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

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * I2C bus driver for CSR SiRFprimaII
  *
  * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
  */

 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/platform_device.h>
 #include <linux/i2c.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/io.h>

 #define SIRFSOC_I2C_CLK_CTRL		0x00
 #define SIRFSOC_I2C_STATUS		0x0C
 #define SIRFSOC_I2C_CTRL		0x10
 #define SIRFSOC_I2C_IO_CTRL		0x14
 #define SIRFSOC_I2C_SDA_DELAY		0x18
 #define SIRFSOC_I2C_CMD_START		0x1C
 #define SIRFSOC_I2C_CMD_BUF		0x30
 #define SIRFSOC_I2C_DATA_BUF		0x80

 #define SIRFSOC_I2C_CMD_BUF_MAX		16
 #define SIRFSOC_I2C_DATA_BUF_MAX	16

 #define SIRFSOC_I2C_CMD(x)		(SIRFSOC_I2C_CMD_BUF + (x)*0x04)
 #define SIRFSOC_I2C_DATA_MASK(x)        (0xFF<<(((x)&3)*8))
 #define SIRFSOC_I2C_DATA_SHIFT(x)       (((x)&3)*8)

 #define SIRFSOC_I2C_DIV_MASK		(0xFFFF)

 /* I2C status flags */
 #define SIRFSOC_I2C_STAT_BUSY		BIT(0)
 #define SIRFSOC_I2C_STAT_TIP		BIT(1)
 #define SIRFSOC_I2C_STAT_NACK		BIT(2)
 #define SIRFSOC_I2C_STAT_TR_INT		BIT(4)
 #define SIRFSOC_I2C_STAT_STOP		BIT(6)
 #define SIRFSOC_I2C_STAT_CMD_DONE	BIT(8)
 #define SIRFSOC_I2C_STAT_ERR		BIT(9)
 #define SIRFSOC_I2C_CMD_INDEX		(0x1F<<16)

 /* I2C control flags */
 #define SIRFSOC_I2C_RESET		BIT(0)
 #define SIRFSOC_I2C_CORE_EN		BIT(1)
 #define SIRFSOC_I2C_MASTER_MODE		BIT(2)
 #define SIRFSOC_I2C_CMD_DONE_EN		BIT(11)
 #define SIRFSOC_I2C_ERR_INT_EN		BIT(12)

 #define SIRFSOC_I2C_SDA_DELAY_MASK	(0xFF)
 #define SIRFSOC_I2C_SCLF_FILTER		(3<<8)

 #define SIRFSOC_I2C_START_CMD		BIT(0)

 #define SIRFSOC_I2C_CMD_RP(x)		((x)&0x7)
 #define SIRFSOC_I2C_NACK		BIT(3)
 #define SIRFSOC_I2C_WRITE		BIT(4)
 #define SIRFSOC_I2C_READ		BIT(5)
 #define SIRFSOC_I2C_STOP		BIT(6)
 #define SIRFSOC_I2C_START		BIT(7)

 #define SIRFSOC_I2C_DEFAULT_SPEED 100000
 #define SIRFSOC_I2C_ERR_NOACK      1
 #define SIRFSOC_I2C_ERR_TIMEOUT    2

 struct sirfsoc_i2c {
 	void __iomem *base;
 	struct clk *clk;
 	u32 cmd_ptr;		/* Current position in CMD buffer */
 	u8 *buf;		/* Buffer passed by user */
 	u32 msg_len;		/* Message length */
 	u32 finished_len;	/* number of bytes read/written */
 	u32 read_cmd_len;	/* number of read cmd sent */
 	int msg_read;		/* 1 indicates a read message */
 	int err_status;		/* 1 indicates an error on bus */

 	u32 sda_delay;		/* For suspend/resume */
 	u32 clk_div;
 	int last;		/* Last message in transfer, STOP cmd can be sent */

 	struct completion done;	/* indicates completion of message transfer */
 	struct i2c_adapter adapter;
 };

 static void i2c_sirfsoc_read_data(struct sirfsoc_i2c *siic)
 {
 	u32 data = 0;
 	int i;

 	for (i = 0; i < siic->read_cmd_len; i++) {
 		if (!(i & 0x3))
 			data = readl(siic->base + SIRFSOC_I2C_DATA_BUF + i);
 		siic->buf[siic->finished_len++] =
 			(u8)((data & SIRFSOC_I2C_DATA_MASK(i)) >>
 				SIRFSOC_I2C_DATA_SHIFT(i));
 	}
 }

 static void i2c_sirfsoc_queue_cmd(struct sirfsoc_i2c *siic)
 {
 	u32 regval;
 	int i = 0;

