arch/arm/mach-aspeed/ast2500/sdram_ast2500.c - filogic/uboot - Gitiles

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2012-2020  ASPEED Technology Inc.
  *
  * Copyright 2016 Google, Inc
  */

 #include <common.h>
 #include <clk.h>
 #include <dm.h>
 #include <errno.h>
 #include <log.h>
 #include <ram.h>
 #include <regmap.h>
 #include <reset.h>
 #include <asm/io.h>
 #include <asm/arch/scu_ast2500.h>
 #include <asm/arch/sdram_ast2500.h>
 #include <asm/arch/wdt.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <dt-bindings/clock/ast2500-scu.h>

 /* These configuration parameters are taken from Aspeed SDK */
 #define DDR4_MR46_MODE		0x08000000
 #define DDR4_MR5_MODE		0x400
 #define DDR4_MR13_MODE		0x101
 #define DDR4_MR02_MODE		0x410
 #define DDR4_TRFC		0x45457188

 #define PHY_CFG_SIZE		15

 static const u32 ddr4_ac_timing[3] = {0x63604e37, 0xe97afa99, 0x00019000};
 static const struct {
 	u32 index[PHY_CFG_SIZE];
 	u32 value[PHY_CFG_SIZE];
 } ddr4_phy_config = {
 	.index = {0, 1, 3, 4, 5, 56, 57, 58, 59, 60, 61, 62, 36, 49, 50},
 	.value = {
 		0x42492aae, 0x09002000, 0x55e00b0b, 0x20000000, 0x24,
 		0x03002900, 0x0e0000a0, 0x000e001c, 0x35b8c106, 0x08080607,
 		0x9b000900, 0x0e400a00, 0x00100008, 0x3c183c3c, 0x00631e0e,
 	},
 };

 #define SDRAM_MAX_SIZE		(1024 * 1024 * 1024)
 #define SDRAM_MIN_SIZE		(128 * 1024 * 1024)

 DECLARE_GLOBAL_DATA_PTR;

 /*
  * Bandwidth configuration parameters for different SDRAM requests.
  * These are hardcoded settings taken from Aspeed SDK.
  */
 static const u32 ddr_max_grant_params[4] = {
 	0x88448844, 0x24422288, 0x22222222, 0x22222222
 };

 /*
  * These registers are not documented by Aspeed at all.
  * All writes and reads are taken pretty much as is from SDK.
  */
 struct ast2500_ddr_phy {
 	u32 phy[117];
 };

 struct dram_info {
 	struct ram_info info;
 	struct clk ddr_clk;
 	struct ast2500_sdrammc_regs *regs;
 	struct ast2500_scu *scu;
 	struct ast2500_ddr_phy *phy;
 	ulong clock_rate;
 };

 static int ast2500_sdrammc_init_phy(struct ast2500_ddr_phy *phy)
 {
 	writel(0, &phy->phy[2]);
 	writel(0, &phy->phy[6]);
 	writel(0, &phy->phy[8]);
 	writel(0, &phy->phy[10]);
 	writel(0, &phy->phy[12]);
 	writel(0, &phy->phy[42]);
 	writel(0, &phy->phy[44]);

 	writel(0x86000000, &phy->phy[16]);
 	writel(0x00008600, &phy->phy[17]);
 	writel(0x80000000, &phy->phy[18]);
 	writel(0x80808080, &phy->phy[19]);

 	return 0;
 }

 static void ast2500_ddr_phy_init_process(struct dram_info *info)
 {
 	struct ast2500_sdrammc_regs *regs = info->regs;

 	writel(0, &regs->phy_ctrl[0]);
 	writel(0x4040, &info->phy->phy[51]);

 	writel(SDRAM_PHYCTRL0_NRST | SDRAM_PHYCTRL0_INIT, &regs->phy_ctrl[0]);
 	while ((readl(&regs->phy_ctrl[0]) & SDRAM_PHYCTRL0_INIT))
 		;
 	writel(SDRAM_PHYCTRL0_NRST | SDRAM_PHYCTRL0_AUTO_UPDATE,
 	       &regs->phy_ctrl[0]);
 }

 static void ast2500_sdrammc_set_vref(struct dram_info *info, u32 vref)
 {
 	writel(0, &info->regs->phy_ctrl[0]);
 	writel((vref << 8) | 0x6, &info->phy->phy[48]);
 	ast2500_ddr_phy_init_process(info);
 }

