/*
 * Driver for Cadence QSPI Controller
 *
 * Copyright Altera Corporation (C) 2012-2014. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/mtd/spi-nor.h>
#include <linux/of_device.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/sched.h>
#include <linux/spi/spi.h>
#include <linux/timer.h>

#define CQSPI_NAME			"cadence-qspi"
#define CQSPI_MAX_CHIPSELECT		16

/* Quirks */
#define CQSPI_NEEDS_WR_DELAY		BIT(0)

struct cqspi_st;

struct cqspi_flash_pdata {
	struct spi_nor	nor;
	struct cqspi_st	*cqspi;
	u32		clk_rate;
	u32		read_delay;
	u32		tshsl_ns;
	u32		tsd2d_ns;
	u32		tchsh_ns;
	u32		tslch_ns;
	u8		inst_width;
	u8		addr_width;
	u8		data_width;
	u8		cs;
	bool		registered;
	bool		use_direct_mode;
};

struct cqspi_st {
	struct platform_device	*pdev;

	struct clk		*clk;
	unsigned int		sclk;

	void __iomem		*iobase;
	void __iomem		*ahb_base;
	resource_size_t		ahb_size;
	struct completion	transfer_complete;
	struct mutex		bus_mutex;

	struct dma_chan		*rx_chan;
	struct completion	rx_dma_complete;
	dma_addr_t		mmap_phys_base;

	int			current_cs;
	int			current_page_size;
	int			current_erase_size;
	int			current_addr_width;
	unsigned long		master_ref_clk_hz;
	bool			is_decoded_cs;
	u32			fifo_depth;
	u32			fifo_width;
	bool			rclk_en;
	u32			trigger_address;
	u32			wr_delay;
	struct cqspi_flash_pdata f_pdata[CQSPI_MAX_CHIPSELECT];
};

/* Operation timeout value */
#define CQSPI_TIMEOUT_MS			500
#define CQSPI_READ_TIMEOUT_MS			10

/* Instruction type */
#define CQSPI_INST_TYPE_SINGLE			0
#define CQSPI_INST_TYPE_DUAL			1
#define CQSPI_INST_TYPE_QUAD			2

#define CQSPI_DUMMY_CLKS_PER_BYTE		8
#define CQSPI_DUMMY_BYTES_MAX			4
#define CQSPI_DUMMY_CLKS_MAX			31

#define CQSPI_STIG_DATA_LEN_MAX			8

/* Register map */
#define CQSPI_REG_CONFIG			0x00
#define CQSPI_REG_CONFIG_ENABLE_MASK		BIT(0)
#define CQSPI_REG_CONFIG_ENB_DIR_ACC_CTRL	BIT(7)
#define CQSPI_REG_CONFIG_DECODE_MASK		BIT(9)
#define CQSPI_REG_CONFIG_CHIPSELECT_LSB		10
#define CQSPI_REG_CONFIG_DMA_MASK		BIT(15)
#define CQSPI_REG_CONFIG_BAUD_LSB		19
#define CQSPI_REG_CONFIG_IDLE_LSB		31
#define CQSPI_REG_CONFIG_CHIPSELECT_MASK	0xF
#define CQSPI_REG_CONFIG_BAUD_MASK		0xF

#define CQSPI_REG_RD_INSTR			0x04
#define CQSPI_REG_RD_INSTR_OPCODE_LSB		0
#define CQSPI_REG_RD_INSTR_TYPE_INSTR_LSB	8
#define CQSPI_REG_RD_INSTR_TYPE_ADDR_LSB	12
#define CQSPI_REG_RD_INSTR_TYPE_DATA_LSB	16
#define CQSPI_REG_RD_INSTR_MODE_EN_LSB		20
#define CQSPI_REG_RD_INSTR_DUMMY_LSB		24
#define CQSPI_REG_RD_INSTR_TYPE_INSTR_MASK	0x3
#define CQSPI_REG_RD_INSTR_TYPE_ADDR_MASK	0x3
#define CQSPI_REG_RD_INSTR_TYPE_DATA_MASK	0x3
#define CQSPI_REG_RD_INSTR_DUMMY_MASK		0x1F

#define CQSPI_REG_WR_INSTR			0x08
#define CQSPI_REG_WR_INSTR_OPCODE_LSB		0
#define CQSPI_REG_WR_INSTR_TYPE_ADDR_LSB	12
#define CQSPI_REG_WR_INSTR_TYPE_DATA_LSB	16

#define CQSPI_REG_DELAY				0x0C
#define CQSPI_REG_DELAY_TSLCH_LSB		0
#define CQSPI_REG_DELAY_TCHSH_LSB		8
#define CQSPI_REG_DELAY_TSD2D_LSB		16
#define CQSPI_REG_DELAY_TSHSL_LSB		24
#define CQSPI_REG_DELAY_TSLCH_MASK		0xFF
#define CQSPI_REG_DELAY_TCHSH_MASK		0xFF
#define CQSPI_REG_DELAY_TSD2D_MASK		0xFF
#define CQSPI_REG_DELAY_TSHSL_MASK		0xFF

#define CQSPI_REG_READCAPTURE			0x10
#define CQSPI_REG_READCAPTURE_BYPASS_LSB	0
#define CQSPI_REG_READCAPTURE_DELAY_LSB		1
#define CQSPI_REG_READCAPTURE_DELAY_MASK	0xF

#define CQSPI_REG_SIZE				0x14
#define CQSPI_REG_SIZE_ADDRESS_LSB		0
#define CQSPI_REG_SIZE_PAGE_LSB			4
#define CQSPI_REG_SIZE_BLOCK_LSB		16
#define CQSPI_REG_SIZE_ADDRESS_MASK		0xF
#define CQSPI_REG_SIZE_PAGE_MASK		0xFFF
#define CQSPI_REG_SIZE_BLOCK_MASK		0x3F

#define CQSPI_REG_SRAMPARTITION			0x18
#define CQSPI_REG_INDIRECTTRIGGER		0x1C

#define CQSPI_REG_DMA				0x20
#define CQSPI_REG_DMA_SINGLE_LSB		0
#define CQSPI_REG_DMA_BURST_LSB			8
#define CQSPI_REG_DMA_SINGLE_MASK		0xFF
#define CQSPI_REG_DMA_BURST_MASK		0xFF

#define CQSPI_REG_REMAP				0x24
#define CQSPI_REG_MODE_BIT			0x28

#define CQSPI_REG_SDRAMLEVEL			0x2C
#define CQSPI_REG_SDRAMLEVEL_RD_LSB		0
#define CQSPI_REG_SDRAMLEVEL_WR_LSB		16
#define CQSPI_REG_SDRAMLEVEL_RD_MASK		0xFFFF
#define CQSPI_REG_SDRAMLEVEL_WR_MASK		0xFFFF

