[PATCH v2 16/22] sunxi: add R528/T113-s3/D1(s) DRAM initialisation code

[Andre Przywara <andre.przywara@arm.com>]

The Allwinner R528/T113-s/D1/D1s SoCs all share the same die, so use the
same DRAM initialisation code.
Make use of prior art here and lift some code from awboot[1], which
carried init code based on earlier decompilation efforts, but with a
GPL2 license tag.
This code has been heavily reworked and cleaned up, to match previous
DRAM routines for other SoCs, and also to be closer to U-Boot's coding
style and support routines.
The actual DRAM chip timing parameters are included in the main file,
since they cover all DRAM types, and are protected by a new Kconfig
CONFIG_SUNXI_DRAM_TYPE symbol, which allows the compiler to pick only
the relevant settings, at build time.

The relevant DRAM chips/board specific configuration parameters are
delivered via Kconfig, so this code here should work for all supported
SoCs and DRAM chips combinations.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Sam Edwards <CFSworks@gmail.com>
---
 drivers/Makefile                   |    1 +
 drivers/ram/Makefile               |    3 +
 drivers/ram/sunxi/Kconfig          |   59 ++
 drivers/ram/sunxi/Makefile         |    4 +
 drivers/ram/sunxi/dram_sun20i_d1.c | 1432 ++++++++++++++++++++++++++++
 drivers/ram/sunxi/dram_sun20i_d1.h |   73 ++
 6 files changed, 1572 insertions(+)
 create mode 100644 drivers/ram/sunxi/Makefile
 create mode 100644 drivers/ram/sunxi/dram_sun20i_d1.c
 create mode 100644 drivers/ram/sunxi/dram_sun20i_d1.h

diff --git a/drivers/Makefile b/drivers/Makefile
index efc2a4afb24..5a4bedf7305 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_$(SPL_)ALTERA_SDRAM) += ddr/altera/
 obj-$(CONFIG_ARCH_IMX8M) += ddr/imx/imx8m/
 obj-$(CONFIG_IMX8ULP_DRAM) += ddr/imx/imx8ulp/
 obj-$(CONFIG_ARCH_IMX9) += ddr/imx/imx9/
+obj-$(CONFIG_DRAM_SUN8I_R528) += ram/
 obj-$(CONFIG_SPL_DM_RESET) += reset/
 obj-$(CONFIG_SPL_MUSB_NEW) += usb/musb-new/
 obj-$(CONFIG_SPL_USB_GADGET) += usb/gadget/
diff --git a/drivers/ram/Makefile b/drivers/ram/Makefile
index 6eb1a241359..b4750ea11c4 100644
--- a/drivers/ram/Makefile
+++ b/drivers/ram/Makefile
@@ -23,6 +23,9 @@ obj-$(CONFIG_RAM_SIFIVE) += sifive/
 ifdef CONFIG_SPL_BUILD
 obj-$(CONFIG_SPL_STARFIVE_DDR) += starfive/
 endif
+
+obj-$(CONFIG_DRAM_SUN8I_R528) += sunxi/
+
 obj-$(CONFIG_ARCH_OCTEON) += octeon/
 
 obj-$(CONFIG_ARCH_RMOBILE) += renesas/
diff --git a/drivers/ram/sunxi/Kconfig b/drivers/ram/sunxi/Kconfig
index 261d7f57409..35eeda58efa 100644
--- a/drivers/ram/sunxi/Kconfig
+++ b/drivers/ram/sunxi/Kconfig
@@ -12,3 +12,62 @@ config DRAM_SUN8I_R528
 	default y if MACH_SUN8I_R528
 	help
 	  Select this DRAM controller driver for the R528/T113s SoCs.
+
+if DRAM_SUN20I_D1 || DRAM_SUN8I_R528
+
+config DRAM_SUNXI_ODT_EN
+	hex "DRAM ODT EN parameter"
+	default 0x1
+	help
+	  ODT EN value from vendor DRAM settings.
+
+config DRAM_SUNXI_TPR0
+	hex "DRAM TPR0 parameter"
+	default 0x0
+	help
+	  TPR0 value from vendor DRAM settings.
+
+config DRAM_SUNXI_TPR11
+	hex "DRAM TPR11 parameter"
+	default 0x0
+	help
+	  TPR11 value from vendor DRAM settings.
+
+config DRAM_SUNXI_TPR12
+	hex "DRAM TPR12 parameter"
+	default 0x0
+	help
+	  TPR12 value from vendor DRAM settings.
+
+config DRAM_SUNXI_TPR13
+	hex "DRAM TPR13 parameter"
+	default 0x0
+	help
+	  TPR13 value from vendor DRAM settings. It tells which features
+	  should be configured.
+
+choice
+	prompt "DRAM chip type"
+	default SUNXI_DRAM_TYPE_DDR3 if DRAM_SUN8I_R528 || DRAM_SUN20I_D1
+
+config SUNXI_DRAM_TYPE_DDR2
+        bool "DDR2 chips"
+
+config SUNXI_DRAM_TYPE_DDR3
+        bool "DDR3 chips"
+
+config SUNXI_DRAM_TYPE_LPDDR2
+        bool "LPDDR2 chips"
+
+config SUNXI_DRAM_TYPE_LPDDR3
+        bool "LPDDR3 chips"
+endchoice
+
+config SUNXI_DRAM_TYPE
+	int
+	default 2 if SUNXI_DRAM_TYPE_DDR2
+	default 3 if SUNXI_DRAM_TYPE_DDR3
+	default 6 if SUNXI_DRAM_TYPE_LPDDR2
+	default 7 if SUNXI_DRAM_TYPE_LPDDR3
+
+endif
diff --git a/drivers/ram/sunxi/Makefile b/drivers/ram/sunxi/Makefile
new file mode 100644
index 00000000000..d6fb2cf0b65
--- /dev/null
+++ b/drivers/ram/sunxi/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+obj-$(CONFIG_DRAM_SUN20I_D1) += dram_sun20i_d1.o
+obj-$(CONFIG_DRAM_SUN8I_R528) += dram_sun20i_d1.o
diff --git a/drivers/ram/sunxi/dram_sun20i_d1.c b/drivers/ram/sunxi/dram_sun20i_d1.c
new file mode 100644
index 00000000000..c766fc24065
--- /dev/null
+++ b/drivers/ram/sunxi/dram_sun20i_d1.c
@@ -0,0 +1,1432 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Allwinner D1/D1s/R528/T113-sx DRAM initialisation
+ *
+ * As usual there is no documentation for the memory controller or PHY IP
+ * used here. The baseline of this code was lifted from awboot[1], which
+ * seems to be based on some form of de-compilation of some original Allwinner
+ * code bits (with a GPL2 license tag from the very beginning).
+ * This version here is a reworked version, to match the U-Boot coding style
+ * and style of the other Allwinner DRAM drivers.