 static int ast2500_ddr_cbr_test(struct dram_info *info)
 {
 	struct ast2500_sdrammc_regs *regs = info->regs;
 	int i;
 	const u32 test_params = SDRAM_TEST_EN
 			| SDRAM_TEST_ERRSTOP
 			| SDRAM_TEST_TWO_MODES;
 	int ret = 0;

 	writel((1 << SDRAM_REFRESH_CYCLES_SHIFT) |
 	       (0x5c << SDRAM_REFRESH_PERIOD_SHIFT), &regs->refresh_timing);
 	writel((0xfff << SDRAM_TEST_LEN_SHIFT), &regs->test_addr);
 	writel(0xff00ff00, &regs->test_init_val);
 	writel(SDRAM_TEST_EN | (SDRAM_TEST_MODE_RW << SDRAM_TEST_MODE_SHIFT) |
 	       SDRAM_TEST_ERRSTOP, &regs->ecc_test_ctrl);

 	while (!(readl(&regs->ecc_test_ctrl) & SDRAM_TEST_DONE))
 		;

 	if (readl(&regs->ecc_test_ctrl) & SDRAM_TEST_FAIL) {
 		ret = -EIO;
 	} else {
 		for (i = 0; i <= SDRAM_TEST_GEN_MODE_MASK; ++i) {
 			writel((i << SDRAM_TEST_GEN_MODE_SHIFT) | test_params,
 			       &regs->ecc_test_ctrl);
 			while (!(readl(&regs->ecc_test_ctrl) & SDRAM_TEST_DONE))
 				;
 			if (readl(&regs->ecc_test_ctrl) & SDRAM_TEST_FAIL) {
 				ret = -EIO;
 				break;
 			}
 		}
 	}

 	writel(0, &regs->refresh_timing);
 	writel(0, &regs->ecc_test_ctrl);

 	return ret;
 }

 static int ast2500_sdrammc_ddr4_calibrate_vref(struct dram_info *info)
 {
 	int i;
 	int vref_min = 0xff;
 	int vref_max = 0;
 	int range_size = 0;

 	for (i = 1; i < 0x40; ++i) {
 		int res;

 		ast2500_sdrammc_set_vref(info, i);
 		res = ast2500_ddr_cbr_test(info);
 		if (res < 0) {
 			if (range_size > 0)
 				break;
 		} else {
 			++range_size;
 			vref_min = min(vref_min, i);
 			vref_max = max(vref_max, i);
 		}
 	}

 	/* Pick average setting */
 	ast2500_sdrammc_set_vref(info, (vref_min + vref_max + 1) / 2);

 	return 0;
 }

 static size_t ast2500_sdrammc_get_vga_mem_size(struct dram_info *info)
 {
 	size_t vga_mem_size_base = 8 * 1024 * 1024;
 	u32 vga_hwconf = (readl(&info->scu->hwstrap) & SCU_HWSTRAP_VGAMEM_MASK)
 	    >> SCU_HWSTRAP_VGAMEM_SHIFT;

 	return vga_mem_size_base << vga_hwconf;
 }

 /*
  * Find out RAM size and save it in dram_info
  *
  * The procedure is taken from Aspeed SDK
  */
 static void ast2500_sdrammc_calc_size(struct dram_info *info)
 {
 	/* The controller supports 128/256/512/1024 MB ram */
 	size_t ram_size = SDRAM_MIN_SIZE;
 	const int write_test_offset = 0x100000;
 	u32 test_pattern = 0xdeadbeef;
 	u32 cap_param = SDRAM_CONF_CAP_1024M;
 	u32 refresh_timing_param = DDR4_TRFC;
 	const u32 write_addr_base = CONFIG_SYS_SDRAM_BASE + write_test_offset;

 	for (ram_size = SDRAM_MAX_SIZE; ram_size > SDRAM_MIN_SIZE;
 	     ram_size >>= 1) {
 		writel(test_pattern, write_addr_base + (ram_size >> 1));
 		test_pattern = (test_pattern >> 4) | (test_pattern << 28);
 	}

 	/* One last write to overwrite all wrapped values */
 	writel(test_pattern, write_addr_base);

 	/* Reset the pattern and see which value was really written */
 	test_pattern = 0xdeadbeef;
 	for (ram_size = SDRAM_MAX_SIZE; ram_size > SDRAM_MIN_SIZE;
 	     ram_size >>= 1) {
 		if (readl(write_addr_base + (ram_size >> 1)) == test_pattern)
 			break;

