drivers/spi/spi-fsl-lpspi.c - linux-mtk - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 //
 // Freescale i.MX7ULP LPSPI driver
 //
 // Copyright 2016 Freescale Semiconductor, Inc.

 #include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/irq.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
 #include <linux/spi/spi_bitbang.h>
 #include <linux/types.h>

 #define DRIVER_NAME "fsl_lpspi"

 /* i.MX7ULP LPSPI registers */
 #define IMX7ULP_VERID	0x0
 #define IMX7ULP_PARAM	0x4
 #define IMX7ULP_CR	0x10
 #define IMX7ULP_SR	0x14
 #define IMX7ULP_IER	0x18
 #define IMX7ULP_DER	0x1c
 #define IMX7ULP_CFGR0	0x20
 #define IMX7ULP_CFGR1	0x24
 #define IMX7ULP_DMR0	0x30
 #define IMX7ULP_DMR1	0x34
 #define IMX7ULP_CCR	0x40
 #define IMX7ULP_FCR	0x58
 #define IMX7ULP_FSR	0x5c
 #define IMX7ULP_TCR	0x60
 #define IMX7ULP_TDR	0x64
 #define IMX7ULP_RSR	0x70
 #define IMX7ULP_RDR	0x74

 /* General control register field define */
 #define CR_RRF		BIT(9)
 #define CR_RTF		BIT(8)
 #define CR_RST		BIT(1)
 #define CR_MEN		BIT(0)
 #define SR_TCF		BIT(10)
 #define SR_RDF		BIT(1)
 #define SR_TDF		BIT(0)
 #define IER_TCIE	BIT(10)
 #define IER_RDIE	BIT(1)
 #define IER_TDIE	BIT(0)
 #define CFGR1_PCSCFG	BIT(27)
 #define CFGR1_PCSPOL	BIT(8)
 #define CFGR1_NOSTALL	BIT(3)
 #define CFGR1_MASTER	BIT(0)
 #define RSR_RXEMPTY	BIT(1)
 #define TCR_CPOL	BIT(31)
 #define TCR_CPHA	BIT(30)
 #define TCR_CONT	BIT(21)
 #define TCR_CONTC	BIT(20)
 #define TCR_RXMSK	BIT(19)
 #define TCR_TXMSK	BIT(18)

 static int clkdivs[] = {1, 2, 4, 8, 16, 32, 64, 128};

 struct lpspi_config {
 	u8 bpw;
 	u8 chip_select;
 	u8 prescale;
 	u16 mode;
 	u32 speed_hz;
 };

 struct fsl_lpspi_data {
 	struct device *dev;
 	void __iomem *base;
 	struct clk *clk;

 	void *rx_buf;
 	const void *tx_buf;
 	void (*tx)(struct fsl_lpspi_data *);
 	void (*rx)(struct fsl_lpspi_data *);

 	u32 remain;
 	u8 txfifosize;
 	u8 rxfifosize;

 	struct lpspi_config config;
 	struct completion xfer_done;
 };

 static const struct of_device_id fsl_lpspi_dt_ids[] = {
 	{ .compatible = "fsl,imx7ulp-spi", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, fsl_lpspi_dt_ids);

 #define LPSPI_BUF_RX(type)						\
 static void fsl_lpspi_buf_rx_##type(struct fsl_lpspi_data *fsl_lpspi)	\
 {									\
 	unsigned int val = readl(fsl_lpspi->base + IMX7ULP_RDR);	\
 									\
 	if (fsl_lpspi->rx_buf) {					\
 		*(type *)fsl_lpspi->rx_buf = val;			\
 		fsl_lpspi->rx_buf += sizeof(type);                      \
 	}								\
 }

 #define LPSPI_BUF_TX(type)						\
 static void fsl_lpspi_buf_tx_##type(struct fsl_lpspi_data *fsl_lpspi)	\
 {									\
 	type val = 0;							\
 									\
 	if (fsl_lpspi->tx_buf) {					\
 		val = *(type *)fsl_lpspi->tx_buf;			\
 		fsl_lpspi->tx_buf += sizeof(type);			\
 	}								\
 									\
 	fsl_lpspi->remain -= sizeof(type);				\
 	writel(val, fsl_lpspi->base + IMX7ULP_TDR);			\
 }

