drivers/ram/imxrt_sdram.c - platform/external/u-boot - Gitiles

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (C) 2019
  * Author(s): Giulio Benetti <giulio.benetti@benettiengineering.com>
  */

 #include <common.h>
 #include <clk.h>
 #include <dm.h>
 #include <dm/device_compat.h>
 #include <init.h>
 #include <log.h>
 #include <ram.h>
 #include <asm/io.h>
 #include <linux/bitops.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/printk.h>

 /* SDRAM Command Code */
 #define SD_CC_ARD		0x0     /* Master Bus (AXI) command - Read */
 #define SD_CC_AWR		0x1     /* Master Bus (AXI) command - Write */
 #define SD_CC_IRD		0x8     /* IP command - Read */
 #define SD_CC_IWR		0x9     /* IP command - Write */
 #define SD_CC_IMS		0xA     /* IP command - Set Mode Register */
 #define SD_CC_IACT		0xB     /* IP command - ACTIVE */
 #define SD_CC_IAF		0xC     /* IP command - Auto Refresh */
 #define SD_CC_ISF		0xD     /* IP Command - Self Refresh */
 #define SD_CC_IPRE		0xE     /* IP command - Precharge */
 #define SD_CC_IPREA		0xF     /* IP command - Precharge ALL */

 #define SEMC_MCR_MDIS		BIT(1)
 #define SEMC_MCR_DQSMD		BIT(2)

 #define SEMC_INTR_IPCMDERR	BIT(1)
 #define SEMC_INTR_IPCMDDONE	BIT(0)

 #define SEMC_IPCMD_KEY		0xA55A0000

 struct imxrt_semc_regs {
 	/* 0x0 */
 	u32 mcr;
 	u32 iocr;
 	u32 bmcr0;
 	u32 bmcr1;
 	u32 br[9];

 	/* 0x34 */
 	u32 res1;
 	u32 inten;
 	u32 intr;
 	/* 0x40 */
 	u32 sdramcr0;
 	u32 sdramcr1;
 	u32 sdramcr2;
 	u32 sdramcr3;
 	/* 0x50 */
 	u32 nandcr0;
 	u32 nandcr1;
 	u32 nandcr2;
 	u32 nandcr3;
 	/* 0x60 */
 	u32 norcr0;
 	u32 norcr1;
 	u32 norcr2;
 	u32 norcr3;
 	/* 0x70 */
 	u32 sramcr0;
 	u32 sramcr1;
 	u32 sramcr2;
 	u32 sramcr3;
 	/* 0x80 */
 	u32 dbicr0;
 	u32 dbicr1;
 	u32 res2[2];
 	/* 0x90 */
 	u32 ipcr0;
 	u32 ipcr1;
 	u32 ipcr2;
 	u32 ipcmd;
 	/* 0xA0 */
 	u32 iptxdat;
 	u32 res3[3];
 	/* 0xB0 */
 	u32 iprxdat;
 	u32 res4[3];
 	/* 0xC0 */
 	u32 sts[16];
 };

 #if !defined(TARGET_IMXRT1170_EVK)
 #define SEMC_IOCR_MUX_A8_SHIFT		0
 #define SEMC_IOCR_MUX_CSX0_SHIFT	3
 #define SEMC_IOCR_MUX_CSX1_SHIFT	6
 #define SEMC_IOCR_MUX_CSX2_SHIFT	9
 #define SEMC_IOCR_MUX_CSX3_SHIFT	12
 #define SEMC_IOCR_MUX_RDY_SHIFT		15
 #else
 #define SEMC_IOCR_MUX_A8_SHIFT		0
 #define SEMC_IOCR_MUX_CSX0_SHIFT	4
 #define SEMC_IOCR_MUX_CSX1_SHIFT	8
 #define SEMC_IOCR_MUX_CSX2_SHIFT	12
 #define SEMC_IOCR_MUX_CSX3_SHIFT	16
 #define SEMC_IOCR_MUX_RDY_SHIFT		20
 #endif

 struct imxrt_sdram_mux {
 	u8 a8;
 	u8 csx0;
 	u8 csx1;
 	u8 csx2;
 	u8 csx3;
 	u8 rdy;
 };