#define CQSPI_REG_IRQSTATUS			0x40
#define CQSPI_REG_IRQMASK			0x44

#define CQSPI_REG_INDIRECTRD			0x60
#define CQSPI_REG_INDIRECTRD_START_MASK		BIT(0)
#define CQSPI_REG_INDIRECTRD_CANCEL_MASK	BIT(1)
#define CQSPI_REG_INDIRECTRD_DONE_MASK		BIT(5)

#define CQSPI_REG_INDIRECTRDWATERMARK		0x64
#define CQSPI_REG_INDIRECTRDSTARTADDR		0x68
#define CQSPI_REG_INDIRECTRDBYTES		0x6C

#define CQSPI_REG_CMDCTRL			0x90
#define CQSPI_REG_CMDCTRL_EXECUTE_MASK		BIT(0)
#define CQSPI_REG_CMDCTRL_INPROGRESS_MASK	BIT(1)
#define CQSPI_REG_CMDCTRL_WR_BYTES_LSB		12
#define CQSPI_REG_CMDCTRL_WR_EN_LSB		15
#define CQSPI_REG_CMDCTRL_ADD_BYTES_LSB		16
#define CQSPI_REG_CMDCTRL_ADDR_EN_LSB		19
#define CQSPI_REG_CMDCTRL_RD_BYTES_LSB		20
#define CQSPI_REG_CMDCTRL_RD_EN_LSB		23
#define CQSPI_REG_CMDCTRL_OPCODE_LSB		24
#define CQSPI_REG_CMDCTRL_WR_BYTES_MASK		0x7
#define CQSPI_REG_CMDCTRL_ADD_BYTES_MASK	0x3
#define CQSPI_REG_CMDCTRL_RD_BYTES_MASK		0x7

#define CQSPI_REG_INDIRECTWR			0x70
#define CQSPI_REG_INDIRECTWR_START_MASK		BIT(0)
#define CQSPI_REG_INDIRECTWR_CANCEL_MASK	BIT(1)
#define CQSPI_REG_INDIRECTWR_DONE_MASK		BIT(5)

#define CQSPI_REG_INDIRECTWRWATERMARK		0x74
#define CQSPI_REG_INDIRECTWRSTARTADDR		0x78
#define CQSPI_REG_INDIRECTWRBYTES		0x7C

#define CQSPI_REG_CMDADDRESS			0x94
#define CQSPI_REG_CMDREADDATALOWER		0xA0
#define CQSPI_REG_CMDREADDATAUPPER		0xA4
#define CQSPI_REG_CMDWRITEDATALOWER		0xA8
#define CQSPI_REG_CMDWRITEDATAUPPER		0xAC

/* Interrupt status bits */
#define CQSPI_REG_IRQ_MODE_ERR			BIT(0)
#define CQSPI_REG_IRQ_UNDERFLOW			BIT(1)
#define CQSPI_REG_IRQ_IND_COMP			BIT(2)
#define CQSPI_REG_IRQ_IND_RD_REJECT		BIT(3)
#define CQSPI_REG_IRQ_WR_PROTECTED_ERR		BIT(4)
#define CQSPI_REG_IRQ_ILLEGAL_AHB_ERR		BIT(5)
#define CQSPI_REG_IRQ_WATERMARK			BIT(6)
#define CQSPI_REG_IRQ_IND_SRAM_FULL		BIT(12)

#define CQSPI_IRQ_MASK_RD		(CQSPI_REG_IRQ_WATERMARK	| \
					 CQSPI_REG_IRQ_IND_SRAM_FULL	| \
					 CQSPI_REG_IRQ_IND_COMP)

#define CQSPI_IRQ_MASK_WR		(CQSPI_REG_IRQ_IND_COMP		| \
					 CQSPI_REG_IRQ_WATERMARK	| \
					 CQSPI_REG_IRQ_UNDERFLOW)

#define CQSPI_IRQ_STATUS_MASK		0x1FFFF

static int cqspi_wait_for_bit(void __iomem *reg, const u32 mask, bool clear)
{
	unsigned long end = jiffies + msecs_to_jiffies(CQSPI_TIMEOUT_MS);
	u32 val;

	while (1) {
		val = readl(reg);
		if (clear)
			val = ~val;
		val &= mask;

		if (val == mask)
			return 0;

		if (time_after(jiffies, end))
			return -ETIMEDOUT;
	}
}

static bool cqspi_is_idle(struct cqspi_st *cqspi)
{
	u32 reg = readl(cqspi->iobase + CQSPI_REG_CONFIG);

	return reg & (1 << CQSPI_REG_CONFIG_IDLE_LSB);
}

static u32 cqspi_get_rd_sram_level(struct cqspi_st *cqspi)
{
	u32 reg = readl(cqspi->iobase + CQSPI_REG_SDRAMLEVEL);

	reg >>= CQSPI_REG_SDRAMLEVEL_RD_LSB;
	return reg & CQSPI_REG_SDRAMLEVEL_RD_MASK;
}

static irqreturn_t cqspi_irq_handler(int this_irq, void *dev)
{
	struct cqspi_st *cqspi = dev;
	unsigned int irq_status;

	/* Read interrupt status */
	irq_status = readl(cqspi->iobase + CQSPI_REG_IRQSTATUS);

	/* Clear interrupt */
	writel(irq_status, cqspi->iobase + CQSPI_REG_IRQSTATUS);

	irq_status &= CQSPI_IRQ_MASK_RD | CQSPI_IRQ_MASK_WR;

	if (irq_status)
		complete(&cqspi->transfer_complete);

	return IRQ_HANDLED;
}

static unsigned int cqspi_calc_rdreg(struct spi_nor *nor, const u8 opcode)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	u32 rdreg = 0;

	rdreg |= f_pdata->inst_width << CQSPI_REG_RD_INSTR_TYPE_INSTR_LSB;
	rdreg |= f_pdata->addr_width << CQSPI_REG_RD_INSTR_TYPE_ADDR_LSB;
	rdreg |= f_pdata->data_width << CQSPI_REG_RD_INSTR_TYPE_DATA_LSB;

	return rdreg;
}

static int cqspi_wait_idle(struct cqspi_st *cqspi)
{
	const unsigned int poll_idle_retry = 3;
	unsigned int count = 0;
	unsigned long timeout;

	timeout = jiffies + msecs_to_jiffies(CQSPI_TIMEOUT_MS);
	while (1) {
		/*
		 * Read few times in succession to ensure the controller
		 * is indeed idle, that is, the bit does not transition
		 * low again.
		 */
		if (cqspi_is_idle(cqspi))
			count++;
		else
			count = 0;

		if (count >= poll_idle_retry)
			return 0;

		if (time_after(jiffies, timeout)) {
			/* Timeout, in busy mode. */
			dev_err(&cqspi->pdev->dev,
				"QSPI is still busy after %dms timeout.\n",
				CQSPI_TIMEOUT_MS);
			return -ETIMEDOUT;
		}

		cpu_relax();
	}
}

static int cqspi_exec_flash_cmd(struct cqspi_st *cqspi, unsigned int reg)
{
	void __iomem *reg_base = cqspi->iobase;
	int ret;

