drivers/spi/spi-sifive.c - filogic/uboot - Gitiles

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright 2018 SiFive, Inc.
  * Copyright 2019 Bhargav Shah <bhargavshah1988@gmail.com>
  *
  * SiFive SPI controller driver (master mode only)
  */

 #include <dm.h>
 #include <dm/device_compat.h>
 #include <malloc.h>
 #include <spi.h>
 #include <spi-mem.h>
 #include <wait_bit.h>
 #include <asm/io.h>
 #include <linux/bitops.h>
 #include <linux/log2.h>
 #include <clk.h>

 #define SIFIVE_SPI_MAX_CS		32

 #define SIFIVE_SPI_DEFAULT_DEPTH	8
 #define SIFIVE_SPI_DEFAULT_BITS		8

 /* register offsets */
 #define SIFIVE_SPI_REG_SCKDIV            0x00 /* Serial clock divisor */
 #define SIFIVE_SPI_REG_SCKMODE           0x04 /* Serial clock mode */
 #define SIFIVE_SPI_REG_CSID              0x10 /* Chip select ID */
 #define SIFIVE_SPI_REG_CSDEF             0x14 /* Chip select default */
 #define SIFIVE_SPI_REG_CSMODE            0x18 /* Chip select mode */
 #define SIFIVE_SPI_REG_DELAY0            0x28 /* Delay control 0 */
 #define SIFIVE_SPI_REG_DELAY1            0x2c /* Delay control 1 */
 #define SIFIVE_SPI_REG_FMT               0x40 /* Frame format */
 #define SIFIVE_SPI_REG_TXDATA            0x48 /* Tx FIFO data */
 #define SIFIVE_SPI_REG_RXDATA            0x4c /* Rx FIFO data */
 #define SIFIVE_SPI_REG_TXMARK            0x50 /* Tx FIFO watermark */
 #define SIFIVE_SPI_REG_RXMARK            0x54 /* Rx FIFO watermark */
 #define SIFIVE_SPI_REG_FCTRL             0x60 /* SPI flash interface control */
 #define SIFIVE_SPI_REG_FFMT              0x64 /* SPI flash instruction format */
 #define SIFIVE_SPI_REG_IE                0x70 /* Interrupt Enable Register */
 #define SIFIVE_SPI_REG_IP                0x74 /* Interrupt Pendings Register */

 /* sckdiv bits */
 #define SIFIVE_SPI_SCKDIV_DIV_MASK       0xfffU

 /* sckmode bits */
 #define SIFIVE_SPI_SCKMODE_PHA           BIT(0)
 #define SIFIVE_SPI_SCKMODE_POL           BIT(1)
 #define SIFIVE_SPI_SCKMODE_MODE_MASK     (SIFIVE_SPI_SCKMODE_PHA | \
 					  SIFIVE_SPI_SCKMODE_POL)

 /* csmode bits */
 #define SIFIVE_SPI_CSMODE_MODE_AUTO      0U
 #define SIFIVE_SPI_CSMODE_MODE_HOLD      2U
 #define SIFIVE_SPI_CSMODE_MODE_OFF       3U

 /* delay0 bits */
 #define SIFIVE_SPI_DELAY0_CSSCK(x)       ((u32)(x))
 #define SIFIVE_SPI_DELAY0_CSSCK_MASK     0xffU
 #define SIFIVE_SPI_DELAY0_SCKCS(x)       ((u32)(x) << 16)
 #define SIFIVE_SPI_DELAY0_SCKCS_MASK     (0xffU << 16)

 /* delay1 bits */
 #define SIFIVE_SPI_DELAY1_INTERCS(x)     ((u32)(x))
 #define SIFIVE_SPI_DELAY1_INTERCS_MASK   0xffU
 #define SIFIVE_SPI_DELAY1_INTERXFR(x)    ((u32)(x) << 16)
 #define SIFIVE_SPI_DELAY1_INTERXFR_MASK  (0xffU << 16)

 /* fmt bits */
 #define SIFIVE_SPI_FMT_PROTO_SINGLE      0U
 #define SIFIVE_SPI_FMT_PROTO_DUAL        1U
 #define SIFIVE_SPI_FMT_PROTO_QUAD        2U
 #define SIFIVE_SPI_FMT_PROTO_MASK        3U
 #define SIFIVE_SPI_FMT_ENDIAN            BIT(2)
 #define SIFIVE_SPI_FMT_DIR               BIT(3)
 #define SIFIVE_SPI_FMT_LEN(x)            ((u32)(x) << 16)
 #define SIFIVE_SPI_FMT_LEN_MASK          (0xfU << 16)

 /* txdata bits */
 #define SIFIVE_SPI_TXDATA_DATA_MASK      0xffU
 #define SIFIVE_SPI_TXDATA_FULL           BIT(31)

 /* rxdata bits */
 #define SIFIVE_SPI_RXDATA_DATA_MASK      0xffU
 #define SIFIVE_SPI_RXDATA_EMPTY          BIT(31)

