drivers/i2c/busses/i2c-ls2x.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Loongson-2K/Loongson LS7A I2C controller mode driver
  *
  * Copyright (C) 2013 Loongson Technology Corporation Limited.
  * Copyright (C) 2014-2017 Lemote, Inc.
  * Copyright (C) 2018-2022 Loongson Technology Corporation Limited.
  *
  * Originally written by liushaozong
  * Rewritten for mainline by Binbin Zhou <zhoubinbin@loongson.cn>
  */

 #include <linux/bits.h>
 #include <linux/completion.h>
 #include <linux/device.h>
 #include <linux/iopoll.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/units.h>

 /* I2C Registers */
 #define I2C_LS2X_PRER		0x0 /* Freq Division Register(16 bits) */
 #define I2C_LS2X_CTR		0x2 /* Control Register */
 #define I2C_LS2X_TXR		0x3 /* Transport Data Register */
 #define I2C_LS2X_RXR		0x3 /* Receive Data Register */
 #define I2C_LS2X_CR		0x4 /* Command Control Register */
 #define I2C_LS2X_SR		0x4 /* State Register */

 /* Command Control Register Bit */
 #define LS2X_CR_START		BIT(7) /* Start signal */
 #define LS2X_CR_STOP		BIT(6) /* Stop signal */
 #define LS2X_CR_READ		BIT(5) /* Read signal */
 #define LS2X_CR_WRITE		BIT(4) /* Write signal */
 #define LS2X_CR_ACK		BIT(3) /* Response signal */
 #define LS2X_CR_IACK		BIT(0) /* Interrupt response signal */

 /* State Register Bit */
 #define LS2X_SR_NOACK		BIT(7) /* Receive NACK */
 #define LS2X_SR_BUSY		BIT(6) /* Bus busy state */
 #define LS2X_SR_AL		BIT(5) /* Arbitration lost */
 #define LS2X_SR_TIP		BIT(1) /* Transmission state */
 #define LS2X_SR_IF		BIT(0) /* Interrupt flag */

 /* Control Register Bit */
 #define LS2X_CTR_EN		BIT(7) /* 0: I2c frequency setting 1: Normal */
 #define LS2X_CTR_IEN		BIT(6) /* Enable i2c interrupt */
 #define LS2X_CTR_MST		BIT(5) /* 0: Target mode 1: Controller mode */
 #define CTR_FREQ_MASK		GENMASK(7, 6)
 #define CTR_READY_MASK		GENMASK(7, 5)

 /* The PCLK frequency from LPB */
 #define LS2X_I2C_PCLK_FREQ	(50 * HZ_PER_MHZ)

 /* The default bus frequency, which is an empirical value */
 #define LS2X_I2C_FREQ_STD	(33 * HZ_PER_KHZ)

 struct ls2x_i2c_priv {
 	struct i2c_adapter	adapter;
 	void __iomem		*base;
 	struct i2c_timings	i2c_t;
 	struct completion	cmd_complete;
 };

 /*
  * Interrupt service routine.
  * This gets called whenever an I2C interrupt occurs.
  */
 static irqreturn_t ls2x_i2c_isr(int this_irq, void *dev_id)
 {
 	struct ls2x_i2c_priv *priv = dev_id;

 	if (!(readb(priv->base + I2C_LS2X_SR) & LS2X_SR_IF))
 		return IRQ_NONE;

 	writeb(LS2X_CR_IACK, priv->base + I2C_LS2X_CR);
 	complete(&priv->cmd_complete);
 	return IRQ_HANDLED;
 }

 /*
  * The ls2x i2c controller supports standard mode and fast mode, so the
  * maximum bus frequency is '400kHz'.
  * The bus frequency is set to the empirical value of '33KHz' by default,
  * but it can also be taken from ACPI or FDT for compatibility with more
  * devices.
  */
 static void ls2x_i2c_adjust_bus_speed(struct ls2x_i2c_priv *priv)
 {
 	struct i2c_timings *t = &priv->i2c_t;
 	struct device *dev = priv->adapter.dev.parent;
 	u32 acpi_speed = i2c_acpi_find_bus_speed(dev);

 	i2c_parse_fw_timings(dev, t, false);

 	if (acpi_speed || t->bus_freq_hz)
 		t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);
 	else
 		t->bus_freq_hz = LS2X_I2C_FREQ_STD;