 		--cap_param;
 		refresh_timing_param >>= 8;
 		test_pattern = (test_pattern >> 4) | (test_pattern << 28);
 	}

 	clrsetbits_le32(&info->regs->ac_timing[1],
 			(SDRAM_AC_TRFC_MASK << SDRAM_AC_TRFC_SHIFT),
 			((refresh_timing_param & SDRAM_AC_TRFC_MASK)
 			 << SDRAM_AC_TRFC_SHIFT));

 	info->info.base = CONFIG_SYS_SDRAM_BASE;
 	info->info.size = ram_size - ast2500_sdrammc_get_vga_mem_size(info);
 	clrsetbits_le32(&info->regs->config,
 			(SDRAM_CONF_CAP_MASK << SDRAM_CONF_CAP_SHIFT),
 			((cap_param & SDRAM_CONF_CAP_MASK)
 			 << SDRAM_CONF_CAP_SHIFT));
 }

 static int ast2500_sdrammc_init_ddr4(struct dram_info *info)
 {
 	int i;
 	const u32 power_control = SDRAM_PCR_CKE_EN
 	    | (1 << SDRAM_PCR_CKE_DELAY_SHIFT)
 	    | (2 << SDRAM_PCR_TCKE_PW_SHIFT)
 	    | SDRAM_PCR_RESETN_DIS
 	    | SDRAM_PCR_RGAP_CTRL_EN | SDRAM_PCR_ODT_EN | SDRAM_PCR_ODT_EXT_EN;
 	const u32 conf = (SDRAM_CONF_CAP_1024M << SDRAM_CONF_CAP_SHIFT)
 #ifdef CONFIG_DUALX8_RAM
 	    | SDRAM_CONF_DUALX8
 #endif
 	    | SDRAM_CONF_SCRAMBLE | SDRAM_CONF_SCRAMBLE_PAT2 | SDRAM_CONF_DDR4;
 	int ret;

 	writel(conf, &info->regs->config);
 	for (i = 0; i < ARRAY_SIZE(ddr4_ac_timing); ++i)
 		writel(ddr4_ac_timing[i], &info->regs->ac_timing[i]);

 	writel(DDR4_MR46_MODE, &info->regs->mr46_mode_setting);
 	writel(DDR4_MR5_MODE, &info->regs->mr5_mode_setting);
 	writel(DDR4_MR02_MODE, &info->regs->mr02_mode_setting);
 	writel(DDR4_MR13_MODE, &info->regs->mr13_mode_setting);

 	for (i = 0; i < PHY_CFG_SIZE; ++i) {
 		writel(ddr4_phy_config.value[i],
 		       &info->phy->phy[ddr4_phy_config.index[i]]);
 	}

 	writel(power_control, &info->regs->power_control);

 	ast2500_ddr_phy_init_process(info);

 	ret = ast2500_sdrammc_ddr4_calibrate_vref(info);
 	if (ret < 0) {
 		debug("Vref calibration failed!\n");
 		return ret;
 	}

 	writel((1 << SDRAM_REFRESH_CYCLES_SHIFT)
 	       | SDRAM_REFRESH_ZQCS_EN | (0x2f << SDRAM_REFRESH_PERIOD_SHIFT),
 	       &info->regs->refresh_timing);

 	setbits_le32(&info->regs->power_control,
 		     SDRAM_PCR_AUTOPWRDN_EN | SDRAM_PCR_ODT_AUTO_ON);

 	ast2500_sdrammc_calc_size(info);

 	setbits_le32(&info->regs->config, SDRAM_CONF_CACHE_INIT_EN);
 	while (!(readl(&info->regs->config) & SDRAM_CONF_CACHE_INIT_DONE))
 		;
 	setbits_le32(&info->regs->config, SDRAM_CONF_CACHE_EN);

 	writel(SDRAM_MISC_DDR4_TREFRESH, &info->regs->misc_control);