+ *
+ * [1] https://github.com/szemzoa/awboot.git
+ */
+
+#include <asm/io.h>
+#include <common.h>
+#ifdef CONFIG_RAM
+  #include <dm.h>
+  #include <ram.h>
+#endif
+#include <linux/delay.h>
+
+#include "dram_sun20i_d1.h"
+
+#ifndef SUNXI_SID_BASE
+#define SUNXI_SID_BASE	0x3006200
+#endif
+
+#ifndef SUNXI_CCM_BASE
+#define SUNXI_CCM_BASE	0x2001000
+#endif
+
+static void sid_read_ldoB_cal(const dram_para_t *para)
+{
+	uint32_t reg;
+
+	reg = (readl(SUNXI_SID_BASE + 0x1c) & 0xff00) >> 8;
+
+	if (reg == 0)
+		return;
+
+	switch (para->dram_type) {
+	case SUNXI_DRAM_TYPE_DDR2:
+		break;
+	case SUNXI_DRAM_TYPE_DDR3:
+		if (reg > 0x20)
+			reg -= 0x16;
+		break;
+	default:
+		reg = 0;
+		break;
+	}
+
+	clrsetbits_le32(0x3000150, 0xff00, reg << 8);
+}
+
+static void dram_voltage_set(const dram_para_t *para)
+{
+	int vol;
+
+	switch (para->dram_type) {
+	case SUNXI_DRAM_TYPE_DDR2:
+		vol = 47;
+		break;
+	case SUNXI_DRAM_TYPE_DDR3:
+		vol = 25;
+		break;
+	default:
+		vol = 0;
+		break;
+	}
+
+	clrsetbits_le32(0x3000150, 0x20ff00, vol << 8);
+
+	udelay(1);
+
+	sid_read_ldoB_cal(para);
+}
+
+static void dram_enable_all_master(void)
+{
+	writel(~0, 0x3102020);
+	writel(0xff, 0x3102024);
+	writel(0xffff, 0x3102028);
+	udelay(10);
+}
+
+static void dram_disable_all_master(void)
+{
+	writel(1, 0x3102020);
+	writel(0, 0x3102024);
+	writel(0, 0x3102028);
+	udelay(10);
+}
+
+static void eye_delay_compensation(const dram_para_t *para)
+{
+	uint32_t delay;
+	unsigned long ptr;
+
+	// DATn0IOCR, n =  0...7
+	delay = (para->dram_tpr11 & 0xf) << 9;
+	delay |= (para->dram_tpr12 & 0xf) << 1;
+	for (ptr = 0x3103310; ptr < 0x3103334; ptr += 4)
+		setbits_le32(ptr, delay);
+
+	// DATn1IOCR, n =  0...7
+	delay = (para->dram_tpr11 & 0xf0) << 5;
+	delay |= (para->dram_tpr12 & 0xf0) >> 3;
+	for (ptr = 0x3103390; ptr != 0x31033b4; ptr += 4)
+		setbits_le32(ptr, delay);
+
+	// PGCR0: assert AC loopback FIFO reset
+	clrbits_le32(0x3103100, 0x04000000);
+
+	// ??
+
+	delay = (para->dram_tpr11 & 0xf0000) >> 7;
+	delay |= (para->dram_tpr12 & 0xf0000) >> 15;
+	setbits_le32(0x3103334, delay);
+	setbits_le32(0x3103338, delay);
+
+	delay = (para->dram_tpr11 & 0xf00000) >> 11;
+	delay |= (para->dram_tpr12 & 0xf00000) >> 19;
+	setbits_le32(0x31033b4, delay);
+	setbits_le32(0x31033b8, delay);
+
+	setbits_le32(0x310333c, (para->dram_tpr11 & 0xf0000) << 9);
+	setbits_le32(0x31033bc, (para->dram_tpr11 & 0xf00000) << 5);
+
+	// PGCR0: release AC loopback FIFO reset
+	setbits_le32(0x3103100, BIT(26));
+
+	udelay(1);
+
+	delay = (para->dram_tpr10 & 0xf0) << 4;
+	for (ptr = 0x3103240; ptr != 0x310327c; ptr += 4)
+		setbits_le32(ptr, delay);
+	for (ptr = 0x3103228; ptr != 0x3103240; ptr += 4)
+		setbits_le32(ptr, delay);
+
+	setbits_le32(0x3103218, (para->dram_tpr10 & 0x0f) << 8);
+	setbits_le32(0x310321c, (para->dram_tpr10 & 0x0f) << 8);
+
+	setbits_le32(0x3103280, (para->dram_tpr10 & 0xf00) >> 4);
+}
+
+/*
+ * Main purpose of the auto_set_timing routine seems to be to calculate all
+ * timing settings for the specific type of sdram used. Read together with
+ * an sdram datasheet for context on the various variables.
+ */
+static void mctl_set_timing_params(const dram_para_t *para,
+				   const dram_config_t *config)
+{
+	/* DRAM_TPR0 */
+	u8 tccd		= 2;
+	u8 tfaw;
+	u8 trrd;
+	u8 trcd;
+	u8 trc;
+
+	/* DRAM_TPR1 */
+	u8 txp;
+	u8 twtr;
+	u8 trtp		= 4;
+	u8 twr;
+	u8 trp;
+	u8 tras;
+
+	/* DRAM_TPR2 */
+	u16 trefi;
+	u16 trfc;
+
+	u8 tcksrx;
+	u8 tckesr;
+	u8 trd2wr;
+	u8 twr2rd;
+	u8 trasmax;
+	u8 twtp;
+	u8 tcke;
+	u8 tmod;
+	u8 tmrd;
+	u8 tmrw;
+
+	u8 tcl;
+	u8 tcwl;
+	u8 t_rdata_en;
+	u8 wr_latency;
+
+	u32 mr0;
+	u32 mr1;
+	u32 mr2;
+	u32 mr3;
+
+	u32 tdinit0;
+	u32 tdinit1;
+	u32 tdinit2;
+	u32 tdinit3;
+
+	switch (para->dram_type) {
+	case SUNXI_DRAM_TYPE_DDR2:
+		/* DRAM_TPR0 */
+		tfaw		= ns_to_t(50);
+		trrd		= ns_to_t(10);
+		trcd		= ns_to_t(20);
+		trc		= ns_to_t(65);
+
+		/* DRAM_TPR1 */
+		txp		= 2;
+		twtr		= ns_to_t(8);
+		twr		= ns_to_t(15);
+		trp		= ns_to_t(15);
+		tras		= ns_to_t(45);
+
+		/* DRAM_TRP2 */
+		trfc		= ns_to_t(328);
+		trefi		= ns_to_t(7800) / 32;
+
+		trasmax		= CONFIG_DRAM_CLK / 30;
+		if (CONFIG_DRAM_CLK < 409) {
+			t_rdata_en	= 1;
+			tcl		= 3;
+			mr0		= 0x06a3;
+		} else {
+			t_rdata_en	= 2;
+			tcl		= 4;
+			mr0		= 0x0e73;
+		}
+		tmrd		= 2;
+		twtp		= twr + 5;
+		tcksrx		= 5;
+		tckesr		= 4;
+		trd2wr		= 4;
+		tcke		= 3;
+		tmod		= 12;
+		wr_latency	= 1;
+		tmrw		= 0;
+		twr2rd		= twtr + 5;
+		tcwl		= 0;
+
+		mr1		= para->dram_mr1;
+		mr2		= 0;
+		mr3		= 0;
+
+		tdinit0		= 200 * CONFIG_DRAM_CLK + 1;
+		tdinit1		= 100 * CONFIG_DRAM_CLK / 1000 + 1;
+		tdinit2		= 200 * CONFIG_DRAM_CLK + 1;
+		tdinit3		= 1 * CONFIG_DRAM_CLK + 1;
+
+		break;
+	case SUNXI_DRAM_TYPE_DDR3:
+		trfc		= ns_to_t(350);
+		trefi		= ns_to_t(7800) / 32 + 1;	// XXX
+
+		twtr		= ns_to_t(8) + 2;		// + 2 ? XXX
+		/* Only used by trd2wr calculation, which gets discard below */
+//		twr		= max(ns_to_t(15), 2);
+		trrd		= max(ns_to_t(10), 2);
