1;
+       else if (twr_ck <= 8)
+               return twr_ck - 4;
+       else if (twr_ck <= 10)
+               return 5;
+       else
+               return 6;
+}
+
+/*
+ * If the dram->ppwrsctl (SDR_DPCR) register has the lowest bit set to 1, this
+ * means that DRAM is currently in self-refresh mode and retaining the old
+ * data. Since we have no idea what to do in this situation yet, just set this
+ * register to 0 and initialize DRAM in the same way as on any normal reboot
+ * (discarding whatever was stored there).
+ *
+ * Note: on sun7i hardware, the highest 16 bits need to be set to 0x1651 magic
+ * value for this write operation to have any effect. On sun5i hadware this
+ * magic value is not necessary. And on sun4i hardware the writes to this
+ * register seem to have no effect at all.
+ */
+static void mctl_disable_power_save(void)
+{
+       struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
+       writel(0x16510000, &dram->ppwrsctl);
+}
+
+/*
+ * After the DRAM is powered up or reset, the DDR3 spec requires to wait at
+ * least 500 us before driving the CKE pin (Clock Enable) high. The dram->idct
+ * (SDR_IDCR) register appears to configure this delay, which gets applied
+ * right at the time when the DRAM initialization is activated in the
+ * 'mctl_ddr3_initialize' function.
+ */
+static void mctl_set_cke_delay(void)
+{
+       struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
+
+       /* The CKE delay is represented in DRAM clock cycles, multiplied by N
+        * (where N=2 for sun4i/sun5i and N=3 for sun7i). Here it is set to
+        * the maximum possible value 0x1ffff, just like in the Allwinner's
+        * boot0 bootloader. The resulting delay value is somewhere between
+        * ~0.4 ms (sun5i with 648 MHz DRAM clock speed) and ~1.1 ms (sun7i
+        * with 360 MHz DRAM clock speed). */
+       setbits_le32(&dram->idcr, 0x1ffff);
+}
+
+/*
+ * This triggers the DRAM initialization. It performs sending the mode registers
+ * to the DRAM among other things. Very likely the ZQCL command is also getting
+ * executed (to do the initial impedance calibration on the DRAM side of the
+ * wire). The memory controller and the PHY must be already configured before
+ * calling this function.
+ */
+static void mctl_ddr3_initialize(void)
+{
+       struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
+       setbits_le32(&dram->ccr, DRAM_CCR_INIT);
+       await_bits_clear(&dram->ccr, DRAM_CCR_INIT);
+}
+
+/*
+ * Perform impedance calibration on the DRAM controller side of the wire.
+ */
+static void mctl_set_impedance(u32 zq, u32 odt_en)
+{
+       struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
+       u32 reg_val;
+       u32 zprog = zq & 0xFF, zdata = (zq >> 8) & 0xFFFFF;
+
+#ifndef CONFIG_MACH_SUN7I
+       /* Appears that some kind of automatically initiated default
+        * ZQ calibration is already in progress at this point on sun4i/sun5i
+        * hardware, but not on sun7i. So it is reasonable to wait for its
+        * completion before doing anything else. */
+       await_bits_set(&dram->zqsr, DRAM_ZQSR_ZDONE);
+#endif
+
+       /* ZQ calibration is not really useful unless ODT is enabled */
+       if (!odt_en)
+               return;
+
+#ifdef CONFIG_MACH_SUN7I
+       /* Enabling ODT in SDR_IOCR on sun7i hardware results in a deadlock
+        * unless bit 24 is set in SDR_ZQCR1. Not much is known about the
+        * SDR_ZQCR1 register, but there are hints indicating that it might
+        * be related to periodic impedance re-calibration. This particular
+        * magic value is borrowed from the Allwinner boot0 bootloader, and
+        * using it helps to avoid troubles */
+       writel((1 << 24) | (1 << 1), &dram->zqcr1);
+#endif
+
+       /* Needed at least for sun5i, because it does not self clear there */
+       clrbits_le32(&dram->zqcr0, DRAM_ZQCR0_ZCAL);
+
+       if (zdata) {
+               /* Set the user supplied impedance data */
+               reg_val = DRAM_ZQCR0_ZDEN | zdata;
+               writel(reg_val, &dram->zqcr0);
+               /* no need to wait, this takes effect immediately */
+       } else {
+               /* Do the calibration using the external resistor */
+               reg_val = DRAM_ZQCR0_ZCAL | DRAM_ZQCR0_IMP_DIV(zprog);
+               writel(reg_val, &dram->zqcr0);
+               /* Wait for the new impedance configuration to settle */
+               await_bits_set(&dram->zqsr, DRAM_ZQSR_ZDONE);
+       }
+
+       /* Needed at least for sun5i, because it does not self clear there */
+       clrbits_le32(&dram->zqcr0, DRAM_ZQCR0_ZCAL);
+
+       /* Set I/O configure register */
+       writel(DRAM_IOCR_ODT_EN(odt_en), &dram->iocr);
+}
+
+static unsigned long dramc_init_helper(struct dram_para *para)
 {
        struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
        u32 reg_val;
        u32 density;
        int ret_val;
 
