drivers/spi/spi-amd.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
 //
 // AMD SPI controller driver
 //
 // Copyright (c) 2020, Advanced Micro Devices, Inc.
 //
 // Author: Sanjay R Mehta <sanju.mehta@amd.com>

 #include <linux/acpi.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/delay.h>
 #include <linux/spi/spi.h>
 #include <linux/iopoll.h>
 #include <linux/spi/spi-mem.h>

 #define AMD_SPI_CTRL0_REG	0x00
 #define AMD_SPI_EXEC_CMD	BIT(16)
 #define AMD_SPI_FIFO_CLEAR	BIT(20)
 #define AMD_SPI_BUSY		BIT(31)

 #define AMD_SPI_OPCODE_REG	0x45
 #define AMD_SPI_CMD_TRIGGER_REG	0x47
 #define AMD_SPI_TRIGGER_CMD	BIT(7)

 #define AMD_SPI_OPCODE_MASK	0xFF

 #define AMD_SPI_ALT_CS_REG	0x1D
 #define AMD_SPI_ALT_CS_MASK	0x3

 #define AMD_SPI_FIFO_BASE	0x80
 #define AMD_SPI_TX_COUNT_REG	0x48
 #define AMD_SPI_RX_COUNT_REG	0x4B
 #define AMD_SPI_STATUS_REG	0x4C

 #define AMD_SPI_FIFO_SIZE	70
 #define AMD_SPI_MEM_SIZE	200
 #define AMD_SPI_MAX_DATA	64

 #define AMD_SPI_ENA_REG		0x20
 #define AMD_SPI_ALT_SPD_SHIFT	20
 #define AMD_SPI_ALT_SPD_MASK	GENMASK(23, AMD_SPI_ALT_SPD_SHIFT)
 #define AMD_SPI_SPI100_SHIFT	0
 #define AMD_SPI_SPI100_MASK	GENMASK(AMD_SPI_SPI100_SHIFT, AMD_SPI_SPI100_SHIFT)
 #define AMD_SPI_SPEED_REG	0x6C
 #define AMD_SPI_SPD7_SHIFT	8
 #define AMD_SPI_SPD7_MASK	GENMASK(13, AMD_SPI_SPD7_SHIFT)

 #define AMD_SPI_MAX_HZ		100000000
 #define AMD_SPI_MIN_HZ		800000

 /**
  * enum amd_spi_versions - SPI controller versions
  * @AMD_SPI_V1:		AMDI0061 hardware version
  * @AMD_SPI_V2:		AMDI0062 hardware version
  */
 enum amd_spi_versions {
 	AMD_SPI_V1 = 1,
 	AMD_SPI_V2,
 };

 enum amd_spi_speed {
 	F_66_66MHz,
 	F_33_33MHz,
 	F_22_22MHz,
 	F_16_66MHz,
 	F_100MHz,
 	F_800KHz,
 	SPI_SPD7 = 0x7,
 	F_50MHz = 0x4,
 	F_4MHz = 0x32,
 	F_3_17MHz = 0x3F
 };

 /**
  * struct amd_spi_freq - Matches device speed with values to write in regs
  * @speed_hz: Device frequency
  * @enable_val: Value to be written to "enable register"
  * @spd7_val: Some frequencies requires to have a value written at SPISPEED register
  */
 struct amd_spi_freq {
 	u32 speed_hz;
 	u32 enable_val;
 	u32 spd7_val;
 };

 /**
  * struct amd_spi - SPI driver instance
  * @io_remap_addr:	Start address of the SPI controller registers
  * @version:		SPI controller hardware version
  * @speed_hz:		Device frequency
  */
 struct amd_spi {
 	void __iomem *io_remap_addr;
 	enum amd_spi_versions version;
 	unsigned int speed_hz;
 };

 static inline u8 amd_spi_readreg8(struct amd_spi *amd_spi, int idx)
 {
 	return ioread8((u8 __iomem *)amd_spi->io_remap_addr + idx);
 }

 static inline void amd_spi_writereg8(struct amd_spi *amd_spi, int idx, u8 val)
 {
 	iowrite8(val, ((u8 __iomem *)amd_spi->io_remap_addr + idx));
 }

 static void amd_spi_setclear_reg8(struct amd_spi *amd_spi, int idx, u8 set, u8 clear)
 {
 	u8 tmp = amd_spi_readreg8(amd_spi, idx);

 	tmp = (tmp & ~clear) | set;
 	amd_spi_writereg8(amd_spi, idx, tmp);
 }

 static inline u32 amd_spi_readreg32(struct amd_spi *amd_spi, int idx)
 {
 	return ioread32((u8 __iomem *)amd_spi->io_remap_addr + idx);
 }

 static inline void amd_spi_writereg32(struct amd_spi *amd_spi, int idx, u32 val)
 {
 	iowrite32(val, ((u8 __iomem *)amd_spi->io_remap_addr + idx));
 }

 static inline void amd_spi_setclear_reg32(struct amd_spi *amd_spi, int idx, u32 set, u32 clear)
 {
 	u32 tmp = amd_spi_readreg32(amd_spi, idx);