 	/* Calculate and set i2c frequency. */
 	writew(LS2X_I2C_PCLK_FREQ / (5 * t->bus_freq_hz) - 1,
 	       priv->base + I2C_LS2X_PRER);
 }

 static void ls2x_i2c_init(struct ls2x_i2c_priv *priv)
 {
 	/* Set i2c frequency setting mode and disable interrupts. */
 	writeb(readb(priv->base + I2C_LS2X_CTR) & ~CTR_FREQ_MASK,
 	       priv->base + I2C_LS2X_CTR);

 	ls2x_i2c_adjust_bus_speed(priv);

 	/* Set i2c normal operating mode and enable interrupts. */
 	writeb(readb(priv->base + I2C_LS2X_CTR) | CTR_READY_MASK,
 	       priv->base + I2C_LS2X_CTR);
 }

 static int ls2x_i2c_xfer_byte(struct ls2x_i2c_priv *priv, u8 txdata, u8 *rxdatap)
 {
 	u8 rxdata;
 	unsigned long time_left;

 	writeb(txdata, priv->base + I2C_LS2X_CR);

 	time_left = wait_for_completion_timeout(&priv->cmd_complete,
 						priv->adapter.timeout);
 	if (!time_left)
 		return -ETIMEDOUT;

 	rxdata = readb(priv->base + I2C_LS2X_SR);
 	if (rxdatap)
 		*rxdatap = rxdata;

 	return 0;
 }

 static int ls2x_i2c_send_byte(struct ls2x_i2c_priv *priv, u8 txdata)
 {
 	int ret;
 	u8 rxdata;

 	ret = ls2x_i2c_xfer_byte(priv, txdata, &rxdata);
 	if (ret)
 		return ret;

 	if (rxdata & LS2X_SR_AL)
 		return -EAGAIN;

 	if (rxdata & LS2X_SR_NOACK)
 		return -ENXIO;

 	return 0;
 }

 static int ls2x_i2c_stop(struct ls2x_i2c_priv *priv)
 {
 	u8 value;

 	writeb(LS2X_CR_STOP, priv->base + I2C_LS2X_CR);
 	return readb_poll_timeout(priv->base + I2C_LS2X_SR, value,
 				  !(value & LS2X_SR_BUSY), 100,
 				  jiffies_to_usecs(priv->adapter.timeout));
 }

 static int ls2x_i2c_start(struct ls2x_i2c_priv *priv, struct i2c_msg *msgs)
 {
 	reinit_completion(&priv->cmd_complete);

 	writeb(i2c_8bit_addr_from_msg(msgs), priv->base + I2C_LS2X_TXR);
 	return ls2x_i2c_send_byte(priv, LS2X_CR_START | LS2X_CR_WRITE);
 }

 static int ls2x_i2c_rx(struct ls2x_i2c_priv *priv, struct i2c_msg *msg)
 {
 	int ret;
 	u8 rxdata, *buf = msg->buf;
 	u16 len = msg->len;

 	/* Contains steps to send start condition and address. */
 	ret = ls2x_i2c_start(priv, msg);
 	if (ret)
 		return ret;

 	while (len--) {
 		ret = ls2x_i2c_xfer_byte(priv,
 					 LS2X_CR_READ | (len ? 0 : LS2X_CR_ACK),
 					 &rxdata);
 		if (ret)
 			return ret;

 		*buf++ = readb(priv->base + I2C_LS2X_RXR);
 	}

 	return 0;
 }

 static int ls2x_i2c_tx(struct ls2x_i2c_priv *priv, struct i2c_msg *msg)
 {
 	int ret;
 	u8 *buf = msg->buf;
 	u16 len = msg->len;