+		txp		= max(ns_to_t(10), 2);
+
+		if (CONFIG_DRAM_CLK <= 800) {
+			tfaw		= ns_to_t(50);
+			trcd		= ns_to_t(15);
+			trp		= ns_to_t(15);
+			trc		= ns_to_t(53);
+			tras		= ns_to_t(38);
+
+			mr0		= 0x1c70;
+			mr2		= 0x18;
+			tcl		= 6;
+			wr_latency	= 2;
+			tcwl		= 4;
+			t_rdata_en	= 4;
+		} else {
+			tfaw		= ns_to_t(35);
+			trcd		= ns_to_t(14);
+			trp		= ns_to_t(14);
+			trc		= ns_to_t(48);
+			tras		= ns_to_t(34);
+
+			mr0		= 0x1e14;
+			mr2		= 0x20;
+			tcl		= 7;
+			wr_latency	= 3;
+			tcwl		= 5;
+			t_rdata_en	= 5;
+		}
+
+		trasmax		= CONFIG_DRAM_CLK / 30;
+		twtp		= tcwl + 2 + twtr;		// WL+BL/2+tWTR
+		/* Gets overwritten below */
+//		trd2wr		= tcwl + 2 + twr;		// WL+BL/2+tWR
+		twr2rd		= tcwl + twtr;			// WL+tWTR
+
+		tdinit0		= 500 * CONFIG_DRAM_CLK + 1;	// 500 us
+		tdinit1		= 360 * CONFIG_DRAM_CLK / 1000 + 1;   // 360 ns
+		tdinit2		= 200 * CONFIG_DRAM_CLK + 1;	// 200 us
+		tdinit3		= 1 * CONFIG_DRAM_CLK + 1;	//   1 us
+
+		mr1		= para->dram_mr1;
+		mr3		= 0;
+		tcke		= 3;
+		tcksrx		= 5;
+		tckesr		= 4;
+		if (((config->dram_tpr13 & 0xc) == 0x04) || CONFIG_DRAM_CLK < 912)
+			trd2wr	   = 5;
+		else
+			trd2wr	   = 6;
+
+		tmod		= 12;
+		tmrd		= 4;
+		tmrw		= 0;
+
+		break;
+	case SUNXI_DRAM_TYPE_LPDDR2:
+		tfaw		= max(ns_to_t(50), 4);
+		trrd		= max(ns_to_t(10), 1);
+		trcd		= max(ns_to_t(24), 2);
+		trc		= ns_to_t(70);
+		txp		= ns_to_t(8);
+		if (txp < 2) {
+			txp++;
+			twtr	= 2;
+		} else {
+			twtr	= txp;
+		}
+		twr		= max(ns_to_t(15), 2);
+		trp		= ns_to_t(17);
+		tras		= ns_to_t(42);
+		trefi		= ns_to_t(3900) / 32;
+		trfc		= ns_to_t(210);
+
+		trasmax		= CONFIG_DRAM_CLK / 60;
+		mr3		= para->dram_mr3;
+		twtp		= twr + 5;
+		mr2		= 6;
+		mr1		= 5;
+		tcksrx		= 5;
+		tckesr		= 5;
+		trd2wr		= 10;
+		tcke		= 2;
+		tmod		= 5;
+		tmrd		= 5;
+		tmrw		= 3;
+		tcl		= 4;
+		wr_latency	= 1;
+		t_rdata_en	= 1;
+
+		tdinit0		= 200 * CONFIG_DRAM_CLK + 1;
+		tdinit1		= 100 * CONFIG_DRAM_CLK / 1000 + 1;
+		tdinit2		= 11 * CONFIG_DRAM_CLK + 1;
+		tdinit3		= 1 * CONFIG_DRAM_CLK + 1;
+		twr2rd		= twtr + 5;
+		tcwl		= 2;
+		mr1		= 195;
+		mr0		= 0;
+
+		break;
+	case SUNXI_DRAM_TYPE_LPDDR3:
+		tfaw		= max(ns_to_t(50), 4);
+		trrd		= max(ns_to_t(10), 1);
+		trcd		= max(ns_to_t(24), 2);
+		trc		= ns_to_t(70);
+		twtr		= max(ns_to_t(8), 2);
+		twr		= max(ns_to_t(15), 2);
+		trp		= ns_to_t(17);
+		tras		= ns_to_t(42);
+		trefi		= ns_to_t(3900) / 32;
+		trfc		= ns_to_t(210);
+		txp		= twtr;
+
+		trasmax		= CONFIG_DRAM_CLK / 60;
+		if (CONFIG_DRAM_CLK < 800) {
+			tcwl	   = 4;
+			wr_latency = 3;
+			t_rdata_en = 6;
+			mr2		   = 12;
+		} else {
+			tcwl	   = 3;
+			tcke	   = 6;
+			wr_latency = 2;
+			t_rdata_en = 5;
+			mr2		   = 10;
+		}
+		twtp		= tcwl + 5;
+		tcl		= 7;
+		mr3		= para->dram_mr3;
+		tcksrx		= 5;
+		tckesr		= 5;
+		trd2wr		= 13;
+		tcke		= 3;
+		tmod		= 12;
+		tdinit0		= 400 * CONFIG_DRAM_CLK + 1;
+		tdinit1		= 500 * CONFIG_DRAM_CLK / 1000 + 1;
+		tdinit2		= 11 * CONFIG_DRAM_CLK + 1;
+		tdinit3		= 1 * CONFIG_DRAM_CLK + 1;
+		tmrd		= 5;
+		tmrw		= 5;
+		twr2rd		= tcwl + twtr + 5;
+		mr1		= 195;
+		mr0		= 0;
+
+		break;
+	default:
+		trfc		= 128;
+		trp		= 6;
+		trefi		= 98;
+		txp		= 10;
+		twr		= 8;
+		twtr		= 3;
+		tras		= 14;
+		tfaw		= 16;
+		trc		= 20;
+		trcd		= 6;
+		trrd		= 3;
+
+		twr2rd		= 8;
+		tcksrx		= 4;
+		tckesr		= 3;
+		trd2wr		= 4;
+		trasmax		= 27;
+		twtp		= 12;
+		tcke		= 2;
+		tmod		= 6;
+		tmrd		= 2;
+		tmrw		= 0;
+		tcwl		= 3;
+		tcl		= 3;
+		wr_latency	= 1;
+		t_rdata_en	= 1;
+		mr3		= 0;
+		mr2		= 0;
+		mr1		= 0;
+		mr0		= 0;
+		tdinit3		= 0;
+		tdinit2		= 0;
+		tdinit1		= 0;
+		tdinit0		= 0;
+
+		break;
+	}
+
+	/* Set mode registers */
+	writel(mr0, 0x3103030);
+	writel(mr1, 0x3103034);
+	writel(mr2, 0x3103038);
+	writel(mr3, 0x310303c);
+	/* TODO: dram_odt_en is either 0x0 or 0x1, so right shift looks weird */
+	writel((para->dram_odt_en >> 4) & 0x3, 0x310302c);
+
+	/* Set dram timing DRAMTMG0 - DRAMTMG5 */
+	writel((twtp << 24) | (tfaw << 16) | (trasmax << 8) | (tras << 0),
+		0x3103058);
+	writel((txp << 16) | (trtp << 8) | (trc << 0),
+		0x310305c);
+	writel((tcwl << 24) | (tcl << 16) | (trd2wr << 8) | (twr2rd << 0),
+		0x3103060);
+	writel((tmrw << 16) | (tmrd << 12) | (tmod << 0),
+		0x3103064);
+	writel((trcd << 24) | (tccd << 16) | (trrd << 8) | (trp << 0),
+		0x3103068);
+	writel((tcksrx << 24) | (tcksrx << 16) | (tckesr << 8) | (tcke << 0),
+		0x310306c);
+
+	/* Set dual rank timing */
+	clrsetbits_le32(0x3103078, 0xf000ffff,
+			(CONFIG_DRAM_CLK < 800) ? 0xf0006610 : 0xf0007610);
+
+	/* Set phy interface time PITMG0, PTR3, PTR4 */
+	writel((0x2 << 24) | (t_rdata_en << 16) | BIT(8) | (wr_latency << 0),
+		0x3103080);
+	writel(((tdinit0 << 0) | (tdinit1 << 20)), 0x3103050);
+	writel(((tdinit2 << 0) | (tdinit3 << 20)), 0x3103054);
+
+	/* Set refresh timing and mode */
+	writel((trefi << 16) | (trfc << 0), 0x3103090);
+	writel((trefi << 15) & 0x0fff0000, 0x3103094);
+}
+
+// Purpose of this routine seems to be to initialize the PLL driving
+// the MBUS and sdram.