 	tmp = (tmp & ~clear) | set;
 	amd_spi_writereg32(amd_spi, idx, tmp);
 }

 static void amd_spi_select_chip(struct amd_spi *amd_spi, u8 cs)
 {
 	amd_spi_setclear_reg8(amd_spi, AMD_SPI_ALT_CS_REG, cs, AMD_SPI_ALT_CS_MASK);
 }

 static inline void amd_spi_clear_chip(struct amd_spi *amd_spi, u8 chip_select)
 {
 	amd_spi_writereg8(amd_spi, AMD_SPI_ALT_CS_REG, chip_select & ~AMD_SPI_ALT_CS_MASK);
 }

 static void amd_spi_clear_fifo_ptr(struct amd_spi *amd_spi)
 {
 	amd_spi_setclear_reg32(amd_spi, AMD_SPI_CTRL0_REG, AMD_SPI_FIFO_CLEAR, AMD_SPI_FIFO_CLEAR);
 }

 static int amd_spi_set_opcode(struct amd_spi *amd_spi, u8 cmd_opcode)
 {
 	switch (amd_spi->version) {
 	case AMD_SPI_V1:
 		amd_spi_setclear_reg32(amd_spi, AMD_SPI_CTRL0_REG, cmd_opcode,
 				       AMD_SPI_OPCODE_MASK);
 		return 0;
 	case AMD_SPI_V2:
 		amd_spi_writereg8(amd_spi, AMD_SPI_OPCODE_REG, cmd_opcode);
 		return 0;
 	default:
 		return -ENODEV;
 	}
 }

 static inline void amd_spi_set_rx_count(struct amd_spi *amd_spi, u8 rx_count)
 {
 	amd_spi_setclear_reg8(amd_spi, AMD_SPI_RX_COUNT_REG, rx_count, 0xff);
 }

 static inline void amd_spi_set_tx_count(struct amd_spi *amd_spi, u8 tx_count)
 {
 	amd_spi_setclear_reg8(amd_spi, AMD_SPI_TX_COUNT_REG, tx_count, 0xff);
 }

 static int amd_spi_busy_wait(struct amd_spi *amd_spi)
 {
 	u32 val;
 	int reg;

 	switch (amd_spi->version) {
 	case AMD_SPI_V1:
 		reg = AMD_SPI_CTRL0_REG;
 		break;
 	case AMD_SPI_V2:
 		reg = AMD_SPI_STATUS_REG;
 		break;
 	default:
 		return -ENODEV;
 	}

 	return readl_poll_timeout(amd_spi->io_remap_addr + reg, val,
 				  !(val & AMD_SPI_BUSY), 20, 2000000);
 }

 static int amd_spi_execute_opcode(struct amd_spi *amd_spi)
 {
 	int ret;

 	ret = amd_spi_busy_wait(amd_spi);
 	if (ret)
 		return ret;

 	switch (amd_spi->version) {
 	case AMD_SPI_V1:
 		/* Set ExecuteOpCode bit in the CTRL0 register */
 		amd_spi_setclear_reg32(amd_spi, AMD_SPI_CTRL0_REG, AMD_SPI_EXEC_CMD,
 				       AMD_SPI_EXEC_CMD);
 		return 0;
 	case AMD_SPI_V2:
 		/* Trigger the command execution */
 		amd_spi_setclear_reg8(amd_spi, AMD_SPI_CMD_TRIGGER_REG,
 				      AMD_SPI_TRIGGER_CMD, AMD_SPI_TRIGGER_CMD);
 		return 0;
 	default:
 		return -ENODEV;
 	}
 }

 static int amd_spi_host_setup(struct spi_device *spi)
 {
 	struct amd_spi *amd_spi = spi_controller_get_devdata(spi->controller);

 	amd_spi_clear_fifo_ptr(amd_spi);

 	return 0;
 }

 static const struct amd_spi_freq amd_spi_freq[] = {
 	{ AMD_SPI_MAX_HZ,   F_100MHz,         0},
 	{       66660000, F_66_66MHz,         0},
 	{       50000000,   SPI_SPD7,   F_50MHz},
 	{       33330000, F_33_33MHz,         0},
 	{       22220000, F_22_22MHz,         0},
 	{       16660000, F_16_66MHz,         0},
 	{        4000000,   SPI_SPD7,    F_4MHz},
 	{        3170000,   SPI_SPD7, F_3_17MHz},
 	{ AMD_SPI_MIN_HZ,   F_800KHz,         0},
 };

 static int amd_set_spi_freq(struct amd_spi *amd_spi, u32 speed_hz)
 {
 	unsigned int i, spd7_val, alt_spd;

 	if (speed_hz < AMD_SPI_MIN_HZ)
 		return -EINVAL;

 	for (i = 0; i < ARRAY_SIZE(amd_spi_freq); i++)
 		if (speed_hz >= amd_spi_freq[i].speed_hz)
 			break;

 	if (amd_spi->speed_hz == amd_spi_freq[i].speed_hz)
 		return 0;

 	amd_spi->speed_hz = amd_spi_freq[i].speed_hz;

 	alt_spd = (amd_spi_freq[i].enable_val << AMD_SPI_ALT_SPD_SHIFT)
 		   & AMD_SPI_ALT_SPD_MASK;
 	amd_spi_setclear_reg32(amd_spi, AMD_SPI_ENA_REG, alt_spd,
 			       AMD_SPI_ALT_SPD_MASK);

