drivers/i2c/busses/i2c-owl.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Actions Semiconductor Owl SoC's I2C driver
  *
  * Copyright (c) 2014 Actions Semi Inc.
  * Author: David Liu <liuwei@actions-semi.com>
  *
  * Copyright (c) 2018 Linaro Ltd.
  * Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
  */

 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of_device.h>

 /* I2C registers */
 #define OWL_I2C_REG_CTL		0x0000
 #define OWL_I2C_REG_CLKDIV	0x0004
 #define OWL_I2C_REG_STAT	0x0008
 #define OWL_I2C_REG_ADDR	0x000C
 #define OWL_I2C_REG_TXDAT	0x0010
 #define OWL_I2C_REG_RXDAT	0x0014
 #define OWL_I2C_REG_CMD		0x0018
 #define OWL_I2C_REG_FIFOCTL	0x001C
 #define OWL_I2C_REG_FIFOSTAT	0x0020
 #define OWL_I2C_REG_DATCNT	0x0024
 #define OWL_I2C_REG_RCNT	0x0028

 /* I2Cx_CTL Bit Mask */
 #define OWL_I2C_CTL_RB		BIT(1)
 #define OWL_I2C_CTL_GBCC(x)	(((x) & 0x3) << 2)
 #define	OWL_I2C_CTL_GBCC_NONE	OWL_I2C_CTL_GBCC(0)
 #define	OWL_I2C_CTL_GBCC_START	OWL_I2C_CTL_GBCC(1)
 #define	OWL_I2C_CTL_GBCC_STOP	OWL_I2C_CTL_GBCC(2)
 #define	OWL_I2C_CTL_GBCC_RSTART	OWL_I2C_CTL_GBCC(3)
 #define OWL_I2C_CTL_IRQE	BIT(5)
 #define OWL_I2C_CTL_EN		BIT(7)
 #define OWL_I2C_CTL_AE		BIT(8)
 #define OWL_I2C_CTL_SHSM	BIT(10)

 #define OWL_I2C_DIV_FACTOR(x)	((x) & 0xff)

 /* I2Cx_STAT Bit Mask */
 #define OWL_I2C_STAT_RACK	BIT(0)
 #define OWL_I2C_STAT_BEB	BIT(1)
 #define OWL_I2C_STAT_IRQP	BIT(2)
 #define OWL_I2C_STAT_LAB	BIT(3)
 #define OWL_I2C_STAT_STPD	BIT(4)
 #define OWL_I2C_STAT_STAD	BIT(5)
 #define OWL_I2C_STAT_BBB	BIT(6)
 #define OWL_I2C_STAT_TCB	BIT(7)
 #define OWL_I2C_STAT_LBST	BIT(8)
 #define OWL_I2C_STAT_SAMB	BIT(9)
 #define OWL_I2C_STAT_SRGC	BIT(10)

 /* I2Cx_CMD Bit Mask */
 #define OWL_I2C_CMD_SBE		BIT(0)
 #define OWL_I2C_CMD_RBE		BIT(4)
 #define OWL_I2C_CMD_DE		BIT(8)
 #define OWL_I2C_CMD_NS		BIT(9)
 #define OWL_I2C_CMD_SE		BIT(10)
 #define OWL_I2C_CMD_MSS		BIT(11)
 #define OWL_I2C_CMD_WRS		BIT(12)
 #define OWL_I2C_CMD_SECL	BIT(15)

 #define OWL_I2C_CMD_AS(x)	(((x) & 0x7) << 1)
 #define OWL_I2C_CMD_SAS(x)	(((x) & 0x7) << 5)

 /* I2Cx_FIFOCTL Bit Mask */
 #define OWL_I2C_FIFOCTL_NIB	BIT(0)
 #define OWL_I2C_FIFOCTL_RFR	BIT(1)
 #define OWL_I2C_FIFOCTL_TFR	BIT(2)