	/* Write the CMDCTRL without start execution. */
	writel(reg, reg_base + CQSPI_REG_CMDCTRL);
	/* Start execute */
	reg |= CQSPI_REG_CMDCTRL_EXECUTE_MASK;
	writel(reg, reg_base + CQSPI_REG_CMDCTRL);

	/* Polling for completion. */
	ret = cqspi_wait_for_bit(reg_base + CQSPI_REG_CMDCTRL,
				 CQSPI_REG_CMDCTRL_INPROGRESS_MASK, 1);
	if (ret) {
		dev_err(&cqspi->pdev->dev,
			"Flash command execution timed out.\n");
		return ret;
	}

	/* Polling QSPI idle status. */
	return cqspi_wait_idle(cqspi);
}

static int cqspi_command_read(struct spi_nor *nor,
			      const u8 *txbuf, const unsigned n_tx,
			      u8 *rxbuf, const unsigned n_rx)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	void __iomem *reg_base = cqspi->iobase;
	unsigned int rdreg;
	unsigned int reg;
	unsigned int read_len;
	int status;

	if (!n_rx || n_rx > CQSPI_STIG_DATA_LEN_MAX || !rxbuf) {
		dev_err(nor->dev, "Invalid input argument, len %d rxbuf 0x%p\n",
			n_rx, rxbuf);
		return -EINVAL;
	}

	reg = txbuf[0] << CQSPI_REG_CMDCTRL_OPCODE_LSB;

	rdreg = cqspi_calc_rdreg(nor, txbuf[0]);
	writel(rdreg, reg_base + CQSPI_REG_RD_INSTR);

	reg |= (0x1 << CQSPI_REG_CMDCTRL_RD_EN_LSB);

	/* 0 means 1 byte. */
	reg |= (((n_rx - 1) & CQSPI_REG_CMDCTRL_RD_BYTES_MASK)
		<< CQSPI_REG_CMDCTRL_RD_BYTES_LSB);
	status = cqspi_exec_flash_cmd(cqspi, reg);
	if (status)
		return status;

	reg = readl(reg_base + CQSPI_REG_CMDREADDATALOWER);

	/* Put the read value into rx_buf */
	read_len = (n_rx > 4) ? 4 : n_rx;
	memcpy(rxbuf, &reg, read_len);
	rxbuf += read_len;

	if (n_rx > 4) {
		reg = readl(reg_base + CQSPI_REG_CMDREADDATAUPPER);

		read_len = n_rx - read_len;
		memcpy(rxbuf, &reg, read_len);
	}

	return 0;
}

static int cqspi_command_write(struct spi_nor *nor, const u8 opcode,
			       const u8 *txbuf, const unsigned n_tx)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	void __iomem *reg_base = cqspi->iobase;
	unsigned int reg;
	unsigned int data;
	int ret;

	if (n_tx > 4 || (n_tx && !txbuf)) {
		dev_err(nor->dev,
			"Invalid input argument, cmdlen %d txbuf 0x%p\n",
			n_tx, txbuf);
		return -EINVAL;
	}

	reg = opcode << CQSPI_REG_CMDCTRL_OPCODE_LSB;
	if (n_tx) {
		reg |= (0x1 << CQSPI_REG_CMDCTRL_WR_EN_LSB);
		reg |= ((n_tx - 1) & CQSPI_REG_CMDCTRL_WR_BYTES_MASK)
			<< CQSPI_REG_CMDCTRL_WR_BYTES_LSB;
		data = 0;
		memcpy(&data, txbuf, n_tx);
		writel(data, reg_base + CQSPI_REG_CMDWRITEDATALOWER);
	}

	ret = cqspi_exec_flash_cmd(cqspi, reg);
	return ret;
}

static int cqspi_command_write_addr(struct spi_nor *nor,
				    const u8 opcode, const unsigned int addr)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	void __iomem *reg_base = cqspi->iobase;
	unsigned int reg;

	reg = opcode << CQSPI_REG_CMDCTRL_OPCODE_LSB;
	reg |= (0x1 << CQSPI_REG_CMDCTRL_ADDR_EN_LSB);
	reg |= ((nor->addr_width - 1) & CQSPI_REG_CMDCTRL_ADD_BYTES_MASK)
		<< CQSPI_REG_CMDCTRL_ADD_BYTES_LSB;

	writel(addr, reg_base + CQSPI_REG_CMDADDRESS);

	return cqspi_exec_flash_cmd(cqspi, reg);
}

static int cqspi_read_setup(struct spi_nor *nor)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	void __iomem *reg_base = cqspi->iobase;
	unsigned int dummy_clk = 0;
	unsigned int reg;

	reg = nor->read_opcode << CQSPI_REG_RD_INSTR_OPCODE_LSB;
	reg |= cqspi_calc_rdreg(nor, nor->read_opcode);

	/* Setup dummy clock cycles */
	dummy_clk = nor->read_dummy;
	if (dummy_clk > CQSPI_DUMMY_CLKS_MAX)
		return -EOPNOTSUPP;

	if (dummy_clk / 8) {
		reg |= (1 << CQSPI_REG_RD_INSTR_MODE_EN_LSB);
		/* Set mode bits high to ensure chip doesn't enter XIP */
		writel(0xFF, reg_base + CQSPI_REG_MODE_BIT);

		/* Need to subtract the mode byte (8 clocks). */
		if (f_pdata->inst_width != CQSPI_INST_TYPE_QUAD)
			dummy_clk -= 8;

		if (dummy_clk)
			reg |= (dummy_clk & CQSPI_REG_RD_INSTR_DUMMY_MASK)
			       << CQSPI_REG_RD_INSTR_DUMMY_LSB;
	}

	writel(reg, reg_base + CQSPI_REG_RD_INSTR);

	/* Set address width */
	reg = readl(reg_base + CQSPI_REG_SIZE);
	reg &= ~CQSPI_REG_SIZE_ADDRESS_MASK;
	reg |= (nor->addr_width - 1);
	writel(reg, reg_base + CQSPI_REG_SIZE);
	return 0;
}

static int cqspi_indirect_read_execute(struct spi_nor *nor, u8 *rxbuf,
				       loff_t from_addr, const size_t n_rx)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	void __iomem *reg_base = cqspi->iobase;
	void __iomem *ahb_base = cqspi->ahb_base;
	unsigned int remaining = n_rx;
	unsigned int mod_bytes = n_rx % 4;
	unsigned int bytes_to_read = 0;
	u8 *rxbuf_end = rxbuf + n_rx;
	int ret = 0;

	writel(from_addr, reg_base + CQSPI_REG_INDIRECTRDSTARTADDR);
	writel(remaining, reg_base + CQSPI_REG_INDIRECTRDBYTES);