 	if (siic->msg_read) {
 		while (((siic->finished_len + i) < siic->msg_len)
 				&& (siic->cmd_ptr < SIRFSOC_I2C_CMD_BUF_MAX)) {
 			regval = SIRFSOC_I2C_READ | SIRFSOC_I2C_CMD_RP(0);
 			if (((siic->finished_len + i) ==
 					(siic->msg_len - 1)) && siic->last)
 				regval |= SIRFSOC_I2C_STOP | SIRFSOC_I2C_NACK;
 			writel(regval,
 				siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
 			i++;
 		}

 		siic->read_cmd_len = i;
 	} else {
 		while ((siic->cmd_ptr < SIRFSOC_I2C_CMD_BUF_MAX - 1)
 				&& (siic->finished_len < siic->msg_len)) {
 			regval = SIRFSOC_I2C_WRITE | SIRFSOC_I2C_CMD_RP(0);
 			if ((siic->finished_len == (siic->msg_len - 1))
 				&& siic->last)
 				regval |= SIRFSOC_I2C_STOP;
 			writel(regval,
 				siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
 			writel(siic->buf[siic->finished_len++],
 				siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
 		}
 	}
 	siic->cmd_ptr = 0;

 	/* Trigger the transfer */
 	writel(SIRFSOC_I2C_START_CMD, siic->base + SIRFSOC_I2C_CMD_START);
 }

 static irqreturn_t i2c_sirfsoc_irq(int irq, void *dev_id)
 {
 	struct sirfsoc_i2c *siic = (struct sirfsoc_i2c *)dev_id;
 	u32 i2c_stat = readl(siic->base + SIRFSOC_I2C_STATUS);

 	if (i2c_stat & SIRFSOC_I2C_STAT_ERR) {
 		/* Error conditions */
 		siic->err_status = SIRFSOC_I2C_ERR_NOACK;
 		writel(SIRFSOC_I2C_STAT_ERR, siic->base + SIRFSOC_I2C_STATUS);

 		if (i2c_stat & SIRFSOC_I2C_STAT_NACK)
 			dev_dbg(&siic->adapter.dev, "ACK not received\n");
 		else
 			dev_err(&siic->adapter.dev, "I2C error\n");

 		/*
 		 * Due to hardware ANOMALY, we need to reset I2C earlier after
 		 * we get NOACK while accessing non-existing clients, otherwise
 		 * we will get errors even we access existing clients later
 		 */
 		writel(readl(siic->base + SIRFSOC_I2C_CTRL) | SIRFSOC_I2C_RESET,
 				siic->base + SIRFSOC_I2C_CTRL);
 		while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
 			cpu_relax();

 		complete(&siic->done);
 	} else if (i2c_stat & SIRFSOC_I2C_STAT_CMD_DONE) {
 		/* CMD buffer execution complete */
 		if (siic->msg_read)
 			i2c_sirfsoc_read_data(siic);
 		if (siic->finished_len == siic->msg_len)
 			complete(&siic->done);
 		else /* Fill a new CMD buffer for left data */
 			i2c_sirfsoc_queue_cmd(siic);

 		writel(SIRFSOC_I2C_STAT_CMD_DONE, siic->base + SIRFSOC_I2C_STATUS);
 	}

 	return IRQ_HANDLED;
 }

 static void i2c_sirfsoc_set_address(struct sirfsoc_i2c *siic,
 	struct i2c_msg *msg)
 {
 	unsigned char addr;
 	u32 regval = SIRFSOC_I2C_START | SIRFSOC_I2C_CMD_RP(0) | SIRFSOC_I2C_WRITE;

 	/* no data and last message -> add STOP */
 	if (siic->last && (msg->len == 0))
 		regval |= SIRFSOC_I2C_STOP;

 	writel(regval, siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));

 	addr = i2c_8bit_addr_from_msg(msg);

 	/* Reverse direction bit */
 	if (msg->flags & I2C_M_REV_DIR_ADDR)
 		addr ^= 1;

 	writel(addr, siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
 }

 static int i2c_sirfsoc_xfer_msg(struct sirfsoc_i2c *siic, struct i2c_msg *msg)
 {
 	u32 regval = readl(siic->base + SIRFSOC_I2C_CTRL);
 	/* timeout waiting for the xfer to finish or fail */
 	int timeout = msecs_to_jiffies((msg->len + 1) * 50);

 	i2c_sirfsoc_set_address(siic, msg);

 	writel(regval | SIRFSOC_I2C_CMD_DONE_EN | SIRFSOC_I2C_ERR_INT_EN,
 		siic->base + SIRFSOC_I2C_CTRL);
 	i2c_sirfsoc_queue_cmd(siic);

 	if (wait_for_completion_timeout(&siic->done, timeout) == 0) {
 		siic->err_status = SIRFSOC_I2C_ERR_TIMEOUT;
 		dev_err(&siic->adapter.dev, "Transfer timeout\n");
 	}

 	writel(regval & ~(SIRFSOC_I2C_CMD_DONE_EN | SIRFSOC_I2C_ERR_INT_EN),
 		siic->base + SIRFSOC_I2C_CTRL);
 	writel(0, siic->base + SIRFSOC_I2C_CMD_START);