 LPSPI_BUF_RX(u8)
 LPSPI_BUF_TX(u8)
 LPSPI_BUF_RX(u16)
 LPSPI_BUF_TX(u16)
 LPSPI_BUF_RX(u32)
 LPSPI_BUF_TX(u32)

 static void fsl_lpspi_intctrl(struct fsl_lpspi_data *fsl_lpspi,
 			      unsigned int enable)
 {
 	writel(enable, fsl_lpspi->base + IMX7ULP_IER);
 }

 static int lpspi_prepare_xfer_hardware(struct spi_master *master)
 {
 	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);

 	return clk_prepare_enable(fsl_lpspi->clk);
 }

 static int lpspi_unprepare_xfer_hardware(struct spi_master *master)
 {
 	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);

 	clk_disable_unprepare(fsl_lpspi->clk);

 	return 0;
 }

 static int fsl_lpspi_txfifo_empty(struct fsl_lpspi_data *fsl_lpspi)
 {
 	u32 txcnt;
 	unsigned long orig_jiffies = jiffies;

 	do {
 		txcnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;

 		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
 			dev_dbg(fsl_lpspi->dev, "txfifo empty timeout\n");
 			return -ETIMEDOUT;
 		}
 		cond_resched();

 	} while (txcnt);

 	return 0;
 }

 static void fsl_lpspi_write_tx_fifo(struct fsl_lpspi_data *fsl_lpspi)
 {
 	u8 txfifo_cnt;

 	txfifo_cnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;

 	while (txfifo_cnt < fsl_lpspi->txfifosize) {
 		if (!fsl_lpspi->remain)
 			break;
 		fsl_lpspi->tx(fsl_lpspi);
 		txfifo_cnt++;
 	}

 	if (!fsl_lpspi->remain && (txfifo_cnt < fsl_lpspi->txfifosize))
 		writel(0, fsl_lpspi->base + IMX7ULP_TDR);
 	else
 		fsl_lpspi_intctrl(fsl_lpspi, IER_TDIE);
 }

 static void fsl_lpspi_read_rx_fifo(struct fsl_lpspi_data *fsl_lpspi)
 {
 	while (!(readl(fsl_lpspi->base + IMX7ULP_RSR) & RSR_RXEMPTY))
 		fsl_lpspi->rx(fsl_lpspi);
 }

 static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi,
 			      bool is_first_xfer)
 {
 	u32 temp = 0;

 	temp |= fsl_lpspi->config.bpw - 1;
 	temp |= fsl_lpspi->config.prescale << 27;
 	temp |= (fsl_lpspi->config.mode & 0x3) << 30;
 	temp |= (fsl_lpspi->config.chip_select & 0x3) << 24;

 	/*
 	 * Set TCR_CONT will keep SS asserted after current transfer.
 	 * For the first transfer, clear TCR_CONTC to assert SS.
 	 * For subsequent transfer, set TCR_CONTC to keep SS asserted.
 	 */
 	temp |= TCR_CONT;
 	if (is_first_xfer)
 		temp &= ~TCR_CONTC;
 	else
 		temp |= TCR_CONTC;

 	writel(temp, fsl_lpspi->base + IMX7ULP_TCR);

 	dev_dbg(fsl_lpspi->dev, "TCR=0x%x\n", temp);
 }

 static void fsl_lpspi_set_watermark(struct fsl_lpspi_data *fsl_lpspi)
 {
 	u32 temp;

 	temp = fsl_lpspi->txfifosize >> 1 | (fsl_lpspi->rxfifosize >> 1) << 16;

 	writel(temp, fsl_lpspi->base + IMX7ULP_FCR);

 	dev_dbg(fsl_lpspi->dev, "FCR=0x%x\n", temp);
 }

 static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
 {
 	struct lpspi_config config = fsl_lpspi->config;
 	unsigned int perclk_rate, scldiv;
 	u8 prescale;

 	perclk_rate = clk_get_rate(fsl_lpspi->clk);
 	for (prescale = 0; prescale < 8; prescale++) {
 		scldiv = perclk_rate /
 			 (clkdivs[prescale] * config.speed_hz) - 2;
 		if (scldiv < 256) {
 			fsl_lpspi->config.prescale = prescale;
 			break;
 		}
 	}

 	if (prescale == 8 && scldiv >= 256)
 		return -EINVAL;

 	writel(scldiv, fsl_lpspi->base + IMX7ULP_CCR);