 	/* Contains steps to send start condition and address. */
 	ret = ls2x_i2c_start(priv, msg);
 	if (ret)
 		return ret;

 	while (len--) {
 		writeb(*buf++, priv->base + I2C_LS2X_TXR);

 		ret = ls2x_i2c_send_byte(priv, LS2X_CR_WRITE);
 		if (ret)
 			return ret;
 	}

 	return 0;
 }

 static int ls2x_i2c_xfer_one(struct ls2x_i2c_priv *priv,
 			     struct i2c_msg *msg, bool stop)
 {
 	int ret;

 	if (msg->flags & I2C_M_RD)
 		ret = ls2x_i2c_rx(priv, msg);
 	else
 		ret = ls2x_i2c_tx(priv, msg);

 	if (ret < 0) {
 		/* Fatel error. Needs reinit. */
 		if (ret == -ETIMEDOUT)
 			ls2x_i2c_init(priv);

 		return ret;
 	}

 	if (stop) {
 		/* Failed to issue STOP. Needs reinit. */
 		ret = ls2x_i2c_stop(priv);
 		if (ret)
 			ls2x_i2c_init(priv);
 	}

 	return ret;
 }

 static int ls2x_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 {
 	int ret;
 	struct i2c_msg *msg, *emsg = msgs + num;
 	struct ls2x_i2c_priv *priv = i2c_get_adapdata(adap);

 	for (msg = msgs; msg < emsg; msg++) {
 		ret = ls2x_i2c_xfer_one(priv, msg, msg == emsg - 1);
 		if (ret)
 			return ret;
 	}

 	return num;
 }

 static unsigned int ls2x_i2c_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }

 static const struct i2c_algorithm ls2x_i2c_algo = {
 	.xfer = ls2x_i2c_xfer,
 	.functionality = ls2x_i2c_func,
 };

 static int ls2x_i2c_probe(struct platform_device *pdev)
 {
 	int ret, irq;
 	struct i2c_adapter *adap;
 	struct ls2x_i2c_priv *priv;
 	struct device *dev = &pdev->dev;

 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

 	/* Map hardware registers */
 	priv->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(priv->base))
 		return PTR_ERR(priv->base);

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

 	/* Add the i2c adapter */
 	adap = &priv->adapter;
 	adap->retries = 5;
 	adap->nr = pdev->id;
 	adap->dev.parent = dev;
 	adap->owner = THIS_MODULE;
 	adap->algo = &ls2x_i2c_algo;
 	adap->timeout = msecs_to_jiffies(100);
 	device_set_node(&adap->dev, dev_fwnode(dev));
 	i2c_set_adapdata(adap, priv);
 	strscpy(adap->name, pdev->name, sizeof(adap->name));
 	init_completion(&priv->cmd_complete);
 	platform_set_drvdata(pdev, priv);

 	ls2x_i2c_init(priv);

 	ret = devm_request_irq(dev, irq, ls2x_i2c_isr, IRQF_SHARED, "ls2x-i2c",
 			       priv);
 	if (ret < 0)
 		return dev_err_probe(dev, ret, "Unable to request irq %d\n", irq);

 	return devm_i2c_add_adapter(dev, adap);
 }

 static int ls2x_i2c_suspend(struct device *dev)
 {
 	struct ls2x_i2c_priv *priv = dev_get_drvdata(dev);

 	/* Disable interrupts */
 	writeb(readb(priv->base + I2C_LS2X_CTR) & ~LS2X_CTR_IEN,
 	       priv->base + I2C_LS2X_CTR);

 	return 0;
 }

 static int ls2x_i2c_resume(struct device *dev)
 {
 	ls2x_i2c_init(dev_get_drvdata(dev));
 	return 0;
 }

 static DEFINE_RUNTIME_DEV_PM_OPS(ls2x_i2c_pm_ops,
 				 ls2x_i2c_suspend, ls2x_i2c_resume, NULL);

 static const struct of_device_id ls2x_i2c_id_table[] = {
 	{ .compatible = "loongson,ls2k-i2c" },
 	{ .compatible = "loongson,ls7a-i2c" },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, ls2x_i2c_id_table);

 static const struct acpi_device_id ls2x_i2c_acpi_match[] = {
 	{ "LOON0004" }, /* Loongson LS7A */
 	{ }
 };
 MODULE_DEVICE_TABLE(acpi, ls2x_i2c_acpi_match);

 static struct platform_driver ls2x_i2c_driver = {
 	.probe		= ls2x_i2c_probe,
 	.driver		= {
 		.name	= "ls2x-i2c",
 		.pm	= pm_sleep_ptr(&ls2x_i2c_pm_ops),
 		.of_match_table = ls2x_i2c_id_table,
 		.acpi_match_table = ls2x_i2c_acpi_match,
 	},
 };
 module_platform_driver(ls2x_i2c_driver);