 	/* Enable all requests except video & display */
 	writel(SDRAM_REQ_USB20_EHCI1
 	       | SDRAM_REQ_USB20_EHCI2
 	       | SDRAM_REQ_CPU
 	       | SDRAM_REQ_AHB2
 	       | SDRAM_REQ_AHB
 	       | SDRAM_REQ_MAC0
 	       | SDRAM_REQ_MAC1
 	       | SDRAM_REQ_PCIE
 	       | SDRAM_REQ_XDMA
 	       | SDRAM_REQ_ENCRYPTION
 	       | SDRAM_REQ_VIDEO_FLAG
 	       | SDRAM_REQ_VIDEO_LOW_PRI_WRITE
 	       | SDRAM_REQ_2D_RW
 	       | SDRAM_REQ_MEMCHECK, &info->regs->req_limit_mask);

 	return 0;
 }

 static void ast2500_sdrammc_unlock(struct dram_info *info)
 {
 	writel(SDRAM_UNLOCK_KEY, &info->regs->protection_key);
 	while (!readl(&info->regs->protection_key))
 		;
 }

 static void ast2500_sdrammc_lock(struct dram_info *info)
 {
 	writel(~SDRAM_UNLOCK_KEY, &info->regs->protection_key);
 	while (readl(&info->regs->protection_key))
 		;
 }

 static int ast2500_sdrammc_probe(struct udevice *dev)
 {
 	struct reset_ctl reset_ctl;
 	struct dram_info *priv = (struct dram_info *)dev_get_priv(dev);
 	struct ast2500_sdrammc_regs *regs = priv->regs;
 	int i;
 	int ret = clk_get_by_index(dev, 0, &priv->ddr_clk);

 	if (ret) {
 		debug("DDR:No CLK\n");
 		return ret;
 	}

 	priv->scu = ast_get_scu();
 	if (IS_ERR(priv->scu)) {
 		debug("%s(): can't get SCU\n", __func__);
 		return PTR_ERR(priv->scu);
 	}

 	clk_set_rate(&priv->ddr_clk, priv->clock_rate);
 	ret = reset_get_by_index(dev, 0, &reset_ctl);
 	if (ret) {
 		debug("%s(): Failed to get reset signal\n", __func__);
 		return ret;
 	}

 	ret = reset_assert(&reset_ctl);
 	if (ret) {
 		debug("%s(): SDRAM reset failed: %u\n", __func__, ret);
 		return ret;
 	}

 	ast2500_sdrammc_unlock(priv);

 	writel(SDRAM_PCR_MREQI_DIS | SDRAM_PCR_RESETN_DIS,
 	       &regs->power_control);
 	writel(SDRAM_VIDEO_UNLOCK_KEY, &regs->gm_protection_key);

 	/* Mask all requests except CPU and AHB during PHY init */
 	writel(~(SDRAM_REQ_CPU | SDRAM_REQ_AHB), &regs->req_limit_mask);

 	for (i = 0; i < ARRAY_SIZE(ddr_max_grant_params); ++i)
 		writel(ddr_max_grant_params[i], &regs->max_grant_len[i]);

 	setbits_le32(&regs->intr_ctrl, SDRAM_ICR_RESET_ALL);

 	ast2500_sdrammc_init_phy(priv->phy);
 	if (readl(&priv->scu->hwstrap) & SCU_HWSTRAP_DDR4) {
 		ast2500_sdrammc_init_ddr4(priv);
 	} else {
 		debug("Unsupported DRAM3\n");
 		return -EINVAL;
 	}

 	clrbits_le32(&regs->intr_ctrl, SDRAM_ICR_RESET_ALL);
 	ast2500_sdrammc_lock(priv);

 	return 0;
 }

 static int ast2500_sdrammc_ofdata_to_platdata(struct udevice *dev)
 {
 	struct dram_info *priv = dev_get_priv(dev);
 	struct regmap *map;
 	int ret;

 	ret = regmap_init_mem(dev_ofnode(dev), &map);
 	if (ret)
 		return ret;

 	priv->regs = regmap_get_range(map, 0);
 	priv->phy = regmap_get_range(map, 1);

 	priv->clock_rate = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
 					  "clock-frequency", 0);

 	if (!priv->clock_rate) {
 		debug("DDR Clock Rate not defined\n");
 		return -EINVAL;
 	}

 	return 0;
 }

 static int ast2500_sdrammc_get_info(struct udevice *dev, struct ram_info *info)
 {
 	struct dram_info *priv = dev_get_priv(dev);

 	*info = priv->info;

 	return 0;
 }

 static struct ram_ops ast2500_sdrammc_ops = {
 	.get_info = ast2500_sdrammc_get_info,
 };

 static const struct udevice_id ast2500_sdrammc_ids[] = {
 	{ .compatible = "aspeed,ast2500-sdrammc" },
 	{ }
 };