 	dev_dbg(fsl_lpspi->dev, "perclk=%d, speed=%d, prescale =%d, scldiv=%d\n",
 		perclk_rate, config.speed_hz, prescale, scldiv);

 	return 0;
 }

 static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
 {
 	u32 temp;
 	int ret;

 	temp = CR_RST;
 	writel(temp, fsl_lpspi->base + IMX7ULP_CR);
 	writel(0, fsl_lpspi->base + IMX7ULP_CR);

 	ret = fsl_lpspi_set_bitrate(fsl_lpspi);
 	if (ret)
 		return ret;

 	fsl_lpspi_set_watermark(fsl_lpspi);

 	temp = CFGR1_PCSCFG | CFGR1_MASTER;
 	if (fsl_lpspi->config.mode & SPI_CS_HIGH)
 		temp |= CFGR1_PCSPOL;
 	writel(temp, fsl_lpspi->base + IMX7ULP_CFGR1);

 	temp = readl(fsl_lpspi->base + IMX7ULP_CR);
 	temp |= CR_RRF | CR_RTF | CR_MEN;
 	writel(temp, fsl_lpspi->base + IMX7ULP_CR);

 	return 0;
 }

 static void fsl_lpspi_setup_transfer(struct spi_device *spi,
 				     struct spi_transfer *t)
 {
 	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(spi->master);

 	fsl_lpspi->config.mode = spi->mode;
 	fsl_lpspi->config.bpw = t ? t->bits_per_word : spi->bits_per_word;
 	fsl_lpspi->config.speed_hz = t ? t->speed_hz : spi->max_speed_hz;
 	fsl_lpspi->config.chip_select = spi->chip_select;

 	if (!fsl_lpspi->config.speed_hz)
 		fsl_lpspi->config.speed_hz = spi->max_speed_hz;
 	if (!fsl_lpspi->config.bpw)
 		fsl_lpspi->config.bpw = spi->bits_per_word;

 	/* Initialize the functions for transfer */
 	if (fsl_lpspi->config.bpw <= 8) {
 		fsl_lpspi->rx = fsl_lpspi_buf_rx_u8;
 		fsl_lpspi->tx = fsl_lpspi_buf_tx_u8;
 	} else if (fsl_lpspi->config.bpw <= 16) {
 		fsl_lpspi->rx = fsl_lpspi_buf_rx_u16;
 		fsl_lpspi->tx = fsl_lpspi_buf_tx_u16;
 	} else {
 		fsl_lpspi->rx = fsl_lpspi_buf_rx_u32;
 		fsl_lpspi->tx = fsl_lpspi_buf_tx_u32;
 	}

 	fsl_lpspi_config(fsl_lpspi);
 }

 static int fsl_lpspi_transfer_one(struct spi_master *master,
 				  struct spi_device *spi,
 				  struct spi_transfer *t)
 {
 	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
 	int ret;

 	fsl_lpspi->tx_buf = t->tx_buf;
 	fsl_lpspi->rx_buf = t->rx_buf;
 	fsl_lpspi->remain = t->len;

 	reinit_completion(&fsl_lpspi->xfer_done);
 	fsl_lpspi_write_tx_fifo(fsl_lpspi);

 	ret = wait_for_completion_timeout(&fsl_lpspi->xfer_done, HZ);
 	if (!ret) {
 		dev_dbg(fsl_lpspi->dev, "wait for completion timeout\n");
 		return -ETIMEDOUT;
 	}

 	ret = fsl_lpspi_txfifo_empty(fsl_lpspi);
 	if (ret)
 		return ret;

 	fsl_lpspi_read_rx_fifo(fsl_lpspi);

 	return 0;
 }

 static int fsl_lpspi_transfer_one_msg(struct spi_master *master,
 				      struct spi_message *msg)
 {
 	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
 	struct spi_device *spi = msg->spi;
 	struct spi_transfer *xfer;
 	bool is_first_xfer = true;
 	u32 temp;
 	int ret = 0;

 	msg->status = 0;
 	msg->actual_length = 0;

