drivers/spi/spi-mt7621.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 //
 // spi-mt7621.c -- MediaTek MT7621 SPI controller driver
 //
 // Copyright (C) 2011 Sergiy <piratfm@gmail.com>
 // Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org>
 // Copyright (C) 2014-2015 Felix Fietkau <nbd@nbd.name>
 //
 // Some parts are based on spi-orion.c:
 //   Author: Shadi Ammouri <shadi@marvell.com>
 //   Copyright (C) 2007-2008 Marvell Ltd.

 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/reset.h>
 #include <linux/spi/spi.h>

 #define DRIVER_NAME		"spi-mt7621"

 /* in usec */
 #define RALINK_SPI_WAIT_MAX_LOOP 2000

 /* SPISTAT register bit field */
 #define SPISTAT_BUSY		BIT(0)

 #define MT7621_SPI_TRANS	0x00
 #define SPITRANS_BUSY		BIT(16)

 #define MT7621_SPI_OPCODE	0x04
 #define MT7621_SPI_DATA0	0x08
 #define MT7621_SPI_DATA4	0x18
 #define SPI_CTL_TX_RX_CNT_MASK	0xff
 #define SPI_CTL_START		BIT(8)

 #define MT7621_SPI_MASTER	0x28
 #define MASTER_MORE_BUFMODE	BIT(2)
 #define MASTER_FULL_DUPLEX	BIT(10)
 #define MASTER_RS_CLK_SEL	GENMASK(27, 16)
 #define MASTER_RS_CLK_SEL_SHIFT	16
 #define MASTER_RS_SLAVE_SEL	GENMASK(31, 29)

 #define MT7621_SPI_MOREBUF	0x2c
 #define MT7621_SPI_POLAR	0x38
 #define MT7621_SPI_SPACE	0x3c

 #define MT7621_CPHA		BIT(5)
 #define MT7621_CPOL		BIT(4)
 #define MT7621_LSB_FIRST	BIT(3)

 struct mt7621_spi {
 	struct spi_controller	*master;
 	void __iomem		*base;
 	unsigned int		sys_freq;
 	unsigned int		speed;
 	struct clk		*clk;
 	int			pending_write;
 };

 static inline struct mt7621_spi *spidev_to_mt7621_spi(struct spi_device *spi)
 {
 	return spi_controller_get_devdata(spi->master);
 }

 static inline u32 mt7621_spi_read(struct mt7621_spi *rs, u32 reg)
 {
 	return ioread32(rs->base + reg);
 }

 static inline void mt7621_spi_write(struct mt7621_spi *rs, u32 reg, u32 val)
 {
 	iowrite32(val, rs->base + reg);
 }

 static void mt7621_spi_set_cs(struct spi_device *spi, int enable)
 {
 	struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
 	int cs = spi->chip_select;
 	u32 polar = 0;
 	u32 master;

 	/*
 	 * Select SPI device 7, enable "more buffer mode" and disable
 	 * full-duplex (only half-duplex really works on this chip
 	 * reliably)
 	 */
 	master = mt7621_spi_read(rs, MT7621_SPI_MASTER);
 	master |= MASTER_RS_SLAVE_SEL | MASTER_MORE_BUFMODE;
 	master &= ~MASTER_FULL_DUPLEX;
 	mt7621_spi_write(rs, MT7621_SPI_MASTER, master);

 	rs->pending_write = 0;

 	if (enable)
 		polar = BIT(cs);
 	mt7621_spi_write(rs, MT7621_SPI_POLAR, polar);
 }

 static int mt7621_spi_prepare(struct spi_device *spi, unsigned int speed)
 {
 	struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
 	u32 rate;
 	u32 reg;

 	dev_dbg(&spi->dev, "speed:%u\n", speed);

 	rate = DIV_ROUND_UP(rs->sys_freq, speed);
 	dev_dbg(&spi->dev, "rate-1:%u\n", rate);

 	if (rate > 4097)
 		return -EINVAL;

 	if (rate < 2)
 		rate = 2;

 	reg = mt7621_spi_read(rs, MT7621_SPI_MASTER);
 	reg &= ~MASTER_RS_CLK_SEL;
 	reg |= (rate - 2) << MASTER_RS_CLK_SEL_SHIFT;
 	rs->speed = speed;

 	reg &= ~MT7621_LSB_FIRST;
 	if (spi->mode & SPI_LSB_FIRST)
 		reg |= MT7621_LSB_FIRST;