-       /* check input dram parameter structure */
-       if (!para)
+       /*
+        * only single rank DDR3 is supported by this code even though the
+        * hardware can theoretically support DDR2 and up to two ranks
+        */
+       if (para->type != DRAM_MEMORY_TYPE_DDR3 || para->rank_num != 1)
                return 0;
 
        /* setup DRAM relative clock */
-       mctl_setup_dram_clock(para->clock);
+       mctl_setup_dram_clock(para->clock, para->mbus_clock);
 
-#ifdef CONFIG_SUN5I
        /* Disable any pad power save control */
-       writel(0, &dram->ppwrsctl);
-#endif
+       mctl_disable_power_save();
 
-       /* reset external DRAM */
-#ifndef CONFIG_SUN7I
-       mctl_ddr3_reset();
-#endif
        mctl_set_drive();
 
        /* dram clock off */
        dramc_clock_output_en(0);
 
-#ifdef CONFIG_SUN4I
+#ifdef CONFIG_MACH_SUN4I
        /* select dram controller 1 */
        writel(DRAM_CSEL_MAGIC, &dram->csel);
 #endif
@@ -507,9 +606,7 @@ unsigned long dramc_init(struct dram_para *para)
        mctl_enable_dll0(para->tpr3);
 
        /* configure external DRAM */
-       reg_val = 0x0;
-       if (para->type == DRAM_MEMORY_TYPE_DDR3)
-               reg_val |= DRAM_DCR_TYPE_DDR3;
+       reg_val = DRAM_DCR_TYPE_DDR3;
        reg_val |= DRAM_DCR_IO_WIDTH(para->io_width >> 3);
 
        if (para->density == 256)
@@ -534,156 +631,120 @@ unsigned long dramc_init(struct dram_para *para)
        reg_val |= DRAM_DCR_MODE(DRAM_DCR_MODE_INTERLEAVE);
        writel(reg_val, &dram->dcr);
 
-#ifdef CONFIG_SUN7I
-       setbits_le32(&dram->zqcr1, (0x1 << 24) | (0x1 << 1));
-       if (para->tpr4 & 0x2)
-               clrsetbits_le32(&dram->zqcr1, (0x1 << 24), (0x1 << 1));
        dramc_clock_output_en(1);
-#endif
 
-#if (defined(CONFIG_SUN5I) || defined(CONFIG_SUN7I))
-       /* set odt impendance divide ratio */
-       reg_val = ((para->zq) >> 8) & 0xfffff;
-       reg_val |= ((para->zq) & 0xff) << 20;
-       reg_val |= (para->zq) & 0xf0000000;
-       writel(reg_val, &dram->zqcr0);
-#endif
+       mctl_set_impedance(para->zq, para->odt_en);
 
-#ifdef CONFIG_SUN7I
-       /* Set CKE Delay to about 1ms */
-       setbits_le32(&dram->idcr, 0x1ffff);
-#endif
+       mctl_set_cke_delay();
 
-#ifdef CONFIG_SUN7I
-       if ((readl(&dram->ppwrsctl) & 0x1) != 0x1)
-               mctl_ddr3_reset();
-       else
-               setbits_le32(&dram->mcr, DRAM_MCR_RESET);
-#else
-       /* dram clock on */
-       dramc_clock_output_en(1);
-#endif
+       mctl_ddr3_reset();
 
        udelay(1);
 