 #define SEMC_SDRAMCR0_PS_SHIFT		0
 #define SEMC_SDRAMCR0_BL_SHIFT		4
 #define SEMC_SDRAMCR0_COL_SHIFT		8
 #define SEMC_SDRAMCR0_CL_SHIFT		10

 struct imxrt_sdram_control {
 	u8 memory_width;
 	u8 burst_len;
 	u8 no_columns;
 	u8 cas_latency;
 };

 #define SEMC_SDRAMCR1_PRE2ACT_SHIFT	0
 #define SEMC_SDRAMCR1_ACT2RW_SHIFT	4
 #define SEMC_SDRAMCR1_RFRC_SHIFT	8
 #define SEMC_SDRAMCR1_WRC_SHIFT		13
 #define SEMC_SDRAMCR1_CKEOFF_SHIFT	16
 #define SEMC_SDRAMCR1_ACT2PRE_SHIFT	20

 #define SEMC_SDRAMCR2_SRRC_SHIFT	0
 #define SEMC_SDRAMCR2_REF2REF_SHIFT	8
 #define SEMC_SDRAMCR2_ACT2ACT_SHIFT	16
 #define SEMC_SDRAMCR2_ITO_SHIFT		24

 #define SEMC_SDRAMCR3_REN		BIT(0)
 #define SEMC_SDRAMCR3_REBL_SHIFT	1
 #define SEMC_SDRAMCR3_PRESCALE_SHIFT	8
 #define SEMC_SDRAMCR3_RT_SHIFT		16
 #define SEMC_SDRAMCR3_UT_SHIFT		24

 struct imxrt_sdram_timing {
 	u8 pre2act;
 	u8 act2rw;
 	u8 rfrc;
 	u8 wrc;
 	u8 ckeoff;
 	u8 act2pre;

 	u8 srrc;
 	u8 ref2ref;
 	u8 act2act;
 	u8 ito;

 	u8 rebl;
 	u8 prescale;
 	u8 rt;
 	u8 ut;
 };

 enum imxrt_semc_bank {
 	SDRAM_BANK1,
 	SDRAM_BANK2,
 	SDRAM_BANK3,
 	SDRAM_BANK4,
 	MAX_SDRAM_BANK,
 };

 #define SEMC_BR_VLD_MASK		1
 #define SEMC_BR_MS_SHIFT		1

 struct bank_params {
 	enum imxrt_semc_bank target_bank;
 	u32 base_address;
 	u32 memory_size;
 };

 struct imxrt_sdram_params {
 	struct imxrt_semc_regs *base;

 	struct imxrt_sdram_mux *sdram_mux;
 	struct imxrt_sdram_control *sdram_control;
 	struct imxrt_sdram_timing *sdram_timing;

 	struct bank_params bank_params[MAX_SDRAM_BANK];
 	u8 no_sdram_banks;
 };

 static int imxrt_sdram_wait_ipcmd_done(struct imxrt_semc_regs *regs)
 {
 	do {
 		readl(&regs->intr);

 		if (regs->intr & SEMC_INTR_IPCMDDONE)
 			return 0;
 		if (regs->intr & SEMC_INTR_IPCMDERR)
 			return -EIO;

 		mdelay(50);
 	} while (1);
 }

 static int imxrt_sdram_ipcmd(struct imxrt_semc_regs *regs, u32 mem_addr,
 			     u32 ipcmd, u32 wd, u32 *rd)
 {
 	int ret;

 	if (ipcmd == SD_CC_IWR || ipcmd == SD_CC_IMS)
 		writel(wd, &regs->iptxdat);

 	/* set slave address for every command as specified on RM */
 	writel(mem_addr, &regs->ipcr0);

 	/* execute command */
 	writel(SEMC_IPCMD_KEY | ipcmd, &regs->ipcmd);

 	ret = imxrt_sdram_wait_ipcmd_done(regs);
 	if (ret < 0)
 		return ret;

 	if (ipcmd == SD_CC_IRD) {
 		if (!rd)
 			return -EINVAL;