 MODULE_DESCRIPTION("Loongson LS2X I2C Bus driver");
 MODULE_AUTHOR("Loongson Technology Corporation Limited");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Loongson-2K/Loongson LS7A I2C controller mode driver
	*
	* Copyright (C) 2013 Loongson Technology Corporation Limited.
	* Copyright (C) 2014-2017 Lemote, Inc.
	* Copyright (C) 2018-2022 Loongson Technology Corporation Limited.
	*
	* Originally written by liushaozong
	* Rewritten for mainline by Binbin Zhou <zhoubinbin@loongson.cn>
	*/

	#include <linux/bits.h>
	#include <linux/completion.h>
	#include <linux/device.h>
	#include <linux/iopoll.h>
	#include <linux/i2c.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/pm_runtime.h>
	#include <linux/platform_device.h>
	#include <linux/property.h>
	#include <linux/units.h>

	/* I2C Registers */
	#define I2C_LS2X_PRER 0x0 /* Freq Division Register(16 bits) */
	#define I2C_LS2X_CTR 0x2 /* Control Register */
	#define I2C_LS2X_TXR 0x3 /* Transport Data Register */
	#define I2C_LS2X_RXR 0x3 /* Receive Data Register */
	#define I2C_LS2X_CR 0x4 /* Command Control Register */
	#define I2C_LS2X_SR 0x4 /* State Register */

	/* Command Control Register Bit */
	#define LS2X_CR_START BIT(7) /* Start signal */
	#define LS2X_CR_STOP BIT(6) /* Stop signal */
	#define LS2X_CR_READ BIT(5) /* Read signal */
	#define LS2X_CR_WRITE BIT(4) /* Write signal */
	#define LS2X_CR_ACK BIT(3) /* Response signal */
	#define LS2X_CR_IACK BIT(0) /* Interrupt response signal */

	/* State Register Bit */
	#define LS2X_SR_NOACK BIT(7) /* Receive NACK */
	#define LS2X_SR_BUSY BIT(6) /* Bus busy state */
	#define LS2X_SR_AL BIT(5) /* Arbitration lost */
	#define LS2X_SR_TIP BIT(1) /* Transmission state */
	#define LS2X_SR_IF BIT(0) /* Interrupt flag */

	/* Control Register Bit */
	#define LS2X_CTR_EN BIT(7) /* 0: I2c frequency setting 1: Normal */
	#define LS2X_CTR_IEN BIT(6) /* Enable i2c interrupt */
	#define LS2X_CTR_MST BIT(5) /* 0: Target mode 1: Controller mode */
	#define CTR_FREQ_MASK GENMASK(7, 6)
	#define CTR_READY_MASK GENMASK(7, 5)

	/* The PCLK frequency from LPB */
	#define LS2X_I2C_PCLK_FREQ (50 * HZ_PER_MHZ)

	/* The default bus frequency, which is an empirical value */
	#define LS2X_I2C_FREQ_STD (33 * HZ_PER_KHZ)

	struct ls2x_i2c_priv {
	struct i2c_adapter adapter;
	void __iomem *base;
	struct i2c_timings i2c_t;
	struct completion cmd_complete;
	};

	/*
	* Interrupt service routine.
	* This gets called whenever an I2C interrupt occurs.
	*/
	static irqreturn_t ls2x_i2c_isr(int this_irq, void *dev_id)
	{
	struct ls2x_i2c_priv *priv = dev_id;

	if (!(readb(priv->base + I2C_LS2X_SR) & LS2X_SR_IF))
	return IRQ_NONE;

	writeb(LS2X_CR_IACK, priv->base + I2C_LS2X_CR);
	complete(&priv->cmd_complete);
	return IRQ_HANDLED;
	}

	/*
	* The ls2x i2c controller supports standard mode and fast mode, so the
	* maximum bus frequency is '400kHz'.
	* The bus frequency is set to the empirical value of '33KHz' by default,
	* but it can also be taken from ACPI or FDT for compatibility with more
	* devices.
	*/
	static void ls2x_i2c_adjust_bus_speed(struct ls2x_i2c_priv *priv)
	{
	struct i2c_timings *t = &priv->i2c_t;
	struct device *dev = priv->adapter.dev.parent;
	u32 acpi_speed = i2c_acpi_find_bus_speed(dev);

	i2c_parse_fw_timings(dev, t, false);

	if (acpi_speed \|\| t->bus_freq_hz)
	t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);
	else
	t->bus_freq_hz = LS2X_I2C_FREQ_STD;