	/* Clear all interrupts. */
	writel(CQSPI_IRQ_STATUS_MASK, reg_base + CQSPI_REG_IRQSTATUS);

	writel(CQSPI_IRQ_MASK_RD, reg_base + CQSPI_REG_IRQMASK);

	reinit_completion(&cqspi->transfer_complete);
	writel(CQSPI_REG_INDIRECTRD_START_MASK,
	       reg_base + CQSPI_REG_INDIRECTRD);

	while (remaining > 0) {
		if (!wait_for_completion_timeout(&cqspi->transfer_complete,
				msecs_to_jiffies(CQSPI_READ_TIMEOUT_MS)))
			ret = -ETIMEDOUT;

		bytes_to_read = cqspi_get_rd_sram_level(cqspi);

		if (ret && bytes_to_read == 0) {
			dev_err(nor->dev, "Indirect read timeout, no bytes\n");
			goto failrd;
		}

		while (bytes_to_read != 0) {
			unsigned int word_remain = round_down(remaining, 4);

			bytes_to_read *= cqspi->fifo_width;
			bytes_to_read = bytes_to_read > remaining ?
					remaining : bytes_to_read;
			bytes_to_read = round_down(bytes_to_read, 4);
			/* Read 4 byte word chunks then single bytes */
			if (bytes_to_read) {
				ioread32_rep(ahb_base, rxbuf,
					     (bytes_to_read / 4));
			} else if (!word_remain && mod_bytes) {
				unsigned int temp = ioread32(ahb_base);

				bytes_to_read = mod_bytes;
				memcpy(rxbuf, &temp, min((unsigned int)
							 (rxbuf_end - rxbuf),
							 bytes_to_read));
			}
			rxbuf += bytes_to_read;
			remaining -= bytes_to_read;
			bytes_to_read = cqspi_get_rd_sram_level(cqspi);
		}

		if (remaining > 0)
			reinit_completion(&cqspi->transfer_complete);
	}

	/* Check indirect done status */
	ret = cqspi_wait_for_bit(reg_base + CQSPI_REG_INDIRECTRD,
				 CQSPI_REG_INDIRECTRD_DONE_MASK, 0);
	if (ret) {
		dev_err(nor->dev,
			"Indirect read completion error (%i)\n", ret);
		goto failrd;
	}

	/* Disable interrupt */
	writel(0, reg_base + CQSPI_REG_IRQMASK);

	/* Clear indirect completion status */
	writel(CQSPI_REG_INDIRECTRD_DONE_MASK, reg_base + CQSPI_REG_INDIRECTRD);

	return 0;

failrd:
	/* Disable interrupt */
	writel(0, reg_base + CQSPI_REG_IRQMASK);

	/* Cancel the indirect read */
	writel(CQSPI_REG_INDIRECTWR_CANCEL_MASK,
	       reg_base + CQSPI_REG_INDIRECTRD);
	return ret;
}

static int cqspi_write_setup(struct spi_nor *nor)
{
	unsigned int reg;
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	void __iomem *reg_base = cqspi->iobase;

	/* Set opcode. */
	reg = nor->program_opcode << CQSPI_REG_WR_INSTR_OPCODE_LSB;
	writel(reg, reg_base + CQSPI_REG_WR_INSTR);
	reg = cqspi_calc_rdreg(nor, nor->program_opcode);
	writel(reg, reg_base + CQSPI_REG_RD_INSTR);

	reg = readl(reg_base + CQSPI_REG_SIZE);
	reg &= ~CQSPI_REG_SIZE_ADDRESS_MASK;
	reg |= (nor->addr_width - 1);
	writel(reg, reg_base + CQSPI_REG_SIZE);
	return 0;
}

static int cqspi_indirect_write_execute(struct spi_nor *nor, loff_t to_addr,
					const u8 *txbuf, const size_t n_tx)
{
	const unsigned int page_size = nor->page_size;
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	void __iomem *reg_base = cqspi->iobase;
	unsigned int remaining = n_tx;
	unsigned int write_bytes;
	int ret;

	writel(to_addr, reg_base + CQSPI_REG_INDIRECTWRSTARTADDR);
	writel(remaining, reg_base + CQSPI_REG_INDIRECTWRBYTES);

	/* Clear all interrupts. */
	writel(CQSPI_IRQ_STATUS_MASK, reg_base + CQSPI_REG_IRQSTATUS);

	writel(CQSPI_IRQ_MASK_WR, reg_base + CQSPI_REG_IRQMASK);

	reinit_completion(&cqspi->transfer_complete);
	writel(CQSPI_REG_INDIRECTWR_START_MASK,
	       reg_base + CQSPI_REG_INDIRECTWR);
	/*
	 * As per 66AK2G02 TRM SPRUHY8F section 11.15.5.3 Indirect Access
	 * Controller programming sequence, couple of cycles of
	 * QSPI_REF_CLK delay is required for the above bit to
	 * be internally synchronized by the QSPI module. Provide 5
	 * cycles of delay.
	 */
	if (cqspi->wr_delay)
		ndelay(cqspi->wr_delay);

	while (remaining > 0) {
		size_t write_words, mod_bytes;

		write_bytes = remaining > page_size ? page_size : remaining;
		write_words = write_bytes / 4;
		mod_bytes = write_bytes % 4;
		/* Write 4 bytes at a time then single bytes. */
		if (write_words) {
			iowrite32_rep(cqspi->ahb_base, txbuf, write_words);
			txbuf += (write_words * 4);
		}
		if (mod_bytes) {
			unsigned int temp = 0xFFFFFFFF;

			memcpy(&temp, txbuf, mod_bytes);
			iowrite32(temp, cqspi->ahb_base);
			txbuf += mod_bytes;
		}

		if (!wait_for_completion_timeout(&cqspi->transfer_complete,
					msecs_to_jiffies(CQSPI_TIMEOUT_MS))) {
			dev_err(nor->dev, "Indirect write timeout\n");
			ret = -ETIMEDOUT;
			goto failwr;
		}

		remaining -= write_bytes;

		if (remaining > 0)
			reinit_completion(&cqspi->transfer_complete);
	}

	/* Check indirect done status */
	ret = cqspi_wait_for_bit(reg_base + CQSPI_REG_INDIRECTWR,
				 CQSPI_REG_INDIRECTWR_DONE_MASK, 0);
	if (ret) {
		dev_err(nor->dev,
			"Indirect write completion error (%i)\n", ret);
		goto failwr;
	}

	/* Disable interrupt. */
	writel(0, reg_base + CQSPI_REG_IRQMASK);