 		*rd = readl(&regs->iprxdat);
 	}

 	return 0;
 }

 int imxrt_sdram_init(struct udevice *dev)
 {
 	struct imxrt_sdram_params *params = dev_get_plat(dev);
 	struct imxrt_sdram_mux *mux = params->sdram_mux;
 	struct imxrt_sdram_control *ctrl = params->sdram_control;
 	struct imxrt_sdram_timing *time = params->sdram_timing;
 	struct imxrt_semc_regs *regs = params->base;
 	struct bank_params *bank_params;
 	u32 rd;
 	int i;

 	/* enable the SEMC controller */
 	clrbits_le32(&regs->mcr, SEMC_MCR_MDIS);
 	/* set DQS mode from DQS pad */
 	setbits_le32(&regs->mcr, SEMC_MCR_DQSMD);

 	for (i = 0, bank_params = params->bank_params;
 		i < params->no_sdram_banks; bank_params++,
 		i++)
 		writel((bank_params->base_address & 0xfffff000)
 		       | bank_params->memory_size << SEMC_BR_MS_SHIFT
 		       | SEMC_BR_VLD_MASK,
 		       &regs->br[bank_params->target_bank]);

 	writel(mux->a8 << SEMC_IOCR_MUX_A8_SHIFT
 		| mux->csx0 << SEMC_IOCR_MUX_CSX0_SHIFT
 		| mux->csx1 << SEMC_IOCR_MUX_CSX1_SHIFT
 		| mux->csx2 << SEMC_IOCR_MUX_CSX2_SHIFT
 		| mux->csx3 << SEMC_IOCR_MUX_CSX3_SHIFT
 		| mux->rdy << SEMC_IOCR_MUX_RDY_SHIFT,
 		&regs->iocr);

 	writel(ctrl->memory_width << SEMC_SDRAMCR0_PS_SHIFT
 		| ctrl->burst_len << SEMC_SDRAMCR0_BL_SHIFT
 		| ctrl->no_columns << SEMC_SDRAMCR0_COL_SHIFT
 		| ctrl->cas_latency << SEMC_SDRAMCR0_CL_SHIFT,
 		&regs->sdramcr0);

 	writel(time->pre2act << SEMC_SDRAMCR1_PRE2ACT_SHIFT
 		| time->act2rw << SEMC_SDRAMCR1_ACT2RW_SHIFT
 		| time->rfrc << SEMC_SDRAMCR1_RFRC_SHIFT
 		| time->wrc << SEMC_SDRAMCR1_WRC_SHIFT
 		| time->ckeoff << SEMC_SDRAMCR1_CKEOFF_SHIFT
 		| time->act2pre << SEMC_SDRAMCR1_ACT2PRE_SHIFT,
 		&regs->sdramcr1);

 	writel(time->srrc << SEMC_SDRAMCR2_SRRC_SHIFT
 		| time->ref2ref << SEMC_SDRAMCR2_REF2REF_SHIFT
 		| time->act2act << SEMC_SDRAMCR2_ACT2ACT_SHIFT
 		| time->ito << SEMC_SDRAMCR2_ITO_SHIFT,
 		&regs->sdramcr2);

 	writel(time->rebl << SEMC_SDRAMCR3_REBL_SHIFT
 		| time->prescale << SEMC_SDRAMCR3_PRESCALE_SHIFT
 		| time->rt << SEMC_SDRAMCR3_RT_SHIFT
 		| time->ut << SEMC_SDRAMCR3_UT_SHIFT
 		| SEMC_SDRAMCR3_REN,
 		&regs->sdramcr3);

 	writel(2, &regs->ipcr1);

 	for (i = 0, bank_params = params->bank_params;
 		i < params->no_sdram_banks; bank_params++,
 		i++) {
 		mdelay(250);
 		imxrt_sdram_ipcmd(regs, bank_params->base_address, SD_CC_IPREA,
 				  0, &rd);
 		imxrt_sdram_ipcmd(regs, bank_params->base_address, SD_CC_IAF,
 				  0, &rd);
 		imxrt_sdram_ipcmd(regs, bank_params->base_address, SD_CC_IAF,
 				  0, &rd);
 		imxrt_sdram_ipcmd(regs, bank_params->base_address, SD_CC_IMS,
 				  ctrl->burst_len | (ctrl->cas_latency << 4),
 				  &rd);
 		mdelay(250);
 	}

