drivers/spi/spi-axi-spi-engine.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * SPI-Engine SPI controller driver
  * Copyright 2015 Analog Devices Inc.
  *  Author: Lars-Peter Clausen <lars@metafoo.de>
  */

 #include <linux/clk.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/spi/spi.h>

 #define SPI_ENGINE_VERSION_MAJOR(x)	((x >> 16) & 0xff)
 #define SPI_ENGINE_VERSION_MINOR(x)	((x >> 8) & 0xff)
 #define SPI_ENGINE_VERSION_PATCH(x)	(x & 0xff)

 #define SPI_ENGINE_REG_VERSION			0x00

 #define SPI_ENGINE_REG_RESET			0x40

 #define SPI_ENGINE_REG_INT_ENABLE		0x80
 #define SPI_ENGINE_REG_INT_PENDING		0x84
 #define SPI_ENGINE_REG_INT_SOURCE		0x88

 #define SPI_ENGINE_REG_SYNC_ID			0xc0

 #define SPI_ENGINE_REG_CMD_FIFO_ROOM		0xd0
 #define SPI_ENGINE_REG_SDO_FIFO_ROOM		0xd4
 #define SPI_ENGINE_REG_SDI_FIFO_LEVEL		0xd8

 #define SPI_ENGINE_REG_CMD_FIFO			0xe0
 #define SPI_ENGINE_REG_SDO_DATA_FIFO		0xe4
 #define SPI_ENGINE_REG_SDI_DATA_FIFO		0xe8
 #define SPI_ENGINE_REG_SDI_DATA_FIFO_PEEK	0xec

 #define SPI_ENGINE_INT_CMD_ALMOST_EMPTY		BIT(0)
 #define SPI_ENGINE_INT_SDO_ALMOST_EMPTY		BIT(1)
 #define SPI_ENGINE_INT_SDI_ALMOST_FULL		BIT(2)
 #define SPI_ENGINE_INT_SYNC			BIT(3)

 #define SPI_ENGINE_CONFIG_CPHA			BIT(0)
 #define SPI_ENGINE_CONFIG_CPOL			BIT(1)
 #define SPI_ENGINE_CONFIG_3WIRE			BIT(2)

 #define SPI_ENGINE_INST_TRANSFER		0x0
 #define SPI_ENGINE_INST_ASSERT			0x1
 #define SPI_ENGINE_INST_WRITE			0x2
 #define SPI_ENGINE_INST_MISC			0x3

 #define SPI_ENGINE_CMD_REG_CLK_DIV		0x0
 #define SPI_ENGINE_CMD_REG_CONFIG		0x1

 #define SPI_ENGINE_MISC_SYNC			0x0
 #define SPI_ENGINE_MISC_SLEEP			0x1

 #define SPI_ENGINE_TRANSFER_WRITE		0x1
 #define SPI_ENGINE_TRANSFER_READ		0x2

 #define SPI_ENGINE_CMD(inst, arg1, arg2) \
 	(((inst) << 12) | ((arg1) << 8) | (arg2))

 #define SPI_ENGINE_CMD_TRANSFER(flags, n) \
 	SPI_ENGINE_CMD(SPI_ENGINE_INST_TRANSFER, (flags), (n))
 #define SPI_ENGINE_CMD_ASSERT(delay, cs) \
 	SPI_ENGINE_CMD(SPI_ENGINE_INST_ASSERT, (delay), (cs))
 #define SPI_ENGINE_CMD_WRITE(reg, val) \
 	SPI_ENGINE_CMD(SPI_ENGINE_INST_WRITE, (reg), (val))
 #define SPI_ENGINE_CMD_SLEEP(delay) \
 	SPI_ENGINE_CMD(SPI_ENGINE_INST_MISC, SPI_ENGINE_MISC_SLEEP, (delay))
 #define SPI_ENGINE_CMD_SYNC(id) \
 	SPI_ENGINE_CMD(SPI_ENGINE_INST_MISC, SPI_ENGINE_MISC_SYNC, (id))

 struct spi_engine_program {
 	unsigned int length;
 	uint16_t instructions[];
 };

 struct spi_engine {
 	struct clk *clk;
 	struct clk *ref_clk;

 	spinlock_t lock;

 	void __iomem *base;

 	struct spi_message *msg;
 	struct spi_engine_program *p;
 	unsigned cmd_length;
 	const uint16_t *cmd_buf;

 	struct spi_transfer *tx_xfer;
 	unsigned int tx_length;
 	const uint8_t *tx_buf;

 	struct spi_transfer *rx_xfer;
 	unsigned int rx_length;
 	uint8_t *rx_buf;

 	unsigned int sync_id;
 	unsigned int completed_id;

 	unsigned int int_enable;
 };

 static void spi_engine_program_add_cmd(struct spi_engine_program *p,
 	bool dry, uint16_t cmd)
 {
 	if (!dry)
 		p->instructions[p->length] = cmd;
 	p->length++;
 }

 static unsigned int spi_engine_get_config(struct spi_device *spi)
 {
 	unsigned int config = 0;

 	if (spi->mode & SPI_CPOL)
 		config |= SPI_ENGINE_CONFIG_CPOL;
 	if (spi->mode & SPI_CPHA)
 		config |= SPI_ENGINE_CONFIG_CPHA;
 	if (spi->mode & SPI_3WIRE)
 		config |= SPI_ENGINE_CONFIG_3WIRE;