+//
+static int ccu_set_pll_ddr_clk(int index, const dram_para_t *para,
+			       const dram_config_t *config)
+{
+	unsigned int val, clk, n;
+
+	if (config->dram_tpr13 & BIT(6))
+		clk = para->dram_tpr9;
+	else
+		clk = para->dram_clk;
+
+	// set VCO clock divider
+	n = (clk * 2) / 24;
+
+	val = readl(SUNXI_CCM_BASE + 0x10);
+	val &= ~0x0007ff03;			// clear dividers
+	val |= (n - 1) << 8;			// set PLL division
+	val |= BIT(31) | BIT(30);		// enable PLL and LDO
+	writel(val | BIT(29), SUNXI_CCM_BASE + 0x10);
+
+	// wait for PLL to lock
+	while ((readl(SUNXI_CCM_BASE + 0x10) & BIT(28)) == 0)
+		;
+
+	udelay(20);
+
+	// enable PLL output
+	setbits_le32(SUNXI_CCM_BASE + 0x0, BIT(27));
+
+	// turn clock gate on
+	val = readl(SUNXI_CCM_BASE + 0x800);
+	val &= ~0x03000303;		// select DDR clk source, n=1, m=1
+	val |= BIT(31);			// turn clock on
+	writel(val, SUNXI_CCM_BASE + 0x800);
+
+	return n * 24;
+}
+
+/* Set up the PLL and clock gates for the DRAM controller and MBUS clocks. */
+static void mctl_sys_init(const dram_para_t *para, const dram_config_t *config)
+{
+	// assert MBUS reset
+	clrbits_le32(SUNXI_CCM_BASE + 0x540, BIT(30));
+
+	// turn off sdram clock gate, assert sdram reset
+	clrbits_le32(SUNXI_CCM_BASE + 0x80c, 0x10001);
+	clrsetbits_le32(SUNXI_CCM_BASE + 0x800, BIT(31) | BIT(30), BIT(27));
+	udelay(10);
+
+	// set ddr pll clock
+	ccu_set_pll_ddr_clk(0, para, config);
+	udelay(100);
+	dram_disable_all_master();
+
+	// release sdram reset
+	setbits_le32(SUNXI_CCM_BASE + 0x80c, BIT(16));
+
+	// release MBUS reset
+	setbits_le32(SUNXI_CCM_BASE + 0x540, BIT(30));
+	setbits_le32(SUNXI_CCM_BASE + 0x800, BIT(30));
+
+	udelay(5);
+
+	// turn on sdram clock gate
+	setbits_le32(SUNXI_CCM_BASE + 0x80c, BIT(0));
+
+	// turn dram clock gate on, trigger sdr clock update
+	setbits_le32(SUNXI_CCM_BASE + 0x800, BIT(31) | BIT(27));
+	udelay(5);
+
+	// mCTL clock enable
+	writel(0x8000, 0x310300c);
+	udelay(10);
+}
+
+// The main purpose of this routine seems to be to copy an address configuration
+// from the dram_para1 and dram_para2 fields to the PHY configuration registers
+// (0x3102000, 0x3102004).
+//
+static void mctl_com_init(const dram_para_t *para, const dram_config_t *config)
+{
+	uint32_t val, width;
+	unsigned long ptr;
+	int i;
+
+	// purpose ??
+	clrsetbits_le32(0x3102008, 0x3f00, 0x2000);
+
+	// set SDRAM type and word width
+	val  = readl(0x3102000) & ~0x00fff000;
+	val |= (para->dram_type & 0x7) << 16;		// DRAM type
+	val |= (~config->dram_para2 & 0x1) << 12;		// DQ width
+	val |= BIT(22);					// ??
+	if (para->dram_type == SUNXI_DRAM_TYPE_LPDDR2 ||
+	    para->dram_type == SUNXI_DRAM_TYPE_LPDDR3) {
+		val |= BIT(19);		// type 6 and 7 must use 1T
+	} else {
+		if (config->dram_tpr13 & BIT(5))
+			val |= BIT(19);
+	}
+	writel(val, 0x3102000);
+
+	// init rank / bank / row for single/dual or two different ranks
+	if ((config->dram_para2 & BIT(8)) &&
+	    ((config->dram_para2 & 0xf000) != 0x1000))
+		width = 32;
+	else
+		width = 16;
+
+	ptr = 0x3102000;
+	for (i = 0; i < width; i += 16) {
+		val = readl(ptr) & 0xfffff000;
+
+		val |= (config->dram_para2 >> 12) & 0x3; // rank
+		val |= ((config->dram_para1 >> (i + 12)) << 2) & 0x4; // bank - 2
+		val |= (((config->dram_para1 >> (i + 4)) - 1) << 4) & 0xff; // row - 1
+
+		// convert from page size to column addr width - 3
+		switch ((config->dram_para1 >> i) & 0xf) {
+		case 8: val |= 0xa00; break;
+		case 4: val |= 0x900; break;
+		case 2: val |= 0x800; break;
+		case 1: val |= 0x700; break;
+		default: val |= 0x600; break;
+		}
+		writel(val, ptr);
+		ptr += 4;
+	}
+
+	// set ODTMAP based on number of ranks in use
+	val = (readl(0x3102000) & 0x1) ? 0x303 : 0x201;
+	writel(val, 0x3103120);
+
+	// set mctl reg 3c4 to zero when using half DQ
+	if (config->dram_para2 & BIT(0))
+		writel(0, 0x31033c4);
+
+	// purpose ??
+	if (para->dram_tpr4) {
+                setbits_le32(0x3102000, (para->dram_tpr4 & 0x3) << 25);
+                setbits_le32(0x3102004, (para->dram_tpr4 & 0x7fc) << 10);
+	}
+}
+
+static const uint8_t ac_remapping_tables[][22] = {
+	[0] = { 0 },
+	[1] = {  1,  9,  3,  7,  8, 18,  4, 13,  5,  6, 10,
+		 2, 14, 12,  0,  0, 21, 17, 20, 19, 11, 22 },
+	[2] = {  4,  9,  3,  7,  8, 18,  1, 13,  2,  6, 10,
+		 5, 14, 12,  0,  0, 21, 17, 20, 19, 11, 22 },
+	[3] = {  1,  7,  8, 12, 10, 18,  4, 13,  5,  6,  3,
+		 2,  9,  0,  0,  0, 21, 17, 20, 19, 11, 22 },
+	[4] = {  4, 12, 10,  7,  8, 18,  1, 13,  2,  6,  3,
+		 5,  9,  0,  0,  0, 21, 17, 20, 19, 11, 22 },
+	[5] = { 13,  2,  7,  9, 12, 19,  5,  1,  6,  3,  4,
+		 8, 10,  0,  0,  0, 21, 22, 18, 17, 11, 20 },
+	[6] = {  3, 10,  7, 13,  9, 11,  1,  2,  4,  6,  8,
+		 5, 12,  0,  0,  0, 20,  1,  0, 21, 22, 17 },
+	[7] = {  3,  2,  4,  7,  9,  1, 17, 12, 18, 14, 13,
+		 8, 15,  6, 10,  5, 19, 22, 16, 21, 20, 11 },
+};
+
+/*
+ * This routine chooses one of several remapping tables for 22 lines.
+ * It is unclear which lines are being remapped. It seems to pick
+ * table cfg7 for the Nezha board.
+ */
+static void mctl_phy_ac_remapping(const dram_para_t *para,
+				  const dram_config_t *config)
+{
+	const uint8_t *cfg;
+	uint32_t fuse, val;
+
+	/*
+	 * It is unclear whether the LPDDRx types don't need any remapping,
+	 * or whether the original code just didn't provide tables.