 	return 0;
 }

 static int imxrt_semc_of_to_plat(struct udevice *dev)
 {
 	struct imxrt_sdram_params *params = dev_get_plat(dev);
 	ofnode bank_node;
 	u8 bank = 0;

 	params->sdram_mux =
 		(struct imxrt_sdram_mux *)
 		 dev_read_u8_array_ptr(dev,
 				       "fsl,sdram-mux",
 				       sizeof(struct imxrt_sdram_mux));
 	if (!params->sdram_mux) {
 		pr_err("fsl,sdram-mux not found");
 		return -EINVAL;
 	}

 	params->sdram_control =
 		(struct imxrt_sdram_control *)
 		 dev_read_u8_array_ptr(dev,
 				       "fsl,sdram-control",
 				       sizeof(struct imxrt_sdram_control));
 	if (!params->sdram_control) {
 		pr_err("fsl,sdram-control not found");
 		return -EINVAL;
 	}

 	params->sdram_timing =
 		(struct imxrt_sdram_timing *)
 		 dev_read_u8_array_ptr(dev,
 				       "fsl,sdram-timing",
 				       sizeof(struct imxrt_sdram_timing));
 	if (!params->sdram_timing) {
 		pr_err("fsl,sdram-timing not found");
 		return -EINVAL;
 	}

 	dev_for_each_subnode(bank_node, dev) {
 		struct bank_params *bank_params;
 		char *bank_name;
 		int ret;

 		/* extract the bank index from DT */
 		bank_name = (char *)ofnode_get_name(bank_node);
 		strsep(&bank_name, "@");
 		if (!bank_name) {
 			pr_err("missing sdram bank index");
 			return -EINVAL;
 		}

 		bank_params = &params->bank_params[bank];
 		strict_strtoul(bank_name, 10,
 			       (unsigned long *)&bank_params->target_bank);
 		if (bank_params->target_bank >= MAX_SDRAM_BANK) {
 			pr_err("Found bank %d , but only bank 0,1,2,3 are supported",
 			       bank_params->target_bank);
 			return -EINVAL;
 		}

 		ret = ofnode_read_u32(bank_node,
 				      "fsl,memory-size",
 				      &bank_params->memory_size);
 		if (ret < 0) {
 			pr_err("fsl,memory-size not found");
 			return -EINVAL;
 		}

 		ret = ofnode_read_u32(bank_node,
 				      "fsl,base-address",
 				      &bank_params->base_address);
 		if (ret < 0) {
 			pr_err("fsl,base-address not found");
 			return -EINVAL;
 		}

 		debug("Found bank %s %u\n", bank_name,
 		      bank_params->target_bank);
 		bank++;
 	}

 	params->no_sdram_banks = bank;
 	debug("%s, no of banks = %d\n", __func__, params->no_sdram_banks);

 	return 0;
 }

 static int imxrt_semc_probe(struct udevice *dev)
 {
 	struct imxrt_sdram_params *params = dev_get_plat(dev);
 	int ret;
 	fdt_addr_t addr;

 	addr = dev_read_addr(dev);
 	if (addr == FDT_ADDR_T_NONE)
 		return -EINVAL;

 	params->base = (struct imxrt_semc_regs *)addr;

 #ifdef CONFIG_CLK
 	struct clk clk;

 	ret = clk_get_by_index(dev, 0, &clk);
 	if (ret < 0)
 		return ret;

 	ret = clk_enable(&clk);

 	if (ret) {
 		dev_err(dev, "failed to enable clock\n");
 		return ret;
 	}
 #endif
 	ret = imxrt_sdram_init(dev);
 	if (ret)
 		return ret;

 	return 0;
 }

 static int imxrt_semc_get_info(struct udevice *dev, struct ram_info *info)
 {
 	return 0;
 }

 static struct ram_ops imxrt_semc_ops = {
 	.get_info = imxrt_semc_get_info,
 };

 static const struct udevice_id imxrt_semc_ids[] = {
 	{ .compatible = "fsl,imxrt-semc", .data = 0 },
 	{ }
 };