 	/*
 	 * This SPI controller seems to be tested on SPI flash only and some
 	 * bits are swizzled under other SPI modes probably due to incorrect
 	 * wiring inside the silicon. Only mode 0 works correctly.
 	 */
 	reg &= ~(MT7621_CPHA | MT7621_CPOL);

 	mt7621_spi_write(rs, MT7621_SPI_MASTER, reg);

 	return 0;
 }

 static inline int mt7621_spi_wait_till_ready(struct mt7621_spi *rs)
 {
 	int i;

 	for (i = 0; i < RALINK_SPI_WAIT_MAX_LOOP; i++) {
 		u32 status;

 		status = mt7621_spi_read(rs, MT7621_SPI_TRANS);
 		if ((status & SPITRANS_BUSY) == 0)
 			return 0;
 		cpu_relax();
 		udelay(1);
 	}

 	return -ETIMEDOUT;
 }

 static void mt7621_spi_read_half_duplex(struct mt7621_spi *rs,
 					int rx_len, u8 *buf)
 {
 	int tx_len;

 	/*
 	 * Combine with any pending write, and perform one or more half-duplex
 	 * transactions reading 'len' bytes. Data to be written is already in
 	 * MT7621_SPI_DATA.
 	 */
 	tx_len = rs->pending_write;
 	rs->pending_write = 0;

 	while (rx_len || tx_len) {
 		int i;
 		u32 val = (min(tx_len, 4) * 8) << 24;
 		int rx = min(rx_len, 32);

 		if (tx_len > 4)
 			val |= (tx_len - 4) * 8;
 		val |= (rx * 8) << 12;
 		mt7621_spi_write(rs, MT7621_SPI_MOREBUF, val);

 		tx_len = 0;

 		val = mt7621_spi_read(rs, MT7621_SPI_TRANS);
 		val |= SPI_CTL_START;
 		mt7621_spi_write(rs, MT7621_SPI_TRANS, val);

 		mt7621_spi_wait_till_ready(rs);

 		for (i = 0; i < rx; i++) {
 			if ((i % 4) == 0)
 				val = mt7621_spi_read(rs, MT7621_SPI_DATA0 + i);
 			*buf++ = val & 0xff;
 			val >>= 8;
 		}

 		rx_len -= i;
 	}
 }

 static inline void mt7621_spi_flush(struct mt7621_spi *rs)
 {
 	mt7621_spi_read_half_duplex(rs, 0, NULL);
 }

 static void mt7621_spi_write_half_duplex(struct mt7621_spi *rs,
 					 int tx_len, const u8 *buf)
 {
 	int len = rs->pending_write;
 	int val = 0;

 	if (len & 3) {
 		val = mt7621_spi_read(rs, MT7621_SPI_OPCODE + (len & ~3));
 		if (len < 4) {
 			val <<= (4 - len) * 8;
 			val = swab32(val);
 		}
 	}

 	while (tx_len > 0) {
 		if (len >= 36) {
 			rs->pending_write = len;
 			mt7621_spi_flush(rs);
 			len = 0;
 		}

 		val |= *buf++ << (8 * (len & 3));
 		len++;
 		if ((len & 3) == 0) {
 			if (len == 4)
 				/* The byte-order of the opcode is weird! */
 				val = swab32(val);
 			mt7621_spi_write(rs, MT7621_SPI_OPCODE + len - 4, val);
 			val = 0;
 		}
 		tx_len -= 1;
 	}

 	if (len & 3) {
 		if (len < 4) {
 			val = swab32(val);
 			val >>= (4 - len) * 8;
 		}
 		mt7621_spi_write(rs, MT7621_SPI_OPCODE + (len & ~3), val);
 	}

 	rs->pending_write = len;
 }

 static int mt7621_spi_transfer_one_message(struct spi_controller *master,
 					   struct spi_message *m)
 {
 	struct mt7621_spi *rs = spi_controller_get_devdata(master);
 	struct spi_device *spi = m->spi;
 	unsigned int speed = spi->max_speed_hz;
 	struct spi_transfer *t = NULL;
 	int status = 0;

 	mt7621_spi_wait_till_ready(rs);

 	list_for_each_entry(t, &m->transfers, transfer_list)
 		if (t->speed_hz < speed)
 			speed = t->speed_hz;

 	if (mt7621_spi_prepare(spi, speed)) {
 		status = -EIO;
 		goto msg_done;
 	}

 	/* Assert CS */
 	mt7621_spi_set_cs(spi, 1);