+	 */
+	if (para->dram_type != SUNXI_DRAM_TYPE_DDR2 &&
+	    para->dram_type != SUNXI_DRAM_TYPE_DDR3)
+		return;
+
+	fuse = (readl(SUNXI_SID_BASE + 0x28) & 0xf00) >> 8;
+	debug("DDR efuse: 0x%x\n", fuse);
+
+	if (para->dram_type == SUNXI_DRAM_TYPE_DDR2) {
+		if (fuse == 15)
+			return;
+		cfg = ac_remapping_tables[6];
+	} else {
+		if (config->dram_tpr13 & 0xc0000) {
+			cfg = ac_remapping_tables[7];
+		} else {
+			switch (fuse) {
+			case 8: cfg = ac_remapping_tables[2]; break;
+			case 9: cfg = ac_remapping_tables[3]; break;
+			case 10: cfg = ac_remapping_tables[5]; break;
+			case 11: cfg = ac_remapping_tables[4]; break;
+			default:
+			case 12: cfg = ac_remapping_tables[1]; break;
+			case 13:
+			case 14: cfg = ac_remapping_tables[0]; break;
+			}
+		}
+	}
+
+	val = (cfg[4] << 25) | (cfg[3] << 20) | (cfg[2] << 15) |
+	      (cfg[1] << 10) | (cfg[0] << 5);
+	writel(val, 0x3102500);
+
+	val = (cfg[10] << 25) | (cfg[9] << 20) | (cfg[8] << 15) |
+	      (cfg[ 7] << 10) | (cfg[6] <<  5) | cfg[5];
+	writel(val, 0x3102504);
+
+	val = (cfg[15] << 20) | (cfg[14] << 15) | (cfg[13] << 10) |
+	      (cfg[12] <<  5) | cfg[11];
+	writel(val, 0x3102508);
+
+	val = (cfg[21] << 25) | (cfg[20] << 20) | (cfg[19] << 15) |
+	      (cfg[18] << 10) | (cfg[17] <<  5) | cfg[16];
+	writel(val, 0x310250c);
+
+	val = (cfg[4] << 25) | (cfg[3] << 20) | (cfg[2] << 15) |
+	      (cfg[1] << 10) | (cfg[0] <<  5) | 1;
+	writel(val, 0x3102500);
+}
+
+// Init the controller channel. The key part is placing commands in the main
+// command register (PIR, 0x3103000) and checking command status (PGSR0, 0x3103010).
+//
+static unsigned int mctl_channel_init(unsigned int ch_index,
+				      const dram_para_t *para,
+				      const dram_config_t *config)
+{
+	unsigned int val, dqs_gating_mode;
+
+	dqs_gating_mode = (config->dram_tpr13 & 0xc) >> 2;
+
+	// set DDR clock to half of CPU clock
+	clrsetbits_le32(0x310200c, 0xfff, (para->dram_clk / 2) - 1);
+
+	// MRCTRL0 nibble 3 undocumented
+	clrsetbits_le32(0x3103108, 0xf00, 0x300);
+
+	if (para->dram_odt_en)
+		val = 0;
+	else
+		val = BIT(5);
+
+	// DX0GCR0
+	if (para->dram_clk > 672)
+		clrsetbits_le32(0x3103344, 0xf63e, val);
+	else
+		clrsetbits_le32(0x3103344, 0xf03e, val);
+
+	// DX1GCR0
+	if (para->dram_clk > 672) {
+                setbits_le32(0x3103344, 0x400);
+		clrsetbits_le32(0x31033c4, 0xf63e, val);
+	} else {
+		clrsetbits_le32(0x31033c4, 0xf03e, val);
+	}
+
+	// 0x3103208 undocumented
+	setbits_le32(0x3103208, BIT(1));
+
+	eye_delay_compensation(para);
+
+	// set PLL SSCG ?
+	val = readl(0x3103108);
+	if (dqs_gating_mode == 1) {
+		clrsetbits_le32(0x3103108, 0xc0, 0);
+		clrbits_le32(0x31030bc, 0x107);
+	} else if (dqs_gating_mode == 2) {
+		clrsetbits_le32(0x3103108, 0xc0, 0x80);
+
+		clrsetbits_le32(0x31030bc, 0x107,
+				(((config->dram_tpr13 >> 16) & 0x1f) - 2) | 0x100);
+		clrsetbits_le32(0x310311c, BIT(31), BIT(27));
+	} else {
+		clrbits_le32(0x3103108, 0x40);
+		udelay(10);
+		setbits_le32(0x3103108, 0xc0);
+	}
+
+	if (para->dram_type == SUNXI_DRAM_TYPE_LPDDR2 ||
+	    para->dram_type == SUNXI_DRAM_TYPE_LPDDR3) {
+		if (dqs_gating_mode == 1)
+			clrsetbits_le32(0x310311c, 0x080000c0, 0x80000000);
+		else
+			clrsetbits_le32(0x310311c, 0x77000000, 0x22000000);
+	}
+
+	clrsetbits_le32(0x31030c0, 0x0fffffff,
+			(config->dram_para2 & BIT(12)) ? 0x03000001 : 0x01000007);
+
+	if (readl(0x70005d4) & BIT(16)) {
+		clrbits_le32(0x7010250, 0x2);
+		udelay(10);
+	}
+
+	// Set ZQ config
+	clrsetbits_le32(0x3103140, 0x3ffffff,
+			(para->dram_zq & 0x00ffffff) | BIT(25));
+
+	// Initialise DRAM controller
+	if (dqs_gating_mode == 1) {
+		//writel(0x52, 0x3103000); // prep PHY reset + PLL init + z-cal
+		writel(0x53, 0x3103000); // Go
+
+		while ((readl(0x3103010) & 0x1) == 0) {
+		} // wait for IDONE
+		udelay(10);
+
+		// 0x520 = prep DQS gating + DRAM init + d-cal
+		if (para->dram_type == SUNXI_DRAM_TYPE_DDR3)
+			writel(0x5a0, 0x3103000);		// + DRAM reset
+		else
+			writel(0x520, 0x3103000);
+	} else {
+		if ((readl(0x70005d4) & (1 << 16)) == 0) {
+			// prep DRAM init + PHY reset + d-cal + PLL init + z-cal
+			if (para->dram_type == SUNXI_DRAM_TYPE_DDR3)
+				writel(0x1f2, 0x3103000);	// + DRAM reset
+			else
+				writel(0x172, 0x3103000);
+		} else {
+			// prep PHY reset + d-cal + z-cal
+			writel(0x62, 0x3103000);
+		}
+	}
+
+	setbits_le32(0x3103000, 0x1);		 // GO
+
+	udelay(10);
+	while ((readl(0x3103010) & 0x1) == 0) {
+	} // wait for IDONE
+
+	if (readl(0x70005d4) & BIT(16)) {
+		clrsetbits_le32(0x310310c, 0x06000000, 0x04000000);
+		udelay(10);
+
+		setbits_le32(0x3103004, 0x1);
+
+		while ((readl(0x3103018) & 0x7) != 0x3) {
+		}
+
+		clrbits_le32(0x7010250, 0x1);
+		udelay(10);
+
+		clrbits_le32(0x3103004, 0x1);
+
+		while ((readl(0x3103018) & 0x7) != 0x1) {
+		}
+
+		udelay(15);
+
+		if (dqs_gating_mode == 1) {
+			clrbits_le32(0x3103108, 0xc0);
+			clrsetbits_le32(0x310310c, 0x06000000, 0x02000000);
+			udelay(1);
+			writel(0x401, 0x3103000);
+
+			while ((readl(0x3103010) & 0x1) == 0) {
+			}
+		}
+	}
+
+	// Check for training error
+	if (readl(0x3103010) & BIT(20)) {
+		printf("ZQ calibration error, check external 240 ohm resistor\n");
+		return 0;
+	}
+
+	// STATR = Zynq STAT? Wait for status 'normal'?