	/* Calculate and set i2c frequency. */
	writew(LS2X_I2C_PCLK_FREQ / (5 * t->bus_freq_hz) - 1,
	priv->base + I2C_LS2X_PRER);
	}

	static void ls2x_i2c_init(struct ls2x_i2c_priv *priv)
	{
	/* Set i2c frequency setting mode and disable interrupts. */
	writeb(readb(priv->base + I2C_LS2X_CTR) & ~CTR_FREQ_MASK,
	priv->base + I2C_LS2X_CTR);

	ls2x_i2c_adjust_bus_speed(priv);

	/* Set i2c normal operating mode and enable interrupts. */
	writeb(readb(priv->base + I2C_LS2X_CTR) \| CTR_READY_MASK,
	priv->base + I2C_LS2X_CTR);
	}

	static int ls2x_i2c_xfer_byte(struct ls2x_i2c_priv priv, u8 txdata, u8 rxdatap)
	{
	u8 rxdata;
	unsigned long time_left;

	writeb(txdata, priv->base + I2C_LS2X_CR);

	time_left = wait_for_completion_timeout(&priv->cmd_complete,
	priv->adapter.timeout);
	if (!time_left)
	return -ETIMEDOUT;

	rxdata = readb(priv->base + I2C_LS2X_SR);
	if (rxdatap)
	*rxdatap = rxdata;

	return 0;
	}

	static int ls2x_i2c_send_byte(struct ls2x_i2c_priv *priv, u8 txdata)
	{
	int ret;
	u8 rxdata;

	ret = ls2x_i2c_xfer_byte(priv, txdata, &rxdata);
	if (ret)
	return ret;

	if (rxdata & LS2X_SR_AL)
	return -EAGAIN;

	if (rxdata & LS2X_SR_NOACK)
	return -ENXIO;

	return 0;
	}

	static int ls2x_i2c_stop(struct ls2x_i2c_priv *priv)
	{
	u8 value;

	writeb(LS2X_CR_STOP, priv->base + I2C_LS2X_CR);
	return readb_poll_timeout(priv->base + I2C_LS2X_SR, value,
	!(value & LS2X_SR_BUSY), 100,
	jiffies_to_usecs(priv->adapter.timeout));
	}

	static int ls2x_i2c_start(struct ls2x_i2c_priv priv, struct i2c_msg msgs)
	{
	reinit_completion(&priv->cmd_complete);

	writeb(i2c_8bit_addr_from_msg(msgs), priv->base + I2C_LS2X_TXR);
	return ls2x_i2c_send_byte(priv, LS2X_CR_START \| LS2X_CR_WRITE);
	}

	static int ls2x_i2c_rx(struct ls2x_i2c_priv priv, struct i2c_msg msg)
	{
	int ret;
	u8 rxdata, *buf = msg->buf;
	u16 len = msg->len;

	/* Contains steps to send start condition and address. */
	ret = ls2x_i2c_start(priv, msg);
	if (ret)
	return ret;

	while (len--) {
	ret = ls2x_i2c_xfer_byte(priv,
	LS2X_CR_READ \| (len ? 0 : LS2X_CR_ACK),
	&rxdata);
	if (ret)
	return ret;

	*buf++ = readb(priv->base + I2C_LS2X_RXR);
	}

	return 0;
	}

	static int ls2x_i2c_tx(struct ls2x_i2c_priv priv, struct i2c_msg msg)
	{
	int ret;
	u8 *buf = msg->buf;
	u16 len = msg->len;