 /* ie and ip bits */
 #define SIFIVE_SPI_IP_TXWM               BIT(0)
 #define SIFIVE_SPI_IP_RXWM               BIT(1)

 /* format protocol */
 #define SIFIVE_SPI_PROTO_QUAD		4 /* 4 lines I/O protocol transfer */
 #define SIFIVE_SPI_PROTO_DUAL		2 /* 2 lines I/O protocol transfer */
 #define SIFIVE_SPI_PROTO_SINGLE		1 /* 1 line I/O protocol transfer */

 struct sifive_spi {
 	void		*regs;		/* base address of the registers */
 	u32		fifo_depth;
 	u32		bits_per_word;
 	u32		cs_inactive;	/* Level of the CS pins when inactive*/
 	u32		freq;
 	u32		num_cs;
 	u8		fmt_proto;
 };

 static void sifive_spi_prep_device(struct sifive_spi *spi,
 				   struct dm_spi_slave_plat *slave_plat)
 {
 	/* Update the chip select polarity */
 	if (slave_plat->mode & SPI_CS_HIGH)
 		spi->cs_inactive &= ~BIT(slave_plat->cs[0]);
 	else
 		spi->cs_inactive |= BIT(slave_plat->cs[0]);
 	writel(spi->cs_inactive, spi->regs + SIFIVE_SPI_REG_CSDEF);

 	/* Select the correct device */
 	writel(slave_plat->cs[0], spi->regs + SIFIVE_SPI_REG_CSID);
 }

 static int sifive_spi_set_cs(struct sifive_spi *spi,
 			     struct dm_spi_slave_plat *slave_plat)
 {
 	u32 cs_mode = SIFIVE_SPI_CSMODE_MODE_HOLD;

 	if (slave_plat->mode & SPI_CS_HIGH)
 		cs_mode = SIFIVE_SPI_CSMODE_MODE_AUTO;

 	writel(cs_mode, spi->regs + SIFIVE_SPI_REG_CSMODE);

 	return 0;
 }

 static void sifive_spi_clear_cs(struct sifive_spi *spi)
 {
 	writel(SIFIVE_SPI_CSMODE_MODE_AUTO, spi->regs + SIFIVE_SPI_REG_CSMODE);
 }

 static void sifive_spi_prep_transfer(struct sifive_spi *spi,
 				     struct dm_spi_slave_plat *slave_plat,
 				     u8 *rx_ptr)
 {
 	u32 cr;

 	/* Modify the SPI protocol mode */
 	cr = readl(spi->regs + SIFIVE_SPI_REG_FMT);

 	/* Bits per word ? */
 	cr &= ~SIFIVE_SPI_FMT_LEN_MASK;
 	cr |= SIFIVE_SPI_FMT_LEN(spi->bits_per_word);

 	/* LSB first? */
 	cr &= ~SIFIVE_SPI_FMT_ENDIAN;
 	if (slave_plat->mode & SPI_LSB_FIRST)
 		cr |= SIFIVE_SPI_FMT_ENDIAN;

 	/* Number of wires ? */
 	cr &= ~SIFIVE_SPI_FMT_PROTO_MASK;
 	switch (spi->fmt_proto) {
 	case SIFIVE_SPI_PROTO_QUAD:
 		cr |= SIFIVE_SPI_FMT_PROTO_QUAD;
 		break;
 	case SIFIVE_SPI_PROTO_DUAL:
 		cr |= SIFIVE_SPI_FMT_PROTO_DUAL;
 		break;
 	default:
 		cr |= SIFIVE_SPI_FMT_PROTO_SINGLE;
 		break;
 	}

 	/* SPI direction in/out ? */
 	cr &= ~SIFIVE_SPI_FMT_DIR;
 	if (!rx_ptr)
 		cr |= SIFIVE_SPI_FMT_DIR;

 	writel(cr, spi->regs + SIFIVE_SPI_REG_FMT);
 }

 static void sifive_spi_rx(struct sifive_spi *spi, u8 *rx_ptr)
 {
 	u32 data;

 	do {
 		data = readl(spi->regs + SIFIVE_SPI_REG_RXDATA);
 	} while (data & SIFIVE_SPI_RXDATA_EMPTY);

 	if (rx_ptr)
 		*rx_ptr = data & SIFIVE_SPI_RXDATA_DATA_MASK;
 }

 static void sifive_spi_tx(struct sifive_spi *spi, const u8 *tx_ptr)
 {
 	u32 data;
 	u8 tx_data = (tx_ptr) ? *tx_ptr & SIFIVE_SPI_TXDATA_DATA_MASK :
 				SIFIVE_SPI_TXDATA_DATA_MASK;

 	do {
 		data = readl(spi->regs + SIFIVE_SPI_REG_TXDATA);
 	} while (data & SIFIVE_SPI_TXDATA_FULL);