 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 		fsl_lpspi_setup_transfer(spi, xfer);
 		fsl_lpspi_set_cmd(fsl_lpspi, is_first_xfer);

 		is_first_xfer = false;

 		ret = fsl_lpspi_transfer_one(master, spi, xfer);
 		if (ret < 0)
 			goto complete;

 		msg->actual_length += xfer->len;
 	}

 complete:
 	/* de-assert SS, then finalize current message */
 	temp = readl(fsl_lpspi->base + IMX7ULP_TCR);
 	temp &= ~TCR_CONTC;
 	writel(temp, fsl_lpspi->base + IMX7ULP_TCR);

 	msg->status = ret;
 	spi_finalize_current_message(master);

 	return ret;
 }

 static irqreturn_t fsl_lpspi_isr(int irq, void *dev_id)
 {
 	struct fsl_lpspi_data *fsl_lpspi = dev_id;
 	u32 temp;

 	fsl_lpspi_intctrl(fsl_lpspi, 0);
 	temp = readl(fsl_lpspi->base + IMX7ULP_SR);

 	fsl_lpspi_read_rx_fifo(fsl_lpspi);

 	if (temp & SR_TDF) {
 		fsl_lpspi_write_tx_fifo(fsl_lpspi);

 		if (!fsl_lpspi->remain)
 			complete(&fsl_lpspi->xfer_done);

 		return IRQ_HANDLED;
 	}

 	return IRQ_NONE;
 }

 static int fsl_lpspi_probe(struct platform_device *pdev)
 {
 	struct fsl_lpspi_data *fsl_lpspi;
 	struct spi_master *master;
 	struct resource *res;
 	int ret, irq;
 	u32 temp;

 	master = spi_alloc_master(&pdev->dev, sizeof(struct fsl_lpspi_data));
 	if (!master)
 		return -ENOMEM;

 	platform_set_drvdata(pdev, master);

 	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32);
 	master->bus_num = pdev->id;

 	fsl_lpspi = spi_master_get_devdata(master);
 	fsl_lpspi->dev = &pdev->dev;

 	master->transfer_one_message = fsl_lpspi_transfer_one_msg;
 	master->prepare_transfer_hardware = lpspi_prepare_xfer_hardware;
 	master->unprepare_transfer_hardware = lpspi_unprepare_xfer_hardware;
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 	master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;
 	master->dev.of_node = pdev->dev.of_node;
 	master->bus_num = pdev->id;

 	init_completion(&fsl_lpspi->xfer_done);

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	fsl_lpspi->base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(fsl_lpspi->base)) {
 		ret = PTR_ERR(fsl_lpspi->base);
 		goto out_master_put;
 	}

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		ret = irq;
 		goto out_master_put;
 	}

 	ret = devm_request_irq(&pdev->dev, irq, fsl_lpspi_isr, 0,
 			       dev_name(&pdev->dev), fsl_lpspi);
 	if (ret) {
 		dev_err(&pdev->dev, "can't get irq%d: %d\n", irq, ret);
 		goto out_master_put;
 	}

 	fsl_lpspi->clk = devm_clk_get(&pdev->dev, "ipg");
 	if (IS_ERR(fsl_lpspi->clk)) {
 		ret = PTR_ERR(fsl_lpspi->clk);
 		goto out_master_put;
 	}

 	ret = clk_prepare_enable(fsl_lpspi->clk);
 	if (ret) {
 		dev_err(&pdev->dev, "can't enable lpspi clock, ret=%d\n", ret);
 		goto out_master_put;
 	}

 	temp = readl(fsl_lpspi->base + IMX7ULP_PARAM);
 	fsl_lpspi->txfifosize = 1 << (temp & 0x0f);
 	fsl_lpspi->rxfifosize = 1 << ((temp >> 8) & 0x0f);

 	clk_disable_unprepare(fsl_lpspi->clk);

 	ret = devm_spi_register_master(&pdev->dev, master);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "spi_register_master error.\n");
 		goto out_master_put;
 	}

 	return 0;

 out_master_put:
 	spi_master_put(master);

 	return ret;
 }

 static int fsl_lpspi_remove(struct platform_device *pdev)
 {
 	struct spi_master *master = platform_get_drvdata(pdev);
 	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);

 	clk_disable_unprepare(fsl_lpspi->clk);

 	return 0;
 }

 static struct platform_driver fsl_lpspi_driver = {
 	.driver = {
 		.name = DRIVER_NAME,
 		.of_match_table = fsl_lpspi_dt_ids,
 	},
 	.probe = fsl_lpspi_probe,
 	.remove = fsl_lpspi_remove,
 };
 module_platform_driver(fsl_lpspi_driver);

 MODULE_DESCRIPTION("LPSPI Master Controller driver");
 MODULE_AUTHOR("Gao Pan <pandy.gao@nxp.com>");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	//
	// Freescale i.MX7ULP LPSPI driver
	//
	// Copyright 2016 Freescale Semiconductor, Inc.