 /* I2Cc_FIFOSTAT Bit Mask */
 #define OWL_I2C_FIFOSTAT_RNB	BIT(1)
 #define OWL_I2C_FIFOSTAT_RFE	BIT(2)
 #define OWL_I2C_FIFOSTAT_TFF	BIT(5)
 #define OWL_I2C_FIFOSTAT_TFD	GENMASK(23, 16)
 #define OWL_I2C_FIFOSTAT_RFD	GENMASK(15, 8)

 /* I2C bus timeout */
 #define OWL_I2C_TIMEOUT		msecs_to_jiffies(4 * 1000)

 #define OWL_I2C_MAX_RETRIES	50

 struct owl_i2c_dev {
 	struct i2c_adapter	adap;
 	struct i2c_msg		*msg;
 	struct completion	msg_complete;
 	struct clk		*clk;
 	spinlock_t		lock;
 	void __iomem		*base;
 	unsigned long		clk_rate;
 	u32			bus_freq;
 	u32			msg_ptr;
 	int			err;
 };

 static void owl_i2c_update_reg(void __iomem *reg, unsigned int val, bool state)
 {
 	unsigned int regval;

 	regval = readl(reg);

 	if (state)
 		regval |= val;
 	else
 		regval &= ~val;

 	writel(regval, reg);
 }

 static void owl_i2c_reset(struct owl_i2c_dev *i2c_dev)
 {
 	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
 			   OWL_I2C_CTL_EN, false);
 	mdelay(1);
 	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
 			   OWL_I2C_CTL_EN, true);

 	/* Clear status registers */
 	writel(0, i2c_dev->base + OWL_I2C_REG_STAT);
 }

 static int owl_i2c_reset_fifo(struct owl_i2c_dev *i2c_dev)
 {
 	unsigned int val, timeout = 0;

 	/* Reset FIFO */
 	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
 			   OWL_I2C_FIFOCTL_RFR | OWL_I2C_FIFOCTL_TFR,
 			   true);

 	/* Wait 50ms for FIFO reset complete */
 	do {
 		val = readl(i2c_dev->base + OWL_I2C_REG_FIFOCTL);
 		if (!(val & (OWL_I2C_FIFOCTL_RFR | OWL_I2C_FIFOCTL_TFR)))
 			break;
 		usleep_range(500, 1000);
 	} while (timeout++ < OWL_I2C_MAX_RETRIES);

 	if (timeout > OWL_I2C_MAX_RETRIES) {
 		dev_err(&i2c_dev->adap.dev, "FIFO reset timeout\n");
 		return -ETIMEDOUT;
 	}

 	return 0;
 }

 static void owl_i2c_set_freq(struct owl_i2c_dev *i2c_dev)
 {
 	unsigned int val;

 	val = DIV_ROUND_UP(i2c_dev->clk_rate, i2c_dev->bus_freq * 16);

 	/* Set clock divider factor */
 	writel(OWL_I2C_DIV_FACTOR(val), i2c_dev->base + OWL_I2C_REG_CLKDIV);
 }

 static irqreturn_t owl_i2c_interrupt(int irq, void *_dev)
 {
 	struct owl_i2c_dev *i2c_dev = _dev;
 	struct i2c_msg *msg = i2c_dev->msg;
 	unsigned long flags;
 	unsigned int stat, fifostat;

 	spin_lock_irqsave(&i2c_dev->lock, flags);

 	i2c_dev->err = 0;

 	/* Handle NACK from slave */
 	fifostat = readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT);
 	if (fifostat & OWL_I2C_FIFOSTAT_RNB) {
 		i2c_dev->err = -ENXIO;
 		/* Clear NACK error bit by writing "1" */
 		owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOSTAT,
 				   OWL_I2C_FIFOSTAT_RNB, true);
 		goto stop;
 	}