 	writel(tx_data, spi->regs + SIFIVE_SPI_REG_TXDATA);
 }

 static int sifive_spi_wait(struct sifive_spi *spi, u32 bit)
 {
 	return wait_for_bit_le32(spi->regs + SIFIVE_SPI_REG_IP,
 				 bit, true, 100, false);
 }

 static int sifive_spi_xfer(struct udevice *dev, unsigned int bitlen,
 			   const void *dout, void *din, unsigned long flags)
 {
 	struct udevice *bus = dev->parent;
 	struct sifive_spi *spi = dev_get_priv(bus);
 	struct dm_spi_slave_plat *slave_plat = dev_get_parent_plat(dev);
 	const u8 *tx_ptr = dout;
 	u8 *rx_ptr = din;
 	u32 remaining_len;
 	int ret;

 	if (flags & SPI_XFER_BEGIN) {
 		sifive_spi_prep_device(spi, slave_plat);

 		ret = sifive_spi_set_cs(spi, slave_plat);
 		if (ret)
 			return ret;
 	}

 	sifive_spi_prep_transfer(spi, slave_plat, rx_ptr);

 	remaining_len = bitlen / 8;

 	while (remaining_len) {
 		unsigned int n_words = min(remaining_len, spi->fifo_depth);
 		unsigned int tx_words, rx_words;

 		/* Enqueue n_words for transmission */
 		for (tx_words = 0; tx_words < n_words; tx_words++) {
 			if (!tx_ptr)
 				sifive_spi_tx(spi, NULL);
 			else
 				sifive_spi_tx(spi, tx_ptr++);
 		}

 		if (rx_ptr) {
 			/* Wait for transmission + reception to complete */
 			writel(n_words - 1, spi->regs + SIFIVE_SPI_REG_RXMARK);
 			ret = sifive_spi_wait(spi, SIFIVE_SPI_IP_RXWM);
 			if (ret)
 				return ret;

 			/* Read out all the data from the RX FIFO */
 			for (rx_words = 0; rx_words < n_words; rx_words++)
 				sifive_spi_rx(spi, rx_ptr++);
 		} else {
 			/* Wait for transmission to complete */
 			ret = sifive_spi_wait(spi, SIFIVE_SPI_IP_TXWM);
 			if (ret)
 				return ret;
 		}

 		remaining_len -= n_words;
 	}

 	if (flags & SPI_XFER_END)
 		sifive_spi_clear_cs(spi);

 	return 0;
 }

 static int sifive_spi_exec_op(struct spi_slave *slave,
 			      const struct spi_mem_op *op)
 {
 	struct udevice *dev = slave->dev;
 	struct sifive_spi *spi = dev_get_priv(dev->parent);
 	unsigned long flags = SPI_XFER_BEGIN;
 	u8 opcode = op->cmd.opcode;
 	unsigned int pos = 0;
 	const void *tx_buf = NULL;
 	void *rx_buf = NULL;
 	int op_len, i;
 	int ret;

 	if (!op->addr.nbytes && !op->dummy.nbytes && !op->data.nbytes)
 		flags |= SPI_XFER_END;

 	spi->fmt_proto = op->cmd.buswidth;

 	/* send the opcode */
 	ret = sifive_spi_xfer(dev, 8, (void *)&opcode, NULL, flags);
 	if (ret < 0) {
 		dev_err(dev, "failed to xfer opcode\n");
 		return ret;
 	}

 	op_len = op->addr.nbytes + op->dummy.nbytes;
 	u8 op_buf[op_len];

 	/* send the addr + dummy */
 	if (op->addr.nbytes) {
 		/* fill address */
 		for (i = 0; i < op->addr.nbytes; i++)
 			op_buf[pos + i] = op->addr.val >>
 				(8 * (op->addr.nbytes - i - 1));

 		pos += op->addr.nbytes;

 		/* fill dummy */
 		if (op->dummy.nbytes)
 			memset(op_buf + pos, 0xff, op->dummy.nbytes);

 		/* make sure to set end flag, if no data bytes */
 		if (!op->data.nbytes)
 			flags |= SPI_XFER_END;

 		spi->fmt_proto = op->addr.buswidth;

 		ret = sifive_spi_xfer(dev, op_len * 8, op_buf, NULL, flags);
 		if (ret < 0) {
 			dev_err(dev, "failed to xfer addr + dummy\n");
 			return ret;
 		}
 	}

 	/* send/received the data */
 	if (op->data.nbytes) {
 		if (op->data.dir == SPI_MEM_DATA_IN)
 			rx_buf = op->data.buf.in;
 		else
 			tx_buf = op->data.buf.out;

 		spi->fmt_proto = op->data.buswidth;

 		ret = sifive_spi_xfer(dev, op->data.nbytes * 8,
 				      tx_buf, rx_buf, SPI_XFER_END);
 		if (ret) {
 			dev_err(dev, "failed to xfer data\n");
 			return ret;
 		}
 	}

 	return 0;
 }

 static int sifive_spi_set_speed(struct udevice *bus, uint speed)
 {
 	struct sifive_spi *spi = dev_get_priv(bus);
 	u32 scale;

 	if (speed > spi->freq)
 		speed = spi->freq;