+	while ((readl(0x3103018) & 0x1) == 0) {
+	}
+
+	setbits_le32(0x310308c, BIT(31));
+	udelay(10);
+	clrbits_le32(0x310308c, BIT(31));
+	udelay(10);
+	setbits_le32(0x3102014, BIT(31));
+	udelay(10);
+
+	clrbits_le32(0x310310c, 0x06000000);
+
+	if (dqs_gating_mode == 1)
+		clrsetbits_le32(0x310311c, 0xc0, 0x40);
+
+	return 1;
+}
+
+static unsigned int calculate_rank_size(uint32_t regval)
+{
+	unsigned int bits;
+
+	bits = (regval >> 8) & 0xf;	/* page size - 3 */
+	bits += (regval >> 4) & 0xf;	/* row width - 1 */
+	bits += (regval >> 2) & 0x3;	/* bank count - 2 */
+	bits -= 14;			/* 1MB = 20 bits, minus above 6 = 14 */
+
+	return 1U << bits;
+}
+
+/*
+ * The below routine reads the dram config registers and extracts
+ * the number of address bits in each rank available. It then calculates
+ * total memory size in MB.
+ */
+static unsigned int DRAMC_get_dram_size(void)
+{
+	uint32_t val;
+	unsigned int size;
+
+	val = readl(0x3102000);		/* MC_WORK_MODE0 */
+	size = calculate_rank_size(val);
+	if ((val & 0x3) == 0)		/* single rank? */
+		return size;
+
+	val = readl(0x3102004);		/* MC_WORK_MODE1 */
+	if ((val & 0x3) == 0)		/* two identical ranks? */
+		return size * 2;
+
+	/* add sizes of both ranks */
+	return size + calculate_rank_size(val);
+}
+
+/*
+ * The below routine reads the command status register to extract
+ * DQ width and rank count. This follows the DQS training command in
+ * channel_init. If error bit 22 is reset, we have two ranks and full DQ.
+ * If there was an error, figure out whether it was half DQ, single rank,
+ * or both. Set bit 12 and 0 in dram_para2 with the results.
+ */
+static int dqs_gate_detect(dram_config_t *config)
+{
+	uint32_t dx0, dx1;
+
+	if ((readl(0x3103010) & BIT(22)) == 0) {
+		config->dram_para2 = (config->dram_para2 & ~0xf) | BIT(12);
+		debug("dual rank and full DQ\n");
+
+		return 1;
+	}
+
+	dx0 = (readl(0x3103348) & 0x3000000) >> 24;
+	if (dx0 == 0) {
+		config->dram_para2 = (config->dram_para2 & ~0xf) | 0x1001;
+		debug("dual rank and half DQ\n");
+
+		return 1;
+	}
+
+	if (dx0 == 2) {
+		dx1 = (readl(0x31033c8) & 0x3000000) >> 24;
+		if (dx1 == 2) {
+			config->dram_para2 = config->dram_para2 & ~0xf00f;
+			debug("single rank and full DQ\n");
+		} else {
+			config->dram_para2 = (config->dram_para2 & ~0xf00f) | BIT(0);
+			debug("single rank and half DQ\n");
+		}
+
+		return 1;
+	}
+
+	if ((config->dram_tpr13 & BIT(29)) == 0)
+		return 0;
+
+	debug("DX0 state: %d\n", dx0);
+	debug("DX1 state: %d\n", dx1);
+
+	return 0;
+}
+
+static int dramc_simple_wr_test(unsigned int mem_mb, int len)
+{
+	unsigned int  offs	= (mem_mb / 2) << 18; // half of memory size
+	unsigned int  patt1 = 0x01234567;
+	unsigned int  patt2 = 0xfedcba98;
+	unsigned int *addr, v1, v2, i;
+
+	addr = (unsigned int *)CFG_SYS_SDRAM_BASE;
+	for (i = 0; i != len; i++, addr++) {
+		writel(patt1 + i, (unsigned long)addr);
+		writel(patt2 + i, (unsigned long)(addr + offs));
+	}
+
+	addr = (unsigned int *)CFG_SYS_SDRAM_BASE;
+	for (i = 0; i != len; i++) {
+		v1 = readl((unsigned long)(addr + i));
+		v2 = patt1 + i;
+		if (v1 != v2) {
+			printf("DRAM: simple test FAIL\n");
+			printf("%x != %x at address %p\n", v1, v2, addr + i);
+			return 1;
+		}
+		v1 = readl((unsigned long)(addr + offs + i));
+		v2 = patt2 + i;
+		if (v1 != v2) {
+			printf("DRAM: simple test FAIL\n");
+			printf("%x != %x at address %p\n", v1, v2, addr + offs + i);
+			return 1;
+		}
+	}
+
+	debug("DRAM: simple test OK\n");
+	return 0;
+}
+
+// Set the Vref mode for the controller
+//
+static void mctl_vrefzq_init(const dram_para_t *para, const dram_config_t *config)
+{
+	if (config->dram_tpr13 & BIT(17))
+		return;
+
+	clrsetbits_le32(0x3103110, 0x7f7f7f7f, para->dram_tpr5);
+
+	// IOCVR1
+	if ((config->dram_tpr13 & BIT(16)) == 0)
+		clrsetbits_le32(0x3103114, 0x7f, para->dram_tpr6 & 0x7f);
+}
+
+// Perform an init of the controller. This is actually done 3 times. The first
+// time to establish the number of ranks and DQ width. The second time to
+// establish the actual ram size. The third time is final one, with the final
+// settings.
+//
+static int mctl_core_init(const dram_para_t *para, const dram_config_t *config)
+{
+	mctl_sys_init(para, config);
+
+	mctl_vrefzq_init(para, config);
+
+	mctl_com_init(para, config);
+
+	mctl_phy_ac_remapping(para, config);
+
+	mctl_set_timing_params(para, config);
+
+	return mctl_channel_init(0, para, config);
+}
+
+/*
+ * This routine sizes a DRAM device by cycling through address lines and
+ * figuring out if they are connected to a real address line, or if the
+ * address is a mirror.
+ * First the column and bank bit allocations are set to low values (2 and 9
+ * address lines). Then a maximum allocation (16 lines) is set for rows and
+ * this is tested.
+ * Next the BA2 line is checked. This seems to be placed above the column,
+ * BA0-1 and row addresses. Finally, the column address is allocated 13 lines
+ * and these are tested. The results are placed in dram_para1 and dram_para2.
+ */
+static int auto_scan_dram_size(const dram_para_t *para, dram_config_t *config)
+{
+	unsigned int rval, i, j, rank, maxrank, offs;
+	unsigned int shft;
+	unsigned long ptr, mc_work_mode, chk;
+
+	if (mctl_core_init(para, config) == 0) {
+		printf("DRAM initialisation error : 0\n");
+		return 0;
+	}
+
+	maxrank	= (config->dram_para2 & 0xf000) ? 2 : 1;
+	mc_work_mode = 0x3102000;
+	offs = 0;
+
+	/* write test pattern */
+	for (i = 0, ptr = CFG_SYS_SDRAM_BASE; i < 64; i++, ptr += 4)
+		writel((i & 0x1) ? ptr : ~ptr, ptr);
+
+	for (rank = 0; rank < maxrank;) {
+		/* set row mode */
+		clrsetbits_le32(mc_work_mode, 0xf0c, 0x6f0);
+		udelay(1);
+
+		// Scan per address line, until address wraps (i.e. see shadow)
+		for (i = 11; i < 17; i++) {
+			chk = CFG_SYS_SDRAM_BASE + (1U << (i + 11));
+			ptr = CFG_SYS_SDRAM_BASE;
+			for (j = 0; j < 64; j++) {
+				if (readl(chk) != ((j & 1) ? ptr : ~ptr))
+					break;
+				ptr += 4;
+				chk += 4;
+			}
+			if (j == 64)
+				break;
+		}
+		if (i > 16)
+			i = 16;
+		debug("rank %d row = %d\n", rank, i);
+
+		/* Store rows in para 1 */
+		shft = offs + 4;
+		rval = config->dram_para1;
+		rval &= ~(0xff << shft);
+		rval |= i << shft;
+		config->dram_para1 = rval;
+
+		if (rank == 1)		/* Set bank mode for rank0 */
+			clrsetbits_le32(0x3102000, 0xffc, 0x6a4);
+
+		/* Set bank mode for current rank */
+		clrsetbits_le32(mc_work_mode, 0xffc, 0x6a4);
+		udelay(1);
+
+		// Test if bit A23 is BA2 or mirror XXX A22?