 	/* Handle bus error */
 	stat = readl(i2c_dev->base + OWL_I2C_REG_STAT);
 	if (stat & OWL_I2C_STAT_BEB) {
 		i2c_dev->err = -EIO;
 		/* Clear BUS error bit by writing "1" */
 		owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_STAT,
 				   OWL_I2C_STAT_BEB, true);
 		goto stop;
 	}

 	/* Handle FIFO read */
 	if (msg->flags & I2C_M_RD) {
 		while ((readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) &
 			OWL_I2C_FIFOSTAT_RFE) && i2c_dev->msg_ptr < msg->len) {
 			msg->buf[i2c_dev->msg_ptr++] = readl(i2c_dev->base +
 							     OWL_I2C_REG_RXDAT);
 		}
 	} else {
 		/* Handle the remaining bytes which were not sent */
 		while (!(readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) &
 			 OWL_I2C_FIFOSTAT_TFF) && i2c_dev->msg_ptr < msg->len) {
 			writel(msg->buf[i2c_dev->msg_ptr++],
 			       i2c_dev->base + OWL_I2C_REG_TXDAT);
 		}
 	}

 stop:
 	/* Clear pending interrupts */
 	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_STAT,
 			   OWL_I2C_STAT_IRQP, true);

 	complete_all(&i2c_dev->msg_complete);
 	spin_unlock_irqrestore(&i2c_dev->lock, flags);

 	return IRQ_HANDLED;
 }

 static u32 owl_i2c_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }

 static int owl_i2c_check_bus_busy(struct i2c_adapter *adap)
 {
 	struct owl_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
 	unsigned long timeout;

 	/* Check for Bus busy */
 	timeout = jiffies + OWL_I2C_TIMEOUT;
 	while (readl(i2c_dev->base + OWL_I2C_REG_STAT) & OWL_I2C_STAT_BBB) {
 		if (time_after(jiffies, timeout)) {
 			dev_err(&adap->dev, "Bus busy timeout\n");
 			return -ETIMEDOUT;
 		}
 	}

 	return 0;
 }

 static int owl_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			       int num)
 {
 	struct owl_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
 	struct i2c_msg *msg;
 	unsigned long time_left, flags;
 	unsigned int i2c_cmd, val;
 	unsigned int addr;
 	int ret, idx;

 	spin_lock_irqsave(&i2c_dev->lock, flags);

 	/* Reset I2C controller */
 	owl_i2c_reset(i2c_dev);

 	/* Set bus frequency */
 	owl_i2c_set_freq(i2c_dev);

 	/*
 	 * Spinlock should be released before calling reset FIFO and
 	 * bus busy check since those functions may sleep
 	 */
 	spin_unlock_irqrestore(&i2c_dev->lock, flags);

 	/* Reset FIFO */
 	ret = owl_i2c_reset_fifo(i2c_dev);
 	if (ret)
 		goto unlocked_err_exit;

 	/* Check for bus busy */
 	ret = owl_i2c_check_bus_busy(adap);
 	if (ret)
 		goto unlocked_err_exit;

 	spin_lock_irqsave(&i2c_dev->lock, flags);

 	/* Check for Arbitration lost */
 	val = readl(i2c_dev->base + OWL_I2C_REG_STAT);
 	if (val & OWL_I2C_STAT_LAB) {
 		val &= ~OWL_I2C_STAT_LAB;
 		writel(val, i2c_dev->base + OWL_I2C_REG_STAT);
 		ret = -EAGAIN;
 		goto err_exit;
 	}

 	reinit_completion(&i2c_dev->msg_complete);

 	/* Enable I2C controller interrupt */
 	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
 			   OWL_I2C_CTL_IRQE, true);

 	/*
 	 * Select: FIFO enable, Master mode, Stop enable, Data count enable,
 	 * Send start bit
 	 */
 	i2c_cmd = OWL_I2C_CMD_SECL | OWL_I2C_CMD_MSS | OWL_I2C_CMD_SE |
 		  OWL_I2C_CMD_NS | OWL_I2C_CMD_DE | OWL_I2C_CMD_SBE;