 	return config;
 }

 static unsigned int spi_engine_get_clk_div(struct spi_engine *spi_engine,
 	struct spi_device *spi, struct spi_transfer *xfer)
 {
 	unsigned int clk_div;

 	clk_div = DIV_ROUND_UP(clk_get_rate(spi_engine->ref_clk),
 		xfer->speed_hz * 2);
 	if (clk_div > 255)
 		clk_div = 255;
 	else if (clk_div > 0)
 		clk_div -= 1;

 	return clk_div;
 }

 static void spi_engine_gen_xfer(struct spi_engine_program *p, bool dry,
 	struct spi_transfer *xfer)
 {
 	unsigned int len = xfer->len;

 	while (len) {
 		unsigned int n = min(len, 256U);
 		unsigned int flags = 0;

 		if (xfer->tx_buf)
 			flags |= SPI_ENGINE_TRANSFER_WRITE;
 		if (xfer->rx_buf)
 			flags |= SPI_ENGINE_TRANSFER_READ;

 		spi_engine_program_add_cmd(p, dry,
 			SPI_ENGINE_CMD_TRANSFER(flags, n - 1));
 		len -= n;
 	}
 }

 static void spi_engine_gen_sleep(struct spi_engine_program *p, bool dry,
 	struct spi_engine *spi_engine, unsigned int clk_div, unsigned int delay)
 {
 	unsigned int spi_clk = clk_get_rate(spi_engine->ref_clk);
 	unsigned int t;

 	if (delay == 0)
 		return;

 	t = DIV_ROUND_UP(delay * spi_clk, (clk_div + 1) * 2);
 	while (t) {
 		unsigned int n = min(t, 256U);

 		spi_engine_program_add_cmd(p, dry, SPI_ENGINE_CMD_SLEEP(n - 1));
 		t -= n;
 	}
 }

 static void spi_engine_gen_cs(struct spi_engine_program *p, bool dry,
 		struct spi_device *spi, bool assert)
 {
 	unsigned int mask = 0xff;

 	if (assert)
 		mask ^= BIT(spi->chip_select);

 	spi_engine_program_add_cmd(p, dry, SPI_ENGINE_CMD_ASSERT(1, mask));
 }

 static int spi_engine_compile_message(struct spi_engine *spi_engine,
 	struct spi_message *msg, bool dry, struct spi_engine_program *p)
 {
 	struct spi_device *spi = msg->spi;
 	struct spi_transfer *xfer;
 	int clk_div, new_clk_div;
 	bool cs_change = true;

 	clk_div = -1;

 	spi_engine_program_add_cmd(p, dry,
 		SPI_ENGINE_CMD_WRITE(SPI_ENGINE_CMD_REG_CONFIG,
 			spi_engine_get_config(spi)));

 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 		new_clk_div = spi_engine_get_clk_div(spi_engine, spi, xfer);
 		if (new_clk_div != clk_div) {
 			clk_div = new_clk_div;
 			spi_engine_program_add_cmd(p, dry,
 				SPI_ENGINE_CMD_WRITE(SPI_ENGINE_CMD_REG_CLK_DIV,
 					clk_div));
 		}

 		if (cs_change)
 			spi_engine_gen_cs(p, dry, spi, true);

 		spi_engine_gen_xfer(p, dry, xfer);
 		spi_engine_gen_sleep(p, dry, spi_engine, clk_div,
 			xfer->delay_usecs);

 		cs_change = xfer->cs_change;
 		if (list_is_last(&xfer->transfer_list, &msg->transfers))
 			cs_change = !cs_change;

 		if (cs_change)
 			spi_engine_gen_cs(p, dry, spi, false);
 	}

 	return 0;
 }

 static void spi_engine_xfer_next(struct spi_engine *spi_engine,
 	struct spi_transfer **_xfer)
 {
 	struct spi_message *msg = spi_engine->msg;
 	struct spi_transfer *xfer = *_xfer;

 	if (!xfer) {
 		xfer = list_first_entry(&msg->transfers,
 			struct spi_transfer, transfer_list);
 	} else if (list_is_last(&xfer->transfer_list, &msg->transfers)) {
 		xfer = NULL;
 	} else {
 		xfer = list_next_entry(xfer, transfer_list);
 	}

 	*_xfer = xfer;
 }

 static void spi_engine_tx_next(struct spi_engine *spi_engine)
 {
 	struct spi_transfer *xfer = spi_engine->tx_xfer;

 	do {
 		spi_engine_xfer_next(spi_engine, &xfer);
 	} while (xfer && !xfer->tx_buf);

 	spi_engine->tx_xfer = xfer;
 	if (xfer) {
 		spi_engine->tx_length = xfer->len;
 		spi_engine->tx_buf = xfer->tx_buf;
 	} else {
 		spi_engine->tx_buf = NULL;
 	}
 }

 static void spi_engine_rx_next(struct spi_engine *spi_engine)
 {
 	struct spi_transfer *xfer = spi_engine->rx_xfer;

 	do {
 		spi_engine_xfer_next(spi_engine, &xfer);
 	} while (xfer && !xfer->rx_buf);