 U_BOOT_DRIVER(imxrt_semc) = {
 	.name = "imxrt_semc",
 	.id = UCLASS_RAM,
 	.of_match = imxrt_semc_ids,
 	.ops = &imxrt_semc_ops,
 	.of_to_plat = imxrt_semc_of_to_plat,
 	.probe = imxrt_semc_probe,
 	.plat_auto	= sizeof(struct imxrt_sdram_params),
 };
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Copyright (C) 2019
	* Author(s): Giulio Benetti <giulio.benetti@benettiengineering.com>
	*/

	#include <common.h>
	#include <clk.h>
	#include <dm.h>
	#include <dm/device_compat.h>
	#include <init.h>
	#include <log.h>
	#include <ram.h>
	#include <asm/io.h>
	#include <linux/bitops.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/printk.h>

	/* SDRAM Command Code */
	#define SD_CC_ARD 0x0 /* Master Bus (AXI) command - Read */
	#define SD_CC_AWR 0x1 /* Master Bus (AXI) command - Write */
	#define SD_CC_IRD 0x8 /* IP command - Read */
	#define SD_CC_IWR 0x9 /* IP command - Write */
	#define SD_CC_IMS 0xA /* IP command - Set Mode Register */
	#define SD_CC_IACT 0xB /* IP command - ACTIVE */
	#define SD_CC_IAF 0xC /* IP command - Auto Refresh */
	#define SD_CC_ISF 0xD /* IP Command - Self Refresh */
	#define SD_CC_IPRE 0xE /* IP command - Precharge */
	#define SD_CC_IPREA 0xF /* IP command - Precharge ALL */

	#define SEMC_MCR_MDIS BIT(1)
	#define SEMC_MCR_DQSMD BIT(2)

	#define SEMC_INTR_IPCMDERR BIT(1)
	#define SEMC_INTR_IPCMDDONE BIT(0)

	#define SEMC_IPCMD_KEY 0xA55A0000

	struct imxrt_semc_regs {
	/* 0x0 */
	u32 mcr;
	u32 iocr;
	u32 bmcr0;
	u32 bmcr1;
	u32 br[9];

	/* 0x34 */
	u32 res1;
	u32 inten;
	u32 intr;
	/* 0x40 */
	u32 sdramcr0;
	u32 sdramcr1;
	u32 sdramcr2;
	u32 sdramcr3;
	/* 0x50 */
	u32 nandcr0;
	u32 nandcr1;
	u32 nandcr2;
	u32 nandcr3;
	/* 0x60 */
	u32 norcr0;
	u32 norcr1;
	u32 norcr2;
	u32 norcr3;
	/* 0x70 */
	u32 sramcr0;
	u32 sramcr1;
	u32 sramcr2;
	u32 sramcr3;
	/* 0x80 */
	u32 dbicr0;
	u32 dbicr1;
	u32 res2[2];
	/* 0x90 */
	u32 ipcr0;
	u32 ipcr1;
	u32 ipcr2;
	u32 ipcmd;
	/* 0xA0 */
	u32 iptxdat;
	u32 res3[3];
	/* 0xB0 */
	u32 iprxdat;
	u32 res4[3];
	/* 0xC0 */
	u32 sts[16];
	};

	#if !defined(TARGET_IMXRT1170_EVK)
	#define SEMC_IOCR_MUX_A8_SHIFT 0
	#define SEMC_IOCR_MUX_CSX0_SHIFT 3
	#define SEMC_IOCR_MUX_CSX1_SHIFT 6
	#define SEMC_IOCR_MUX_CSX2_SHIFT 9
	#define SEMC_IOCR_MUX_CSX3_SHIFT 12
	#define SEMC_IOCR_MUX_RDY_SHIFT 15
	#else
	#define SEMC_IOCR_MUX_A8_SHIFT 0
	#define SEMC_IOCR_MUX_CSX0_SHIFT 4
	#define SEMC_IOCR_MUX_CSX1_SHIFT 8
	#define SEMC_IOCR_MUX_CSX2_SHIFT 12
	#define SEMC_IOCR_MUX_CSX3_SHIFT 16
	#define SEMC_IOCR_MUX_RDY_SHIFT 20
	#endif

	struct imxrt_sdram_mux {
	u8 a8;
	u8 csx0;
	u8 csx1;
	u8 csx2;
	u8 csx3;
	u8 rdy;
	};