 	if (amd_spi->speed_hz == AMD_SPI_MAX_HZ)
 		amd_spi_setclear_reg32(amd_spi, AMD_SPI_ENA_REG, 1,
 				       AMD_SPI_SPI100_MASK);

 	if (amd_spi_freq[i].spd7_val) {
 		spd7_val = (amd_spi_freq[i].spd7_val << AMD_SPI_SPD7_SHIFT)
 			    & AMD_SPI_SPD7_MASK;
 		amd_spi_setclear_reg32(amd_spi, AMD_SPI_SPEED_REG, spd7_val,
 				       AMD_SPI_SPD7_MASK);
 	}

 	return 0;
 }

 static inline int amd_spi_fifo_xfer(struct amd_spi *amd_spi,
 				    struct spi_controller *host,
 				    struct spi_message *message)
 {
 	struct spi_transfer *xfer = NULL;
 	struct spi_device *spi = message->spi;
 	u8 cmd_opcode = 0, fifo_pos = AMD_SPI_FIFO_BASE;
 	u8 *buf = NULL;
 	u32 i = 0;
 	u32 tx_len = 0, rx_len = 0;

 	list_for_each_entry(xfer, &message->transfers,
 			    transfer_list) {
 		if (xfer->speed_hz)
 			amd_set_spi_freq(amd_spi, xfer->speed_hz);
 		else
 			amd_set_spi_freq(amd_spi, spi->max_speed_hz);

 		if (xfer->tx_buf) {
 			buf = (u8 *)xfer->tx_buf;
 			if (!tx_len) {
 				cmd_opcode = *(u8 *)xfer->tx_buf;
 				buf++;
 				xfer->len--;
 			}
 			tx_len += xfer->len;

 			/* Write data into the FIFO. */
 			for (i = 0; i < xfer->len; i++)
 				amd_spi_writereg8(amd_spi, fifo_pos + i, buf[i]);

 			fifo_pos += xfer->len;
 		}

 		/* Store no. of bytes to be received from FIFO */
 		if (xfer->rx_buf)
 			rx_len += xfer->len;
 	}

 	if (!buf) {
 		message->status = -EINVAL;
 		goto fin_msg;
 	}

 	amd_spi_set_opcode(amd_spi, cmd_opcode);
 	amd_spi_set_tx_count(amd_spi, tx_len);
 	amd_spi_set_rx_count(amd_spi, rx_len);

 	/* Execute command */
 	message->status = amd_spi_execute_opcode(amd_spi);
 	if (message->status)
 		goto fin_msg;

 	if (rx_len) {
 		message->status = amd_spi_busy_wait(amd_spi);
 		if (message->status)
 			goto fin_msg;

 		list_for_each_entry(xfer, &message->transfers, transfer_list)
 			if (xfer->rx_buf) {
 				buf = (u8 *)xfer->rx_buf;
 				/* Read data from FIFO to receive buffer */
 				for (i = 0; i < xfer->len; i++)
 					buf[i] = amd_spi_readreg8(amd_spi, fifo_pos + i);
 				fifo_pos += xfer->len;
 			}
 	}

 	/* Update statistics */
 	message->actual_length = tx_len + rx_len + 1;

 fin_msg:
 	switch (amd_spi->version) {
 	case AMD_SPI_V1:
 		break;
 	case AMD_SPI_V2:
 		amd_spi_clear_chip(amd_spi, spi_get_chipselect(message->spi, 0));
 		break;
 	default:
 		return -ENODEV;
 	}

 	spi_finalize_current_message(host);

 	return message->status;
 }

 static bool amd_spi_supports_op(struct spi_mem *mem,
 				const struct spi_mem_op *op)
 {
 	/* bus width is number of IO lines used to transmit */
 	if (op->cmd.buswidth > 1 || op->addr.buswidth > 1 ||
 	    op->data.buswidth > 1 || op->data.nbytes > AMD_SPI_MAX_DATA)
 		return false;

 	return spi_mem_default_supports_op(mem, op);
 }

 static int amd_spi_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
 {
 	op->data.nbytes = clamp_val(op->data.nbytes, 0, AMD_SPI_MAX_DATA);
 	return 0;
 }

 static void amd_spi_set_addr(struct amd_spi *amd_spi,
 			     const struct spi_mem_op *op)
 {
 	u8 nbytes = op->addr.nbytes;
 	u64 addr_val = op->addr.val;
 	int base_addr, i;

 	base_addr = AMD_SPI_FIFO_BASE + nbytes;

 	for (i = 0; i < nbytes; i++) {
 		amd_spi_writereg8(amd_spi, base_addr - i - 1, addr_val &
 				  GENMASK(7, 0));
 		addr_val >>= 8;
 	}
 }

 static void amd_spi_mem_data_out(struct amd_spi *amd_spi,
 				 const struct spi_mem_op *op)
 {
 	int base_addr = AMD_SPI_FIFO_BASE + op->addr.nbytes;
 	u8 *buf = (u8 *)op->data.buf.out;
 	u32 nbytes = op->data.nbytes;
 	int i;

 	amd_spi_set_opcode(amd_spi, op->cmd.opcode);
 	amd_spi_set_addr(amd_spi, op);

 	for (i = 0; i < nbytes; i++)
 		amd_spi_writereg8(amd_spi, (base_addr + i), buf[i]);