 	spi_engine->rx_xfer = xfer;
 	if (xfer) {
 		spi_engine->rx_length = xfer->len;
 		spi_engine->rx_buf = xfer->rx_buf;
 	} else {
 		spi_engine->rx_buf = NULL;
 	}
 }

 static bool spi_engine_write_cmd_fifo(struct spi_engine *spi_engine)
 {
 	void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_CMD_FIFO;
 	unsigned int n, m, i;
 	const uint16_t *buf;

 	n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_CMD_FIFO_ROOM);
 	while (n && spi_engine->cmd_length) {
 		m = min(n, spi_engine->cmd_length);
 		buf = spi_engine->cmd_buf;
 		for (i = 0; i < m; i++)
 			writel_relaxed(buf[i], addr);
 		spi_engine->cmd_buf += m;
 		spi_engine->cmd_length -= m;
 		n -= m;
 	}

 	return spi_engine->cmd_length != 0;
 }

 static bool spi_engine_write_tx_fifo(struct spi_engine *spi_engine)
 {
 	void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_SDO_DATA_FIFO;
 	unsigned int n, m, i;
 	const uint8_t *buf;

 	n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_SDO_FIFO_ROOM);
 	while (n && spi_engine->tx_length) {
 		m = min(n, spi_engine->tx_length);
 		buf = spi_engine->tx_buf;
 		for (i = 0; i < m; i++)
 			writel_relaxed(buf[i], addr);
 		spi_engine->tx_buf += m;
 		spi_engine->tx_length -= m;
 		n -= m;
 		if (spi_engine->tx_length == 0)
 			spi_engine_tx_next(spi_engine);
 	}

 	return spi_engine->tx_length != 0;
 }

 static bool spi_engine_read_rx_fifo(struct spi_engine *spi_engine)
 {
 	void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_SDI_DATA_FIFO;
 	unsigned int n, m, i;
 	uint8_t *buf;

 	n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_SDI_FIFO_LEVEL);
 	while (n && spi_engine->rx_length) {
 		m = min(n, spi_engine->rx_length);
 		buf = spi_engine->rx_buf;
 		for (i = 0; i < m; i++)
 			buf[i] = readl_relaxed(addr);
 		spi_engine->rx_buf += m;
 		spi_engine->rx_length -= m;
 		n -= m;
 		if (spi_engine->rx_length == 0)
 			spi_engine_rx_next(spi_engine);
 	}

 	return spi_engine->rx_length != 0;
 }

 static irqreturn_t spi_engine_irq(int irq, void *devid)
 {
 	struct spi_master *master = devid;
 	struct spi_engine *spi_engine = spi_master_get_devdata(master);
 	unsigned int disable_int = 0;
 	unsigned int pending;

 	pending = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_INT_PENDING);

 	if (pending & SPI_ENGINE_INT_SYNC) {
 		writel_relaxed(SPI_ENGINE_INT_SYNC,
 			spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
 		spi_engine->completed_id = readl_relaxed(
 			spi_engine->base + SPI_ENGINE_REG_SYNC_ID);
 	}

 	spin_lock(&spi_engine->lock);

 	if (pending & SPI_ENGINE_INT_CMD_ALMOST_EMPTY) {
 		if (!spi_engine_write_cmd_fifo(spi_engine))
 			disable_int |= SPI_ENGINE_INT_CMD_ALMOST_EMPTY;
 	}

 	if (pending & SPI_ENGINE_INT_SDO_ALMOST_EMPTY) {
 		if (!spi_engine_write_tx_fifo(spi_engine))
 			disable_int |= SPI_ENGINE_INT_SDO_ALMOST_EMPTY;
 	}

 	if (pending & (SPI_ENGINE_INT_SDI_ALMOST_FULL | SPI_ENGINE_INT_SYNC)) {
 		if (!spi_engine_read_rx_fifo(spi_engine))
 			disable_int |= SPI_ENGINE_INT_SDI_ALMOST_FULL;
 	}

 	if (pending & SPI_ENGINE_INT_SYNC) {
 		if (spi_engine->msg &&
 		    spi_engine->completed_id == spi_engine->sync_id) {
 			struct spi_message *msg = spi_engine->msg;

 			kfree(spi_engine->p);
 			msg->status = 0;
 			msg->actual_length = msg->frame_length;
 			spi_engine->msg = NULL;
 			spi_finalize_current_message(master);
 			disable_int |= SPI_ENGINE_INT_SYNC;
 		}
 	}

 	if (disable_int) {
 		spi_engine->int_enable &= ~disable_int;
 		writel_relaxed(spi_engine->int_enable,
 			spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
 	}

 	spin_unlock(&spi_engine->lock);

 	return IRQ_HANDLED;
 }

 static int spi_engine_transfer_one_message(struct spi_master *master,
 	struct spi_message *msg)
 {
 	struct spi_engine_program p_dry, *p;
 	struct spi_engine *spi_engine = spi_master_get_devdata(master);
 	unsigned int int_enable = 0;
 	unsigned long flags;
 	size_t size;

 	p_dry.length = 0;
 	spi_engine_compile_message(spi_engine, msg, true, &p_dry);

 	size = sizeof(*p->instructions) * (p_dry.length + 1);
 	p = kzalloc(sizeof(*p) + size, GFP_KERNEL);
 	if (!p)
 		return -ENOMEM;
 	spi_engine_compile_message(spi_engine, msg, false, p);