	#include <linux/clk.h>
	#include <linux/completion.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/irq.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>
	#include <linux/spi/spi.h>
	#include <linux/spi/spi_bitbang.h>
	#include <linux/types.h>

	#define DRIVER_NAME "fsl_lpspi"

	/* i.MX7ULP LPSPI registers */
	#define IMX7ULP_VERID 0x0
	#define IMX7ULP_PARAM 0x4
	#define IMX7ULP_CR 0x10
	#define IMX7ULP_SR 0x14
	#define IMX7ULP_IER 0x18
	#define IMX7ULP_DER 0x1c
	#define IMX7ULP_CFGR0 0x20
	#define IMX7ULP_CFGR1 0x24
	#define IMX7ULP_DMR0 0x30
	#define IMX7ULP_DMR1 0x34
	#define IMX7ULP_CCR 0x40
	#define IMX7ULP_FCR 0x58
	#define IMX7ULP_FSR 0x5c
	#define IMX7ULP_TCR 0x60
	#define IMX7ULP_TDR 0x64
	#define IMX7ULP_RSR 0x70
	#define IMX7ULP_RDR 0x74

	/* General control register field define */
	#define CR_RRF BIT(9)
	#define CR_RTF BIT(8)
	#define CR_RST BIT(1)
	#define CR_MEN BIT(0)
	#define SR_TCF BIT(10)
	#define SR_RDF BIT(1)
	#define SR_TDF BIT(0)
	#define IER_TCIE BIT(10)
	#define IER_RDIE BIT(1)
	#define IER_TDIE BIT(0)
	#define CFGR1_PCSCFG BIT(27)
	#define CFGR1_PCSPOL BIT(8)
	#define CFGR1_NOSTALL BIT(3)
	#define CFGR1_MASTER BIT(0)
	#define RSR_RXEMPTY BIT(1)
	#define TCR_CPOL BIT(31)
	#define TCR_CPHA BIT(30)
	#define TCR_CONT BIT(21)
	#define TCR_CONTC BIT(20)
	#define TCR_RXMSK BIT(19)
	#define TCR_TXMSK BIT(18)

	static int clkdivs[] = {1, 2, 4, 8, 16, 32, 64, 128};

	struct lpspi_config {
	u8 bpw;
	u8 chip_select;
	u8 prescale;
	u16 mode;
	u32 speed_hz;
	};

	struct fsl_lpspi_data {
	struct device *dev;
	void __iomem *base;
	struct clk *clk;

	void *rx_buf;
	const void *tx_buf;
	void (tx)(struct fsl_lpspi_data );
	void (rx)(struct fsl_lpspi_data );

	u32 remain;
	u8 txfifosize;
	u8 rxfifosize;

	struct lpspi_config config;
	struct completion xfer_done;
	};

	static const struct of_device_id fsl_lpspi_dt_ids[] = {
	{ .compatible = "fsl,imx7ulp-spi", },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, fsl_lpspi_dt_ids);

	#define LPSPI_BUF_RX(type) \
	static void fsl_lpspi_buf_rx_##type(struct fsl_lpspi_data *fsl_lpspi) \
	{ \
	unsigned int val = readl(fsl_lpspi->base + IMX7ULP_RDR); \
	\
	if (fsl_lpspi->rx_buf) { \
	(type )fsl_lpspi->rx_buf = val; \
	fsl_lpspi->rx_buf += sizeof(type); \
	} \
	}

	#define LPSPI_BUF_TX(type) \
	static void fsl_lpspi_buf_tx_##type(struct fsl_lpspi_data *fsl_lpspi) \
	{ \
	type val = 0; \
	\
	if (fsl_lpspi->tx_buf) { \
	val = (type )fsl_lpspi->tx_buf; \
	fsl_lpspi->tx_buf += sizeof(type); \
	} \
	\
	fsl_lpspi->remain -= sizeof(type); \
	writel(val, fsl_lpspi->base + IMX7ULP_TDR); \
	}