 	amd_spi_set_tx_count(amd_spi, op->addr.nbytes + op->data.nbytes);
 	amd_spi_set_rx_count(amd_spi, 0);
 	amd_spi_clear_fifo_ptr(amd_spi);
 	amd_spi_execute_opcode(amd_spi);
 }

 static void amd_spi_mem_data_in(struct amd_spi *amd_spi,
 				const struct spi_mem_op *op)
 {
 	int offset = (op->addr.nbytes == 0) ? 0 : 1;
 	u8 *buf = (u8 *)op->data.buf.in;
 	u32 nbytes = op->data.nbytes;
 	int base_addr, i;

 	base_addr = AMD_SPI_FIFO_BASE + op->addr.nbytes + offset;

 	amd_spi_set_opcode(amd_spi, op->cmd.opcode);
 	amd_spi_set_addr(amd_spi, op);
 	amd_spi_set_tx_count(amd_spi, op->addr.nbytes);
 	amd_spi_set_rx_count(amd_spi, op->data.nbytes + 1);
 	amd_spi_clear_fifo_ptr(amd_spi);
 	amd_spi_execute_opcode(amd_spi);
 	amd_spi_busy_wait(amd_spi);

 	for (i = 0; i < nbytes; i++)
 		buf[i] = amd_spi_readreg8(amd_spi, base_addr + i);
 }

 static int amd_spi_exec_mem_op(struct spi_mem *mem,
 			       const struct spi_mem_op *op)
 {
 	struct amd_spi *amd_spi;
 	int ret;

 	amd_spi = spi_controller_get_devdata(mem->spi->controller);

 	ret = amd_set_spi_freq(amd_spi, mem->spi->max_speed_hz);
 	if (ret)
 		return ret;

 	switch (op->data.dir) {
 	case SPI_MEM_DATA_IN:
 		amd_spi_mem_data_in(amd_spi, op);
 		break;
 	case SPI_MEM_DATA_OUT:
 		fallthrough;
 	case SPI_MEM_NO_DATA:
 		amd_spi_mem_data_out(amd_spi, op);
 		break;
 	default:
 		ret = -EOPNOTSUPP;
 	}

 	return ret;
 }

 static const struct spi_controller_mem_ops amd_spi_mem_ops = {
 	.exec_op = amd_spi_exec_mem_op,
 	.adjust_op_size = amd_spi_adjust_op_size,
 	.supports_op = amd_spi_supports_op,
 };

 static int amd_spi_host_transfer(struct spi_controller *host,
 				   struct spi_message *msg)
 {
 	struct amd_spi *amd_spi = spi_controller_get_devdata(host);
 	struct spi_device *spi = msg->spi;

 	amd_spi_select_chip(amd_spi, spi_get_chipselect(spi, 0));

 	/*
 	 * Extract spi_transfers from the spi message and
 	 * program the controller.
 	 */
 	return amd_spi_fifo_xfer(amd_spi, host, msg);
 }

 static size_t amd_spi_max_transfer_size(struct spi_device *spi)
 {
 	return AMD_SPI_FIFO_SIZE;
 }

 static int amd_spi_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct spi_controller *host;
 	struct amd_spi *amd_spi;
 	int err;

 	/* Allocate storage for host and driver private data */
 	host = devm_spi_alloc_host(dev, sizeof(struct amd_spi));
 	if (!host)
 		return dev_err_probe(dev, -ENOMEM, "Error allocating SPI host\n");

 	amd_spi = spi_controller_get_devdata(host);
 	amd_spi->io_remap_addr = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(amd_spi->io_remap_addr))
 		return dev_err_probe(dev, PTR_ERR(amd_spi->io_remap_addr),
 				     "ioremap of SPI registers failed\n");

 	dev_dbg(dev, "io_remap_address: %p\n", amd_spi->io_remap_addr);

 	amd_spi->version = (uintptr_t) device_get_match_data(dev);

 	/* Initialize the spi_controller fields */
 	host->bus_num = 0;
 	host->num_chipselect = 4;
 	host->mode_bits = 0;
 	host->flags = SPI_CONTROLLER_HALF_DUPLEX;
 	host->max_speed_hz = AMD_SPI_MAX_HZ;
 	host->min_speed_hz = AMD_SPI_MIN_HZ;
 	host->setup = amd_spi_host_setup;
 	host->transfer_one_message = amd_spi_host_transfer;
 	host->mem_ops = &amd_spi_mem_ops;
 	host->max_transfer_size = amd_spi_max_transfer_size;
 	host->max_message_size = amd_spi_max_transfer_size;

 	/* Register the controller with SPI framework */
 	err = devm_spi_register_controller(dev, host);
 	if (err)
 		return dev_err_probe(dev, err, "error registering SPI controller\n");

 	return 0;
 }

 #ifdef CONFIG_ACPI
 static const struct acpi_device_id spi_acpi_match[] = {
 	{ "AMDI0061", AMD_SPI_V1 },
 	{ "AMDI0062", AMD_SPI_V2 },
 	{},
 };
 MODULE_DEVICE_TABLE(acpi, spi_acpi_match);
 #endif

 static struct platform_driver amd_spi_driver = {
 	.driver = {
 		.name = "amd_spi",
 		.acpi_match_table = ACPI_PTR(spi_acpi_match),
 	},
 	.probe = amd_spi_probe,
 };

 module_platform_driver(amd_spi_driver);