 	spin_lock_irqsave(&spi_engine->lock, flags);
 	spi_engine->sync_id = (spi_engine->sync_id + 1) & 0xff;
 	spi_engine_program_add_cmd(p, false,
 		SPI_ENGINE_CMD_SYNC(spi_engine->sync_id));

 	spi_engine->msg = msg;
 	spi_engine->p = p;

 	spi_engine->cmd_buf = p->instructions;
 	spi_engine->cmd_length = p->length;
 	if (spi_engine_write_cmd_fifo(spi_engine))
 		int_enable |= SPI_ENGINE_INT_CMD_ALMOST_EMPTY;

 	spi_engine_tx_next(spi_engine);
 	if (spi_engine_write_tx_fifo(spi_engine))
 		int_enable |= SPI_ENGINE_INT_SDO_ALMOST_EMPTY;

 	spi_engine_rx_next(spi_engine);
 	if (spi_engine->rx_length != 0)
 		int_enable |= SPI_ENGINE_INT_SDI_ALMOST_FULL;

 	int_enable |= SPI_ENGINE_INT_SYNC;

 	writel_relaxed(int_enable,
 		spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
 	spi_engine->int_enable = int_enable;
 	spin_unlock_irqrestore(&spi_engine->lock, flags);

 	return 0;
 }

 static int spi_engine_probe(struct platform_device *pdev)
 {
 	struct spi_engine *spi_engine;
 	struct spi_master *master;
 	unsigned int version;
 	struct resource *res;
 	int irq;
 	int ret;

 	irq = platform_get_irq(pdev, 0);
 	if (irq <= 0)
 		return -ENXIO;

 	spi_engine = devm_kzalloc(&pdev->dev, sizeof(*spi_engine), GFP_KERNEL);
 	if (!spi_engine)
 		return -ENOMEM;

 	master = spi_alloc_master(&pdev->dev, 0);
 	if (!master)
 		return -ENOMEM;

 	spi_master_set_devdata(master, spi_engine);

 	spin_lock_init(&spi_engine->lock);

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

 	version = readl(spi_engine->base + SPI_ENGINE_REG_VERSION);
 	if (SPI_ENGINE_VERSION_MAJOR(version) != 1) {
 		dev_err(&pdev->dev, "Unsupported peripheral version %u.%u.%c\n",
 			SPI_ENGINE_VERSION_MAJOR(version),
 			SPI_ENGINE_VERSION_MINOR(version),
 			SPI_ENGINE_VERSION_PATCH(version));
 		ret = -ENODEV;
 		goto err_put_master;
 	}

 	spi_engine->clk = devm_clk_get(&pdev->dev, "s_axi_aclk");
 	if (IS_ERR(spi_engine->clk)) {
 		ret = PTR_ERR(spi_engine->clk);
 		goto err_put_master;
 	}

 	spi_engine->ref_clk = devm_clk_get(&pdev->dev, "spi_clk");
 	if (IS_ERR(spi_engine->ref_clk)) {
 		ret = PTR_ERR(spi_engine->ref_clk);
 		goto err_put_master;
 	}

 	ret = clk_prepare_enable(spi_engine->clk);
 	if (ret)
 		goto err_put_master;

 	ret = clk_prepare_enable(spi_engine->ref_clk);
 	if (ret)
 		goto err_clk_disable;

 	writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_RESET);
 	writel_relaxed(0xff, spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
 	writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);

 	ret = request_irq(irq, spi_engine_irq, 0, pdev->name, master);
 	if (ret)
 		goto err_ref_clk_disable;

 	master->dev.of_node = pdev->dev.of_node;
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_3WIRE;
 	master->bits_per_word_mask = SPI_BPW_MASK(8);
 	master->max_speed_hz = clk_get_rate(spi_engine->ref_clk) / 2;
 	master->transfer_one_message = spi_engine_transfer_one_message;
 	master->num_chipselect = 8;

 	ret = spi_register_master(master);
 	if (ret)
 		goto err_free_irq;

 	platform_set_drvdata(pdev, master);

 	return 0;
 err_free_irq:
 	free_irq(irq, master);
 err_ref_clk_disable:
 	clk_disable_unprepare(spi_engine->ref_clk);
 err_clk_disable:
 	clk_disable_unprepare(spi_engine->clk);
 err_put_master:
 	spi_master_put(master);
 	return ret;
 }

 static int spi_engine_remove(struct platform_device *pdev)
 {
 	struct spi_master *master = spi_master_get(platform_get_drvdata(pdev));
 	struct spi_engine *spi_engine = spi_master_get_devdata(master);
 	int irq = platform_get_irq(pdev, 0);

 	spi_unregister_master(master);

 	free_irq(irq, master);

 	spi_master_put(master);

 	writel_relaxed(0xff, spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
 	writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
 	writel_relaxed(0x01, spi_engine->base + SPI_ENGINE_REG_RESET);

 	clk_disable_unprepare(spi_engine->ref_clk);
 	clk_disable_unprepare(spi_engine->clk);

 	return 0;
 }

 static const struct of_device_id spi_engine_match_table[] = {
 	{ .compatible = "adi,axi-spi-engine-1.00.a" },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, spi_engine_match_table);

 static struct platform_driver spi_engine_driver = {
 	.probe = spi_engine_probe,
 	.remove = spi_engine_remove,
 	.driver = {
 		.name = "spi-engine",
 		.of_match_table = spi_engine_match_table,
 	},
 };
 module_platform_driver(spi_engine_driver);