	#define SEMC_SDRAMCR0_PS_SHIFT 0
	#define SEMC_SDRAMCR0_BL_SHIFT 4
	#define SEMC_SDRAMCR0_COL_SHIFT 8
	#define SEMC_SDRAMCR0_CL_SHIFT 10

	struct imxrt_sdram_control {
	u8 memory_width;
	u8 burst_len;
	u8 no_columns;
	u8 cas_latency;
	};

	#define SEMC_SDRAMCR1_PRE2ACT_SHIFT 0
	#define SEMC_SDRAMCR1_ACT2RW_SHIFT 4
	#define SEMC_SDRAMCR1_RFRC_SHIFT 8
	#define SEMC_SDRAMCR1_WRC_SHIFT 13
	#define SEMC_SDRAMCR1_CKEOFF_SHIFT 16
	#define SEMC_SDRAMCR1_ACT2PRE_SHIFT 20

	#define SEMC_SDRAMCR2_SRRC_SHIFT 0
	#define SEMC_SDRAMCR2_REF2REF_SHIFT 8
	#define SEMC_SDRAMCR2_ACT2ACT_SHIFT 16
	#define SEMC_SDRAMCR2_ITO_SHIFT 24

	#define SEMC_SDRAMCR3_REN BIT(0)
	#define SEMC_SDRAMCR3_REBL_SHIFT 1
	#define SEMC_SDRAMCR3_PRESCALE_SHIFT 8
	#define SEMC_SDRAMCR3_RT_SHIFT 16
	#define SEMC_SDRAMCR3_UT_SHIFT 24

	struct imxrt_sdram_timing {
	u8 pre2act;
	u8 act2rw;
	u8 rfrc;
	u8 wrc;
	u8 ckeoff;
	u8 act2pre;

	u8 srrc;
	u8 ref2ref;
	u8 act2act;
	u8 ito;

	u8 rebl;
	u8 prescale;
	u8 rt;
	u8 ut;
	};

	enum imxrt_semc_bank {
	SDRAM_BANK1,
	SDRAM_BANK2,
	SDRAM_BANK3,
	SDRAM_BANK4,
	MAX_SDRAM_BANK,
	};

	#define SEMC_BR_VLD_MASK 1
	#define SEMC_BR_MS_SHIFT 1

	struct bank_params {
	enum imxrt_semc_bank target_bank;
	u32 base_address;
	u32 memory_size;
	};

	struct imxrt_sdram_params {
	struct imxrt_semc_regs *base;

	struct imxrt_sdram_mux *sdram_mux;
	struct imxrt_sdram_control *sdram_control;
	struct imxrt_sdram_timing *sdram_timing;

	struct bank_params bank_params[MAX_SDRAM_BANK];
	u8 no_sdram_banks;
	};

	static int imxrt_sdram_wait_ipcmd_done(struct imxrt_semc_regs *regs)
	{
	do {
	readl(&regs->intr);

	if (regs->intr & SEMC_INTR_IPCMDDONE)
	return 0;
	if (regs->intr & SEMC_INTR_IPCMDERR)
	return -EIO;

	mdelay(50);
	} while (1);
	}

	static int imxrt_sdram_ipcmd(struct imxrt_semc_regs *regs, u32 mem_addr,
	u32 ipcmd, u32 wd, u32 *rd)
	{
	int ret;

	if (ipcmd == SD_CC_IWR \|\| ipcmd == SD_CC_IMS)
	writel(wd, &regs->iptxdat);

	/* set slave address for every command as specified on RM */
	writel(mem_addr, &regs->ipcr0);

	/* execute command */
	writel(SEMC_IPCMD_KEY \| ipcmd, &regs->ipcmd);

	ret = imxrt_sdram_wait_ipcmd_done(regs);
	if (ret < 0)
	return ret;

	if (ipcmd == SD_CC_IRD) {
	if (!rd)
	return -EINVAL;