 	/* Handle repeated start condition */
 	if (num > 1) {
 		/* Set internal address length and enable repeated start */
 		i2c_cmd |= OWL_I2C_CMD_AS(msgs[0].len + 1) |
 			   OWL_I2C_CMD_SAS(1) | OWL_I2C_CMD_RBE;

 		/* Write slave address */
 		addr = i2c_8bit_addr_from_msg(&msgs[0]);
 		writel(addr, i2c_dev->base + OWL_I2C_REG_TXDAT);

 		/* Write internal register address */
 		for (idx = 0; idx < msgs[0].len; idx++)
 			writel(msgs[0].buf[idx],
 			       i2c_dev->base + OWL_I2C_REG_TXDAT);

 		msg = &msgs[1];
 	} else {
 		/* Set address length */
 		i2c_cmd |= OWL_I2C_CMD_AS(1);
 		msg = &msgs[0];
 	}

 	i2c_dev->msg = msg;
 	i2c_dev->msg_ptr = 0;

 	/* Set data count for the message */
 	writel(msg->len, i2c_dev->base + OWL_I2C_REG_DATCNT);

 	addr = i2c_8bit_addr_from_msg(msg);
 	writel(addr, i2c_dev->base + OWL_I2C_REG_TXDAT);

 	if (!(msg->flags & I2C_M_RD)) {
 		/* Write data to FIFO */
 		for (idx = 0; idx < msg->len; idx++) {
 			/* Check for FIFO full */
 			if (readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) &
 			    OWL_I2C_FIFOSTAT_TFF)
 				break;

 			writel(msg->buf[idx],
 			       i2c_dev->base + OWL_I2C_REG_TXDAT);
 		}

 		i2c_dev->msg_ptr = idx;
 	}

 	/* Ignore the NACK if needed */
 	if (msg->flags & I2C_M_IGNORE_NAK)
 		owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
 				   OWL_I2C_FIFOCTL_NIB, true);
 	else
 		owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
 				   OWL_I2C_FIFOCTL_NIB, false);

 	/* Start the transfer */
 	writel(i2c_cmd, i2c_dev->base + OWL_I2C_REG_CMD);

 	spin_unlock_irqrestore(&i2c_dev->lock, flags);

 	time_left = wait_for_completion_timeout(&i2c_dev->msg_complete,
 						adap->timeout);

 	spin_lock_irqsave(&i2c_dev->lock, flags);
 	if (time_left == 0) {
 		dev_err(&adap->dev, "Transaction timed out\n");
 		/* Send stop condition and release the bus */
 		owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
 				   OWL_I2C_CTL_GBCC_STOP | OWL_I2C_CTL_RB,
 				   true);
 		ret = -ETIMEDOUT;
 		goto err_exit;
 	}

 	ret = i2c_dev->err < 0 ? i2c_dev->err : num;

 err_exit:
 	spin_unlock_irqrestore(&i2c_dev->lock, flags);

 unlocked_err_exit:
 	/* Disable I2C controller */
 	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
 			   OWL_I2C_CTL_EN, false);

 	return ret;
 }

 static const struct i2c_algorithm owl_i2c_algorithm = {
 	.master_xfer    = owl_i2c_master_xfer,
 	.functionality  = owl_i2c_func,
 };

 static const struct i2c_adapter_quirks owl_i2c_quirks = {
 	.flags		= I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST,
 	.max_read_len   = 240,
 	.max_write_len  = 240,
 	.max_comb_1st_msg_len = 6,
 	.max_comb_2nd_msg_len = 240,
 };

 static int owl_i2c_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct owl_i2c_dev *i2c_dev;
 	struct resource *res;
 	int ret, irq;

 	i2c_dev = devm_kzalloc(dev, sizeof(*i2c_dev), GFP_KERNEL);
 	if (!i2c_dev)
 		return -ENOMEM;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	i2c_dev->base = devm_ioremap_resource(dev, res);
 	if (IS_ERR(i2c_dev->base))
 		return PTR_ERR(i2c_dev->base);