 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 MODULE_DESCRIPTION("Analog Devices SPI engine peripheral driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* SPI-Engine SPI controller driver
	* Copyright 2015 Analog Devices Inc.
	* Author: Lars-Peter Clausen <lars@metafoo.de>
	*/

	#include <linux/clk.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/of.h>
	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/spi/spi.h>

	#define SPI_ENGINE_VERSION_MAJOR(x) ((x >> 16) & 0xff)
	#define SPI_ENGINE_VERSION_MINOR(x) ((x >> 8) & 0xff)
	#define SPI_ENGINE_VERSION_PATCH(x) (x & 0xff)

	#define SPI_ENGINE_REG_VERSION 0x00

	#define SPI_ENGINE_REG_RESET 0x40

	#define SPI_ENGINE_REG_INT_ENABLE 0x80
	#define SPI_ENGINE_REG_INT_PENDING 0x84
	#define SPI_ENGINE_REG_INT_SOURCE 0x88

	#define SPI_ENGINE_REG_SYNC_ID 0xc0

	#define SPI_ENGINE_REG_CMD_FIFO_ROOM 0xd0
	#define SPI_ENGINE_REG_SDO_FIFO_ROOM 0xd4
	#define SPI_ENGINE_REG_SDI_FIFO_LEVEL 0xd8

	#define SPI_ENGINE_REG_CMD_FIFO 0xe0
	#define SPI_ENGINE_REG_SDO_DATA_FIFO 0xe4
	#define SPI_ENGINE_REG_SDI_DATA_FIFO 0xe8
	#define SPI_ENGINE_REG_SDI_DATA_FIFO_PEEK 0xec

	#define SPI_ENGINE_INT_CMD_ALMOST_EMPTY BIT(0)
	#define SPI_ENGINE_INT_SDO_ALMOST_EMPTY BIT(1)
	#define SPI_ENGINE_INT_SDI_ALMOST_FULL BIT(2)
	#define SPI_ENGINE_INT_SYNC BIT(3)

	#define SPI_ENGINE_CONFIG_CPHA BIT(0)
	#define SPI_ENGINE_CONFIG_CPOL BIT(1)
	#define SPI_ENGINE_CONFIG_3WIRE BIT(2)

	#define SPI_ENGINE_INST_TRANSFER 0x0
	#define SPI_ENGINE_INST_ASSERT 0x1
	#define SPI_ENGINE_INST_WRITE 0x2
	#define SPI_ENGINE_INST_MISC 0x3

	#define SPI_ENGINE_CMD_REG_CLK_DIV 0x0
	#define SPI_ENGINE_CMD_REG_CONFIG 0x1

	#define SPI_ENGINE_MISC_SYNC 0x0
	#define SPI_ENGINE_MISC_SLEEP 0x1

	#define SPI_ENGINE_TRANSFER_WRITE 0x1
	#define SPI_ENGINE_TRANSFER_READ 0x2

	#define SPI_ENGINE_CMD(inst, arg1, arg2) \
	(((inst) << 12) \| ((arg1) << 8) \| (arg2))

	#define SPI_ENGINE_CMD_TRANSFER(flags, n) \
	SPI_ENGINE_CMD(SPI_ENGINE_INST_TRANSFER, (flags), (n))
	#define SPI_ENGINE_CMD_ASSERT(delay, cs) \
	SPI_ENGINE_CMD(SPI_ENGINE_INST_ASSERT, (delay), (cs))
	#define SPI_ENGINE_CMD_WRITE(reg, val) \
	SPI_ENGINE_CMD(SPI_ENGINE_INST_WRITE, (reg), (val))
	#define SPI_ENGINE_CMD_SLEEP(delay) \
	SPI_ENGINE_CMD(SPI_ENGINE_INST_MISC, SPI_ENGINE_MISC_SLEEP, (delay))
	#define SPI_ENGINE_CMD_SYNC(id) \
	SPI_ENGINE_CMD(SPI_ENGINE_INST_MISC, SPI_ENGINE_MISC_SYNC, (id))

	struct spi_engine_program {
	unsigned int length;
	uint16_t instructions[];
	};

	struct spi_engine {
	struct clk *clk;
	struct clk *ref_clk;

	spinlock_t lock;

	void __iomem *base;

	struct spi_message *msg;
	struct spi_engine_program *p;
	unsigned cmd_length;
	const uint16_t *cmd_buf;

	struct spi_transfer *tx_xfer;
	unsigned int tx_length;
	const uint8_t *tx_buf;

	struct spi_transfer *rx_xfer;
	unsigned int rx_length;
	uint8_t *rx_buf;

	unsigned int sync_id;
	unsigned int completed_id;

	unsigned int int_enable;
	};

	static void spi_engine_program_add_cmd(struct spi_engine_program *p,
	bool dry, uint16_t cmd)
	{
	if (!dry)
	p->instructions[p->length] = cmd;
	p->length++;
	}

	static unsigned int spi_engine_get_config(struct spi_device *spi)
	{
	unsigned int config = 0;