	*rd = readl(&regs->iprxdat);
	}

	return 0;
	}

	int imxrt_sdram_init(struct udevice *dev)
	{
	struct imxrt_sdram_params *params = dev_get_plat(dev);
	struct imxrt_sdram_mux *mux = params->sdram_mux;
	struct imxrt_sdram_control *ctrl = params->sdram_control;
	struct imxrt_sdram_timing *time = params->sdram_timing;
	struct imxrt_semc_regs *regs = params->base;
	struct bank_params *bank_params;
	u32 rd;
	int i;

	/* enable the SEMC controller */
	clrbits_le32(&regs->mcr, SEMC_MCR_MDIS);
	/* set DQS mode from DQS pad */
	setbits_le32(&regs->mcr, SEMC_MCR_DQSMD);

	for (i = 0, bank_params = params->bank_params;
	i < params->no_sdram_banks; bank_params++,
	i++)
	writel((bank_params->base_address & 0xfffff000)
	\| bank_params->memory_size << SEMC_BR_MS_SHIFT
	\| SEMC_BR_VLD_MASK,
	&regs->br[bank_params->target_bank]);

	writel(mux->a8 << SEMC_IOCR_MUX_A8_SHIFT
	\| mux->csx0 << SEMC_IOCR_MUX_CSX0_SHIFT
	\| mux->csx1 << SEMC_IOCR_MUX_CSX1_SHIFT
	\| mux->csx2 << SEMC_IOCR_MUX_CSX2_SHIFT
	\| mux->csx3 << SEMC_IOCR_MUX_CSX3_SHIFT
	\| mux->rdy << SEMC_IOCR_MUX_RDY_SHIFT,
	&regs->iocr);

	writel(ctrl->memory_width << SEMC_SDRAMCR0_PS_SHIFT
	\| ctrl->burst_len << SEMC_SDRAMCR0_BL_SHIFT
	\| ctrl->no_columns << SEMC_SDRAMCR0_COL_SHIFT
	\| ctrl->cas_latency << SEMC_SDRAMCR0_CL_SHIFT,
	&regs->sdramcr0);

	writel(time->pre2act << SEMC_SDRAMCR1_PRE2ACT_SHIFT
	\| time->act2rw << SEMC_SDRAMCR1_ACT2RW_SHIFT
	\| time->rfrc << SEMC_SDRAMCR1_RFRC_SHIFT
	\| time->wrc << SEMC_SDRAMCR1_WRC_SHIFT
	\| time->ckeoff << SEMC_SDRAMCR1_CKEOFF_SHIFT
	\| time->act2pre << SEMC_SDRAMCR1_ACT2PRE_SHIFT,
	&regs->sdramcr1);

	writel(time->srrc << SEMC_SDRAMCR2_SRRC_SHIFT
	\| time->ref2ref << SEMC_SDRAMCR2_REF2REF_SHIFT
	\| time->act2act << SEMC_SDRAMCR2_ACT2ACT_SHIFT
	\| time->ito << SEMC_SDRAMCR2_ITO_SHIFT,
	&regs->sdramcr2);

	writel(time->rebl << SEMC_SDRAMCR3_REBL_SHIFT
	\| time->prescale << SEMC_SDRAMCR3_PRESCALE_SHIFT
	\| time->rt << SEMC_SDRAMCR3_RT_SHIFT
	\| time->ut << SEMC_SDRAMCR3_UT_SHIFT
	\| SEMC_SDRAMCR3_REN,
	&regs->sdramcr3);

	writel(2, &regs->ipcr1);

	for (i = 0, bank_params = params->bank_params;
	i < params->no_sdram_banks; bank_params++,
	i++) {
	mdelay(250);
	imxrt_sdram_ipcmd(regs, bank_params->base_address, SD_CC_IPREA,
	0, &rd);
	imxrt_sdram_ipcmd(regs, bank_params->base_address, SD_CC_IAF,
	0, &rd);
	imxrt_sdram_ipcmd(regs, bank_params->base_address, SD_CC_IAF,
	0, &rd);
	imxrt_sdram_ipcmd(regs, bank_params->base_address, SD_CC_IMS,
	ctrl->burst_len \| (ctrl->cas_latency << 4),
	&rd);
	mdelay(250);
	}