 	/* Configure max speed */
 	scale = (DIV_ROUND_UP(spi->freq >> 1, speed) - 1)
 					& SIFIVE_SPI_SCKDIV_DIV_MASK;
 	writel(scale, spi->regs + SIFIVE_SPI_REG_SCKDIV);

 	return 0;
 }

 static int sifive_spi_set_mode(struct udevice *bus, uint mode)
 {
 	struct sifive_spi *spi = dev_get_priv(bus);
 	u32 cr;

 	/* Switch clock mode bits */
 	cr = readl(spi->regs + SIFIVE_SPI_REG_SCKMODE) &
 				~SIFIVE_SPI_SCKMODE_MODE_MASK;
 	if (mode & SPI_CPHA)
 		cr |= SIFIVE_SPI_SCKMODE_PHA;
 	if (mode & SPI_CPOL)
 		cr |= SIFIVE_SPI_SCKMODE_POL;

 	writel(cr, spi->regs + SIFIVE_SPI_REG_SCKMODE);

 	return 0;
 }

 static int sifive_spi_cs_info(struct udevice *bus, uint cs,
 			      struct spi_cs_info *info)
 {
 	struct sifive_spi *spi = dev_get_priv(bus);

 	if (cs >= spi->num_cs)
 		return -EINVAL;

 	return 0;
 }

 static void sifive_spi_init_hw(struct sifive_spi *spi)
 {
 	u32 cs_bits;

 	/* probe the number of CS lines */
 	spi->cs_inactive = readl(spi->regs + SIFIVE_SPI_REG_CSDEF);
 	writel(0xffffffffU, spi->regs + SIFIVE_SPI_REG_CSDEF);
 	cs_bits = readl(spi->regs + SIFIVE_SPI_REG_CSDEF);
 	writel(spi->cs_inactive, spi->regs + SIFIVE_SPI_REG_CSDEF);
 	if (!cs_bits) {
 		printf("Could not auto probe CS lines\n");
 		return;
 	}

 	spi->num_cs = ilog2(cs_bits) + 1;
 	if (spi->num_cs > SIFIVE_SPI_MAX_CS) {
 		printf("Invalid number of spi slaves\n");
 		return;
 	}

 	/* Watermark interrupts are disabled by default */
 	writel(0, spi->regs + SIFIVE_SPI_REG_IE);

 	/* Default watermark FIFO threshold values */
 	writel(1, spi->regs + SIFIVE_SPI_REG_TXMARK);
 	writel(0, spi->regs + SIFIVE_SPI_REG_RXMARK);

 	/* Set CS/SCK Delays and Inactive Time to defaults */
 	writel(SIFIVE_SPI_DELAY0_CSSCK(1) | SIFIVE_SPI_DELAY0_SCKCS(1),
 	       spi->regs + SIFIVE_SPI_REG_DELAY0);
 	writel(SIFIVE_SPI_DELAY1_INTERCS(1) | SIFIVE_SPI_DELAY1_INTERXFR(0),
 	       spi->regs + SIFIVE_SPI_REG_DELAY1);

 	/* Exit specialized memory-mapped SPI flash mode */
 	writel(0, spi->regs + SIFIVE_SPI_REG_FCTRL);
 }

 static int sifive_spi_probe(struct udevice *bus)
 {
 	struct sifive_spi *spi = dev_get_priv(bus);
 	struct clk clkdev;
 	int ret;

 	spi->regs = (void *)(ulong)dev_remap_addr(bus);
 	if (!spi->regs)
 		return -ENODEV;

 	spi->fifo_depth = dev_read_u32_default(bus,
 					       "sifive,fifo-depth",
 					       SIFIVE_SPI_DEFAULT_DEPTH);

 	spi->bits_per_word = dev_read_u32_default(bus,
 						  "sifive,max-bits-per-word",
 						  SIFIVE_SPI_DEFAULT_BITS);

 	ret = clk_get_by_index(bus, 0, &clkdev);
 	if (ret)
 		return ret;
 	spi->freq = clk_get_rate(&clkdev);

 	/* init the sifive spi hw */
 	sifive_spi_init_hw(spi);

 	return 0;
 }

 static const struct spi_controller_mem_ops sifive_spi_mem_ops = {
 	.exec_op	= sifive_spi_exec_op,
 };

 static const struct dm_spi_ops sifive_spi_ops = {
 	.xfer		= sifive_spi_xfer,
 	.set_speed	= sifive_spi_set_speed,
 	.set_mode	= sifive_spi_set_mode,
 	.cs_info        = sifive_spi_cs_info,
 	.mem_ops	= &sifive_spi_mem_ops,
 };

 static const struct udevice_id sifive_spi_ids[] = {
 	{ .compatible = "sifive,spi0" },
 	{ }
 };