 	m->actual_length = 0;
 	list_for_each_entry(t, &m->transfers, transfer_list) {
 		if ((t->rx_buf) && (t->tx_buf)) {
 			/*
 			 * This controller will shift some extra data out
 			 * of spi_opcode if (mosi_bit_cnt > 0) &&
 			 * (cmd_bit_cnt == 0). So the claimed full-duplex
 			 * support is broken since we have no way to read
 			 * the MISO value during that bit.
 			 */
 			status = -EIO;
 			goto msg_done;
 		} else if (t->rx_buf) {
 			mt7621_spi_read_half_duplex(rs, t->len, t->rx_buf);
 		} else if (t->tx_buf) {
 			mt7621_spi_write_half_duplex(rs, t->len, t->tx_buf);
 		}
 		m->actual_length += t->len;
 	}

 	/* Flush data and deassert CS */
 	mt7621_spi_flush(rs);
 	mt7621_spi_set_cs(spi, 0);

 msg_done:
 	m->status = status;
 	spi_finalize_current_message(master);

 	return 0;
 }

 static int mt7621_spi_setup(struct spi_device *spi)
 {
 	struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);

 	if ((spi->max_speed_hz == 0) ||
 	    (spi->max_speed_hz > (rs->sys_freq / 2)))
 		spi->max_speed_hz = rs->sys_freq / 2;

 	if (spi->max_speed_hz < (rs->sys_freq / 4097)) {
 		dev_err(&spi->dev, "setup: requested speed is too low %d Hz\n",
 			spi->max_speed_hz);
 		return -EINVAL;
 	}

 	return 0;
 }

 static const struct of_device_id mt7621_spi_match[] = {
 	{ .compatible = "ralink,mt7621-spi" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, mt7621_spi_match);

 static int mt7621_spi_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *match;
 	struct spi_controller *master;
 	struct mt7621_spi *rs;
 	void __iomem *base;
 	struct resource *r;
 	int status = 0;
 	struct clk *clk;
 	int ret;

 	match = of_match_device(mt7621_spi_match, &pdev->dev);
 	if (!match)
 		return -EINVAL;

 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	base = devm_ioremap_resource(&pdev->dev, r);
 	if (IS_ERR(base))
 		return PTR_ERR(base);

 	clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(clk)) {
 		dev_err(&pdev->dev, "unable to get SYS clock, err=%d\n",
 			status);
 		return PTR_ERR(clk);
 	}

 	status = clk_prepare_enable(clk);
 	if (status)
 		return status;

 	master = spi_alloc_master(&pdev->dev, sizeof(*rs));
 	if (!master) {
 		dev_info(&pdev->dev, "master allocation failed\n");
 		return -ENOMEM;
 	}

 	master->mode_bits = SPI_LSB_FIRST;
 	master->flags = SPI_CONTROLLER_HALF_DUPLEX;
 	master->setup = mt7621_spi_setup;
 	master->transfer_one_message = mt7621_spi_transfer_one_message;
 	master->bits_per_word_mask = SPI_BPW_MASK(8);
 	master->dev.of_node = pdev->dev.of_node;
 	master->num_chipselect = 2;

 	dev_set_drvdata(&pdev->dev, master);

 	rs = spi_controller_get_devdata(master);
 	rs->base = base;
 	rs->clk = clk;
 	rs->master = master;
 	rs->sys_freq = clk_get_rate(rs->clk);
 	rs->pending_write = 0;
 	dev_info(&pdev->dev, "sys_freq: %u\n", rs->sys_freq);

 	ret = device_reset(&pdev->dev);
 	if (ret) {
 		dev_err(&pdev->dev, "SPI reset failed!\n");
 		return ret;
 	}

 	return devm_spi_register_controller(&pdev->dev, master);
 }

 static int mt7621_spi_remove(struct platform_device *pdev)
 {
 	struct spi_controller *master;
 	struct mt7621_spi *rs;

 	master = dev_get_drvdata(&pdev->dev);
 	rs = spi_controller_get_devdata(master);

 	clk_disable_unprepare(rs->clk);

 	return 0;
 }

 MODULE_ALIAS("platform:" DRIVER_NAME);

 static struct platform_driver mt7621_spi_driver = {
 	.driver = {
 		.name = DRIVER_NAME,
 		.of_match_table = mt7621_spi_match,
 	},
 	.probe = mt7621_spi_probe,
 	.remove = mt7621_spi_remove,
 };

 module_platform_driver(mt7621_spi_driver);