-       await_completion(&dram->ccr, DRAM_CCR_INIT);
+       await_bits_clear(&dram->ccr, DRAM_CCR_INIT);
 
        mctl_enable_dllx(para->tpr3);
 
-#ifdef CONFIG_SUN4I
-       /* set odt impedance divide ratio */
-       reg_val = ((para->zq) >> 8) & 0xfffff;
-       reg_val |= ((para->zq) & 0xff) << 20;
-       reg_val |= (para->zq) & 0xf0000000;
-       writel(reg_val, &dram->zqcr0);
-#endif
-
-#ifdef CONFIG_SUN4I
-       /* set I/O configure register */
-       reg_val = 0x00cc0000;
-       reg_val |= (para->odt_en) & 0x3;
-       reg_val |= ((para->odt_en) & 0x3) << 30;
-       writel(reg_val, &dram->iocr);
-#endif
-
        /* set refresh period */
-       dramc_set_autorefresh_cycle(para->clock, para->type - 2, density);
+       dramc_set_autorefresh_cycle(para->clock, density);
 
        /* set timing parameters */
        writel(para->tpr0, &dram->tpr0);
        writel(para->tpr1, &dram->tpr1);
        writel(para->tpr2, &dram->tpr2);
 
-       if (para->type == DRAM_MEMORY_TYPE_DDR3) {
-               reg_val = DRAM_MR_BURST_LENGTH(0x0);
-#if (defined(CONFIG_SUN5I) || defined(CONFIG_SUN7I))
-               reg_val |= DRAM_MR_POWER_DOWN;
+       reg_val = DRAM_MR_BURST_LENGTH(0x0);
+#if (defined(CONFIG_MACH_SUN5I) || defined(CONFIG_MACH_SUN7I))
+       reg_val |= DRAM_MR_POWER_DOWN;
 #endif
-               reg_val |= DRAM_MR_CAS_LAT(para->cas - 4);
-               reg_val |= DRAM_MR_WRITE_RECOVERY(0x5);
-       } else if (para->type == DRAM_MEMORY_TYPE_DDR2) {
-               reg_val = DRAM_MR_BURST_LENGTH(0x2);
-               reg_val |= DRAM_MR_CAS_LAT(para->cas);
-               reg_val |= DRAM_MR_WRITE_RECOVERY(0x5);
-       }
+       reg_val |= DRAM_MR_CAS_LAT(para->cas - 4);
+       reg_val |= DRAM_MR_WRITE_RECOVERY(ddr3_write_recovery(para->clock));
        writel(reg_val, &dram->mr);
 
        writel(para->emr1, &dram->emr);
        writel(para->emr2, &dram->emr2);
        writel(para->emr3, &dram->emr3);
 
-       /* set DQS window mode */
+       /* disable drift compensation and set passive DQS window mode */
        clrsetbits_le32(&dram->ccr, DRAM_CCR_DQS_DRIFT_COMP, DRAM_CCR_DQS_GATE);
 
-#ifdef CONFIG_SUN7I
+#ifdef CONFIG_MACH_SUN7I
        /* Command rate timing mode 2T & 1T */
        if (para->tpr4 & 0x1)
                setbits_le32(&dram->ccr, DRAM_CCR_COMMAND_RATE_1T);
 #endif
-       /* reset external DRAM */
-       setbits_le32(&dram->ccr, DRAM_CCR_INIT);
-       await_completion(&dram->ccr, DRAM_CCR_INIT);
+       /* initialize external DRAM */
+       mctl_ddr3_initialize();
 
-#ifdef CONFIG_SUN7I
-       /* setup zq calibration manual */
-       reg_val = readl(&dram->ppwrsctl);
-       if ((reg_val & 0x1) == 1) {
-               /* super_standby_flag = 1 */
+       /* scan read pipe value */
+       mctl_itm_enable();
 
-               reg_val = readl(0x01c20c00 + 0x120); /* rtc */
-               reg_val &= 0x000fffff;
-               reg_val |= 0x17b00000;
-               writel(reg_val, &dram->zqcr0);
+       /* Hardware DQS gate training */
+       ret_val = dramc_scan_readpipe();
 