	return 0;
	}

	static int imxrt_semc_of_to_plat(struct udevice *dev)
	{
	struct imxrt_sdram_params *params = dev_get_plat(dev);
	ofnode bank_node;
	u8 bank = 0;

	params->sdram_mux =
	(struct imxrt_sdram_mux *)
	dev_read_u8_array_ptr(dev,
	"fsl,sdram-mux",
	sizeof(struct imxrt_sdram_mux));
	if (!params->sdram_mux) {
	pr_err("fsl,sdram-mux not found");
	return -EINVAL;
	}

	params->sdram_control =
	(struct imxrt_sdram_control *)
	dev_read_u8_array_ptr(dev,
	"fsl,sdram-control",
	sizeof(struct imxrt_sdram_control));
	if (!params->sdram_control) {
	pr_err("fsl,sdram-control not found");
	return -EINVAL;
	}

	params->sdram_timing =
	(struct imxrt_sdram_timing *)
	dev_read_u8_array_ptr(dev,
	"fsl,sdram-timing",
	sizeof(struct imxrt_sdram_timing));
	if (!params->sdram_timing) {
	pr_err("fsl,sdram-timing not found");
	return -EINVAL;
	}

	dev_for_each_subnode(bank_node, dev) {
	struct bank_params *bank_params;
	char *bank_name;
	int ret;

	/* extract the bank index from DT */
	bank_name = (char *)ofnode_get_name(bank_node);
	strsep(&bank_name, "@");
	if (!bank_name) {
	pr_err("missing sdram bank index");
	return -EINVAL;
	}

	bank_params = &params->bank_params[bank];
	strict_strtoul(bank_name, 10,
	(unsigned long *)&bank_params->target_bank);
	if (bank_params->target_bank >= MAX_SDRAM_BANK) {
	pr_err("Found bank %d , but only bank 0,1,2,3 are supported",
	bank_params->target_bank);
	return -EINVAL;
	}

	ret = ofnode_read_u32(bank_node,
	"fsl,memory-size",
	&bank_params->memory_size);
	if (ret < 0) {
	pr_err("fsl,memory-size not found");
	return -EINVAL;
	}

	ret = ofnode_read_u32(bank_node,
	"fsl,base-address",
	&bank_params->base_address);
	if (ret < 0) {
	pr_err("fsl,base-address not found");
	return -EINVAL;
	}

	debug("Found bank %s %u\n", bank_name,
	bank_params->target_bank);
	bank++;
	}

	params->no_sdram_banks = bank;
	debug("%s, no of banks = %d\n", __func__, params->no_sdram_banks);

	return 0;
	}

	static int imxrt_semc_probe(struct udevice *dev)
	{
	struct imxrt_sdram_params *params = dev_get_plat(dev);
	int ret;
	fdt_addr_t addr;

	addr = dev_read_addr(dev);
	if (addr == FDT_ADDR_T_NONE)
	return -EINVAL;

	params->base = (struct imxrt_semc_regs *)addr;

	#ifdef CONFIG_CLK
	struct clk clk;

	ret = clk_get_by_index(dev, 0, &clk);
	if (ret < 0)
	return ret;

	ret = clk_enable(&clk);

	if (ret) {
	dev_err(dev, "failed to enable clock\n");
	return ret;
	}
	#endif
	ret = imxrt_sdram_init(dev);
	if (ret)
	return ret;

	return 0;
	}

	static int imxrt_semc_get_info(struct udevice dev, struct ram_info info)
	{
	return 0;
	}

	static struct ram_ops imxrt_semc_ops = {
	.get_info = imxrt_semc_get_info,
	};

	static const struct udevice_id imxrt_semc_ids[] = {
	{ .compatible = "fsl,imxrt-semc", .data = 0 },
	{ }
	};

	U_BOOT_DRIVER(imxrt_semc) = {
	.name = "imxrt_semc",
	.id = UCLASS_RAM,
	.of_match = imxrt_semc_ids,
	.ops = &imxrt_semc_ops,
	.of_to_plat = imxrt_semc_of_to_plat,
	.probe = imxrt_semc_probe,
	.plat_auto = sizeof(struct imxrt_sdram_params),
	};