 MODULE_DESCRIPTION("MT7621 SPI driver");
 MODULE_AUTHOR("Felix Fietkau <nbd@nbd.name>");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0
	//
	// spi-mt7621.c -- MediaTek MT7621 SPI controller driver
	//
	// Copyright (C) 2011 Sergiy <piratfm@gmail.com>
	// Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org>
	// Copyright (C) 2014-2015 Felix Fietkau <nbd@nbd.name>
	//
	// Some parts are based on spi-orion.c:
	// Author: Shadi Ammouri <shadi@marvell.com>
	// Copyright (C) 2007-2008 Marvell Ltd.

	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/io.h>
	#include <linux/module.h>
	#include <linux/of_device.h>
	#include <linux/reset.h>
	#include <linux/spi/spi.h>

	#define DRIVER_NAME "spi-mt7621"

	/* in usec */
	#define RALINK_SPI_WAIT_MAX_LOOP 2000

	/* SPISTAT register bit field */
	#define SPISTAT_BUSY BIT(0)

	#define MT7621_SPI_TRANS 0x00
	#define SPITRANS_BUSY BIT(16)

	#define MT7621_SPI_OPCODE 0x04
	#define MT7621_SPI_DATA0 0x08
	#define MT7621_SPI_DATA4 0x18
	#define SPI_CTL_TX_RX_CNT_MASK 0xff
	#define SPI_CTL_START BIT(8)

	#define MT7621_SPI_MASTER 0x28
	#define MASTER_MORE_BUFMODE BIT(2)
	#define MASTER_FULL_DUPLEX BIT(10)
	#define MASTER_RS_CLK_SEL GENMASK(27, 16)
	#define MASTER_RS_CLK_SEL_SHIFT 16
	#define MASTER_RS_SLAVE_SEL GENMASK(31, 29)

	#define MT7621_SPI_MOREBUF 0x2c
	#define MT7621_SPI_POLAR 0x38
	#define MT7621_SPI_SPACE 0x3c

	#define MT7621_CPHA BIT(5)
	#define MT7621_CPOL BIT(4)
	#define MT7621_LSB_FIRST BIT(3)

	struct mt7621_spi {
	struct spi_controller *master;
	void __iomem *base;
	unsigned int sys_freq;
	unsigned int speed;
	struct clk *clk;
	int pending_write;
	};

	static inline struct mt7621_spi spidev_to_mt7621_spi(struct spi_device spi)
	{
	return spi_controller_get_devdata(spi->master);
	}

	static inline u32 mt7621_spi_read(struct mt7621_spi *rs, u32 reg)
	{
	return ioread32(rs->base + reg);
	}

	static inline void mt7621_spi_write(struct mt7621_spi *rs, u32 reg, u32 val)
	{
	iowrite32(val, rs->base + reg);
	}

	static void mt7621_spi_set_cs(struct spi_device *spi, int enable)
	{
	struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
	int cs = spi->chip_select;
	u32 polar = 0;
	u32 master;

	/*
	* Select SPI device 7, enable "more buffer mode" and disable
	* full-duplex (only half-duplex really works on this chip
	* reliably)
	*/
	master = mt7621_spi_read(rs, MT7621_SPI_MASTER);
	master \|= MASTER_RS_SLAVE_SEL \| MASTER_MORE_BUFMODE;
	master &= ~MASTER_FULL_DUPLEX;
	mt7621_spi_write(rs, MT7621_SPI_MASTER, master);

	rs->pending_write = 0;

	if (enable)
	polar = BIT(cs);
	mt7621_spi_write(rs, MT7621_SPI_POLAR, polar);
	}

	static int mt7621_spi_prepare(struct spi_device *spi, unsigned int speed)
	{
	struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
	u32 rate;
	u32 reg;

	dev_dbg(&spi->dev, "speed:%u\n", speed);

	rate = DIV_ROUND_UP(rs->sys_freq, speed);
	dev_dbg(&spi->dev, "rate-1:%u\n", rate);

	if (rate > 4097)
	return -EINVAL;

	if (rate < 2)
	rate = 2;

	reg = mt7621_spi_read(rs, MT7621_SPI_MASTER);
	reg &= ~MASTER_RS_CLK_SEL;
	reg \|= (rate - 2) << MASTER_RS_CLK_SEL_SHIFT;
	rs->speed = speed;

	reg &= ~MT7621_LSB_FIRST;
	if (spi->mode & SPI_LSB_FIRST)
	reg \|= MT7621_LSB_FIRST;