 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_AUTHOR("Sanjay Mehta <sanju.mehta@amd.com>");
 MODULE_DESCRIPTION("AMD SPI Master Controller Driver");
	// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
	//
	// AMD SPI controller driver
	//
	// Copyright (c) 2020, Advanced Micro Devices, Inc.
	//
	// Author: Sanjay R Mehta <sanju.mehta@amd.com>

	#include <linux/acpi.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/delay.h>
	#include <linux/spi/spi.h>
	#include <linux/iopoll.h>
	#include <linux/spi/spi-mem.h>

	#define AMD_SPI_CTRL0_REG 0x00
	#define AMD_SPI_EXEC_CMD BIT(16)
	#define AMD_SPI_FIFO_CLEAR BIT(20)
	#define AMD_SPI_BUSY BIT(31)

	#define AMD_SPI_OPCODE_REG 0x45
	#define AMD_SPI_CMD_TRIGGER_REG 0x47
	#define AMD_SPI_TRIGGER_CMD BIT(7)

	#define AMD_SPI_OPCODE_MASK 0xFF

	#define AMD_SPI_ALT_CS_REG 0x1D
	#define AMD_SPI_ALT_CS_MASK 0x3

	#define AMD_SPI_FIFO_BASE 0x80
	#define AMD_SPI_TX_COUNT_REG 0x48
	#define AMD_SPI_RX_COUNT_REG 0x4B
	#define AMD_SPI_STATUS_REG 0x4C

	#define AMD_SPI_FIFO_SIZE 70
	#define AMD_SPI_MEM_SIZE 200
	#define AMD_SPI_MAX_DATA 64

	#define AMD_SPI_ENA_REG 0x20
	#define AMD_SPI_ALT_SPD_SHIFT 20
	#define AMD_SPI_ALT_SPD_MASK GENMASK(23, AMD_SPI_ALT_SPD_SHIFT)
	#define AMD_SPI_SPI100_SHIFT 0
	#define AMD_SPI_SPI100_MASK GENMASK(AMD_SPI_SPI100_SHIFT, AMD_SPI_SPI100_SHIFT)
	#define AMD_SPI_SPEED_REG 0x6C
	#define AMD_SPI_SPD7_SHIFT 8
	#define AMD_SPI_SPD7_MASK GENMASK(13, AMD_SPI_SPD7_SHIFT)

	#define AMD_SPI_MAX_HZ 100000000
	#define AMD_SPI_MIN_HZ 800000

	/**
	* enum amd_spi_versions - SPI controller versions
	* @AMD_SPI_V1: AMDI0061 hardware version
	* @AMD_SPI_V2: AMDI0062 hardware version
	*/
	enum amd_spi_versions {
	AMD_SPI_V1 = 1,
	AMD_SPI_V2,
	};

	enum amd_spi_speed {
	F_66_66MHz,
	F_33_33MHz,
	F_22_22MHz,
	F_16_66MHz,
	F_100MHz,
	F_800KHz,
	SPI_SPD7 = 0x7,
	F_50MHz = 0x4,
	F_4MHz = 0x32,
	F_3_17MHz = 0x3F
	};

	/**
	* struct amd_spi_freq - Matches device speed with values to write in regs
	* @speed_hz: Device frequency
	* @enable_val: Value to be written to "enable register"
	* @spd7_val: Some frequencies requires to have a value written at SPISPEED register
	*/
	struct amd_spi_freq {
	u32 speed_hz;
	u32 enable_val;
	u32 spd7_val;
	};

	/**
	* struct amd_spi - SPI driver instance
	* @io_remap_addr: Start address of the SPI controller registers
	* @version: SPI controller hardware version
	* @speed_hz: Device frequency
	*/
	struct amd_spi {
	void __iomem *io_remap_addr;
	enum amd_spi_versions version;
	unsigned int speed_hz;
	};

	static inline u8 amd_spi_readreg8(struct amd_spi *amd_spi, int idx)
	{
	return ioread8((u8 __iomem *)amd_spi->io_remap_addr + idx);
	}

	static inline void amd_spi_writereg8(struct amd_spi *amd_spi, int idx, u8 val)
	{
	iowrite8(val, ((u8 __iomem *)amd_spi->io_remap_addr + idx));
	}

	static void amd_spi_setclear_reg8(struct amd_spi *amd_spi, int idx, u8 set, u8 clear)
	{
	u8 tmp = amd_spi_readreg8(amd_spi, idx);

	tmp = (tmp & ~clear) \| set;
	amd_spi_writereg8(amd_spi, idx, tmp);
	}

	static inline u32 amd_spi_readreg32(struct amd_spi *amd_spi, int idx)
	{
	return ioread32((u8 __iomem *)amd_spi->io_remap_addr + idx);
	}

	static inline void amd_spi_writereg32(struct amd_spi *amd_spi, int idx, u32 val)
	{
	iowrite32(val, ((u8 __iomem *)amd_spi->io_remap_addr + idx));
	}

	static inline void amd_spi_setclear_reg32(struct amd_spi *amd_spi, int idx, u32 set, u32 clear)
	{
	u32 tmp = amd_spi_readreg32(amd_spi, idx);