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		dev_err(dev, "failed to get IRQ number\n");
 		return irq;
 	}

 	if (of_property_read_u32(dev->of_node, "clock-frequency",
 				 &i2c_dev->bus_freq))
 		i2c_dev->bus_freq = I2C_MAX_STANDARD_MODE_FREQ;

 	/* We support only frequencies of 100k and 400k for now */
 	if (i2c_dev->bus_freq != I2C_MAX_STANDARD_MODE_FREQ &&
 	    i2c_dev->bus_freq != I2C_MAX_FAST_MODE_FREQ) {
 		dev_err(dev, "invalid clock-frequency %d\n", i2c_dev->bus_freq);
 		return -EINVAL;
 	}

 	i2c_dev->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(i2c_dev->clk)) {
 		dev_err(dev, "failed to get clock\n");
 		return PTR_ERR(i2c_dev->clk);
 	}

 	ret = clk_prepare_enable(i2c_dev->clk);
 	if (ret)
 		return ret;

 	i2c_dev->clk_rate = clk_get_rate(i2c_dev->clk);
 	if (!i2c_dev->clk_rate) {
 		dev_err(dev, "input clock rate should not be zero\n");
 		ret = -EINVAL;
 		goto disable_clk;
 	}

 	init_completion(&i2c_dev->msg_complete);
 	spin_lock_init(&i2c_dev->lock);
 	i2c_dev->adap.owner = THIS_MODULE;
 	i2c_dev->adap.algo = &owl_i2c_algorithm;
 	i2c_dev->adap.timeout = OWL_I2C_TIMEOUT;
 	i2c_dev->adap.quirks = &owl_i2c_quirks;
 	i2c_dev->adap.dev.parent = dev;
 	i2c_dev->adap.dev.of_node = dev->of_node;
 	snprintf(i2c_dev->adap.name, sizeof(i2c_dev->adap.name),
 		 "%s", "OWL I2C adapter");
 	i2c_set_adapdata(&i2c_dev->adap, i2c_dev);

 	platform_set_drvdata(pdev, i2c_dev);

 	ret = devm_request_irq(dev, irq, owl_i2c_interrupt, 0, pdev->name,
 			       i2c_dev);
 	if (ret) {
 		dev_err(dev, "failed to request irq %d\n", irq);
 		goto disable_clk;
 	}

 	return i2c_add_adapter(&i2c_dev->adap);

 disable_clk:
 	clk_disable_unprepare(i2c_dev->clk);

 	return ret;
 }

 static const struct of_device_id owl_i2c_of_match[] = {
 	{ .compatible = "actions,s700-i2c" },
 	{ .compatible = "actions,s900-i2c" },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, owl_i2c_of_match);

 static struct platform_driver owl_i2c_driver = {
 	.probe		= owl_i2c_probe,
 	.driver		= {
 		.name	= "owl-i2c",
 		.of_match_table = of_match_ptr(owl_i2c_of_match),
 	},
 };
 module_platform_driver(owl_i2c_driver);

 MODULE_AUTHOR("David Liu <liuwei@actions-semi.com>");
 MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
 MODULE_DESCRIPTION("Actions Semiconductor Owl SoC's I2C driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Actions Semiconductor Owl SoC's I2C driver
	*
	* Copyright (c) 2014 Actions Semi Inc.
	* Author: David Liu <liuwei@actions-semi.com>
	*
	* Copyright (c) 2018 Linaro Ltd.
	* Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
	*/

	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/i2c.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/module.h>
	#include <linux/of_device.h>