	if (spi->mode & SPI_CPOL)
	config \|= SPI_ENGINE_CONFIG_CPOL;
	if (spi->mode & SPI_CPHA)
	config \|= SPI_ENGINE_CONFIG_CPHA;
	if (spi->mode & SPI_3WIRE)
	config \|= SPI_ENGINE_CONFIG_3WIRE;

	return config;
	}

	static unsigned int spi_engine_get_clk_div(struct spi_engine *spi_engine,
	struct spi_device spi, struct spi_transfer xfer)
	{
	unsigned int clk_div;

	clk_div = DIV_ROUND_UP(clk_get_rate(spi_engine->ref_clk),
	xfer->speed_hz * 2);
	if (clk_div > 255)
	clk_div = 255;
	else if (clk_div > 0)
	clk_div -= 1;

	return clk_div;
	}

	static void spi_engine_gen_xfer(struct spi_engine_program *p, bool dry,
	struct spi_transfer *xfer)
	{
	unsigned int len = xfer->len;

	while (len) {
	unsigned int n = min(len, 256U);
	unsigned int flags = 0;

	if (xfer->tx_buf)
	flags \|= SPI_ENGINE_TRANSFER_WRITE;
	if (xfer->rx_buf)
	flags \|= SPI_ENGINE_TRANSFER_READ;

	spi_engine_program_add_cmd(p, dry,
	SPI_ENGINE_CMD_TRANSFER(flags, n - 1));
	len -= n;
	}
	}

	static void spi_engine_gen_sleep(struct spi_engine_program *p, bool dry,
	struct spi_engine *spi_engine, unsigned int clk_div, unsigned int delay)
	{
	unsigned int spi_clk = clk_get_rate(spi_engine->ref_clk);
	unsigned int t;

	if (delay == 0)
	return;

	t = DIV_ROUND_UP(delay * spi_clk, (clk_div + 1) * 2);
	while (t) {
	unsigned int n = min(t, 256U);

	spi_engine_program_add_cmd(p, dry, SPI_ENGINE_CMD_SLEEP(n - 1));
	t -= n;
	}
	}

	static void spi_engine_gen_cs(struct spi_engine_program *p, bool dry,
	struct spi_device *spi, bool assert)
	{
	unsigned int mask = 0xff;

	if (assert)
	mask ^= BIT(spi->chip_select);

	spi_engine_program_add_cmd(p, dry, SPI_ENGINE_CMD_ASSERT(1, mask));
	}

	static int spi_engine_compile_message(struct spi_engine *spi_engine,
	struct spi_message msg, bool dry, struct spi_engine_program p)
	{
	struct spi_device *spi = msg->spi;
	struct spi_transfer *xfer;
	int clk_div, new_clk_div;
	bool cs_change = true;

	clk_div = -1;

	spi_engine_program_add_cmd(p, dry,
	SPI_ENGINE_CMD_WRITE(SPI_ENGINE_CMD_REG_CONFIG,
	spi_engine_get_config(spi)));

	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
	new_clk_div = spi_engine_get_clk_div(spi_engine, spi, xfer);
	if (new_clk_div != clk_div) {
	clk_div = new_clk_div;
	spi_engine_program_add_cmd(p, dry,
	SPI_ENGINE_CMD_WRITE(SPI_ENGINE_CMD_REG_CLK_DIV,
	clk_div));
	}

	if (cs_change)
	spi_engine_gen_cs(p, dry, spi, true);

	spi_engine_gen_xfer(p, dry, xfer);
	spi_engine_gen_sleep(p, dry, spi_engine, clk_div,
	xfer->delay_usecs);

	cs_change = xfer->cs_change;
	if (list_is_last(&xfer->transfer_list, &msg->transfers))
	cs_change = !cs_change;

	if (cs_change)
	spi_engine_gen_cs(p, dry, spi, false);
	}

	return 0;
	}

	static void spi_engine_xfer_next(struct spi_engine *spi_engine,
	struct spi_transfer **_xfer)
	{
	struct spi_message *msg = spi_engine->msg;
	struct spi_transfer xfer = _xfer;

	if (!xfer) {
	xfer = list_first_entry(&msg->transfers,
	struct spi_transfer, transfer_list);
	} else if (list_is_last(&xfer->transfer_list, &msg->transfers)) {
	xfer = NULL;
	} else {
	xfer = list_next_entry(xfer, transfer_list);
	}

	*_xfer = xfer;
	}

	static void spi_engine_tx_next(struct spi_engine *spi_engine)
	{
	struct spi_transfer *xfer = spi_engine->tx_xfer;

	do {
	spi_engine_xfer_next(spi_engine, &xfer);
	} while (xfer && !xfer->tx_buf);

	spi_engine->tx_xfer = xfer;
	if (xfer) {
	spi_engine->tx_length = xfer->len;
	spi_engine->tx_buf = xfer->tx_buf;
	} else {
	spi_engine->tx_buf = NULL;
	}
	}

	static void spi_engine_rx_next(struct spi_engine *spi_engine)
	{
	struct spi_transfer *xfer = spi_engine->rx_xfer;

	do {
	spi_engine_xfer_next(spi_engine, &xfer);
	} while (xfer && !xfer->rx_buf);