+		chk = CFG_SYS_SDRAM_BASE + (1U << 22);
+		ptr = CFG_SYS_SDRAM_BASE;
+		for (i = 0, j = 0; i < 64; i++) {
+			if (readl(chk) != ((i & 1) ? ptr : ~ptr)) {
+				j = 1;
+				break;
+			}
+			ptr += 4;
+			chk += 4;
+		}
+
+		debug("rank %d bank = %d\n", rank, (j + 1) << 2); /* 4 or 8 */
+
+		/* Store banks in para 1 */
+		shft = 12 + offs;
+		rval = config->dram_para1;
+		rval &= ~(0xf << shft);
+		rval |= j << shft;
+		config->dram_para1 = rval;
+
+		if (rank == 1)		/* Set page mode for rank0 */
+			clrsetbits_le32(0x3102000, 0xffc, 0xaa0);
+
+		/* Set page mode for current rank */
+		clrsetbits_le32(mc_work_mode, 0xffc, 0xaa0);
+		udelay(1);
+
+		// Scan per address line, until address wraps (i.e. see shadow)
+		for (i = 9; i < 14; i++) {
+			chk = CFG_SYS_SDRAM_BASE + (1U << i);
+			ptr = CFG_SYS_SDRAM_BASE;
+			for (j = 0; j < 64; j++) {
+				if (readl(chk) != ((j & 1) ? ptr : ~ptr))
+					break;
+				ptr += 4;
+				chk += 4;
+			}
+			if (j == 64)
+				break;
+		}
+		if (i > 13)
+			i = 13;
+
+		unsigned int pgsize = (i == 9) ? 0 : (1 << (i - 10));
+		debug("rank %d page size = %d KB\n", rank, pgsize);
+
+		/* Store page size */
+		shft = offs;
+		rval = config->dram_para1;
+		rval &= ~(0xf << shft);
+		rval |= pgsize << shft;
+		config->dram_para1 = rval;
+
+		// Move to next rank
+		rank++;
+		if (rank != maxrank) {
+			if (rank == 1) {
+				/* MC_WORK_MODE */
+				clrsetbits_le32(0x3202000, 0xffc, 0x6f0);
+
+				/* MC_WORK_MODE2 */
+				clrsetbits_le32(0x3202004, 0xffc, 0x6f0);
+			}
+			/* store rank1 config in upper half of para1 */
+			offs += 16;
+			mc_work_mode += 4;	/* move to MC_WORK_MODE2 */
+		}
+	}
+	if (maxrank == 2) {
+		config->dram_para2 &= 0xfffff0ff;
+		/* note: rval is equal to para->dram_para1 here */
+		if ((rval & 0xffff) == (rval >> 16)) {
+			debug("rank1 config same as rank0\n");
+		} else {
+			config->dram_para2 |= BIT(8);
+			debug("rank1 config different from rank0\n");
+		}
+	}
+
+	return 1;
+}
+
+/*
+ * This routine sets up parameters with dqs_gating_mode equal to 1 and two
+ * ranks enabled. It then configures the core and tests for 1 or 2 ranks and
+ * full or half DQ width. It then resets the parameters to the original values.
+ * dram_para2 is updated with the rank and width findings.
+ */
+static int auto_scan_dram_rank_width(const dram_para_t *para,
+				     dram_config_t *config)
+{
+	unsigned int s1 = config->dram_tpr13;
+	unsigned int s2 = config->dram_para1;
+
+	config->dram_para1 = 0x00b000b0;
+	config->dram_para2 = (config->dram_para2 & ~0xf) | BIT(12);
+
+	/* set DQS probe mode */
+	config->dram_tpr13 = (config->dram_tpr13 & ~0x8) | BIT(2) | BIT(0);
+
+	mctl_core_init(para, config);
+
+	if (readl(0x3103010) & BIT(20))
+		return 0;
+
+	if (dqs_gate_detect(config) == 0)
+		return 0;
+
+	config->dram_tpr13 = s1;
+	config->dram_para1 = s2;
+
+	return 1;
+}
+
+/*
+ * This routine determines the SDRAM topology. It first establishes the number
+ * of ranks and the DQ width. Then it scans the SDRAM address lines to establish
+ * the size of each rank. It then updates dram_tpr13 to reflect that the sizes
+ * are now known: a re-init will not repeat the autoscan.
+ */
+static int auto_scan_dram_config(const dram_para_t *para,
+				 dram_config_t *config)
+{
+	if (((config->dram_tpr13 & BIT(14)) == 0) &&
+	    (auto_scan_dram_rank_width(para, config) == 0)) {
+		printf("ERROR: auto scan dram rank & width failed\n");
+		return 0;
+	}
+
+	if (((config->dram_tpr13 & BIT(0)) == 0) &&
+	    (auto_scan_dram_size(para, config) == 0)) {
+		printf("ERROR: auto scan dram size failed\n");
+		return 0;
+	}
+
+	if ((config->dram_tpr13 & BIT(15)) == 0)
+		config->dram_tpr13 |= BIT(14) | BIT(13) | BIT(1) | BIT(0);
+
+	return 1;
+}
+
+static int init_DRAM(int type, const dram_para_t *para)
+{
+	dram_config_t config = {
+		.dram_para1	= 0x000010d2,
+		.dram_para2	= 0,
+		.dram_tpr13	= CONFIG_DRAM_SUNXI_TPR13,
+	};
+	u32 rc, mem_size_mb;
+
+	debug("DRAM BOOT DRIVE INFO: %s\n", "V0.24");
+	debug("DRAM CLK = %d MHz\n", para->dram_clk);
+	debug("DRAM Type = %d (2:DDR2,3:DDR3)\n", para->dram_type);
+	if ((para->dram_odt_en & 0x1) == 0)
+		debug("DRAMC read ODT off\n");
+	else
+		debug("DRAMC ZQ value: 0x%x\n", para->dram_zq);
+
+	/* Test ZQ status */
+	if (config.dram_tpr13 & BIT(16)) {
+		debug("DRAM only have internal ZQ\n");
+		setbits_le32(0x3000160, BIT(8));
+		writel(0, 0x3000168);
+		udelay(10);
+	} else {
+		clrbits_le32(0x3000160, 0x3);
+		writel(config.dram_tpr13 & BIT(16), 0x7010254);
+		udelay(10);
+		clrsetbits_le32(0x3000160, 0x108, BIT(1));
+		udelay(10);
+		setbits_le32(0x3000160, BIT(0));
+		udelay(20);
+		debug("ZQ value = 0x%x\n", readl(0x300016c));
+	}
+
+	dram_voltage_set(para);
+
+	/* Set SDRAM controller auto config */
+	if ((config.dram_tpr13 & BIT(0)) == 0) {
+		if (auto_scan_dram_config(para, &config) == 0) {
+			printf("auto_scan_dram_config() FAILED\n");
+			return 0;
+		}
+	}
+
+	/* report ODT */
+	rc = para->dram_mr1;
+	if ((rc & 0x44) == 0)
+		debug("DRAM ODT off\n");
+	else
+		debug("DRAM ODT value: 0x%x\n", rc);
+
+	/* Init core, final run */
+	if (mctl_core_init(para, &config) == 0) {
+		printf("DRAM initialisation error: 1\n");
+		return 0;
+	}
+
+	/* Get SDRAM size */
+	/* TODO: who ever puts a negative number in the top half? */
+	rc = config.dram_para2;
+	if (rc & BIT(31)) {
+		rc = (rc >> 16) & ~BIT(15);
+	} else {
+		rc = DRAMC_get_dram_size();
+		debug("DRAM: size = %dMB\n", rc);