	/* I2C registers */
	#define OWL_I2C_REG_CTL 0x0000
	#define OWL_I2C_REG_CLKDIV 0x0004
	#define OWL_I2C_REG_STAT 0x0008
	#define OWL_I2C_REG_ADDR 0x000C
	#define OWL_I2C_REG_TXDAT 0x0010
	#define OWL_I2C_REG_RXDAT 0x0014
	#define OWL_I2C_REG_CMD 0x0018
	#define OWL_I2C_REG_FIFOCTL 0x001C
	#define OWL_I2C_REG_FIFOSTAT 0x0020
	#define OWL_I2C_REG_DATCNT 0x0024
	#define OWL_I2C_REG_RCNT 0x0028

	/* I2Cx_CTL Bit Mask */
	#define OWL_I2C_CTL_RB BIT(1)
	#define OWL_I2C_CTL_GBCC(x) (((x) & 0x3) << 2)
	#define OWL_I2C_CTL_GBCC_NONE OWL_I2C_CTL_GBCC(0)
	#define OWL_I2C_CTL_GBCC_START OWL_I2C_CTL_GBCC(1)
	#define OWL_I2C_CTL_GBCC_STOP OWL_I2C_CTL_GBCC(2)
	#define OWL_I2C_CTL_GBCC_RSTART OWL_I2C_CTL_GBCC(3)
	#define OWL_I2C_CTL_IRQE BIT(5)
	#define OWL_I2C_CTL_EN BIT(7)
	#define OWL_I2C_CTL_AE BIT(8)
	#define OWL_I2C_CTL_SHSM BIT(10)

	#define OWL_I2C_DIV_FACTOR(x) ((x) & 0xff)

	/* I2Cx_STAT Bit Mask */
	#define OWL_I2C_STAT_RACK BIT(0)
	#define OWL_I2C_STAT_BEB BIT(1)
	#define OWL_I2C_STAT_IRQP BIT(2)
	#define OWL_I2C_STAT_LAB BIT(3)
	#define OWL_I2C_STAT_STPD BIT(4)
	#define OWL_I2C_STAT_STAD BIT(5)
	#define OWL_I2C_STAT_BBB BIT(6)
	#define OWL_I2C_STAT_TCB BIT(7)
	#define OWL_I2C_STAT_LBST BIT(8)
	#define OWL_I2C_STAT_SAMB BIT(9)
	#define OWL_I2C_STAT_SRGC BIT(10)

	/* I2Cx_CMD Bit Mask */
	#define OWL_I2C_CMD_SBE BIT(0)
	#define OWL_I2C_CMD_RBE BIT(4)
	#define OWL_I2C_CMD_DE BIT(8)
	#define OWL_I2C_CMD_NS BIT(9)
	#define OWL_I2C_CMD_SE BIT(10)
	#define OWL_I2C_CMD_MSS BIT(11)
	#define OWL_I2C_CMD_WRS BIT(12)
	#define OWL_I2C_CMD_SECL BIT(15)

	#define OWL_I2C_CMD_AS(x) (((x) & 0x7) << 1)
	#define OWL_I2C_CMD_SAS(x) (((x) & 0x7) << 5)

	/* I2Cx_FIFOCTL Bit Mask */
	#define OWL_I2C_FIFOCTL_NIB BIT(0)
	#define OWL_I2C_FIFOCTL_RFR BIT(1)
	#define OWL_I2C_FIFOCTL_TFR BIT(2)

	/* I2Cc_FIFOSTAT Bit Mask */
	#define OWL_I2C_FIFOSTAT_RNB BIT(1)
	#define OWL_I2C_FIFOSTAT_RFE BIT(2)
	#define OWL_I2C_FIFOSTAT_TFF BIT(5)
	#define OWL_I2C_FIFOSTAT_TFD GENMASK(23, 16)
	#define OWL_I2C_FIFOSTAT_RFD GENMASK(15, 8)