	spi_engine->rx_xfer = xfer;
	if (xfer) {
	spi_engine->rx_length = xfer->len;
	spi_engine->rx_buf = xfer->rx_buf;
	} else {
	spi_engine->rx_buf = NULL;
	}
	}

	static bool spi_engine_write_cmd_fifo(struct spi_engine *spi_engine)
	{
	void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_CMD_FIFO;
	unsigned int n, m, i;
	const uint16_t *buf;

	n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_CMD_FIFO_ROOM);
	while (n && spi_engine->cmd_length) {
	m = min(n, spi_engine->cmd_length);
	buf = spi_engine->cmd_buf;
	for (i = 0; i < m; i++)
	writel_relaxed(buf[i], addr);
	spi_engine->cmd_buf += m;
	spi_engine->cmd_length -= m;
	n -= m;
	}

	return spi_engine->cmd_length != 0;
	}

	static bool spi_engine_write_tx_fifo(struct spi_engine *spi_engine)
	{
	void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_SDO_DATA_FIFO;
	unsigned int n, m, i;
	const uint8_t *buf;

	n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_SDO_FIFO_ROOM);
	while (n && spi_engine->tx_length) {
	m = min(n, spi_engine->tx_length);
	buf = spi_engine->tx_buf;
	for (i = 0; i < m; i++)
	writel_relaxed(buf[i], addr);
	spi_engine->tx_buf += m;
	spi_engine->tx_length -= m;
	n -= m;
	if (spi_engine->tx_length == 0)
	spi_engine_tx_next(spi_engine);
	}

	return spi_engine->tx_length != 0;
	}

	static bool spi_engine_read_rx_fifo(struct spi_engine *spi_engine)
	{
	void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_SDI_DATA_FIFO;
	unsigned int n, m, i;
	uint8_t *buf;

	n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_SDI_FIFO_LEVEL);
	while (n && spi_engine->rx_length) {
	m = min(n, spi_engine->rx_length);
	buf = spi_engine->rx_buf;
	for (i = 0; i < m; i++)
	buf[i] = readl_relaxed(addr);
	spi_engine->rx_buf += m;
	spi_engine->rx_length -= m;
	n -= m;
	if (spi_engine->rx_length == 0)
	spi_engine_rx_next(spi_engine);
	}

	return spi_engine->rx_length != 0;
	}

	static irqreturn_t spi_engine_irq(int irq, void *devid)
	{
	struct spi_master *master = devid;
	struct spi_engine *spi_engine = spi_master_get_devdata(master);
	unsigned int disable_int = 0;
	unsigned int pending;

	pending = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_INT_PENDING);

	if (pending & SPI_ENGINE_INT_SYNC) {
	writel_relaxed(SPI_ENGINE_INT_SYNC,
	spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
	spi_engine->completed_id = readl_relaxed(
	spi_engine->base + SPI_ENGINE_REG_SYNC_ID);
	}

	spin_lock(&spi_engine->lock);

	if (pending & SPI_ENGINE_INT_CMD_ALMOST_EMPTY) {
	if (!spi_engine_write_cmd_fifo(spi_engine))
	disable_int \|= SPI_ENGINE_INT_CMD_ALMOST_EMPTY;
	}

	if (pending & SPI_ENGINE_INT_SDO_ALMOST_EMPTY) {
	if (!spi_engine_write_tx_fifo(spi_engine))
	disable_int \|= SPI_ENGINE_INT_SDO_ALMOST_EMPTY;
	}

	if (pending & (SPI_ENGINE_INT_SDI_ALMOST_FULL \| SPI_ENGINE_INT_SYNC)) {
	if (!spi_engine_read_rx_fifo(spi_engine))
	disable_int \|= SPI_ENGINE_INT_SDI_ALMOST_FULL;
	}

	if (pending & SPI_ENGINE_INT_SYNC) {
	if (spi_engine->msg &&
	spi_engine->completed_id == spi_engine->sync_id) {
	struct spi_message *msg = spi_engine->msg;

	kfree(spi_engine->p);
	msg->status = 0;
	msg->actual_length = msg->frame_length;
	spi_engine->msg = NULL;
	spi_finalize_current_message(master);
	disable_int \|= SPI_ENGINE_INT_SYNC;
	}
	}

	if (disable_int) {
	spi_engine->int_enable &= ~disable_int;
	writel_relaxed(spi_engine->int_enable,
	spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
	}

	spin_unlock(&spi_engine->lock);

	return IRQ_HANDLED;
	}

	static int spi_engine_transfer_one_message(struct spi_master *master,
	struct spi_message *msg)
	{
	struct spi_engine_program p_dry, *p;
	struct spi_engine *spi_engine = spi_master_get_devdata(master);
	unsigned int int_enable = 0;
	unsigned long flags;
	size_t size;

	p_dry.length = 0;
	spi_engine_compile_message(spi_engine, msg, true, &p_dry);

	size = sizeof(p->instructions) (p_dry.length + 1);
	p = kzalloc(sizeof(*p) + size, GFP_KERNEL);
	if (!p)
	return -ENOMEM;
	spi_engine_compile_message(spi_engine, msg, false, p);

	spin_lock_irqsave(&spi_engine->lock, flags);
	spi_engine->sync_id = (spi_engine->sync_id + 1) & 0xff;
	spi_engine_program_add_cmd(p, false,
	SPI_ENGINE_CMD_SYNC(spi_engine->sync_id));