	LPSPI_BUF_RX(u8)
	LPSPI_BUF_TX(u8)
	LPSPI_BUF_RX(u16)
	LPSPI_BUF_TX(u16)
	LPSPI_BUF_RX(u32)
	LPSPI_BUF_TX(u32)

	static void fsl_lpspi_intctrl(struct fsl_lpspi_data *fsl_lpspi,
	unsigned int enable)
	{
	writel(enable, fsl_lpspi->base + IMX7ULP_IER);
	}

	static int lpspi_prepare_xfer_hardware(struct spi_master *master)
	{
	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);

	return clk_prepare_enable(fsl_lpspi->clk);
	}

	static int lpspi_unprepare_xfer_hardware(struct spi_master *master)
	{
	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);

	clk_disable_unprepare(fsl_lpspi->clk);

	return 0;
	}

	static int fsl_lpspi_txfifo_empty(struct fsl_lpspi_data *fsl_lpspi)
	{
	u32 txcnt;
	unsigned long orig_jiffies = jiffies;

	do {
	txcnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;

	if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
	dev_dbg(fsl_lpspi->dev, "txfifo empty timeout\n");
	return -ETIMEDOUT;
	}
	cond_resched();

	} while (txcnt);

	return 0;
	}

	static void fsl_lpspi_write_tx_fifo(struct fsl_lpspi_data *fsl_lpspi)
	{
	u8 txfifo_cnt;

	txfifo_cnt = readl(fsl_lpspi->base + IMX7ULP_FSR) & 0xff;

	while (txfifo_cnt < fsl_lpspi->txfifosize) {
	if (!fsl_lpspi->remain)
	break;
	fsl_lpspi->tx(fsl_lpspi);
	txfifo_cnt++;
	}

	if (!fsl_lpspi->remain && (txfifo_cnt < fsl_lpspi->txfifosize))
	writel(0, fsl_lpspi->base + IMX7ULP_TDR);
	else
	fsl_lpspi_intctrl(fsl_lpspi, IER_TDIE);
	}

	static void fsl_lpspi_read_rx_fifo(struct fsl_lpspi_data *fsl_lpspi)
	{
	while (!(readl(fsl_lpspi->base + IMX7ULP_RSR) & RSR_RXEMPTY))
	fsl_lpspi->rx(fsl_lpspi);
	}

	static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi,
	bool is_first_xfer)
	{
	u32 temp = 0;

	temp \|= fsl_lpspi->config.bpw - 1;
	temp \|= fsl_lpspi->config.prescale << 27;
	temp \|= (fsl_lpspi->config.mode & 0x3) << 30;
	temp \|= (fsl_lpspi->config.chip_select & 0x3) << 24;

	/*
	* Set TCR_CONT will keep SS asserted after current transfer.
	* For the first transfer, clear TCR_CONTC to assert SS.
	* For subsequent transfer, set TCR_CONTC to keep SS asserted.
	*/
	temp \|= TCR_CONT;
	if (is_first_xfer)
	temp &= ~TCR_CONTC;
	else
	temp \|= TCR_CONTC;

	writel(temp, fsl_lpspi->base + IMX7ULP_TCR);

	dev_dbg(fsl_lpspi->dev, "TCR=0x%x\n", temp);
	}

	static void fsl_lpspi_set_watermark(struct fsl_lpspi_data *fsl_lpspi)
	{
	u32 temp;

	temp = fsl_lpspi->txfifosize >> 1 \| (fsl_lpspi->rxfifosize >> 1) << 16;

	writel(temp, fsl_lpspi->base + IMX7ULP_FCR);

	dev_dbg(fsl_lpspi->dev, "FCR=0x%x\n", temp);
	}

	static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
	{
	struct lpspi_config config = fsl_lpspi->config;
	unsigned int perclk_rate, scldiv;
	u8 prescale;

	perclk_rate = clk_get_rate(fsl_lpspi->clk);
	for (prescale = 0; prescale < 8; prescale++) {
	scldiv = perclk_rate /
	(clkdivs[prescale] * config.speed_hz) - 2;
	if (scldiv < 256) {
	fsl_lpspi->config.prescale = prescale;
	break;
	}
	}

	if (prescale == 8 && scldiv >= 256)
	return -EINVAL;

	writel(scldiv, fsl_lpspi->base + IMX7ULP_CCR);

	dev_dbg(fsl_lpspi->dev, "perclk=%d, speed=%d, prescale =%d, scldiv=%d\n",
	perclk_rate, config.speed_hz, prescale, scldiv);