 U_BOOT_DRIVER(sifive_spi) = {
 	.name	= "sifive_spi",
 	.id	= UCLASS_SPI,
 	.of_match = sifive_spi_ids,
 	.ops	= &sifive_spi_ops,
 	.priv_auto	= sizeof(struct sifive_spi),
 	.probe	= sifive_spi_probe,
 };
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Copyright 2018 SiFive, Inc.
	* Copyright 2019 Bhargav Shah <bhargavshah1988@gmail.com>
	*
	* SiFive SPI controller driver (master mode only)
	*/

	#include <dm.h>
	#include <dm/device_compat.h>
	#include <malloc.h>
	#include <spi.h>
	#include <spi-mem.h>
	#include <wait_bit.h>
	#include <asm/io.h>
	#include <linux/bitops.h>
	#include <linux/log2.h>
	#include <clk.h>

	#define SIFIVE_SPI_MAX_CS 32

	#define SIFIVE_SPI_DEFAULT_DEPTH 8
	#define SIFIVE_SPI_DEFAULT_BITS 8

	/* register offsets */
	#define SIFIVE_SPI_REG_SCKDIV 0x00 /* Serial clock divisor */
	#define SIFIVE_SPI_REG_SCKMODE 0x04 /* Serial clock mode */
	#define SIFIVE_SPI_REG_CSID 0x10 /* Chip select ID */
	#define SIFIVE_SPI_REG_CSDEF 0x14 /* Chip select default */
	#define SIFIVE_SPI_REG_CSMODE 0x18 /* Chip select mode */
	#define SIFIVE_SPI_REG_DELAY0 0x28 /* Delay control 0 */
	#define SIFIVE_SPI_REG_DELAY1 0x2c /* Delay control 1 */
	#define SIFIVE_SPI_REG_FMT 0x40 /* Frame format */
	#define SIFIVE_SPI_REG_TXDATA 0x48 /* Tx FIFO data */
	#define SIFIVE_SPI_REG_RXDATA 0x4c /* Rx FIFO data */
	#define SIFIVE_SPI_REG_TXMARK 0x50 /* Tx FIFO watermark */
	#define SIFIVE_SPI_REG_RXMARK 0x54 /* Rx FIFO watermark */
	#define SIFIVE_SPI_REG_FCTRL 0x60 /* SPI flash interface control */
	#define SIFIVE_SPI_REG_FFMT 0x64 /* SPI flash instruction format */
	#define SIFIVE_SPI_REG_IE 0x70 /* Interrupt Enable Register */
	#define SIFIVE_SPI_REG_IP 0x74 /* Interrupt Pendings Register */

	/* sckdiv bits */
	#define SIFIVE_SPI_SCKDIV_DIV_MASK 0xfffU

	/* sckmode bits */
	#define SIFIVE_SPI_SCKMODE_PHA BIT(0)
	#define SIFIVE_SPI_SCKMODE_POL BIT(1)
	#define SIFIVE_SPI_SCKMODE_MODE_MASK (SIFIVE_SPI_SCKMODE_PHA \| \
	SIFIVE_SPI_SCKMODE_POL)

	/* csmode bits */
	#define SIFIVE_SPI_CSMODE_MODE_AUTO 0U
	#define SIFIVE_SPI_CSMODE_MODE_HOLD 2U
	#define SIFIVE_SPI_CSMODE_MODE_OFF 3U

	/* delay0 bits */
	#define SIFIVE_SPI_DELAY0_CSSCK(x) ((u32)(x))
	#define SIFIVE_SPI_DELAY0_CSSCK_MASK 0xffU
	#define SIFIVE_SPI_DELAY0_SCKCS(x) ((u32)(x) << 16)
	#define SIFIVE_SPI_DELAY0_SCKCS_MASK (0xffU << 16)

	/* delay1 bits */
	#define SIFIVE_SPI_DELAY1_INTERCS(x) ((u32)(x))
	#define SIFIVE_SPI_DELAY1_INTERCS_MASK 0xffU
	#define SIFIVE_SPI_DELAY1_INTERXFR(x) ((u32)(x) << 16)
	#define SIFIVE_SPI_DELAY1_INTERXFR_MASK (0xffU << 16)

	/* fmt bits */
	#define SIFIVE_SPI_FMT_PROTO_SINGLE 0U
	#define SIFIVE_SPI_FMT_PROTO_DUAL 1U
	#define SIFIVE_SPI_FMT_PROTO_QUAD 2U
	#define SIFIVE_SPI_FMT_PROTO_MASK 3U
	#define SIFIVE_SPI_FMT_ENDIAN BIT(2)
	#define SIFIVE_SPI_FMT_DIR BIT(3)
	#define SIFIVE_SPI_FMT_LEN(x) ((u32)(x) << 16)
	#define SIFIVE_SPI_FMT_LEN_MASK (0xfU << 16)