 	/* i2c control doesn't response, reset it */
 	if (siic->err_status == SIRFSOC_I2C_ERR_TIMEOUT) {
 		writel(readl(siic->base + SIRFSOC_I2C_CTRL) | SIRFSOC_I2C_RESET,
 			siic->base + SIRFSOC_I2C_CTRL);
 		while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
 			cpu_relax();
 	}
 	return siic->err_status ? -EAGAIN : 0;
 }

 static u32 i2c_sirfsoc_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }

 static int i2c_sirfsoc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	int num)
 {
 	struct sirfsoc_i2c *siic = adap->algo_data;
 	int i, ret;

 	clk_enable(siic->clk);

 	for (i = 0; i < num; i++) {
 		siic->buf = msgs[i].buf;
 		siic->msg_len = msgs[i].len;
 		siic->msg_read = !!(msgs[i].flags & I2C_M_RD);
 		siic->err_status = 0;
 		siic->cmd_ptr = 0;
 		siic->finished_len = 0;
 		siic->last = (i == (num - 1));

 		ret = i2c_sirfsoc_xfer_msg(siic, &msgs[i]);
 		if (ret) {
 			clk_disable(siic->clk);
 			return ret;
 		}
 	}

 	clk_disable(siic->clk);
 	return num;
 }

 /* I2C algorithms associated with this master controller driver */
 static const struct i2c_algorithm i2c_sirfsoc_algo = {
 	.master_xfer = i2c_sirfsoc_xfer,
 	.functionality = i2c_sirfsoc_func,
 };

 static int i2c_sirfsoc_probe(struct platform_device *pdev)
 {
 	struct sirfsoc_i2c *siic;
 	struct i2c_adapter *adap;
 	struct resource *mem_res;
 	struct clk *clk;
 	int bitrate;
 	int ctrl_speed;
 	int irq;

 	int err;
 	u32 regval;

 	clk = clk_get(&pdev->dev, NULL);
 	if (IS_ERR(clk)) {
 		err = PTR_ERR(clk);
 		dev_err(&pdev->dev, "Clock get failed\n");
 		goto err_get_clk;
 	}

 	err = clk_prepare(clk);
 	if (err) {
 		dev_err(&pdev->dev, "Clock prepare failed\n");
 		goto err_clk_prep;
 	}

 	err = clk_enable(clk);
 	if (err) {
 		dev_err(&pdev->dev, "Clock enable failed\n");
 		goto err_clk_en;
 	}

 	ctrl_speed = clk_get_rate(clk);

 	siic = devm_kzalloc(&pdev->dev, sizeof(*siic), GFP_KERNEL);
 	if (!siic) {
 		err = -ENOMEM;
 		goto out;
 	}
 	adap = &siic->adapter;
 	adap->class = I2C_CLASS_DEPRECATED;

 	mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	siic->base = devm_ioremap_resource(&pdev->dev, mem_res);
 	if (IS_ERR(siic->base)) {
 		err = PTR_ERR(siic->base);
 		goto out;
 	}

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		err = irq;
 		goto out;
 	}
 	err = devm_request_irq(&pdev->dev, irq, i2c_sirfsoc_irq, 0,
 		dev_name(&pdev->dev), siic);
 	if (err)
 		goto out;

 	adap->algo = &i2c_sirfsoc_algo;
 	adap->algo_data = siic;
 	adap->retries = 3;

 	adap->dev.of_node = pdev->dev.of_node;
 	adap->dev.parent = &pdev->dev;
 	adap->nr = pdev->id;

 	strlcpy(adap->name, "sirfsoc-i2c", sizeof(adap->name));

 	platform_set_drvdata(pdev, adap);
 	init_completion(&siic->done);

 	/* Controller initialisation */

 	writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
 	while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
 		cpu_relax();
 	writel(SIRFSOC_I2C_CORE_EN | SIRFSOC_I2C_MASTER_MODE,
 		siic->base + SIRFSOC_I2C_CTRL);

 	siic->clk = clk;

 	err = of_property_read_u32(pdev->dev.of_node,
 		"clock-frequency", &bitrate);
 	if (err < 0)
 		bitrate = SIRFSOC_I2C_DEFAULT_SPEED;