+		config.dram_para2 = (config.dram_para2 & 0xffffU) | rc << 16;
+	}
+	mem_size_mb = rc;
+
+	/* Purpose ?? */
+	if (config.dram_tpr13 & BIT(30)) {
+		rc = para->dram_tpr8;
+		if (rc == 0)
+			rc = 0x10000200;
+		writel(rc, 0x31030a0);
+		writel(0x40a, 0x310309c);
+		setbits_le32(0x3103004, BIT(0));
+		debug("Enable Auto SR\n");
+	} else {
+		clrbits_le32(0x31030a0, 0xffff);
+		clrbits_le32(0x3103004, 0x1);
+	}
+
+	/* Purpose ?? */
+	if (config.dram_tpr13 & BIT(9)) {
+		clrsetbits_le32(0x3103100, 0xf000, 0x5000);
+	} else {
+		if (para->dram_type != SUNXI_DRAM_TYPE_LPDDR2)
+			clrbits_le32(0x3103100, 0xf000);
+	}
+
+	setbits_le32(0x3103140, BIT(31));
+
+	/* CHECK: is that really writing to a different register? */
+	if (config.dram_tpr13 & BIT(8))
+		writel(readl(0x3103140) | 0x300, 0x31030b8);
+
+	if (config.dram_tpr13 & BIT(16))
+		clrbits_le32(0x3103108, BIT(13));
+	else
+		setbits_le32(0x3103108, BIT(13));
+
+	/* Purpose ?? */
+	if (para->dram_type == SUNXI_DRAM_TYPE_LPDDR3)
+		clrsetbits_le32(0x310307c, 0xf0000, 0x1000);
+
+	dram_enable_all_master();
+	if (config.dram_tpr13 & BIT(28)) {
+		if ((readl(0x70005d4) & BIT(16)) ||
+		    dramc_simple_wr_test(mem_size_mb, 4096))
+			return 0;
+	}
+
+	return mem_size_mb;
+}
+
+	static const dram_para_t para = {
+		.dram_clk	= CONFIG_DRAM_CLK,
+		.dram_type	= CONFIG_SUNXI_DRAM_TYPE,
+		.dram_zq	= CONFIG_DRAM_ZQ,
+		.dram_odt_en	= CONFIG_DRAM_SUNXI_ODT_EN,
+		.dram_mr0	= 0x1c70,
+		.dram_mr1	= 0x42,
+		.dram_mr2	= 0x18,
+		.dram_mr3	= 0,
+		.dram_tpr0	= 0x004a2195,
+		.dram_tpr1	= 0x02423190,
+		.dram_tpr2	= 0x0008b061,
+		.dram_tpr3	= 0xb4787896, // unused
+		.dram_tpr4	= 0,
+		.dram_tpr5	= 0x48484848,
+		.dram_tpr6	= 0x00000048,
+		.dram_tpr7	= 0x1620121e, // unused
+		.dram_tpr8	= 0,
+		.dram_tpr9	= 0, // clock?
+		.dram_tpr10	= 0,
+		.dram_tpr11	= CONFIG_DRAM_SUNXI_TPR11,
+		.dram_tpr12	= CONFIG_DRAM_SUNXI_TPR12,
+	};
+
+unsigned long sunxi_dram_init(void)
+{
+	return init_DRAM(0, &para) * 1024UL * 1024;
+};
+
+#ifdef CONFIG_RAM		/* using the driver model */
+struct sunxi_ram_priv {
+	size_t size;
+};
+
+static int sunxi_ram_probe(struct udevice *dev)
+{
+	struct sunxi_ram_priv *priv = dev_get_priv(dev);
+	unsigned long dram_size;
+
+	debug("%s: %s: probing\n", __func__, dev->name);
+
+	dram_size = sunxi_dram_init();
+	if (!dram_size) {
+		printf("DRAM init failed: %d\n", ret);
+		return -ENODEV;
+	}
+
+	priv->size = dram_size;
+
+	return 0;
+}
+
+static int sunxi_ram_get_info(struct udevice *dev, struct ram_info *info)
+{
+	struct sunxi_ram_priv *priv = dev_get_priv(dev);
+
+	debug("%s: %s: getting info\n", __func__, dev->name);
+
+	info->base = CFG_SYS_SDRAM_BASE;
+	info->size = priv->size;
+
+	return 0;
+}
+
+static struct ram_ops sunxi_ram_ops = {
+	.get_info = sunxi_ram_get_info,
+};
+
+static const struct udevice_id sunxi_ram_ids[] = {
+	{ .compatible = "allwinner,sun20i-d1-mbus" },
+	{ }
+};
+
+U_BOOT_DRIVER(sunxi_ram) = {
+	.name = "sunxi_ram",
+	.id = UCLASS_RAM,
+	.of_match = sunxi_ram_ids,
+	.ops = &sunxi_ram_ops,
+	.probe = sunxi_ram_probe,
+	.priv_auto = sizeof(struct sunxi_ram_priv),
+};
+#endif				/* CONFIG_RAM (using driver model) */
diff --git a/drivers/ram/sunxi/dram_sun20i_d1.h b/drivers/ram/sunxi/dram_sun20i_d1.h
new file mode 100644
index 00000000000..91383f6cf10
--- /dev/null
+++ b/drivers/ram/sunxi/dram_sun20i_d1.h
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier:	GPL-2.0+
+/*
+ * D1/R528/T113 DRAM controller register and constant defines
+ *
+ * (C) Copyright 2022 Arm Ltd.
+ * Based on H6 and H616 header, which are:
+ * (C) Copyright 2017  Icenowy Zheng <icenowy@aosc.io>
+ * (C) Copyright 2020  Jernej Skrabec <jernej.skrabec@siol.net>
+ *
+ */
+
+#ifndef _SUNXI_DRAM_SUN20I_D1_H
+#define _SUNXI_DRAM_SUN20I_D1_H
+
+enum sunxi_dram_type {
+	SUNXI_DRAM_TYPE_DDR2 = 2,
+	SUNXI_DRAM_TYPE_DDR3 = 3,
+	SUNXI_DRAM_TYPE_LPDDR2 = 6,
+	SUNXI_DRAM_TYPE_LPDDR3 = 7,
+};
+
+/*
+ * This structure contains a mixture of fixed configuration settings,
+ * variables that are used at runtime to communicate settings between
+ * different stages and functions, and unused values.
+ * This is copied from Allwinner's boot0 data structure, which can be
+ * found at offset 0x38 in any boot0 binary. To allow matching up some
+ * board specific settings, this struct is kept compatible, even though
+ * we don't need all members in our code.
+ */
+typedef struct dram_para {
+	/* normal configuration */
+	const u32	dram_clk;
+	const u32	dram_type;
+	const u32	dram_zq;
+	const u32	dram_odt_en;
+
+	/* timing configuration */
+	const u32	dram_mr0;
+	const u32	dram_mr1;
+	const u32	dram_mr2;
+	const u32	dram_mr3;
+	const u32	dram_tpr0;	//DRAMTMG0
+	const u32	dram_tpr1;	//DRAMTMG1
+	const u32	dram_tpr2;	//DRAMTMG2
+	const u32	dram_tpr3;	//DRAMTMG3
+	const u32	dram_tpr4;	//DRAMTMG4
+	const u32	dram_tpr5;	//DRAMTMG5
+	const u32	dram_tpr6;	//DRAMTMG8
+	const u32	dram_tpr7;
+	const u32	dram_tpr8;
+	const u32	dram_tpr9;
+	const u32	dram_tpr10;
+	const u32	dram_tpr11;
+	const u32	dram_tpr12;
+} dram_para_t;
+
+typedef struct dram_config {
+	/* control configuration */
+	u32	dram_para1;
+	u32	dram_para2;
+	/* contains a bitfield of DRAM setup settings */
+	u32	dram_tpr13;
+} dram_config_t;
+
+static inline int ns_to_t(int nanoseconds)
+{
+	const unsigned int ctrl_freq = CONFIG_DRAM_CLK / 2;
+
+	return DIV_ROUND_UP(ctrl_freq * nanoseconds, 1000);
+}
+
+#endif /* _SUNXI_DRAM_SUN20I_D1_H */
-- 
2.35.8