	/* Clear indirect completion status */
	writel(CQSPI_REG_INDIRECTWR_DONE_MASK, reg_base + CQSPI_REG_INDIRECTWR);

	cqspi_wait_idle(cqspi);

	return 0;

failwr:
	/* Disable interrupt. */
	writel(0, reg_base + CQSPI_REG_IRQMASK);

	/* Cancel the indirect write */
	writel(CQSPI_REG_INDIRECTWR_CANCEL_MASK,
	       reg_base + CQSPI_REG_INDIRECTWR);
	return ret;
}

static void cqspi_chipselect(struct spi_nor *nor)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	void __iomem *reg_base = cqspi->iobase;
	unsigned int chip_select = f_pdata->cs;
	unsigned int reg;

	reg = readl(reg_base + CQSPI_REG_CONFIG);
	if (cqspi->is_decoded_cs) {
		reg |= CQSPI_REG_CONFIG_DECODE_MASK;
	} else {
		reg &= ~CQSPI_REG_CONFIG_DECODE_MASK;

		/* Convert CS if without decoder.
		 * CS0 to 4b'1110
		 * CS1 to 4b'1101
		 * CS2 to 4b'1011
		 * CS3 to 4b'0111
		 */
		chip_select = 0xF & ~(1 << chip_select);
	}

	reg &= ~(CQSPI_REG_CONFIG_CHIPSELECT_MASK
		 << CQSPI_REG_CONFIG_CHIPSELECT_LSB);
	reg |= (chip_select & CQSPI_REG_CONFIG_CHIPSELECT_MASK)
	    << CQSPI_REG_CONFIG_CHIPSELECT_LSB;
	writel(reg, reg_base + CQSPI_REG_CONFIG);
}

static void cqspi_configure_cs_and_sizes(struct spi_nor *nor)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	void __iomem *iobase = cqspi->iobase;
	unsigned int reg;

	/* configure page size and block size. */
	reg = readl(iobase + CQSPI_REG_SIZE);
	reg &= ~(CQSPI_REG_SIZE_PAGE_MASK << CQSPI_REG_SIZE_PAGE_LSB);
	reg &= ~(CQSPI_REG_SIZE_BLOCK_MASK << CQSPI_REG_SIZE_BLOCK_LSB);
	reg &= ~CQSPI_REG_SIZE_ADDRESS_MASK;
	reg |= (nor->page_size << CQSPI_REG_SIZE_PAGE_LSB);
	reg |= (ilog2(nor->mtd.erasesize) << CQSPI_REG_SIZE_BLOCK_LSB);
	reg |= (nor->addr_width - 1);
	writel(reg, iobase + CQSPI_REG_SIZE);

	/* configure the chip select */
	cqspi_chipselect(nor);

	/* Store the new configuration of the controller */
	cqspi->current_page_size = nor->page_size;
	cqspi->current_erase_size = nor->mtd.erasesize;
	cqspi->current_addr_width = nor->addr_width;
}

static unsigned int calculate_ticks_for_ns(const unsigned int ref_clk_hz,
					   const unsigned int ns_val)
{
	unsigned int ticks;

	ticks = ref_clk_hz / 1000;	/* kHz */
	ticks = DIV_ROUND_UP(ticks * ns_val, 1000000);

	return ticks;
}

static void cqspi_delay(struct spi_nor *nor)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	void __iomem *iobase = cqspi->iobase;
	const unsigned int ref_clk_hz = cqspi->master_ref_clk_hz;
	unsigned int tshsl, tchsh, tslch, tsd2d;
	unsigned int reg;
	unsigned int tsclk;

	/* calculate the number of ref ticks for one sclk tick */
	tsclk = DIV_ROUND_UP(ref_clk_hz, cqspi->sclk);

	tshsl = calculate_ticks_for_ns(ref_clk_hz, f_pdata->tshsl_ns);
	/* this particular value must be at least one sclk */
	if (tshsl < tsclk)
		tshsl = tsclk;

	tchsh = calculate_ticks_for_ns(ref_clk_hz, f_pdata->tchsh_ns);
	tslch = calculate_ticks_for_ns(ref_clk_hz, f_pdata->tslch_ns);
	tsd2d = calculate_ticks_for_ns(ref_clk_hz, f_pdata->tsd2d_ns);

	reg = (tshsl & CQSPI_REG_DELAY_TSHSL_MASK)
	       << CQSPI_REG_DELAY_TSHSL_LSB;
	reg |= (tchsh & CQSPI_REG_DELAY_TCHSH_MASK)
		<< CQSPI_REG_DELAY_TCHSH_LSB;
	reg |= (tslch & CQSPI_REG_DELAY_TSLCH_MASK)
		<< CQSPI_REG_DELAY_TSLCH_LSB;
	reg |= (tsd2d & CQSPI_REG_DELAY_TSD2D_MASK)
		<< CQSPI_REG_DELAY_TSD2D_LSB;
	writel(reg, iobase + CQSPI_REG_DELAY);
}

static void cqspi_config_baudrate_div(struct cqspi_st *cqspi)
{
	const unsigned int ref_clk_hz = cqspi->master_ref_clk_hz;
	void __iomem *reg_base = cqspi->iobase;
	u32 reg, div;

	/* Recalculate the baudrate divisor based on QSPI specification. */
	div = DIV_ROUND_UP(ref_clk_hz, 2 * cqspi->sclk) - 1;

	reg = readl(reg_base + CQSPI_REG_CONFIG);
	reg &= ~(CQSPI_REG_CONFIG_BAUD_MASK << CQSPI_REG_CONFIG_BAUD_LSB);
	reg |= (div & CQSPI_REG_CONFIG_BAUD_MASK) << CQSPI_REG_CONFIG_BAUD_LSB;
	writel(reg, reg_base + CQSPI_REG_CONFIG);
}

static void cqspi_readdata_capture(struct cqspi_st *cqspi,
				   const bool bypass,
				   const unsigned int delay)
{
	void __iomem *reg_base = cqspi->iobase;
	unsigned int reg;

	reg = readl(reg_base + CQSPI_REG_READCAPTURE);

	if (bypass)
		reg |= (1 << CQSPI_REG_READCAPTURE_BYPASS_LSB);
	else
		reg &= ~(1 << CQSPI_REG_READCAPTURE_BYPASS_LSB);

	reg &= ~(CQSPI_REG_READCAPTURE_DELAY_MASK
		 << CQSPI_REG_READCAPTURE_DELAY_LSB);

	reg |= (delay & CQSPI_REG_READCAPTURE_DELAY_MASK)
		<< CQSPI_REG_READCAPTURE_DELAY_LSB;

	writel(reg, reg_base + CQSPI_REG_READCAPTURE);
}

static void cqspi_controller_enable(struct cqspi_st *cqspi, bool enable)
{
	void __iomem *reg_base = cqspi->iobase;
	unsigned int reg;

	reg = readl(reg_base + CQSPI_REG_CONFIG);

	if (enable)
		reg |= CQSPI_REG_CONFIG_ENABLE_MASK;
	else
		reg &= ~CQSPI_REG_CONFIG_ENABLE_MASK;

	writel(reg, reg_base + CQSPI_REG_CONFIG);
}

static void cqspi_configure(struct spi_nor *nor)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	const unsigned int sclk = f_pdata->clk_rate;
	int switch_cs = (cqspi->current_cs != f_pdata->cs);
	int switch_ck = (cqspi->sclk != sclk);

	if ((cqspi->current_page_size != nor->page_size) ||
	    (cqspi->current_erase_size != nor->mtd.erasesize) ||
	    (cqspi->current_addr_width != nor->addr_width))
		switch_cs = 1;

	if (switch_cs || switch_ck)
		cqspi_controller_enable(cqspi, 0);