	/*
	* This SPI controller seems to be tested on SPI flash only and some
	* bits are swizzled under other SPI modes probably due to incorrect
	* wiring inside the silicon. Only mode 0 works correctly.
	*/
	reg &= ~(MT7621_CPHA \| MT7621_CPOL);

	mt7621_spi_write(rs, MT7621_SPI_MASTER, reg);

	return 0;
	}

	static inline int mt7621_spi_wait_till_ready(struct mt7621_spi *rs)
	{
	int i;

	for (i = 0; i < RALINK_SPI_WAIT_MAX_LOOP; i++) {
	u32 status;

	status = mt7621_spi_read(rs, MT7621_SPI_TRANS);
	if ((status & SPITRANS_BUSY) == 0)
	return 0;
	cpu_relax();
	udelay(1);
	}

	return -ETIMEDOUT;
	}

	static void mt7621_spi_read_half_duplex(struct mt7621_spi *rs,
	int rx_len, u8 *buf)
	{
	int tx_len;

	/*
	* Combine with any pending write, and perform one or more half-duplex
	* transactions reading 'len' bytes. Data to be written is already in
	* MT7621_SPI_DATA.
	*/
	tx_len = rs->pending_write;
	rs->pending_write = 0;

	while (rx_len \|\| tx_len) {
	int i;
	u32 val = (min(tx_len, 4) * 8) << 24;
	int rx = min(rx_len, 32);

	if (tx_len > 4)
	val \|= (tx_len - 4) * 8;
	val \|= (rx * 8) << 12;
	mt7621_spi_write(rs, MT7621_SPI_MOREBUF, val);

	tx_len = 0;

	val = mt7621_spi_read(rs, MT7621_SPI_TRANS);
	val \|= SPI_CTL_START;
	mt7621_spi_write(rs, MT7621_SPI_TRANS, val);

	mt7621_spi_wait_till_ready(rs);

	for (i = 0; i < rx; i++) {
	if ((i % 4) == 0)
	val = mt7621_spi_read(rs, MT7621_SPI_DATA0 + i);
	*buf++ = val & 0xff;
	val >>= 8;
	}

	rx_len -= i;
	}
	}

	static inline void mt7621_spi_flush(struct mt7621_spi *rs)
	{
	mt7621_spi_read_half_duplex(rs, 0, NULL);
	}

	static void mt7621_spi_write_half_duplex(struct mt7621_spi *rs,
	int tx_len, const u8 *buf)
	{
	int len = rs->pending_write;
	int val = 0;

	if (len & 3) {
	val = mt7621_spi_read(rs, MT7621_SPI_OPCODE + (len & ~3));
	if (len < 4) {
	val <<= (4 - len) * 8;
	val = swab32(val);
	}
	}

	while (tx_len > 0) {
	if (len >= 36) {
	rs->pending_write = len;
	mt7621_spi_flush(rs);
	len = 0;
	}

	val \|= buf++ << (8 (len & 3));
	len++;
	if ((len & 3) == 0) {
	if (len == 4)
	/* The byte-order of the opcode is weird! */
	val = swab32(val);
	mt7621_spi_write(rs, MT7621_SPI_OPCODE + len - 4, val);
	val = 0;
	}
	tx_len -= 1;
	}

	if (len & 3) {
	if (len < 4) {
	val = swab32(val);
	val >>= (4 - len) * 8;
	}
	mt7621_spi_write(rs, MT7621_SPI_OPCODE + (len & ~3), val);
	}

	rs->pending_write = len;
	}

	static int mt7621_spi_transfer_one_message(struct spi_controller *master,
	struct spi_message *m)
	{
	struct mt7621_spi *rs = spi_controller_get_devdata(master);
	struct spi_device *spi = m->spi;
	unsigned int speed = spi->max_speed_hz;
	struct spi_transfer *t = NULL;
	int status = 0;

	mt7621_spi_wait_till_ready(rs);

	list_for_each_entry(t, &m->transfers, transfer_list)
	if (t->speed_hz < speed)
	speed = t->speed_hz;

	if (mt7621_spi_prepare(spi, speed)) {
	status = -EIO;
	goto msg_done;
	}

	/* Assert CS */
	mt7621_spi_set_cs(spi, 1);

	m->actual_length = 0;
	list_for_each_entry(t, &m->transfers, transfer_list) {
	if ((t->rx_buf) && (t->tx_buf)) {
	/*
	* This controller will shift some extra data out
	* of spi_opcode if (mosi_bit_cnt > 0) &&
	* (cmd_bit_cnt == 0). So the claimed full-duplex
	* support is broken since we have no way to read
	* the MISO value during that bit.
	*/
	status = -EIO;
	goto msg_done;
	} else if (t->rx_buf) {
	mt7621_spi_read_half_duplex(rs, t->len, t->rx_buf);
	} else if (t->tx_buf) {
	mt7621_spi_write_half_duplex(rs, t->len, t->tx_buf);
	}
	m->actual_length += t->len;
	}