 	/*
 	 * Due to some hardware design issues, we need to tune the formula.
 	 * Since i2c is open drain interface that allows the slave to
 	 * stall the transaction by holding the SCL line at '0', the RTL
 	 * implementation is waiting for SCL feedback from the pin after
 	 * setting it to High-Z ('1'). This wait adds to the high-time
 	 * interval counter few cycles of the input synchronization
 	 * (depending on the SCL_FILTER_REG field), and also the time it
 	 * takes for the board pull-up resistor to rise the SCL line.
 	 * For slow SCL settings these additions are negligible,
 	 * but they start to affect the speed when clock is set to faster
 	 * frequencies.
 	 * Through the actual tests, use the different user_div value(which
 	 * in the divider formula 'Fio / (Fi2c * user_div)') to adapt
 	 * the different ranges of i2c bus clock frequency, to make the SCL
 	 * more accurate.
 	 */
 	if (bitrate <= 30000)
 		regval = ctrl_speed / (bitrate * 5);
 	else if (bitrate > 30000 && bitrate <= 280000)
 		regval = (2 * ctrl_speed) / (bitrate * 11);
 	else
 		regval = ctrl_speed / (bitrate * 6);

 	writel(regval, siic->base + SIRFSOC_I2C_CLK_CTRL);
 	if (regval > 0xFF)
 		writel(0xFF, siic->base + SIRFSOC_I2C_SDA_DELAY);
 	else
 		writel(regval, siic->base + SIRFSOC_I2C_SDA_DELAY);

 	err = i2c_add_numbered_adapter(adap);
 	if (err < 0)
 		goto out;

 	clk_disable(clk);

 	dev_info(&pdev->dev, " I2C adapter ready to operate\n");

 	return 0;

 out:
 	clk_disable(clk);
 err_clk_en:
 	clk_unprepare(clk);
 err_clk_prep:
 	clk_put(clk);
 err_get_clk:
 	return err;
 }

 static int i2c_sirfsoc_remove(struct platform_device *pdev)
 {
 	struct i2c_adapter *adapter = platform_get_drvdata(pdev);
 	struct sirfsoc_i2c *siic = adapter->algo_data;

 	writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
 	i2c_del_adapter(adapter);
 	clk_unprepare(siic->clk);
 	clk_put(siic->clk);
 	return 0;
 }

 #ifdef CONFIG_PM
 static int i2c_sirfsoc_suspend(struct device *dev)
 {
 	struct i2c_adapter *adapter = dev_get_drvdata(dev);
 	struct sirfsoc_i2c *siic = adapter->algo_data;

 	clk_enable(siic->clk);
 	siic->sda_delay = readl(siic->base + SIRFSOC_I2C_SDA_DELAY);
 	siic->clk_div = readl(siic->base + SIRFSOC_I2C_CLK_CTRL);
 	clk_disable(siic->clk);
 	return 0;
 }

 static int i2c_sirfsoc_resume(struct device *dev)
 {
 	struct i2c_adapter *adapter = dev_get_drvdata(dev);
 	struct sirfsoc_i2c *siic = adapter->algo_data;

 	clk_enable(siic->clk);
 	writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
 	while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
 		cpu_relax();
 	writel(SIRFSOC_I2C_CORE_EN | SIRFSOC_I2C_MASTER_MODE,
 		siic->base + SIRFSOC_I2C_CTRL);
 	writel(siic->clk_div, siic->base + SIRFSOC_I2C_CLK_CTRL);
 	writel(siic->sda_delay, siic->base + SIRFSOC_I2C_SDA_DELAY);
 	clk_disable(siic->clk);
 	return 0;
 }

 static const struct dev_pm_ops i2c_sirfsoc_pm_ops = {
 	.suspend = i2c_sirfsoc_suspend,
 	.resume = i2c_sirfsoc_resume,
 };
 #endif

 static const struct of_device_id sirfsoc_i2c_of_match[] = {
 	{ .compatible = "sirf,prima2-i2c", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, sirfsoc_i2c_of_match);

 static struct platform_driver i2c_sirfsoc_driver = {
 	.driver = {
 		.name = "sirfsoc_i2c",
 #ifdef CONFIG_PM
 		.pm = &i2c_sirfsoc_pm_ops,
 #endif
 		.of_match_table = sirfsoc_i2c_of_match,
 	},
 	.probe = i2c_sirfsoc_probe,
 	.remove = i2c_sirfsoc_remove,
 };
 module_platform_driver(i2c_sirfsoc_driver);