	/* Switch chip select. */
	if (switch_cs) {
		cqspi->current_cs = f_pdata->cs;
		cqspi_configure_cs_and_sizes(nor);
	}

	/* Setup baudrate divisor and delays */
	if (switch_ck) {
		cqspi->sclk = sclk;
		cqspi_config_baudrate_div(cqspi);
		cqspi_delay(nor);
		cqspi_readdata_capture(cqspi, !cqspi->rclk_en,
				       f_pdata->read_delay);
	}

	if (switch_cs || switch_ck)
		cqspi_controller_enable(cqspi, 1);
}

static int cqspi_set_protocol(struct spi_nor *nor, const int read)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;

	f_pdata->inst_width = CQSPI_INST_TYPE_SINGLE;
	f_pdata->addr_width = CQSPI_INST_TYPE_SINGLE;
	f_pdata->data_width = CQSPI_INST_TYPE_SINGLE;

	if (read) {
		switch (nor->read_proto) {
		case SNOR_PROTO_1_1_1:
			f_pdata->data_width = CQSPI_INST_TYPE_SINGLE;
			break;
		case SNOR_PROTO_1_1_2:
			f_pdata->data_width = CQSPI_INST_TYPE_DUAL;
			break;
		case SNOR_PROTO_1_1_4:
			f_pdata->data_width = CQSPI_INST_TYPE_QUAD;
			break;
		default:
			return -EINVAL;
		}
	}

	cqspi_configure(nor);

	return 0;
}

static ssize_t cqspi_write(struct spi_nor *nor, loff_t to,
			   size_t len, const u_char *buf)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	int ret;

	ret = cqspi_set_protocol(nor, 0);
	if (ret)
		return ret;

	ret = cqspi_write_setup(nor);
	if (ret)
		return ret;

	if (f_pdata->use_direct_mode) {
		memcpy_toio(cqspi->ahb_base + to, buf, len);
		ret = cqspi_wait_idle(cqspi);
	} else {
		ret = cqspi_indirect_write_execute(nor, to, buf, len);
	}
	if (ret)
		return ret;

	return len;
}

static void cqspi_rx_dma_callback(void *param)
{
	struct cqspi_st *cqspi = param;

	complete(&cqspi->rx_dma_complete);
}

static int cqspi_direct_read_execute(struct spi_nor *nor, u_char *buf,
				     loff_t from, size_t len)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;
	enum dma_ctrl_flags flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
	dma_addr_t dma_src = (dma_addr_t)cqspi->mmap_phys_base + from;
	int ret = 0;
	struct dma_async_tx_descriptor *tx;
	dma_cookie_t cookie;
	dma_addr_t dma_dst;

	if (!cqspi->rx_chan || !virt_addr_valid(buf)) {
		memcpy_fromio(buf, cqspi->ahb_base + from, len);
		return 0;
	}

	dma_dst = dma_map_single(nor->dev, buf, len, DMA_FROM_DEVICE);
	if (dma_mapping_error(nor->dev, dma_dst)) {
		dev_err(nor->dev, "dma mapping failed\n");
		return -ENOMEM;
	}
	tx = dmaengine_prep_dma_memcpy(cqspi->rx_chan, dma_dst, dma_src,
				       len, flags);
	if (!tx) {
		dev_err(nor->dev, "device_prep_dma_memcpy error\n");
		ret = -EIO;
		goto err_unmap;
	}

	tx->callback = cqspi_rx_dma_callback;
	tx->callback_param = cqspi;
	cookie = tx->tx_submit(tx);
	reinit_completion(&cqspi->rx_dma_complete);

	ret = dma_submit_error(cookie);
	if (ret) {
		dev_err(nor->dev, "dma_submit_error %d\n", cookie);
		ret = -EIO;
		goto err_unmap;
	}

	dma_async_issue_pending(cqspi->rx_chan);
	if (!wait_for_completion_timeout(&cqspi->rx_dma_complete,
					 msecs_to_jiffies(len))) {
		dmaengine_terminate_sync(cqspi->rx_chan);
		dev_err(nor->dev, "DMA wait_for_completion_timeout\n");
		ret = -ETIMEDOUT;
		goto err_unmap;
	}

err_unmap:
	dma_unmap_single(nor->dev, dma_dst, len, DMA_FROM_DEVICE);

	return ret;
}

static ssize_t cqspi_read(struct spi_nor *nor, loff_t from,
			  size_t len, u_char *buf)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	int ret;

	ret = cqspi_set_protocol(nor, 1);
	if (ret)
		return ret;

	ret = cqspi_read_setup(nor);
	if (ret)
		return ret;

	if (f_pdata->use_direct_mode)
		ret = cqspi_direct_read_execute(nor, buf, from, len);
	else
		ret = cqspi_indirect_read_execute(nor, buf, from, len);
	if (ret)
		return ret;

	return len;
}

static int cqspi_erase(struct spi_nor *nor, loff_t offs)
{
	int ret;

	ret = cqspi_set_protocol(nor, 0);
	if (ret)
		return ret;

	/* Send write enable, then erase commands. */
	ret = nor->write_reg(nor, SPINOR_OP_WREN, NULL, 0);
	if (ret)
		return ret;