 U_BOOT_DRIVER(sdrammc_ast2500) = {
 	.name = "aspeed_ast2500_sdrammc",
 	.id = UCLASS_RAM,
 	.of_match = ast2500_sdrammc_ids,
 	.ops = &ast2500_sdrammc_ops,
 	.ofdata_to_platdata = ast2500_sdrammc_ofdata_to_platdata,
 	.probe = ast2500_sdrammc_probe,
 	.priv_auto_alloc_size = sizeof(struct dram_info),
 };
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (C) 2012-2020 ASPEED Technology Inc.
	*
	* Copyright 2016 Google, Inc
	*/

	#include <common.h>
	#include <clk.h>
	#include <dm.h>
	#include <errno.h>
	#include <log.h>
	#include <ram.h>
	#include <regmap.h>
	#include <reset.h>
	#include <asm/io.h>
	#include <asm/arch/scu_ast2500.h>
	#include <asm/arch/sdram_ast2500.h>
	#include <asm/arch/wdt.h>
	#include <linux/err.h>
	#include <linux/kernel.h>
	#include <dt-bindings/clock/ast2500-scu.h>

	/* These configuration parameters are taken from Aspeed SDK */
	#define DDR4_MR46_MODE 0x08000000
	#define DDR4_MR5_MODE 0x400
	#define DDR4_MR13_MODE 0x101
	#define DDR4_MR02_MODE 0x410
	#define DDR4_TRFC 0x45457188

	#define PHY_CFG_SIZE 15

	static const u32 ddr4_ac_timing[3] = {0x63604e37, 0xe97afa99, 0x00019000};
	static const struct {
	u32 index[PHY_CFG_SIZE];
	u32 value[PHY_CFG_SIZE];
	} ddr4_phy_config = {
	.index = {0, 1, 3, 4, 5, 56, 57, 58, 59, 60, 61, 62, 36, 49, 50},
	.value = {
	0x42492aae, 0x09002000, 0x55e00b0b, 0x20000000, 0x24,
	0x03002900, 0x0e0000a0, 0x000e001c, 0x35b8c106, 0x08080607,
	0x9b000900, 0x0e400a00, 0x00100008, 0x3c183c3c, 0x00631e0e,
	},
	};

	#define SDRAM_MAX_SIZE (1024 * 1024 * 1024)
	#define SDRAM_MIN_SIZE (128 * 1024 * 1024)

	DECLARE_GLOBAL_DATA_PTR;

	/*
	* Bandwidth configuration parameters for different SDRAM requests.
	* These are hardcoded settings taken from Aspeed SDK.
	*/
	static const u32 ddr_max_grant_params[4] = {
	0x88448844, 0x24422288, 0x22222222, 0x22222222
	};

	/*
	* These registers are not documented by Aspeed at all.
	* All writes and reads are taken pretty much as is from SDK.
	*/
	struct ast2500_ddr_phy {
	u32 phy[117];
	};

	struct dram_info {
	struct ram_info info;
	struct clk ddr_clk;
	struct ast2500_sdrammc_regs *regs;
	struct ast2500_scu *scu;
	struct ast2500_ddr_phy *phy;
	ulong clock_rate;
	};

	static int ast2500_sdrammc_init_phy(struct ast2500_ddr_phy *phy)
	{
	writel(0, &phy->phy[2]);
	writel(0, &phy->phy[6]);
	writel(0, &phy->phy[8]);
	writel(0, &phy->phy[10]);
	writel(0, &phy->phy[12]);
	writel(0, &phy->phy[42]);
	writel(0, &phy->phy[44]);

	writel(0x86000000, &phy->phy[16]);
	writel(0x00008600, &phy->phy[17]);
	writel(0x80000000, &phy->phy[18]);
	writel(0x80808080, &phy->phy[19]);

	return 0;
	}

	static void ast2500_ddr_phy_init_process(struct dram_info *info)
	{
	struct ast2500_sdrammc_regs *regs = info->regs;

	writel(0, &regs->phy_ctrl[0]);
	writel(0x4040, &info->phy->phy[51]);

	writel(SDRAM_PHYCTRL0_NRST \| SDRAM_PHYCTRL0_INIT, &regs->phy_ctrl[0]);
	while ((readl(&regs->phy_ctrl[0]) & SDRAM_PHYCTRL0_INIT))
	;
	writel(SDRAM_PHYCTRL0_NRST \| SDRAM_PHYCTRL0_AUTO_UPDATE,
	&regs->phy_ctrl[0]);
	}