	return 0;
	}

	static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
	{
	u32 temp;
	int ret;

	temp = CR_RST;
	writel(temp, fsl_lpspi->base + IMX7ULP_CR);
	writel(0, fsl_lpspi->base + IMX7ULP_CR);

	ret = fsl_lpspi_set_bitrate(fsl_lpspi);
	if (ret)
	return ret;

	fsl_lpspi_set_watermark(fsl_lpspi);

	temp = CFGR1_PCSCFG \| CFGR1_MASTER;
	if (fsl_lpspi->config.mode & SPI_CS_HIGH)
	temp \|= CFGR1_PCSPOL;
	writel(temp, fsl_lpspi->base + IMX7ULP_CFGR1);

	temp = readl(fsl_lpspi->base + IMX7ULP_CR);
	temp \|= CR_RRF \| CR_RTF \| CR_MEN;
	writel(temp, fsl_lpspi->base + IMX7ULP_CR);

	return 0;
	}

	static void fsl_lpspi_setup_transfer(struct spi_device *spi,
	struct spi_transfer *t)
	{
	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(spi->master);

	fsl_lpspi->config.mode = spi->mode;
	fsl_lpspi->config.bpw = t ? t->bits_per_word : spi->bits_per_word;
	fsl_lpspi->config.speed_hz = t ? t->speed_hz : spi->max_speed_hz;
	fsl_lpspi->config.chip_select = spi->chip_select;

	if (!fsl_lpspi->config.speed_hz)
	fsl_lpspi->config.speed_hz = spi->max_speed_hz;
	if (!fsl_lpspi->config.bpw)
	fsl_lpspi->config.bpw = spi->bits_per_word;

	/* Initialize the functions for transfer */
	if (fsl_lpspi->config.bpw <= 8) {
	fsl_lpspi->rx = fsl_lpspi_buf_rx_u8;
	fsl_lpspi->tx = fsl_lpspi_buf_tx_u8;
	} else if (fsl_lpspi->config.bpw <= 16) {
	fsl_lpspi->rx = fsl_lpspi_buf_rx_u16;
	fsl_lpspi->tx = fsl_lpspi_buf_tx_u16;
	} else {
	fsl_lpspi->rx = fsl_lpspi_buf_rx_u32;
	fsl_lpspi->tx = fsl_lpspi_buf_tx_u32;
	}

	fsl_lpspi_config(fsl_lpspi);
	}

	static int fsl_lpspi_transfer_one(struct spi_master *master,
	struct spi_device *spi,
	struct spi_transfer *t)
	{
	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
	int ret;

	fsl_lpspi->tx_buf = t->tx_buf;
	fsl_lpspi->rx_buf = t->rx_buf;
	fsl_lpspi->remain = t->len;

	reinit_completion(&fsl_lpspi->xfer_done);
	fsl_lpspi_write_tx_fifo(fsl_lpspi);

	ret = wait_for_completion_timeout(&fsl_lpspi->xfer_done, HZ);
	if (!ret) {
	dev_dbg(fsl_lpspi->dev, "wait for completion timeout\n");
	return -ETIMEDOUT;
	}

	ret = fsl_lpspi_txfifo_empty(fsl_lpspi);
	if (ret)
	return ret;

	fsl_lpspi_read_rx_fifo(fsl_lpspi);

	return 0;
	}

	static int fsl_lpspi_transfer_one_msg(struct spi_master *master,
	struct spi_message *msg)
	{
	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);
	struct spi_device *spi = msg->spi;
	struct spi_transfer *xfer;
	bool is_first_xfer = true;
	u32 temp;
	int ret = 0;

	msg->status = 0;
	msg->actual_length = 0;