 MODULE_DESCRIPTION("SiRF SoC I2C master controller driver");
 MODULE_AUTHOR("Zhiwu Song <Zhiwu.Song@csr.com>, "
 	"Xiangzhen Ye <Xiangzhen.Ye@csr.com>");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* I2C bus driver for CSR SiRFprimaII
	*
	* Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
	*/

	#include <linux/interrupt.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/platform_device.h>
	#include <linux/i2c.h>
	#include <linux/clk.h>
	#include <linux/err.h>
	#include <linux/io.h>

	#define SIRFSOC_I2C_CLK_CTRL 0x00
	#define SIRFSOC_I2C_STATUS 0x0C
	#define SIRFSOC_I2C_CTRL 0x10
	#define SIRFSOC_I2C_IO_CTRL 0x14
	#define SIRFSOC_I2C_SDA_DELAY 0x18
	#define SIRFSOC_I2C_CMD_START 0x1C
	#define SIRFSOC_I2C_CMD_BUF 0x30
	#define SIRFSOC_I2C_DATA_BUF 0x80

	#define SIRFSOC_I2C_CMD_BUF_MAX 16
	#define SIRFSOC_I2C_DATA_BUF_MAX 16

	#define SIRFSOC_I2C_CMD(x) (SIRFSOC_I2C_CMD_BUF + (x)*0x04)
	#define SIRFSOC_I2C_DATA_MASK(x) (0xFF<<(((x)&3)*8))
	#define SIRFSOC_I2C_DATA_SHIFT(x) (((x)&3)*8)

	#define SIRFSOC_I2C_DIV_MASK (0xFFFF)

	/* I2C status flags */
	#define SIRFSOC_I2C_STAT_BUSY BIT(0)
	#define SIRFSOC_I2C_STAT_TIP BIT(1)
	#define SIRFSOC_I2C_STAT_NACK BIT(2)
	#define SIRFSOC_I2C_STAT_TR_INT BIT(4)
	#define SIRFSOC_I2C_STAT_STOP BIT(6)
	#define SIRFSOC_I2C_STAT_CMD_DONE BIT(8)
	#define SIRFSOC_I2C_STAT_ERR BIT(9)
	#define SIRFSOC_I2C_CMD_INDEX (0x1F<<16)

	/* I2C control flags */
	#define SIRFSOC_I2C_RESET BIT(0)
	#define SIRFSOC_I2C_CORE_EN BIT(1)
	#define SIRFSOC_I2C_MASTER_MODE BIT(2)
	#define SIRFSOC_I2C_CMD_DONE_EN BIT(11)
	#define SIRFSOC_I2C_ERR_INT_EN BIT(12)

	#define SIRFSOC_I2C_SDA_DELAY_MASK (0xFF)
	#define SIRFSOC_I2C_SCLF_FILTER (3<<8)

	#define SIRFSOC_I2C_START_CMD BIT(0)

	#define SIRFSOC_I2C_CMD_RP(x) ((x)&0x7)
	#define SIRFSOC_I2C_NACK BIT(3)
	#define SIRFSOC_I2C_WRITE BIT(4)
	#define SIRFSOC_I2C_READ BIT(5)
	#define SIRFSOC_I2C_STOP BIT(6)
	#define SIRFSOC_I2C_START BIT(7)

	#define SIRFSOC_I2C_DEFAULT_SPEED 100000
	#define SIRFSOC_I2C_ERR_NOACK 1
	#define SIRFSOC_I2C_ERR_TIMEOUT 2

	struct sirfsoc_i2c {
	void __iomem *base;
	struct clk *clk;
	u32 cmd_ptr; /* Current position in CMD buffer */
	u8 buf; / Buffer passed by user */
	u32 msg_len; /* Message length */
	u32 finished_len; /* number of bytes read/written */
	u32 read_cmd_len; /* number of read cmd sent */
	int msg_read; /* 1 indicates a read message */
	int err_status; /* 1 indicates an error on bus */

	u32 sda_delay; /* For suspend/resume */
	u32 clk_div;
	int last; /* Last message in transfer, STOP cmd can be sent */

	struct completion done; /* indicates completion of message transfer */
	struct i2c_adapter adapter;
	};

	static void i2c_sirfsoc_read_data(struct sirfsoc_i2c *siic)
	{
	u32 data = 0;
	int i;

	for (i = 0; i < siic->read_cmd_len; i++) {
	if (!(i & 0x3))
	data = readl(siic->base + SIRFSOC_I2C_DATA_BUF + i);
	siic->buf[siic->finished_len++] =
	(u8)((data & SIRFSOC_I2C_DATA_MASK(i)) >>
	SIRFSOC_I2C_DATA_SHIFT(i));
	}
	}

	static void i2c_sirfsoc_queue_cmd(struct sirfsoc_i2c *siic)
	{
	u32 regval;
	int i = 0;