	/* txdata bits */
	#define SIFIVE_SPI_TXDATA_DATA_MASK 0xffU
	#define SIFIVE_SPI_TXDATA_FULL BIT(31)

	/* rxdata bits */
	#define SIFIVE_SPI_RXDATA_DATA_MASK 0xffU
	#define SIFIVE_SPI_RXDATA_EMPTY BIT(31)

	/* ie and ip bits */
	#define SIFIVE_SPI_IP_TXWM BIT(0)
	#define SIFIVE_SPI_IP_RXWM BIT(1)

	/* format protocol */
	#define SIFIVE_SPI_PROTO_QUAD 4 /* 4 lines I/O protocol transfer */
	#define SIFIVE_SPI_PROTO_DUAL 2 /* 2 lines I/O protocol transfer */
	#define SIFIVE_SPI_PROTO_SINGLE 1 /* 1 line I/O protocol transfer */

	struct sifive_spi {
	void regs; / base address of the registers */
	u32 fifo_depth;
	u32 bits_per_word;
	u32 cs_inactive; /* Level of the CS pins when inactive*/
	u32 freq;
	u32 num_cs;
	u8 fmt_proto;
	};

	static void sifive_spi_prep_device(struct sifive_spi *spi,
	struct dm_spi_slave_plat *slave_plat)
	{
	/* Update the chip select polarity */
	if (slave_plat->mode & SPI_CS_HIGH)
	spi->cs_inactive &= ~BIT(slave_plat->cs[0]);
	else
	spi->cs_inactive \|= BIT(slave_plat->cs[0]);
	writel(spi->cs_inactive, spi->regs + SIFIVE_SPI_REG_CSDEF);

	/* Select the correct device */
	writel(slave_plat->cs[0], spi->regs + SIFIVE_SPI_REG_CSID);
	}

	static int sifive_spi_set_cs(struct sifive_spi *spi,
	struct dm_spi_slave_plat *slave_plat)
	{
	u32 cs_mode = SIFIVE_SPI_CSMODE_MODE_HOLD;

	if (slave_plat->mode & SPI_CS_HIGH)
	cs_mode = SIFIVE_SPI_CSMODE_MODE_AUTO;

	writel(cs_mode, spi->regs + SIFIVE_SPI_REG_CSMODE);

	return 0;
	}

	static void sifive_spi_clear_cs(struct sifive_spi *spi)
	{
	writel(SIFIVE_SPI_CSMODE_MODE_AUTO, spi->regs + SIFIVE_SPI_REG_CSMODE);
	}

	static void sifive_spi_prep_transfer(struct sifive_spi *spi,
	struct dm_spi_slave_plat *slave_plat,
	u8 *rx_ptr)
	{
	u32 cr;

	/* Modify the SPI protocol mode */
	cr = readl(spi->regs + SIFIVE_SPI_REG_FMT);

	/* Bits per word ? */
	cr &= ~SIFIVE_SPI_FMT_LEN_MASK;
	cr \|= SIFIVE_SPI_FMT_LEN(spi->bits_per_word);

	/* LSB first? */
	cr &= ~SIFIVE_SPI_FMT_ENDIAN;
	if (slave_plat->mode & SPI_LSB_FIRST)
	cr \|= SIFIVE_SPI_FMT_ENDIAN;

	/* Number of wires ? */
	cr &= ~SIFIVE_SPI_FMT_PROTO_MASK;
	switch (spi->fmt_proto) {
	case SIFIVE_SPI_PROTO_QUAD:
	cr \|= SIFIVE_SPI_FMT_PROTO_QUAD;
	break;
	case SIFIVE_SPI_PROTO_DUAL:
	cr \|= SIFIVE_SPI_FMT_PROTO_DUAL;
	break;
	default:
	cr \|= SIFIVE_SPI_FMT_PROTO_SINGLE;
	break;
	}

	/* SPI direction in/out ? */
	cr &= ~SIFIVE_SPI_FMT_DIR;
	if (!rx_ptr)
	cr \|= SIFIVE_SPI_FMT_DIR;

	writel(cr, spi->regs + SIFIVE_SPI_REG_FMT);
	}

	static void sifive_spi_rx(struct sifive_spi spi, u8 rx_ptr)
	{
	u32 data;

	do {
	data = readl(spi->regs + SIFIVE_SPI_REG_RXDATA);
	} while (data & SIFIVE_SPI_RXDATA_EMPTY);

	if (rx_ptr)
	*rx_ptr = data & SIFIVE_SPI_RXDATA_DATA_MASK;
	}

	static void sifive_spi_tx(struct sifive_spi spi, const u8 tx_ptr)
	{
	u32 data;
	u8 tx_data = (tx_ptr) ? *tx_ptr & SIFIVE_SPI_TXDATA_DATA_MASK :
	SIFIVE_SPI_TXDATA_DATA_MASK;

	do {
	data = readl(spi->regs + SIFIVE_SPI_REG_TXDATA);
	} while (data & SIFIVE_SPI_TXDATA_FULL);