	spi_engine->msg = msg;
	spi_engine->p = p;

	spi_engine->cmd_buf = p->instructions;
	spi_engine->cmd_length = p->length;
	if (spi_engine_write_cmd_fifo(spi_engine))
	int_enable \|= SPI_ENGINE_INT_CMD_ALMOST_EMPTY;

	spi_engine_tx_next(spi_engine);
	if (spi_engine_write_tx_fifo(spi_engine))
	int_enable \|= SPI_ENGINE_INT_SDO_ALMOST_EMPTY;

	spi_engine_rx_next(spi_engine);
	if (spi_engine->rx_length != 0)
	int_enable \|= SPI_ENGINE_INT_SDI_ALMOST_FULL;

	int_enable \|= SPI_ENGINE_INT_SYNC;

	writel_relaxed(int_enable,
	spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
	spi_engine->int_enable = int_enable;
	spin_unlock_irqrestore(&spi_engine->lock, flags);

	return 0;
	}

	static int spi_engine_probe(struct platform_device *pdev)
	{
	struct spi_engine *spi_engine;
	struct spi_master *master;
	unsigned int version;
	struct resource *res;
	int irq;
	int ret;

	irq = platform_get_irq(pdev, 0);
	if (irq <= 0)
	return -ENXIO;

	spi_engine = devm_kzalloc(&pdev->dev, sizeof(*spi_engine), GFP_KERNEL);
	if (!spi_engine)
	return -ENOMEM;

	master = spi_alloc_master(&pdev->dev, 0);
	if (!master)
	return -ENOMEM;

	spi_master_set_devdata(master, spi_engine);

	spin_lock_init(&spi_engine->lock);

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

	version = readl(spi_engine->base + SPI_ENGINE_REG_VERSION);
	if (SPI_ENGINE_VERSION_MAJOR(version) != 1) {
	dev_err(&pdev->dev, "Unsupported peripheral version %u.%u.%c\n",
	SPI_ENGINE_VERSION_MAJOR(version),
	SPI_ENGINE_VERSION_MINOR(version),
	SPI_ENGINE_VERSION_PATCH(version));
	ret = -ENODEV;
	goto err_put_master;
	}

	spi_engine->clk = devm_clk_get(&pdev->dev, "s_axi_aclk");
	if (IS_ERR(spi_engine->clk)) {
	ret = PTR_ERR(spi_engine->clk);
	goto err_put_master;
	}

	spi_engine->ref_clk = devm_clk_get(&pdev->dev, "spi_clk");
	if (IS_ERR(spi_engine->ref_clk)) {
	ret = PTR_ERR(spi_engine->ref_clk);
	goto err_put_master;
	}

	ret = clk_prepare_enable(spi_engine->clk);
	if (ret)
	goto err_put_master;

	ret = clk_prepare_enable(spi_engine->ref_clk);
	if (ret)
	goto err_clk_disable;

	writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_RESET);
	writel_relaxed(0xff, spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
	writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);

	ret = request_irq(irq, spi_engine_irq, 0, pdev->name, master);
	if (ret)
	goto err_ref_clk_disable;

	master->dev.of_node = pdev->dev.of_node;
	master->mode_bits = SPI_CPOL \| SPI_CPHA \| SPI_3WIRE;
	master->bits_per_word_mask = SPI_BPW_MASK(8);
	master->max_speed_hz = clk_get_rate(spi_engine->ref_clk) / 2;
	master->transfer_one_message = spi_engine_transfer_one_message;
	master->num_chipselect = 8;

	ret = spi_register_master(master);
	if (ret)
	goto err_free_irq;

	platform_set_drvdata(pdev, master);

	return 0;
	err_free_irq:
	free_irq(irq, master);
	err_ref_clk_disable:
	clk_disable_unprepare(spi_engine->ref_clk);
	err_clk_disable:
	clk_disable_unprepare(spi_engine->clk);
	err_put_master:
	spi_master_put(master);
	return ret;
	}

	static int spi_engine_remove(struct platform_device *pdev)
	{
	struct spi_master *master = spi_master_get(platform_get_drvdata(pdev));
	struct spi_engine *spi_engine = spi_master_get_devdata(master);
	int irq = platform_get_irq(pdev, 0);

	spi_unregister_master(master);

	free_irq(irq, master);

	spi_master_put(master);

	writel_relaxed(0xff, spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
	writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
	writel_relaxed(0x01, spi_engine->base + SPI_ENGINE_REG_RESET);

	clk_disable_unprepare(spi_engine->ref_clk);
	clk_disable_unprepare(spi_engine->clk);

	return 0;
	}

	static const struct of_device_id spi_engine_match_table[] = {
	{ .compatible = "adi,axi-spi-engine-1.00.a" },
	{ },
	};
	MODULE_DEVICE_TABLE(of, spi_engine_match_table);

	static struct platform_driver spi_engine_driver = {
	.probe = spi_engine_probe,
	.remove = spi_engine_remove,
	.driver = {
	.name = "spi-engine",
	.of_match_table = spi_engine_match_table,
	},
	};
	module_platform_driver(spi_engine_driver);

	MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
	MODULE_DESCRIPTION("Analog Devices SPI engine peripheral driver");
	MODULE_LICENSE("GPL");