	if (siic->msg_read) {
	while (((siic->finished_len + i) < siic->msg_len)
	&& (siic->cmd_ptr < SIRFSOC_I2C_CMD_BUF_MAX)) {
	regval = SIRFSOC_I2C_READ \| SIRFSOC_I2C_CMD_RP(0);
	if (((siic->finished_len + i) ==
	(siic->msg_len - 1)) && siic->last)
	regval \|= SIRFSOC_I2C_STOP \| SIRFSOC_I2C_NACK;
	writel(regval,
	siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
	i++;
	}

	siic->read_cmd_len = i;
	} else {
	while ((siic->cmd_ptr < SIRFSOC_I2C_CMD_BUF_MAX - 1)
	&& (siic->finished_len < siic->msg_len)) {
	regval = SIRFSOC_I2C_WRITE \| SIRFSOC_I2C_CMD_RP(0);
	if ((siic->finished_len == (siic->msg_len - 1))
	&& siic->last)
	regval \|= SIRFSOC_I2C_STOP;
	writel(regval,
	siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
	writel(siic->buf[siic->finished_len++],
	siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
	}
	}
	siic->cmd_ptr = 0;

	/* Trigger the transfer */
	writel(SIRFSOC_I2C_START_CMD, siic->base + SIRFSOC_I2C_CMD_START);
	}

	static irqreturn_t i2c_sirfsoc_irq(int irq, void *dev_id)
	{
	struct sirfsoc_i2c siic = (struct sirfsoc_i2c )dev_id;
	u32 i2c_stat = readl(siic->base + SIRFSOC_I2C_STATUS);

	if (i2c_stat & SIRFSOC_I2C_STAT_ERR) {
	/* Error conditions */
	siic->err_status = SIRFSOC_I2C_ERR_NOACK;
	writel(SIRFSOC_I2C_STAT_ERR, siic->base + SIRFSOC_I2C_STATUS);

	if (i2c_stat & SIRFSOC_I2C_STAT_NACK)
	dev_dbg(&siic->adapter.dev, "ACK not received\n");
	else
	dev_err(&siic->adapter.dev, "I2C error\n");

	/*
	* Due to hardware ANOMALY, we need to reset I2C earlier after
	* we get NOACK while accessing non-existing clients, otherwise
	* we will get errors even we access existing clients later
	*/
	writel(readl(siic->base + SIRFSOC_I2C_CTRL) \| SIRFSOC_I2C_RESET,
	siic->base + SIRFSOC_I2C_CTRL);
	while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
	cpu_relax();

	complete(&siic->done);
	} else if (i2c_stat & SIRFSOC_I2C_STAT_CMD_DONE) {
	/* CMD buffer execution complete */
	if (siic->msg_read)
	i2c_sirfsoc_read_data(siic);
	if (siic->finished_len == siic->msg_len)
	complete(&siic->done);
	else /* Fill a new CMD buffer for left data */
	i2c_sirfsoc_queue_cmd(siic);

	writel(SIRFSOC_I2C_STAT_CMD_DONE, siic->base + SIRFSOC_I2C_STATUS);
	}

	return IRQ_HANDLED;
	}

	static void i2c_sirfsoc_set_address(struct sirfsoc_i2c *siic,
	struct i2c_msg *msg)
	{
	unsigned char addr;
	u32 regval = SIRFSOC_I2C_START \| SIRFSOC_I2C_CMD_RP(0) \| SIRFSOC_I2C_WRITE;

	/* no data and last message -> add STOP */
	if (siic->last && (msg->len == 0))
	regval \|= SIRFSOC_I2C_STOP;

	writel(regval, siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));

	addr = i2c_8bit_addr_from_msg(msg);

	/* Reverse direction bit */
	if (msg->flags & I2C_M_REV_DIR_ADDR)
	addr ^= 1;

	writel(addr, siic->base + SIRFSOC_I2C_CMD(siic->cmd_ptr++));
	}

	static int i2c_sirfsoc_xfer_msg(struct sirfsoc_i2c siic, struct i2c_msg msg)
	{
	u32 regval = readl(siic->base + SIRFSOC_I2C_CTRL);
	/* timeout waiting for the xfer to finish or fail */
	int timeout = msecs_to_jiffies((msg->len + 1) * 50);

	i2c_sirfsoc_set_address(siic, msg);

	writel(regval \| SIRFSOC_I2C_CMD_DONE_EN \| SIRFSOC_I2C_ERR_INT_EN,
	siic->base + SIRFSOC_I2C_CTRL);
	i2c_sirfsoc_queue_cmd(siic);

	if (wait_for_completion_timeout(&siic->done, timeout) == 0) {
	siic->err_status = SIRFSOC_I2C_ERR_TIMEOUT;
	dev_err(&siic->adapter.dev, "Transfer timeout\n");
	}

	writel(regval & ~(SIRFSOC_I2C_CMD_DONE_EN \| SIRFSOC_I2C_ERR_INT_EN),
	siic->base + SIRFSOC_I2C_CTRL);
	writel(0, siic->base + SIRFSOC_I2C_CMD_START);