	/* Set up command buffer. */
	ret = cqspi_command_write_addr(nor, nor->erase_opcode, offs);
	if (ret)
		return ret;

	return 0;
}

static int cqspi_prep(struct spi_nor *nor, enum spi_nor_ops ops)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;

	mutex_lock(&cqspi->bus_mutex);

	return 0;
}

static void cqspi_unprep(struct spi_nor *nor, enum spi_nor_ops ops)
{
	struct cqspi_flash_pdata *f_pdata = nor->priv;
	struct cqspi_st *cqspi = f_pdata->cqspi;

	mutex_unlock(&cqspi->bus_mutex);
}

static int cqspi_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
{
	int ret;

	ret = cqspi_set_protocol(nor, 0);
	if (!ret)
		ret = cqspi_command_read(nor, &opcode, 1, buf, len);

	return ret;
}

static int cqspi_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
{
	int ret;

	ret = cqspi_set_protocol(nor, 0);
	if (!ret)
		ret = cqspi_command_write(nor, opcode, buf, len);

	return ret;
}

static int cqspi_of_get_flash_pdata(struct platform_device *pdev,
				    struct cqspi_flash_pdata *f_pdata,
				    struct device_node *np)
{
	if (of_property_read_u32(np, "cdns,read-delay", &f_pdata->read_delay)) {
		dev_err(&pdev->dev, "couldn't determine read-delay\n");
		return -ENXIO;
	}

	if (of_property_read_u32(np, "cdns,tshsl-ns", &f_pdata->tshsl_ns)) {
		dev_err(&pdev->dev, "couldn't determine tshsl-ns\n");
		return -ENXIO;
	}

	if (of_property_read_u32(np, "cdns,tsd2d-ns", &f_pdata->tsd2d_ns)) {
		dev_err(&pdev->dev, "couldn't determine tsd2d-ns\n");
		return -ENXIO;
	}

	if (of_property_read_u32(np, "cdns,tchsh-ns", &f_pdata->tchsh_ns)) {
		dev_err(&pdev->dev, "couldn't determine tchsh-ns\n");
		return -ENXIO;
	}

	if (of_property_read_u32(np, "cdns,tslch-ns", &f_pdata->tslch_ns)) {
		dev_err(&pdev->dev, "couldn't determine tslch-ns\n");
		return -ENXIO;
	}

	if (of_property_read_u32(np, "spi-max-frequency", &f_pdata->clk_rate)) {
		dev_err(&pdev->dev, "couldn't determine spi-max-frequency\n");
		return -ENXIO;
	}

	return 0;
}

static int cqspi_of_get_pdata(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct cqspi_st *cqspi = platform_get_drvdata(pdev);

	cqspi->is_decoded_cs = of_property_read_bool(np, "cdns,is-decoded-cs");

	if (of_property_read_u32(np, "cdns,fifo-depth", &cqspi->fifo_depth)) {
		dev_err(&pdev->dev, "couldn't determine fifo-depth\n");
		return -ENXIO;
	}

	if (of_property_read_u32(np, "cdns,fifo-width", &cqspi->fifo_width)) {
		dev_err(&pdev->dev, "couldn't determine fifo-width\n");
		return -ENXIO;
	}

	if (of_property_read_u32(np, "cdns,trigger-address",
				 &cqspi->trigger_address)) {
		dev_err(&pdev->dev, "couldn't determine trigger-address\n");
		return -ENXIO;
	}

	cqspi->rclk_en = of_property_read_bool(np, "cdns,rclk-en");

	return 0;
}

static void cqspi_controller_init(struct cqspi_st *cqspi)
{
	u32 reg;

	cqspi_controller_enable(cqspi, 0);

	/* Configure the remap address register, no remap */
	writel(0, cqspi->iobase + CQSPI_REG_REMAP);

	/* Disable all interrupts. */
	writel(0, cqspi->iobase + CQSPI_REG_IRQMASK);

	/* Configure the SRAM split to 1:1 . */
	writel(cqspi->fifo_depth / 2, cqspi->iobase + CQSPI_REG_SRAMPARTITION);

	/* Load indirect trigger address. */
	writel(cqspi->trigger_address,
	       cqspi->iobase + CQSPI_REG_INDIRECTTRIGGER);

	/* Program read watermark -- 1/2 of the FIFO. */
	writel(cqspi->fifo_depth * cqspi->fifo_width / 2,
	       cqspi->iobase + CQSPI_REG_INDIRECTRDWATERMARK);
	/* Program write watermark -- 1/8 of the FIFO. */
	writel(cqspi->fifo_depth * cqspi->fifo_width / 8,
	       cqspi->iobase + CQSPI_REG_INDIRECTWRWATERMARK);

	/* Enable Direct Access Controller */
	reg = readl(cqspi->iobase + CQSPI_REG_CONFIG);
	reg |= CQSPI_REG_CONFIG_ENB_DIR_ACC_CTRL;
	writel(reg, cqspi->iobase + CQSPI_REG_CONFIG);

	cqspi_controller_enable(cqspi, 1);
}

static void cqspi_request_mmap_dma(struct cqspi_st *cqspi)
{
	dma_cap_mask_t mask;

	dma_cap_zero(mask);
	dma_cap_set(DMA_MEMCPY, mask);

	cqspi->rx_chan = dma_request_chan_by_mask(&mask);
	if (IS_ERR(cqspi->rx_chan)) {
		dev_err(&cqspi->pdev->dev, "No Rx DMA available\n");
		cqspi->rx_chan = NULL;
	}
	init_completion(&cqspi->rx_dma_complete);
}

static int cqspi_setup_flash(struct cqspi_st *cqspi, struct device_node *np)
{
	const struct spi_nor_hwcaps hwcaps = {
		.mask = SNOR_HWCAPS_READ |
			SNOR_HWCAPS_READ_FAST |
			SNOR_HWCAPS_READ_1_1_2 |
			SNOR_HWCAPS_READ_1_1_4 |
			SNOR_HWCAPS_PP,
	};
	struct platform_device *pdev = cqspi->pdev;
	struct device *dev = &pdev->dev;
	struct cqspi_flash_pdata *f_pdata;
	struct spi_nor *nor;
	struct mtd_info *mtd;
	unsigned int cs;
	int i, ret;

	/* Get flash device data */
	for_each_available_child_of_node(dev->of_node, np) {
		ret = of_property_read_u32(np, "reg", &cs);
		if (ret) {
			dev_err(dev, "Couldn't determine chip select.\n");
			goto err;
		}

		if (cs >= CQSPI_MAX_CHIPSELECT) {
			ret = -EINVAL;
			dev_err(dev, "Chip select %d out of range.\n", cs);
			goto err;
		}

		f_pdata = &cqspi->f_pdata[cs];
		f_pdata->cqspi = cqspi;
		f_pdata->cs = cs;

		ret = cqspi_of_get_flash_pdata(pdev, f_pdata, np);
		if (ret)
			goto err;

		nor = &f_pdata->nor;
		mtd = &nor->mtd;

		mtd->priv = nor;

		nor->dev = dev;
		spi_nor_set_flash_node(nor, np);
		nor->priv = f_pdata;

		nor->read_reg = cqspi_read_reg;
		nor->write_reg = cqspi_write_reg;
		nor->read = cqspi_read;
		nor->write = cqspi_write;
		nor->erase = cqspi_erase;
		nor->prepare = cqspi_prep;
		nor->unprepare = cqspi_unprep;

		mtd->name = devm_kasprintf(dev, GFP_KERNEL, "%s.%d",
					   dev_name(dev), cs);
		if (!mtd->name) {
			ret = -ENOMEM;
			goto err;
		}