	tmp = (tmp & ~clear) \| set;
	amd_spi_writereg32(amd_spi, idx, tmp);
	}

	static void amd_spi_select_chip(struct amd_spi *amd_spi, u8 cs)
	{
	amd_spi_setclear_reg8(amd_spi, AMD_SPI_ALT_CS_REG, cs, AMD_SPI_ALT_CS_MASK);
	}

	static inline void amd_spi_clear_chip(struct amd_spi *amd_spi, u8 chip_select)
	{
	amd_spi_writereg8(amd_spi, AMD_SPI_ALT_CS_REG, chip_select & ~AMD_SPI_ALT_CS_MASK);
	}

	static void amd_spi_clear_fifo_ptr(struct amd_spi *amd_spi)
	{
	amd_spi_setclear_reg32(amd_spi, AMD_SPI_CTRL0_REG, AMD_SPI_FIFO_CLEAR, AMD_SPI_FIFO_CLEAR);
	}

	static int amd_spi_set_opcode(struct amd_spi *amd_spi, u8 cmd_opcode)
	{
	switch (amd_spi->version) {
	case AMD_SPI_V1:
	amd_spi_setclear_reg32(amd_spi, AMD_SPI_CTRL0_REG, cmd_opcode,
	AMD_SPI_OPCODE_MASK);
	return 0;
	case AMD_SPI_V2:
	amd_spi_writereg8(amd_spi, AMD_SPI_OPCODE_REG, cmd_opcode);
	return 0;
	default:
	return -ENODEV;
	}
	}

	static inline void amd_spi_set_rx_count(struct amd_spi *amd_spi, u8 rx_count)
	{
	amd_spi_setclear_reg8(amd_spi, AMD_SPI_RX_COUNT_REG, rx_count, 0xff);
	}

	static inline void amd_spi_set_tx_count(struct amd_spi *amd_spi, u8 tx_count)
	{
	amd_spi_setclear_reg8(amd_spi, AMD_SPI_TX_COUNT_REG, tx_count, 0xff);
	}

	static int amd_spi_busy_wait(struct amd_spi *amd_spi)
	{
	u32 val;
	int reg;

	switch (amd_spi->version) {
	case AMD_SPI_V1:
	reg = AMD_SPI_CTRL0_REG;
	break;
	case AMD_SPI_V2:
	reg = AMD_SPI_STATUS_REG;
	break;
	default:
	return -ENODEV;
	}

	return readl_poll_timeout(amd_spi->io_remap_addr + reg, val,
	!(val & AMD_SPI_BUSY), 20, 2000000);
	}

	static int amd_spi_execute_opcode(struct amd_spi *amd_spi)
	{
	int ret;

	ret = amd_spi_busy_wait(amd_spi);
	if (ret)
	return ret;

	switch (amd_spi->version) {
	case AMD_SPI_V1:
	/* Set ExecuteOpCode bit in the CTRL0 register */
	amd_spi_setclear_reg32(amd_spi, AMD_SPI_CTRL0_REG, AMD_SPI_EXEC_CMD,
	AMD_SPI_EXEC_CMD);
	return 0;
	case AMD_SPI_V2:
	/* Trigger the command execution */
	amd_spi_setclear_reg8(amd_spi, AMD_SPI_CMD_TRIGGER_REG,
	AMD_SPI_TRIGGER_CMD, AMD_SPI_TRIGGER_CMD);
	return 0;
	default:
	return -ENODEV;
	}
	}

	static int amd_spi_host_setup(struct spi_device *spi)
	{
	struct amd_spi *amd_spi = spi_controller_get_devdata(spi->controller);

	amd_spi_clear_fifo_ptr(amd_spi);

	return 0;
	}

	static const struct amd_spi_freq amd_spi_freq[] = {
	{ AMD_SPI_MAX_HZ, F_100MHz, 0},
	{ 66660000, F_66_66MHz, 0},
	{ 50000000, SPI_SPD7, F_50MHz},
	{ 33330000, F_33_33MHz, 0},
	{ 22220000, F_22_22MHz, 0},
	{ 16660000, F_16_66MHz, 0},
	{ 4000000, SPI_SPD7, F_4MHz},
	{ 3170000, SPI_SPD7, F_3_17MHz},
	{ AMD_SPI_MIN_HZ, F_800KHz, 0},
	};

	static int amd_set_spi_freq(struct amd_spi *amd_spi, u32 speed_hz)
	{
	unsigned int i, spd7_val, alt_spd;

	if (speed_hz < AMD_SPI_MIN_HZ)
	return -EINVAL;

	for (i = 0; i < ARRAY_SIZE(amd_spi_freq); i++)
	if (speed_hz >= amd_spi_freq[i].speed_hz)
	break;

	if (amd_spi->speed_hz == amd_spi_freq[i].speed_hz)
	return 0;

	amd_spi->speed_hz = amd_spi_freq[i].speed_hz;

	alt_spd = (amd_spi_freq[i].enable_val << AMD_SPI_ALT_SPD_SHIFT)
	& AMD_SPI_ALT_SPD_MASK;
	amd_spi_setclear_reg32(amd_spi, AMD_SPI_ENA_REG, alt_spd,
	AMD_SPI_ALT_SPD_MASK);