	static void ast2500_sdrammc_set_vref(struct dram_info *info, u32 vref)
	{
	writel(0, &info->regs->phy_ctrl[0]);
	writel((vref << 8) \| 0x6, &info->phy->phy[48]);
	ast2500_ddr_phy_init_process(info);
	}

	static int ast2500_ddr_cbr_test(struct dram_info *info)
	{
	struct ast2500_sdrammc_regs *regs = info->regs;
	int i;
	const u32 test_params = SDRAM_TEST_EN
	\| SDRAM_TEST_ERRSTOP
	\| SDRAM_TEST_TWO_MODES;
	int ret = 0;

	writel((1 << SDRAM_REFRESH_CYCLES_SHIFT) \|
	(0x5c << SDRAM_REFRESH_PERIOD_SHIFT), &regs->refresh_timing);
	writel((0xfff << SDRAM_TEST_LEN_SHIFT), &regs->test_addr);
	writel(0xff00ff00, &regs->test_init_val);
	writel(SDRAM_TEST_EN \| (SDRAM_TEST_MODE_RW << SDRAM_TEST_MODE_SHIFT) \|
	SDRAM_TEST_ERRSTOP, &regs->ecc_test_ctrl);

	while (!(readl(&regs->ecc_test_ctrl) & SDRAM_TEST_DONE))
	;

	if (readl(&regs->ecc_test_ctrl) & SDRAM_TEST_FAIL) {
	ret = -EIO;
	} else {
	for (i = 0; i <= SDRAM_TEST_GEN_MODE_MASK; ++i) {
	writel((i << SDRAM_TEST_GEN_MODE_SHIFT) \| test_params,
	&regs->ecc_test_ctrl);
	while (!(readl(&regs->ecc_test_ctrl) & SDRAM_TEST_DONE))
	;
	if (readl(&regs->ecc_test_ctrl) & SDRAM_TEST_FAIL) {
	ret = -EIO;
	break;
	}
	}
	}

	writel(0, &regs->refresh_timing);
	writel(0, &regs->ecc_test_ctrl);

	return ret;
	}

	static int ast2500_sdrammc_ddr4_calibrate_vref(struct dram_info *info)
	{
	int i;
	int vref_min = 0xff;
	int vref_max = 0;
	int range_size = 0;

	for (i = 1; i < 0x40; ++i) {
	int res;

	ast2500_sdrammc_set_vref(info, i);
	res = ast2500_ddr_cbr_test(info);
	if (res < 0) {
	if (range_size > 0)
	break;
	} else {
	++range_size;
	vref_min = min(vref_min, i);
	vref_max = max(vref_max, i);
	}
	}

	/* Pick average setting */
	ast2500_sdrammc_set_vref(info, (vref_min + vref_max + 1) / 2);

	return 0;
	}

	static size_t ast2500_sdrammc_get_vga_mem_size(struct dram_info *info)
	{
	size_t vga_mem_size_base = 8 * 1024 * 1024;
	u32 vga_hwconf = (readl(&info->scu->hwstrap) & SCU_HWSTRAP_VGAMEM_MASK)
	>> SCU_HWSTRAP_VGAMEM_SHIFT;

	return vga_mem_size_base << vga_hwconf;
	}

	/*
	* Find out RAM size and save it in dram_info
	*
	* The procedure is taken from Aspeed SDK
	*/
	static void ast2500_sdrammc_calc_size(struct dram_info *info)
	{
	/* The controller supports 128/256/512/1024 MB ram */
	size_t ram_size = SDRAM_MIN_SIZE;
	const int write_test_offset = 0x100000;
	u32 test_pattern = 0xdeadbeef;
	u32 cap_param = SDRAM_CONF_CAP_1024M;
	u32 refresh_timing_param = DDR4_TRFC;
	const u32 write_addr_base = CONFIG_SYS_SDRAM_BASE + write_test_offset;

	for (ram_size = SDRAM_MAX_SIZE; ram_size > SDRAM_MIN_SIZE;
	ram_size >>= 1) {
	writel(test_pattern, write_addr_base + (ram_size >> 1));
	test_pattern = (test_pattern >> 4) \| (test_pattern << 28);
	}

	/* One last write to overwrite all wrapped values */
	writel(test_pattern, write_addr_base);

	/* Reset the pattern and see which value was really written */
	test_pattern = 0xdeadbeef;
	for (ram_size = SDRAM_MAX_SIZE; ram_size > SDRAM_MIN_SIZE;
	ram_size >>= 1) {
	if (readl(write_addr_base + (ram_size >> 1)) == test_pattern)
	break;