	/* Flush data and deassert CS */
	mt7621_spi_flush(rs);
	mt7621_spi_set_cs(spi, 0);

	msg_done:
	m->status = status;
	spi_finalize_current_message(master);

	return 0;
	}

	static int mt7621_spi_setup(struct spi_device *spi)
	{
	struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);

	if ((spi->max_speed_hz == 0) \|\|
	(spi->max_speed_hz > (rs->sys_freq / 2)))
	spi->max_speed_hz = rs->sys_freq / 2;

	if (spi->max_speed_hz < (rs->sys_freq / 4097)) {
	dev_err(&spi->dev, "setup: requested speed is too low %d Hz\n",
	spi->max_speed_hz);
	return -EINVAL;
	}

	return 0;
	}

	static const struct of_device_id mt7621_spi_match[] = {
	{ .compatible = "ralink,mt7621-spi" },
	{},
	};
	MODULE_DEVICE_TABLE(of, mt7621_spi_match);

	static int mt7621_spi_probe(struct platform_device *pdev)
	{
	const struct of_device_id *match;
	struct spi_controller *master;
	struct mt7621_spi *rs;
	void __iomem *base;
	struct resource *r;
	int status = 0;
	struct clk *clk;
	int ret;

	match = of_match_device(mt7621_spi_match, &pdev->dev);
	if (!match)
	return -EINVAL;

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	base = devm_ioremap_resource(&pdev->dev, r);
	if (IS_ERR(base))
	return PTR_ERR(base);

	clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(clk)) {
	dev_err(&pdev->dev, "unable to get SYS clock, err=%d\n",
	status);
	return PTR_ERR(clk);
	}

	status = clk_prepare_enable(clk);
	if (status)
	return status;

	master = spi_alloc_master(&pdev->dev, sizeof(*rs));
	if (!master) {
	dev_info(&pdev->dev, "master allocation failed\n");
	return -ENOMEM;
	}

	master->mode_bits = SPI_LSB_FIRST;
	master->flags = SPI_CONTROLLER_HALF_DUPLEX;
	master->setup = mt7621_spi_setup;
	master->transfer_one_message = mt7621_spi_transfer_one_message;
	master->bits_per_word_mask = SPI_BPW_MASK(8);
	master->dev.of_node = pdev->dev.of_node;
	master->num_chipselect = 2;

	dev_set_drvdata(&pdev->dev, master);

	rs = spi_controller_get_devdata(master);
	rs->base = base;
	rs->clk = clk;
	rs->master = master;
	rs->sys_freq = clk_get_rate(rs->clk);
	rs->pending_write = 0;
	dev_info(&pdev->dev, "sys_freq: %u\n", rs->sys_freq);

	ret = device_reset(&pdev->dev);
	if (ret) {
	dev_err(&pdev->dev, "SPI reset failed!\n");
	return ret;
	}

	return devm_spi_register_controller(&pdev->dev, master);
	}

	static int mt7621_spi_remove(struct platform_device *pdev)
	{
	struct spi_controller *master;
	struct mt7621_spi *rs;

	master = dev_get_drvdata(&pdev->dev);
	rs = spi_controller_get_devdata(master);

	clk_disable_unprepare(rs->clk);

	return 0;
	}

	MODULE_ALIAS("platform:" DRIVER_NAME);

	static struct platform_driver mt7621_spi_driver = {
	.driver = {
	.name = DRIVER_NAME,
	.of_match_table = mt7621_spi_match,
	},
	.probe = mt7621_spi_probe,
	.remove = mt7621_spi_remove,
	};

	module_platform_driver(mt7621_spi_driver);

	MODULE_DESCRIPTION("MT7621 SPI driver");
	MODULE_AUTHOR("Felix Fietkau <nbd@nbd.name>");
	MODULE_LICENSE("GPL");