	/* i2c control doesn't response, reset it */
	if (siic->err_status == SIRFSOC_I2C_ERR_TIMEOUT) {
	writel(readl(siic->base + SIRFSOC_I2C_CTRL) \| SIRFSOC_I2C_RESET,
	siic->base + SIRFSOC_I2C_CTRL);
	while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
	cpu_relax();
	}
	return siic->err_status ? -EAGAIN : 0;
	}

	static u32 i2c_sirfsoc_func(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL;
	}

	static int i2c_sirfsoc_xfer(struct i2c_adapter adap, struct i2c_msg msgs,
	int num)
	{
	struct sirfsoc_i2c *siic = adap->algo_data;
	int i, ret;

	clk_enable(siic->clk);

	for (i = 0; i < num; i++) {
	siic->buf = msgs[i].buf;
	siic->msg_len = msgs[i].len;
	siic->msg_read = !!(msgs[i].flags & I2C_M_RD);
	siic->err_status = 0;
	siic->cmd_ptr = 0;
	siic->finished_len = 0;
	siic->last = (i == (num - 1));

	ret = i2c_sirfsoc_xfer_msg(siic, &msgs[i]);
	if (ret) {
	clk_disable(siic->clk);
	return ret;
	}
	}

	clk_disable(siic->clk);
	return num;
	}

	/* I2C algorithms associated with this master controller driver */
	static const struct i2c_algorithm i2c_sirfsoc_algo = {
	.master_xfer = i2c_sirfsoc_xfer,
	.functionality = i2c_sirfsoc_func,
	};

	static int i2c_sirfsoc_probe(struct platform_device *pdev)
	{
	struct sirfsoc_i2c *siic;
	struct i2c_adapter *adap;
	struct resource *mem_res;
	struct clk *clk;
	int bitrate;
	int ctrl_speed;
	int irq;

	int err;
	u32 regval;

	clk = clk_get(&pdev->dev, NULL);
	if (IS_ERR(clk)) {
	err = PTR_ERR(clk);
	dev_err(&pdev->dev, "Clock get failed\n");
	goto err_get_clk;
	}

	err = clk_prepare(clk);
	if (err) {
	dev_err(&pdev->dev, "Clock prepare failed\n");
	goto err_clk_prep;
	}

	err = clk_enable(clk);
	if (err) {
	dev_err(&pdev->dev, "Clock enable failed\n");
	goto err_clk_en;
	}

	ctrl_speed = clk_get_rate(clk);

	siic = devm_kzalloc(&pdev->dev, sizeof(*siic), GFP_KERNEL);
	if (!siic) {
	err = -ENOMEM;
	goto out;
	}
	adap = &siic->adapter;
	adap->class = I2C_CLASS_DEPRECATED;

	mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	siic->base = devm_ioremap_resource(&pdev->dev, mem_res);
	if (IS_ERR(siic->base)) {
	err = PTR_ERR(siic->base);
	goto out;
	}

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	err = irq;
	goto out;
	}
	err = devm_request_irq(&pdev->dev, irq, i2c_sirfsoc_irq, 0,
	dev_name(&pdev->dev), siic);
	if (err)
	goto out;

	adap->algo = &i2c_sirfsoc_algo;
	adap->algo_data = siic;
	adap->retries = 3;

	adap->dev.of_node = pdev->dev.of_node;
	adap->dev.parent = &pdev->dev;
	adap->nr = pdev->id;

	strlcpy(adap->name, "sirfsoc-i2c", sizeof(adap->name));

	platform_set_drvdata(pdev, adap);
	init_completion(&siic->done);

	/* Controller initialisation */

	writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
	while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
	cpu_relax();
	writel(SIRFSOC_I2C_CORE_EN \| SIRFSOC_I2C_MASTER_MODE,
	siic->base + SIRFSOC_I2C_CTRL);

	siic->clk = clk;

	err = of_property_read_u32(pdev->dev.of_node,
	"clock-frequency", &bitrate);
	if (err < 0)
	bitrate = SIRFSOC_I2C_DEFAULT_SPEED;