	writel(tx_data, spi->regs + SIFIVE_SPI_REG_TXDATA);
	}

	static int sifive_spi_wait(struct sifive_spi *spi, u32 bit)
	{
	return wait_for_bit_le32(spi->regs + SIFIVE_SPI_REG_IP,
	bit, true, 100, false);
	}

	static int sifive_spi_xfer(struct udevice *dev, unsigned int bitlen,
	const void dout, void din, unsigned long flags)
	{
	struct udevice *bus = dev->parent;
	struct sifive_spi *spi = dev_get_priv(bus);
	struct dm_spi_slave_plat *slave_plat = dev_get_parent_plat(dev);
	const u8 *tx_ptr = dout;
	u8 *rx_ptr = din;
	u32 remaining_len;
	int ret;

	if (flags & SPI_XFER_BEGIN) {
	sifive_spi_prep_device(spi, slave_plat);

	ret = sifive_spi_set_cs(spi, slave_plat);
	if (ret)
	return ret;
	}

	sifive_spi_prep_transfer(spi, slave_plat, rx_ptr);

	remaining_len = bitlen / 8;

	while (remaining_len) {
	unsigned int n_words = min(remaining_len, spi->fifo_depth);
	unsigned int tx_words, rx_words;

	/* Enqueue n_words for transmission */
	for (tx_words = 0; tx_words < n_words; tx_words++) {
	if (!tx_ptr)
	sifive_spi_tx(spi, NULL);
	else
	sifive_spi_tx(spi, tx_ptr++);
	}

	if (rx_ptr) {
	/* Wait for transmission + reception to complete */
	writel(n_words - 1, spi->regs + SIFIVE_SPI_REG_RXMARK);
	ret = sifive_spi_wait(spi, SIFIVE_SPI_IP_RXWM);
	if (ret)
	return ret;

	/* Read out all the data from the RX FIFO */
	for (rx_words = 0; rx_words < n_words; rx_words++)
	sifive_spi_rx(spi, rx_ptr++);
	} else {
	/* Wait for transmission to complete */
	ret = sifive_spi_wait(spi, SIFIVE_SPI_IP_TXWM);
	if (ret)
	return ret;
	}

	remaining_len -= n_words;
	}

	if (flags & SPI_XFER_END)
	sifive_spi_clear_cs(spi);

	return 0;
	}

	static int sifive_spi_exec_op(struct spi_slave *slave,
	const struct spi_mem_op *op)
	{
	struct udevice *dev = slave->dev;
	struct sifive_spi *spi = dev_get_priv(dev->parent);
	unsigned long flags = SPI_XFER_BEGIN;
	u8 opcode = op->cmd.opcode;
	unsigned int pos = 0;
	const void *tx_buf = NULL;
	void *rx_buf = NULL;
	int op_len, i;
	int ret;

	if (!op->addr.nbytes && !op->dummy.nbytes && !op->data.nbytes)
	flags \|= SPI_XFER_END;

	spi->fmt_proto = op->cmd.buswidth;

	/* send the opcode */
	ret = sifive_spi_xfer(dev, 8, (void *)&opcode, NULL, flags);
	if (ret < 0) {
	dev_err(dev, "failed to xfer opcode\n");
	return ret;
	}

	op_len = op->addr.nbytes + op->dummy.nbytes;
	u8 op_buf[op_len];

	/* send the addr + dummy */
	if (op->addr.nbytes) {
	/* fill address */
	for (i = 0; i < op->addr.nbytes; i++)
	op_buf[pos + i] = op->addr.val >>
	(8 * (op->addr.nbytes - i - 1));

	pos += op->addr.nbytes;

	/* fill dummy */
	if (op->dummy.nbytes)
	memset(op_buf + pos, 0xff, op->dummy.nbytes);

	/* make sure to set end flag, if no data bytes */
	if (!op->data.nbytes)
	flags \|= SPI_XFER_END;

	spi->fmt_proto = op->addr.buswidth;

	ret = sifive_spi_xfer(dev, op_len * 8, op_buf, NULL, flags);
	if (ret < 0) {
	dev_err(dev, "failed to xfer addr + dummy\n");
	return ret;
	}
	}

	/* send/received the data */
	if (op->data.nbytes) {
	if (op->data.dir == SPI_MEM_DATA_IN)
	rx_buf = op->data.buf.in;
	else
	tx_buf = op->data.buf.out;

	spi->fmt_proto = op->data.buswidth;

	ret = sifive_spi_xfer(dev, op->data.nbytes * 8,
	tx_buf, rx_buf, SPI_XFER_END);
	if (ret) {
	dev_err(dev, "failed to xfer data\n");
	return ret;
	}
	}

	return 0;
	}

	static int sifive_spi_set_speed(struct udevice *bus, uint speed)
	{
	struct sifive_spi *spi = dev_get_priv(bus);
	u32 scale;

	if (speed > spi->freq)
	speed = spi->freq;