-               /* exit self-refresh state */
-               clrsetbits_le32(&dram->dcr, 0x1f << 27, 0x12 << 27);
-               /* check whether command has been executed */
-               await_completion(&dram->dcr, 0x1 << 31);
+       if (ret_val < 0)
+               return 0;
+
+       /* allow to override the DQS training results with a custom delay */
+       if (para->dqs_gating_delay)
+               mctl_set_dqs_gating_delay(0, para->dqs_gating_delay);
 
-               udelay(2);
+       /* set the DQS gating window type */
+       if (para->active_windowing)
+               clrbits_le32(&dram->ccr, DRAM_CCR_DQS_GATE);
+       else
+               setbits_le32(&dram->ccr, DRAM_CCR_DQS_GATE);
 
-               /* dram pad hold off */
-               setbits_le32(&dram->ppwrsctl, 0x16510000);
+       mctl_itm_reset();
 
-               await_completion(&dram->ppwrsctl, 0x1);
+       /* configure all host port */
+       mctl_configure_hostport();
 
-               /* exit self-refresh state */
-               clrsetbits_le32(&dram->dcr, 0x1f << 27, 0x12 << 27);
+       return get_ram_size((long *)PHYS_SDRAM_0, PHYS_SDRAM_0_SIZE);
+}
 
-               /* check whether command has been executed */
-               await_completion(&dram->dcr, 0x1 << 31);
+unsigned long dramc_init(struct dram_para *para)
+{
+       unsigned long dram_size, actual_density;
 
-               udelay(2);
+       /* If the dram configuration is not provided, use a default */
+       if (!para)
+               return 0;
 
-               /* issue a refresh command */
-               clrsetbits_le32(&dram->dcr, 0x1f << 27, 0x13 << 27);
-               await_completion(&dram->dcr, 0x1 << 31);
+       /* if everything is known, then autodetection is not necessary */
+       if (para->io_width && para->bus_width && para->density)
+               return dramc_init_helper(para);
 
-               udelay(2);
-       }
+       /* try to autodetect the DRAM bus width and density */
+       para->io_width  = 16;
+       para->bus_width = 32;
+#if defined(CONFIG_MACH_SUN4I) || defined(CONFIG_MACH_SUN5I)
+       /* only A0-A14 address lines on A10/A13, limiting max density to 4096 */
+       para->density = 4096;
+#else
+       /* all A0-A15 address lines on A20, which allow density 8192 */
+       para->density = 8192;
 #endif
 
-       /* scan read pipe value */
-       mctl_itm_enable();
-       if (para->tpr3 & (0x1 << 31)) {
-               ret_val = dramc_scan_dll_para();
-               if (ret_val == 0)
-                       para->tpr3 =
-                               (((readl(&dram->dllcr[0]) >> 6) & 0x3f) << 16) |
-                               (((readl(&dram->dllcr[1]) >> 14) & 0xf) << 0) |
-                               (((readl(&dram->dllcr[2]) >> 14) & 0xf) << 4) |
-                               (((readl(&dram->dllcr[3]) >> 14) & 0xf) << 8) |
-                               (((readl(&dram->dllcr[4]) >> 14) & 0xf) << 12
-                               );
-       } else {
-               ret_val = dramc_scan_readpipe();
+       dram_size = dramc_init_helper(para);
+       if (!dram_size) {
+               /* if 32-bit bus width failed, try 16-bit bus width instead */
+               para->bus_width = 16;
+               dram_size = dramc_init_helper(para);
+               if (!dram_size) {
+                       /* if 16-bit bus width also failed, then bail out */
+                       return dram_size;
+               }
        }
 
-       if (ret_val < 0)
-               return 0;
+       /* check if we need to adjust the density */
+       actual_density = (dram_size >> 17) * para->io_width / para->bus_width;
 
-       /* configure all host port */
-       mctl_configure_hostport();
+       if (actual_density != para->density) {
+               /* update the density and re-initialize DRAM again */
+               para->density = actual_density;
+               dram_size = dramc_init_helper(para);
+       }
 
-       return get_ram_size((long *)PHYS_SDRAM_0, PHYS_SDRAM_0_SIZE);
+       return dram_size;
 }