	--cap_param;
	refresh_timing_param >>= 8;
	test_pattern = (test_pattern >> 4) \| (test_pattern << 28);
	}

	clrsetbits_le32(&info->regs->ac_timing[1],
	(SDRAM_AC_TRFC_MASK << SDRAM_AC_TRFC_SHIFT),
	((refresh_timing_param & SDRAM_AC_TRFC_MASK)
	<< SDRAM_AC_TRFC_SHIFT));

	info->info.base = CONFIG_SYS_SDRAM_BASE;
	info->info.size = ram_size - ast2500_sdrammc_get_vga_mem_size(info);
	clrsetbits_le32(&info->regs->config,
	(SDRAM_CONF_CAP_MASK << SDRAM_CONF_CAP_SHIFT),
	((cap_param & SDRAM_CONF_CAP_MASK)
	<< SDRAM_CONF_CAP_SHIFT));
	}

	static int ast2500_sdrammc_init_ddr4(struct dram_info *info)
	{
	int i;
	const u32 power_control = SDRAM_PCR_CKE_EN
	\| (1 << SDRAM_PCR_CKE_DELAY_SHIFT)
	\| (2 << SDRAM_PCR_TCKE_PW_SHIFT)
	\| SDRAM_PCR_RESETN_DIS
	\| SDRAM_PCR_RGAP_CTRL_EN \| SDRAM_PCR_ODT_EN \| SDRAM_PCR_ODT_EXT_EN;
	const u32 conf = (SDRAM_CONF_CAP_1024M << SDRAM_CONF_CAP_SHIFT)
	#ifdef CONFIG_DUALX8_RAM
	\| SDRAM_CONF_DUALX8
	#endif
	\| SDRAM_CONF_SCRAMBLE \| SDRAM_CONF_SCRAMBLE_PAT2 \| SDRAM_CONF_DDR4;
	int ret;

	writel(conf, &info->regs->config);
	for (i = 0; i < ARRAY_SIZE(ddr4_ac_timing); ++i)
	writel(ddr4_ac_timing[i], &info->regs->ac_timing[i]);

	writel(DDR4_MR46_MODE, &info->regs->mr46_mode_setting);
	writel(DDR4_MR5_MODE, &info->regs->mr5_mode_setting);
	writel(DDR4_MR02_MODE, &info->regs->mr02_mode_setting);
	writel(DDR4_MR13_MODE, &info->regs->mr13_mode_setting);

	for (i = 0; i < PHY_CFG_SIZE; ++i) {
	writel(ddr4_phy_config.value[i],
	&info->phy->phy[ddr4_phy_config.index[i]]);
	}

	writel(power_control, &info->regs->power_control);

	ast2500_ddr_phy_init_process(info);

	ret = ast2500_sdrammc_ddr4_calibrate_vref(info);
	if (ret < 0) {
	debug("Vref calibration failed!\n");
	return ret;
	}

	writel((1 << SDRAM_REFRESH_CYCLES_SHIFT)
	\| SDRAM_REFRESH_ZQCS_EN \| (0x2f << SDRAM_REFRESH_PERIOD_SHIFT),
	&info->regs->refresh_timing);

	setbits_le32(&info->regs->power_control,
	SDRAM_PCR_AUTOPWRDN_EN \| SDRAM_PCR_ODT_AUTO_ON);

	ast2500_sdrammc_calc_size(info);

	setbits_le32(&info->regs->config, SDRAM_CONF_CACHE_INIT_EN);
	while (!(readl(&info->regs->config) & SDRAM_CONF_CACHE_INIT_DONE))
	;
	setbits_le32(&info->regs->config, SDRAM_CONF_CACHE_EN);

	writel(SDRAM_MISC_DDR4_TREFRESH, &info->regs->misc_control);