	/* Configure max speed */
	scale = (DIV_ROUND_UP(spi->freq >> 1, speed) - 1)
	& SIFIVE_SPI_SCKDIV_DIV_MASK;
	writel(scale, spi->regs + SIFIVE_SPI_REG_SCKDIV);

	return 0;
	}

	static int sifive_spi_set_mode(struct udevice *bus, uint mode)
	{
	struct sifive_spi *spi = dev_get_priv(bus);
	u32 cr;

	/* Switch clock mode bits */
	cr = readl(spi->regs + SIFIVE_SPI_REG_SCKMODE) &
	~SIFIVE_SPI_SCKMODE_MODE_MASK;
	if (mode & SPI_CPHA)
	cr \|= SIFIVE_SPI_SCKMODE_PHA;
	if (mode & SPI_CPOL)
	cr \|= SIFIVE_SPI_SCKMODE_POL;

	writel(cr, spi->regs + SIFIVE_SPI_REG_SCKMODE);

	return 0;
	}

	static int sifive_spi_cs_info(struct udevice *bus, uint cs,
	struct spi_cs_info *info)
	{
	struct sifive_spi *spi = dev_get_priv(bus);

	if (cs >= spi->num_cs)
	return -EINVAL;

	return 0;
	}

	static void sifive_spi_init_hw(struct sifive_spi *spi)
	{
	u32 cs_bits;

	/* probe the number of CS lines */
	spi->cs_inactive = readl(spi->regs + SIFIVE_SPI_REG_CSDEF);
	writel(0xffffffffU, spi->regs + SIFIVE_SPI_REG_CSDEF);
	cs_bits = readl(spi->regs + SIFIVE_SPI_REG_CSDEF);
	writel(spi->cs_inactive, spi->regs + SIFIVE_SPI_REG_CSDEF);
	if (!cs_bits) {
	printf("Could not auto probe CS lines\n");
	return;
	}

	spi->num_cs = ilog2(cs_bits) + 1;
	if (spi->num_cs > SIFIVE_SPI_MAX_CS) {
	printf("Invalid number of spi slaves\n");
	return;
	}

	/* Watermark interrupts are disabled by default */
	writel(0, spi->regs + SIFIVE_SPI_REG_IE);

	/* Default watermark FIFO threshold values */
	writel(1, spi->regs + SIFIVE_SPI_REG_TXMARK);
	writel(0, spi->regs + SIFIVE_SPI_REG_RXMARK);

	/* Set CS/SCK Delays and Inactive Time to defaults */
	writel(SIFIVE_SPI_DELAY0_CSSCK(1) \| SIFIVE_SPI_DELAY0_SCKCS(1),
	spi->regs + SIFIVE_SPI_REG_DELAY0);
	writel(SIFIVE_SPI_DELAY1_INTERCS(1) \| SIFIVE_SPI_DELAY1_INTERXFR(0),
	spi->regs + SIFIVE_SPI_REG_DELAY1);

	/* Exit specialized memory-mapped SPI flash mode */
	writel(0, spi->regs + SIFIVE_SPI_REG_FCTRL);
	}

	static int sifive_spi_probe(struct udevice *bus)
	{
	struct sifive_spi *spi = dev_get_priv(bus);
	struct clk clkdev;
	int ret;

	spi->regs = (void *)(ulong)dev_remap_addr(bus);
	if (!spi->regs)
	return -ENODEV;

	spi->fifo_depth = dev_read_u32_default(bus,
	"sifive,fifo-depth",
	SIFIVE_SPI_DEFAULT_DEPTH);

	spi->bits_per_word = dev_read_u32_default(bus,
	"sifive,max-bits-per-word",
	SIFIVE_SPI_DEFAULT_BITS);

	ret = clk_get_by_index(bus, 0, &clkdev);
	if (ret)
	return ret;
	spi->freq = clk_get_rate(&clkdev);

	/* init the sifive spi hw */
	sifive_spi_init_hw(spi);

	return 0;
	}

	static const struct spi_controller_mem_ops sifive_spi_mem_ops = {
	.exec_op = sifive_spi_exec_op,
	};

	static const struct dm_spi_ops sifive_spi_ops = {
	.xfer = sifive_spi_xfer,
	.set_speed = sifive_spi_set_speed,
	.set_mode = sifive_spi_set_mode,
	.cs_info = sifive_spi_cs_info,
	.mem_ops = &sifive_spi_mem_ops,
	};

	static const struct udevice_id sifive_spi_ids[] = {
	{ .compatible = "sifive,spi0" },
	{ }
	};

	U_BOOT_DRIVER(sifive_spi) = {
	.name = "sifive_spi",
	.id = UCLASS_SPI,
	.of_match = sifive_spi_ids,
	.ops = &sifive_spi_ops,
	.priv_auto = sizeof(struct sifive_spi),
	.probe = sifive_spi_probe,
	};