	if (amd_spi->speed_hz == AMD_SPI_MAX_HZ)
	amd_spi_setclear_reg32(amd_spi, AMD_SPI_ENA_REG, 1,
	AMD_SPI_SPI100_MASK);

	if (amd_spi_freq[i].spd7_val) {
	spd7_val = (amd_spi_freq[i].spd7_val << AMD_SPI_SPD7_SHIFT)
	& AMD_SPI_SPD7_MASK;
	amd_spi_setclear_reg32(amd_spi, AMD_SPI_SPEED_REG, spd7_val,
	AMD_SPI_SPD7_MASK);
	}

	return 0;
	}

	static inline int amd_spi_fifo_xfer(struct amd_spi *amd_spi,
	struct spi_controller *host,
	struct spi_message *message)
	{
	struct spi_transfer *xfer = NULL;
	struct spi_device *spi = message->spi;
	u8 cmd_opcode = 0, fifo_pos = AMD_SPI_FIFO_BASE;
	u8 *buf = NULL;
	u32 i = 0;
	u32 tx_len = 0, rx_len = 0;

	list_for_each_entry(xfer, &message->transfers,
	transfer_list) {
	if (xfer->speed_hz)
	amd_set_spi_freq(amd_spi, xfer->speed_hz);
	else
	amd_set_spi_freq(amd_spi, spi->max_speed_hz);

	if (xfer->tx_buf) {
	buf = (u8 *)xfer->tx_buf;
	if (!tx_len) {
	cmd_opcode = (u8 )xfer->tx_buf;
	buf++;
	xfer->len--;
	}
	tx_len += xfer->len;

	/* Write data into the FIFO. */
	for (i = 0; i < xfer->len; i++)
	amd_spi_writereg8(amd_spi, fifo_pos + i, buf[i]);

	fifo_pos += xfer->len;
	}

	/* Store no. of bytes to be received from FIFO */
	if (xfer->rx_buf)
	rx_len += xfer->len;
	}

	if (!buf) {
	message->status = -EINVAL;
	goto fin_msg;
	}

	amd_spi_set_opcode(amd_spi, cmd_opcode);
	amd_spi_set_tx_count(amd_spi, tx_len);
	amd_spi_set_rx_count(amd_spi, rx_len);

	/* Execute command */
	message->status = amd_spi_execute_opcode(amd_spi);
	if (message->status)
	goto fin_msg;

	if (rx_len) {
	message->status = amd_spi_busy_wait(amd_spi);
	if (message->status)
	goto fin_msg;

	list_for_each_entry(xfer, &message->transfers, transfer_list)
	if (xfer->rx_buf) {
	buf = (u8 *)xfer->rx_buf;
	/* Read data from FIFO to receive buffer */
	for (i = 0; i < xfer->len; i++)
	buf[i] = amd_spi_readreg8(amd_spi, fifo_pos + i);
	fifo_pos += xfer->len;
	}
	}

	/* Update statistics */
	message->actual_length = tx_len + rx_len + 1;

	fin_msg:
	switch (amd_spi->version) {
	case AMD_SPI_V1:
	break;
	case AMD_SPI_V2:
	amd_spi_clear_chip(amd_spi, spi_get_chipselect(message->spi, 0));
	break;
	default:
	return -ENODEV;
	}

	spi_finalize_current_message(host);

	return message->status;
	}

	static bool amd_spi_supports_op(struct spi_mem *mem,
	const struct spi_mem_op *op)
	{
	/* bus width is number of IO lines used to transmit */
	if (op->cmd.buswidth > 1 \|\| op->addr.buswidth > 1 \|\|
	op->data.buswidth > 1 \|\| op->data.nbytes > AMD_SPI_MAX_DATA)
	return false;

	return spi_mem_default_supports_op(mem, op);
	}

	static int amd_spi_adjust_op_size(struct spi_mem mem, struct spi_mem_op op)
	{
	op->data.nbytes = clamp_val(op->data.nbytes, 0, AMD_SPI_MAX_DATA);
	return 0;
	}

	static void amd_spi_set_addr(struct amd_spi *amd_spi,
	const struct spi_mem_op *op)
	{
	u8 nbytes = op->addr.nbytes;
	u64 addr_val = op->addr.val;
	int base_addr, i;

	base_addr = AMD_SPI_FIFO_BASE + nbytes;

	for (i = 0; i < nbytes; i++) {
	amd_spi_writereg8(amd_spi, base_addr - i - 1, addr_val &
	GENMASK(7, 0));
	addr_val >>= 8;
	}
	}

	static void amd_spi_mem_data_out(struct amd_spi *amd_spi,
	const struct spi_mem_op *op)
	{
	int base_addr = AMD_SPI_FIFO_BASE + op->addr.nbytes;
	u8 buf = (u8 )op->data.buf.out;
	u32 nbytes = op->data.nbytes;
	int i;

	amd_spi_set_opcode(amd_spi, op->cmd.opcode);
	amd_spi_set_addr(amd_spi, op);

	for (i = 0; i < nbytes; i++)
	amd_spi_writereg8(amd_spi, (base_addr + i), buf[i]);