		ret = spi_nor_scan(nor, NULL, &hwcaps);
		if (ret)
			goto err;

		ret = mtd_device_register(mtd, NULL, 0);
		if (ret)
			goto err;

		f_pdata->registered = true;

		if (mtd->size <= cqspi->ahb_size) {
			f_pdata->use_direct_mode = true;
			dev_dbg(nor->dev, "using direct mode for %s\n",
				mtd->name);

			if (!cqspi->rx_chan)
				cqspi_request_mmap_dma(cqspi);
		}
	}

	return 0;

err:
	for (i = 0; i < CQSPI_MAX_CHIPSELECT; i++)
		if (cqspi->f_pdata[i].registered)
			mtd_device_unregister(&cqspi->f_pdata[i].nor.mtd);
	return ret;
}

static int cqspi_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct device *dev = &pdev->dev;
	struct cqspi_st *cqspi;
	struct resource *res;
	struct resource *res_ahb;
	unsigned long data;
	int ret;
	int irq;

	cqspi = devm_kzalloc(dev, sizeof(*cqspi), GFP_KERNEL);
	if (!cqspi)
		return -ENOMEM;

	mutex_init(&cqspi->bus_mutex);
	cqspi->pdev = pdev;
	platform_set_drvdata(pdev, cqspi);

	/* Obtain configuration from OF. */
	ret = cqspi_of_get_pdata(pdev);
	if (ret) {
		dev_err(dev, "Cannot get mandatory OF data.\n");
		return -ENODEV;
	}

	/* Obtain QSPI clock. */
	cqspi->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(cqspi->clk)) {
		dev_err(dev, "Cannot claim QSPI clock.\n");
		return PTR_ERR(cqspi->clk);
	}

	/* Obtain and remap controller address. */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	cqspi->iobase = devm_ioremap_resource(dev, res);
	if (IS_ERR(cqspi->iobase)) {
		dev_err(dev, "Cannot remap controller address.\n");
		return PTR_ERR(cqspi->iobase);
	}

	/* Obtain and remap AHB address. */
	res_ahb = platform_get_resource(pdev, IORESOURCE_MEM, 1);
	cqspi->ahb_base = devm_ioremap_resource(dev, res_ahb);
	if (IS_ERR(cqspi->ahb_base)) {
		dev_err(dev, "Cannot remap AHB address.\n");
		return PTR_ERR(cqspi->ahb_base);
	}
	cqspi->mmap_phys_base = (dma_addr_t)res_ahb->start;
	cqspi->ahb_size = resource_size(res_ahb);

	init_completion(&cqspi->transfer_complete);

	/* Obtain IRQ line. */
	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
		dev_err(dev, "Cannot obtain IRQ.\n");
		return -ENXIO;
	}

	pm_runtime_enable(dev);
	ret = pm_runtime_get_sync(dev);
	if (ret < 0) {
		pm_runtime_put_noidle(dev);
		return ret;
	}

	ret = clk_prepare_enable(cqspi->clk);
	if (ret) {
		dev_err(dev, "Cannot enable QSPI clock.\n");
		goto probe_clk_failed;
	}

	cqspi->master_ref_clk_hz = clk_get_rate(cqspi->clk);
	data  = (unsigned long)of_device_get_match_data(dev);
	if (data & CQSPI_NEEDS_WR_DELAY)
		cqspi->wr_delay = 5 * DIV_ROUND_UP(NSEC_PER_SEC,
						   cqspi->master_ref_clk_hz);

	ret = devm_request_irq(dev, irq, cqspi_irq_handler, 0,
			       pdev->name, cqspi);
	if (ret) {
		dev_err(dev, "Cannot request IRQ.\n");
		goto probe_irq_failed;
	}

	cqspi_wait_idle(cqspi);
	cqspi_controller_init(cqspi);
	cqspi->current_cs = -1;
	cqspi->sclk = 0;

	ret = cqspi_setup_flash(cqspi, np);
	if (ret) {
		dev_err(dev, "Cadence QSPI NOR probe failed %d\n", ret);
		goto probe_setup_failed;
	}

	return ret;
probe_setup_failed:
	cqspi_controller_enable(cqspi, 0);
probe_irq_failed:
	clk_disable_unprepare(cqspi->clk);
probe_clk_failed:
	pm_runtime_put_sync(dev);
	pm_runtime_disable(dev);
	return ret;
}

static int cqspi_remove(struct platform_device *pdev)
{
	struct cqspi_st *cqspi = platform_get_drvdata(pdev);
	int i;

	for (i = 0; i < CQSPI_MAX_CHIPSELECT; i++)
		if (cqspi->f_pdata[i].registered)
			mtd_device_unregister(&cqspi->f_pdata[i].nor.mtd);

	cqspi_controller_enable(cqspi, 0);

	if (cqspi->rx_chan)
		dma_release_channel(cqspi->rx_chan);

	clk_disable_unprepare(cqspi->clk);

	pm_runtime_put_sync(&pdev->dev);
	pm_runtime_disable(&pdev->dev);

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int cqspi_suspend(struct device *dev)
{
	struct cqspi_st *cqspi = dev_get_drvdata(dev);

	cqspi_controller_enable(cqspi, 0);
	return 0;
}

static int cqspi_resume(struct device *dev)
{
	struct cqspi_st *cqspi = dev_get_drvdata(dev);

	cqspi_controller_enable(cqspi, 1);
	return 0;
}

static const struct dev_pm_ops cqspi__dev_pm_ops = {
	.suspend = cqspi_suspend,
	.resume = cqspi_resume,
};

#define CQSPI_DEV_PM_OPS	(&cqspi__dev_pm_ops)
#else
#define CQSPI_DEV_PM_OPS	NULL
#endif

static const struct of_device_id cqspi_dt_ids[] = {
	{
		.compatible = "cdns,qspi-nor",
		.data = (void *)0,
	},
	{
		.compatible = "ti,k2g-qspi",
		.data = (void *)CQSPI_NEEDS_WR_DELAY,
	},
	{ /* end of table */ }
};

MODULE_DEVICE_TABLE(of, cqspi_dt_ids);

static struct platform_driver cqspi_platform_driver = {
	.probe = cqspi_probe,
	.remove = cqspi_remove,
	.driver = {
		.name = CQSPI_NAME,
		.pm = CQSPI_DEV_PM_OPS,
		.of_match_table = cqspi_dt_ids,
	},
};

module_platform_driver(cqspi_platform_driver);

MODULE_DESCRIPTION("Cadence QSPI Controller Driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" CQSPI_NAME);
MODULE_AUTHOR("Ley Foon Tan <lftan@altera.com>");
MODULE_AUTHOR("Graham Moore <grmoore@opensource.altera.com>");