	/* Enable all requests except video & display */
	writel(SDRAM_REQ_USB20_EHCI1
	\| SDRAM_REQ_USB20_EHCI2
	\| SDRAM_REQ_CPU
	\| SDRAM_REQ_AHB2
	\| SDRAM_REQ_AHB
	\| SDRAM_REQ_MAC0
	\| SDRAM_REQ_MAC1
	\| SDRAM_REQ_PCIE
	\| SDRAM_REQ_XDMA
	\| SDRAM_REQ_ENCRYPTION
	\| SDRAM_REQ_VIDEO_FLAG
	\| SDRAM_REQ_VIDEO_LOW_PRI_WRITE
	\| SDRAM_REQ_2D_RW
	\| SDRAM_REQ_MEMCHECK, &info->regs->req_limit_mask);

	return 0;
	}

	static void ast2500_sdrammc_unlock(struct dram_info *info)
	{
	writel(SDRAM_UNLOCK_KEY, &info->regs->protection_key);
	while (!readl(&info->regs->protection_key))
	;
	}

	static void ast2500_sdrammc_lock(struct dram_info *info)
	{
	writel(~SDRAM_UNLOCK_KEY, &info->regs->protection_key);
	while (readl(&info->regs->protection_key))
	;
	}

	static int ast2500_sdrammc_probe(struct udevice *dev)
	{
	struct reset_ctl reset_ctl;
	struct dram_info priv = (struct dram_info )dev_get_priv(dev);
	struct ast2500_sdrammc_regs *regs = priv->regs;
	int i;
	int ret = clk_get_by_index(dev, 0, &priv->ddr_clk);

	if (ret) {
	debug("DDR:No CLK\n");
	return ret;
	}

	priv->scu = ast_get_scu();
	if (IS_ERR(priv->scu)) {
	debug("%s(): can't get SCU\n", __func__);
	return PTR_ERR(priv->scu);
	}

	clk_set_rate(&priv->ddr_clk, priv->clock_rate);
	ret = reset_get_by_index(dev, 0, &reset_ctl);
	if (ret) {
	debug("%s(): Failed to get reset signal\n", __func__);
	return ret;
	}

	ret = reset_assert(&reset_ctl);
	if (ret) {
	debug("%s(): SDRAM reset failed: %u\n", __func__, ret);
	return ret;
	}

	ast2500_sdrammc_unlock(priv);

	writel(SDRAM_PCR_MREQI_DIS \| SDRAM_PCR_RESETN_DIS,
	&regs->power_control);
	writel(SDRAM_VIDEO_UNLOCK_KEY, &regs->gm_protection_key);

	/* Mask all requests except CPU and AHB during PHY init */
	writel(~(SDRAM_REQ_CPU \| SDRAM_REQ_AHB), &regs->req_limit_mask);

	for (i = 0; i < ARRAY_SIZE(ddr_max_grant_params); ++i)
	writel(ddr_max_grant_params[i], &regs->max_grant_len[i]);

	setbits_le32(&regs->intr_ctrl, SDRAM_ICR_RESET_ALL);

	ast2500_sdrammc_init_phy(priv->phy);
	if (readl(&priv->scu->hwstrap) & SCU_HWSTRAP_DDR4) {
	ast2500_sdrammc_init_ddr4(priv);
	} else {
	debug("Unsupported DRAM3\n");
	return -EINVAL;
	}

	clrbits_le32(&regs->intr_ctrl, SDRAM_ICR_RESET_ALL);
	ast2500_sdrammc_lock(priv);

	return 0;
	}

	static int ast2500_sdrammc_ofdata_to_platdata(struct udevice *dev)
	{
	struct dram_info *priv = dev_get_priv(dev);
	struct regmap *map;
	int ret;

	ret = regmap_init_mem(dev_ofnode(dev), &map);
	if (ret)
	return ret;

	priv->regs = regmap_get_range(map, 0);
	priv->phy = regmap_get_range(map, 1);

	priv->clock_rate = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
	"clock-frequency", 0);

	if (!priv->clock_rate) {
	debug("DDR Clock Rate not defined\n");
	return -EINVAL;
	}

	return 0;
	}

	static int ast2500_sdrammc_get_info(struct udevice dev, struct ram_info info)
	{
	struct dram_info *priv = dev_get_priv(dev);

	*info = priv->info;

	return 0;
	}

	static struct ram_ops ast2500_sdrammc_ops = {
	.get_info = ast2500_sdrammc_get_info,
	};

	static const struct udevice_id ast2500_sdrammc_ids[] = {
	{ .compatible = "aspeed,ast2500-sdrammc" },
	{ }
	};

	U_BOOT_DRIVER(sdrammc_ast2500) = {
	.name = "aspeed_ast2500_sdrammc",
	.id = UCLASS_RAM,
	.of_match = ast2500_sdrammc_ids,
	.ops = &ast2500_sdrammc_ops,
	.ofdata_to_platdata = ast2500_sdrammc_ofdata_to_platdata,
	.probe = ast2500_sdrammc_probe,
	.priv_auto_alloc_size = sizeof(struct dram_info),
	};