	/*
	* Due to some hardware design issues, we need to tune the formula.
	* Since i2c is open drain interface that allows the slave to
	* stall the transaction by holding the SCL line at '0', the RTL
	* implementation is waiting for SCL feedback from the pin after
	* setting it to High-Z ('1'). This wait adds to the high-time
	* interval counter few cycles of the input synchronization
	* (depending on the SCL_FILTER_REG field), and also the time it
	* takes for the board pull-up resistor to rise the SCL line.
	* For slow SCL settings these additions are negligible,
	* but they start to affect the speed when clock is set to faster
	* frequencies.
	* Through the actual tests, use the different user_div value(which
	* in the divider formula 'Fio / (Fi2c * user_div)') to adapt
	* the different ranges of i2c bus clock frequency, to make the SCL
	* more accurate.
	*/
	if (bitrate <= 30000)
	regval = ctrl_speed / (bitrate * 5);
	else if (bitrate > 30000 && bitrate <= 280000)
	regval = (2 * ctrl_speed) / (bitrate * 11);
	else
	regval = ctrl_speed / (bitrate * 6);

	writel(regval, siic->base + SIRFSOC_I2C_CLK_CTRL);
	if (regval > 0xFF)
	writel(0xFF, siic->base + SIRFSOC_I2C_SDA_DELAY);
	else
	writel(regval, siic->base + SIRFSOC_I2C_SDA_DELAY);

	err = i2c_add_numbered_adapter(adap);
	if (err < 0)
	goto out;

	clk_disable(clk);

	dev_info(&pdev->dev, " I2C adapter ready to operate\n");

	return 0;

	out:
	clk_disable(clk);
	err_clk_en:
	clk_unprepare(clk);
	err_clk_prep:
	clk_put(clk);
	err_get_clk:
	return err;
	}

	static int i2c_sirfsoc_remove(struct platform_device *pdev)
	{
	struct i2c_adapter *adapter = platform_get_drvdata(pdev);
	struct sirfsoc_i2c *siic = adapter->algo_data;

	writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
	i2c_del_adapter(adapter);
	clk_unprepare(siic->clk);
	clk_put(siic->clk);
	return 0;
	}

	#ifdef CONFIG_PM
	static int i2c_sirfsoc_suspend(struct device *dev)
	{
	struct i2c_adapter *adapter = dev_get_drvdata(dev);
	struct sirfsoc_i2c *siic = adapter->algo_data;

	clk_enable(siic->clk);
	siic->sda_delay = readl(siic->base + SIRFSOC_I2C_SDA_DELAY);
	siic->clk_div = readl(siic->base + SIRFSOC_I2C_CLK_CTRL);
	clk_disable(siic->clk);
	return 0;
	}

	static int i2c_sirfsoc_resume(struct device *dev)
	{
	struct i2c_adapter *adapter = dev_get_drvdata(dev);
	struct sirfsoc_i2c *siic = adapter->algo_data;

	clk_enable(siic->clk);
	writel(SIRFSOC_I2C_RESET, siic->base + SIRFSOC_I2C_CTRL);
	while (readl(siic->base + SIRFSOC_I2C_CTRL) & SIRFSOC_I2C_RESET)
	cpu_relax();
	writel(SIRFSOC_I2C_CORE_EN \| SIRFSOC_I2C_MASTER_MODE,
	siic->base + SIRFSOC_I2C_CTRL);
	writel(siic->clk_div, siic->base + SIRFSOC_I2C_CLK_CTRL);
	writel(siic->sda_delay, siic->base + SIRFSOC_I2C_SDA_DELAY);
	clk_disable(siic->clk);
	return 0;
	}

	static const struct dev_pm_ops i2c_sirfsoc_pm_ops = {
	.suspend = i2c_sirfsoc_suspend,
	.resume = i2c_sirfsoc_resume,
	};
	#endif

	static const struct of_device_id sirfsoc_i2c_of_match[] = {
	{ .compatible = "sirf,prima2-i2c", },
	{},
	};
	MODULE_DEVICE_TABLE(of, sirfsoc_i2c_of_match);

	static struct platform_driver i2c_sirfsoc_driver = {
	.driver = {
	.name = "sirfsoc_i2c",
	#ifdef CONFIG_PM
	.pm = &i2c_sirfsoc_pm_ops,
	#endif
	.of_match_table = sirfsoc_i2c_of_match,
	},
	.probe = i2c_sirfsoc_probe,
	.remove = i2c_sirfsoc_remove,
	};
	module_platform_driver(i2c_sirfsoc_driver);

	MODULE_DESCRIPTION("SiRF SoC I2C master controller driver");
	MODULE_AUTHOR("Zhiwu Song <Zhiwu.Song@csr.com>, "
	"Xiangzhen Ye <Xiangzhen.Ye@csr.com>");
	MODULE_LICENSE("GPL v2");