	/* Contains steps to send start condition and address. */
	ret = ls2x_i2c_start(priv, msg);
	if (ret)
	return ret;

	while (len--) {
	writeb(*buf++, priv->base + I2C_LS2X_TXR);

	ret = ls2x_i2c_send_byte(priv, LS2X_CR_WRITE);
	if (ret)
	return ret;
	}

	return 0;
	}

	static int ls2x_i2c_xfer_one(struct ls2x_i2c_priv *priv,
	struct i2c_msg *msg, bool stop)
	{
	int ret;

	if (msg->flags & I2C_M_RD)
	ret = ls2x_i2c_rx(priv, msg);
	else
	ret = ls2x_i2c_tx(priv, msg);

	if (ret < 0) {
	/* Fatel error. Needs reinit. */
	if (ret == -ETIMEDOUT)
	ls2x_i2c_init(priv);

	return ret;
	}

	if (stop) {
	/* Failed to issue STOP. Needs reinit. */
	ret = ls2x_i2c_stop(priv);
	if (ret)
	ls2x_i2c_init(priv);
	}

	return ret;
	}

	static int ls2x_i2c_xfer(struct i2c_adapter adap, struct i2c_msg msgs, int num)
	{
	int ret;
	struct i2c_msg msg, emsg = msgs + num;
	struct ls2x_i2c_priv *priv = i2c_get_adapdata(adap);

	for (msg = msgs; msg < emsg; msg++) {
	ret = ls2x_i2c_xfer_one(priv, msg, msg == emsg - 1);
	if (ret)
	return ret;
	}

	return num;
	}

	static unsigned int ls2x_i2c_func(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL;
	}

	static const struct i2c_algorithm ls2x_i2c_algo = {
	.xfer = ls2x_i2c_xfer,
	.functionality = ls2x_i2c_func,
	};

	static int ls2x_i2c_probe(struct platform_device *pdev)
	{
	int ret, irq;
	struct i2c_adapter *adap;
	struct ls2x_i2c_priv *priv;
	struct device *dev = &pdev->dev;

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
	return -ENOMEM;

	/* Map hardware registers */
	priv->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(priv->base))
	return PTR_ERR(priv->base);

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

	/* Add the i2c adapter */
	adap = &priv->adapter;
	adap->retries = 5;
	adap->nr = pdev->id;
	adap->dev.parent = dev;
	adap->owner = THIS_MODULE;
	adap->algo = &ls2x_i2c_algo;
	adap->timeout = msecs_to_jiffies(100);
	device_set_node(&adap->dev, dev_fwnode(dev));
	i2c_set_adapdata(adap, priv);
	strscpy(adap->name, pdev->name, sizeof(adap->name));
	init_completion(&priv->cmd_complete);
	platform_set_drvdata(pdev, priv);

	ls2x_i2c_init(priv);

	ret = devm_request_irq(dev, irq, ls2x_i2c_isr, IRQF_SHARED, "ls2x-i2c",
	priv);
	if (ret < 0)
	return dev_err_probe(dev, ret, "Unable to request irq %d\n", irq);

	return devm_i2c_add_adapter(dev, adap);
	}

	static int ls2x_i2c_suspend(struct device *dev)
	{
	struct ls2x_i2c_priv *priv = dev_get_drvdata(dev);

	/* Disable interrupts */
	writeb(readb(priv->base + I2C_LS2X_CTR) & ~LS2X_CTR_IEN,
	priv->base + I2C_LS2X_CTR);

	return 0;
	}

	static int ls2x_i2c_resume(struct device *dev)
	{
	ls2x_i2c_init(dev_get_drvdata(dev));
	return 0;
	}

	static DEFINE_RUNTIME_DEV_PM_OPS(ls2x_i2c_pm_ops,
	ls2x_i2c_suspend, ls2x_i2c_resume, NULL);

	static const struct of_device_id ls2x_i2c_id_table[] = {
	{ .compatible = "loongson,ls2k-i2c" },
	{ .compatible = "loongson,ls7a-i2c" },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, ls2x_i2c_id_table);

	static const struct acpi_device_id ls2x_i2c_acpi_match[] = {
	{ "LOON0004" }, /* Loongson LS7A */
	{ }
	};
	MODULE_DEVICE_TABLE(acpi, ls2x_i2c_acpi_match);

	static struct platform_driver ls2x_i2c_driver = {
	.probe = ls2x_i2c_probe,
	.driver = {
	.name = "ls2x-i2c",
	.pm = pm_sleep_ptr(&ls2x_i2c_pm_ops),
	.of_match_table = ls2x_i2c_id_table,
	.acpi_match_table = ls2x_i2c_acpi_match,
	},
	};
	module_platform_driver(ls2x_i2c_driver);

	MODULE_DESCRIPTION("Loongson LS2X I2C Bus driver");
	MODULE_AUTHOR("Loongson Technology Corporation Limited");
	MODULE_LICENSE("GPL");