	amd_spi_set_tx_count(amd_spi, op->addr.nbytes + op->data.nbytes);
	amd_spi_set_rx_count(amd_spi, 0);
	amd_spi_clear_fifo_ptr(amd_spi);
	amd_spi_execute_opcode(amd_spi);
	}

	static void amd_spi_mem_data_in(struct amd_spi *amd_spi,
	const struct spi_mem_op *op)
	{
	int offset = (op->addr.nbytes == 0) ? 0 : 1;
	u8 buf = (u8 )op->data.buf.in;
	u32 nbytes = op->data.nbytes;
	int base_addr, i;

	base_addr = AMD_SPI_FIFO_BASE + op->addr.nbytes + offset;

	amd_spi_set_opcode(amd_spi, op->cmd.opcode);
	amd_spi_set_addr(amd_spi, op);
	amd_spi_set_tx_count(amd_spi, op->addr.nbytes);
	amd_spi_set_rx_count(amd_spi, op->data.nbytes + 1);
	amd_spi_clear_fifo_ptr(amd_spi);
	amd_spi_execute_opcode(amd_spi);
	amd_spi_busy_wait(amd_spi);

	for (i = 0; i < nbytes; i++)
	buf[i] = amd_spi_readreg8(amd_spi, base_addr + i);
	}

	static int amd_spi_exec_mem_op(struct spi_mem *mem,
	const struct spi_mem_op *op)
	{
	struct amd_spi *amd_spi;
	int ret;

	amd_spi = spi_controller_get_devdata(mem->spi->controller);

	ret = amd_set_spi_freq(amd_spi, mem->spi->max_speed_hz);
	if (ret)
	return ret;

	switch (op->data.dir) {
	case SPI_MEM_DATA_IN:
	amd_spi_mem_data_in(amd_spi, op);
	break;
	case SPI_MEM_DATA_OUT:
	fallthrough;
	case SPI_MEM_NO_DATA:
	amd_spi_mem_data_out(amd_spi, op);
	break;
	default:
	ret = -EOPNOTSUPP;
	}

	return ret;
	}

	static const struct spi_controller_mem_ops amd_spi_mem_ops = {
	.exec_op = amd_spi_exec_mem_op,
	.adjust_op_size = amd_spi_adjust_op_size,
	.supports_op = amd_spi_supports_op,
	};

	static int amd_spi_host_transfer(struct spi_controller *host,
	struct spi_message *msg)
	{
	struct amd_spi *amd_spi = spi_controller_get_devdata(host);
	struct spi_device *spi = msg->spi;

	amd_spi_select_chip(amd_spi, spi_get_chipselect(spi, 0));

	/*
	* Extract spi_transfers from the spi message and
	* program the controller.
	*/
	return amd_spi_fifo_xfer(amd_spi, host, msg);
	}

	static size_t amd_spi_max_transfer_size(struct spi_device *spi)
	{
	return AMD_SPI_FIFO_SIZE;
	}

	static int amd_spi_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct spi_controller *host;
	struct amd_spi *amd_spi;
	int err;

	/* Allocate storage for host and driver private data */
	host = devm_spi_alloc_host(dev, sizeof(struct amd_spi));
	if (!host)
	return dev_err_probe(dev, -ENOMEM, "Error allocating SPI host\n");

	amd_spi = spi_controller_get_devdata(host);
	amd_spi->io_remap_addr = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(amd_spi->io_remap_addr))
	return dev_err_probe(dev, PTR_ERR(amd_spi->io_remap_addr),
	"ioremap of SPI registers failed\n");

	dev_dbg(dev, "io_remap_address: %p\n", amd_spi->io_remap_addr);

	amd_spi->version = (uintptr_t) device_get_match_data(dev);

	/* Initialize the spi_controller fields */
	host->bus_num = 0;
	host->num_chipselect = 4;
	host->mode_bits = 0;
	host->flags = SPI_CONTROLLER_HALF_DUPLEX;
	host->max_speed_hz = AMD_SPI_MAX_HZ;
	host->min_speed_hz = AMD_SPI_MIN_HZ;
	host->setup = amd_spi_host_setup;
	host->transfer_one_message = amd_spi_host_transfer;
	host->mem_ops = &amd_spi_mem_ops;
	host->max_transfer_size = amd_spi_max_transfer_size;
	host->max_message_size = amd_spi_max_transfer_size;

	/* Register the controller with SPI framework */
	err = devm_spi_register_controller(dev, host);
	if (err)
	return dev_err_probe(dev, err, "error registering SPI controller\n");

	return 0;
	}

	#ifdef CONFIG_ACPI
	static const struct acpi_device_id spi_acpi_match[] = {
	{ "AMDI0061", AMD_SPI_V1 },
	{ "AMDI0062", AMD_SPI_V2 },
	{},
	};
	MODULE_DEVICE_TABLE(acpi, spi_acpi_match);
	#endif

	static struct platform_driver amd_spi_driver = {
	.driver = {
	.name = "amd_spi",
	.acpi_match_table = ACPI_PTR(spi_acpi_match),
	},
	.probe = amd_spi_probe,
	};

	module_platform_driver(amd_spi_driver);

	MODULE_LICENSE("Dual BSD/GPL");
	MODULE_AUTHOR("Sanjay Mehta <sanju.mehta@amd.com>");
	MODULE_DESCRIPTION("AMD SPI Master Controller Driver");