	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
	fsl_lpspi_setup_transfer(spi, xfer);
	fsl_lpspi_set_cmd(fsl_lpspi, is_first_xfer);

	is_first_xfer = false;

	ret = fsl_lpspi_transfer_one(master, spi, xfer);
	if (ret < 0)
	goto complete;

	msg->actual_length += xfer->len;
	}

	complete:
	/* de-assert SS, then finalize current message */
	temp = readl(fsl_lpspi->base + IMX7ULP_TCR);
	temp &= ~TCR_CONTC;
	writel(temp, fsl_lpspi->base + IMX7ULP_TCR);

	msg->status = ret;
	spi_finalize_current_message(master);

	return ret;
	}

	static irqreturn_t fsl_lpspi_isr(int irq, void *dev_id)
	{
	struct fsl_lpspi_data *fsl_lpspi = dev_id;
	u32 temp;

	fsl_lpspi_intctrl(fsl_lpspi, 0);
	temp = readl(fsl_lpspi->base + IMX7ULP_SR);

	fsl_lpspi_read_rx_fifo(fsl_lpspi);

	if (temp & SR_TDF) {
	fsl_lpspi_write_tx_fifo(fsl_lpspi);

	if (!fsl_lpspi->remain)
	complete(&fsl_lpspi->xfer_done);

	return IRQ_HANDLED;
	}

	return IRQ_NONE;
	}

	static int fsl_lpspi_probe(struct platform_device *pdev)
	{
	struct fsl_lpspi_data *fsl_lpspi;
	struct spi_master *master;
	struct resource *res;
	int ret, irq;
	u32 temp;

	master = spi_alloc_master(&pdev->dev, sizeof(struct fsl_lpspi_data));
	if (!master)
	return -ENOMEM;

	platform_set_drvdata(pdev, master);

	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32);
	master->bus_num = pdev->id;

	fsl_lpspi = spi_master_get_devdata(master);
	fsl_lpspi->dev = &pdev->dev;

	master->transfer_one_message = fsl_lpspi_transfer_one_msg;
	master->prepare_transfer_hardware = lpspi_prepare_xfer_hardware;
	master->unprepare_transfer_hardware = lpspi_unprepare_xfer_hardware;
	master->mode_bits = SPI_CPOL \| SPI_CPHA \| SPI_CS_HIGH;
	master->flags = SPI_MASTER_MUST_RX \| SPI_MASTER_MUST_TX;
	master->dev.of_node = pdev->dev.of_node;
	master->bus_num = pdev->id;

	init_completion(&fsl_lpspi->xfer_done);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	fsl_lpspi->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(fsl_lpspi->base)) {
	ret = PTR_ERR(fsl_lpspi->base);
	goto out_master_put;
	}

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	ret = irq;
	goto out_master_put;
	}

	ret = devm_request_irq(&pdev->dev, irq, fsl_lpspi_isr, 0,
	dev_name(&pdev->dev), fsl_lpspi);
	if (ret) {
	dev_err(&pdev->dev, "can't get irq%d: %d\n", irq, ret);
	goto out_master_put;
	}

	fsl_lpspi->clk = devm_clk_get(&pdev->dev, "ipg");
	if (IS_ERR(fsl_lpspi->clk)) {
	ret = PTR_ERR(fsl_lpspi->clk);
	goto out_master_put;
	}

	ret = clk_prepare_enable(fsl_lpspi->clk);
	if (ret) {
	dev_err(&pdev->dev, "can't enable lpspi clock, ret=%d\n", ret);
	goto out_master_put;
	}

	temp = readl(fsl_lpspi->base + IMX7ULP_PARAM);
	fsl_lpspi->txfifosize = 1 << (temp & 0x0f);
	fsl_lpspi->rxfifosize = 1 << ((temp >> 8) & 0x0f);

	clk_disable_unprepare(fsl_lpspi->clk);

	ret = devm_spi_register_master(&pdev->dev, master);
	if (ret < 0) {
	dev_err(&pdev->dev, "spi_register_master error.\n");
	goto out_master_put;
	}

	return 0;

	out_master_put:
	spi_master_put(master);

	return ret;
	}

	static int fsl_lpspi_remove(struct platform_device *pdev)
	{
	struct spi_master *master = platform_get_drvdata(pdev);
	struct fsl_lpspi_data *fsl_lpspi = spi_master_get_devdata(master);

	clk_disable_unprepare(fsl_lpspi->clk);

	return 0;
	}

	static struct platform_driver fsl_lpspi_driver = {
	.driver = {
	.name = DRIVER_NAME,
	.of_match_table = fsl_lpspi_dt_ids,
	},
	.probe = fsl_lpspi_probe,
	.remove = fsl_lpspi_remove,
	};
	module_platform_driver(fsl_lpspi_driver);

	MODULE_DESCRIPTION("LPSPI Master Controller driver");
	MODULE_AUTHOR("Gao Pan <pandy.gao@nxp.com>");
	MODULE_LICENSE("GPL");