	/* I2C bus timeout */
	#define OWL_I2C_TIMEOUT msecs_to_jiffies(4 * 1000)

	#define OWL_I2C_MAX_RETRIES 50

	struct owl_i2c_dev {
	struct i2c_adapter adap;
	struct i2c_msg *msg;
	struct completion msg_complete;
	struct clk *clk;
	spinlock_t lock;
	void __iomem *base;
	unsigned long clk_rate;
	u32 bus_freq;
	u32 msg_ptr;
	int err;
	};

	static void owl_i2c_update_reg(void __iomem *reg, unsigned int val, bool state)
	{
	unsigned int regval;

	regval = readl(reg);

	if (state)
	regval \|= val;
	else
	regval &= ~val;

	writel(regval, reg);
	}

	static void owl_i2c_reset(struct owl_i2c_dev *i2c_dev)
	{
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
	OWL_I2C_CTL_EN, false);
	mdelay(1);
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
	OWL_I2C_CTL_EN, true);

	/* Clear status registers */
	writel(0, i2c_dev->base + OWL_I2C_REG_STAT);
	}

	static int owl_i2c_reset_fifo(struct owl_i2c_dev *i2c_dev)
	{
	unsigned int val, timeout = 0;

	/* Reset FIFO */
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
	OWL_I2C_FIFOCTL_RFR \| OWL_I2C_FIFOCTL_TFR,
	true);

	/* Wait 50ms for FIFO reset complete */
	do {
	val = readl(i2c_dev->base + OWL_I2C_REG_FIFOCTL);
	if (!(val & (OWL_I2C_FIFOCTL_RFR \| OWL_I2C_FIFOCTL_TFR)))
	break;
	usleep_range(500, 1000);
	} while (timeout++ < OWL_I2C_MAX_RETRIES);

	if (timeout > OWL_I2C_MAX_RETRIES) {
	dev_err(&i2c_dev->adap.dev, "FIFO reset timeout\n");
	return -ETIMEDOUT;
	}

	return 0;
	}

	static void owl_i2c_set_freq(struct owl_i2c_dev *i2c_dev)
	{
	unsigned int val;

	val = DIV_ROUND_UP(i2c_dev->clk_rate, i2c_dev->bus_freq * 16);

	/* Set clock divider factor */
	writel(OWL_I2C_DIV_FACTOR(val), i2c_dev->base + OWL_I2C_REG_CLKDIV);
	}

	static irqreturn_t owl_i2c_interrupt(int irq, void *_dev)
	{
	struct owl_i2c_dev *i2c_dev = _dev;
	struct i2c_msg *msg = i2c_dev->msg;
	unsigned long flags;
	unsigned int stat, fifostat;

	spin_lock_irqsave(&i2c_dev->lock, flags);

	i2c_dev->err = 0;

	/* Handle NACK from slave */
	fifostat = readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT);
	if (fifostat & OWL_I2C_FIFOSTAT_RNB) {
	i2c_dev->err = -ENXIO;
	/* Clear NACK error bit by writing "1" */
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOSTAT,
	OWL_I2C_FIFOSTAT_RNB, true);
	goto stop;
	}

	/* Handle bus error */
	stat = readl(i2c_dev->base + OWL_I2C_REG_STAT);
	if (stat & OWL_I2C_STAT_BEB) {
	i2c_dev->err = -EIO;
	/* Clear BUS error bit by writing "1" */
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_STAT,
	OWL_I2C_STAT_BEB, true);
	goto stop;
	}

	/* Handle FIFO read */
	if (msg->flags & I2C_M_RD) {
	while ((readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) &
	OWL_I2C_FIFOSTAT_RFE) && i2c_dev->msg_ptr < msg->len) {
	msg->buf[i2c_dev->msg_ptr++] = readl(i2c_dev->base +
	OWL_I2C_REG_RXDAT);
	}
	} else {
	/* Handle the remaining bytes which were not sent */
	while (!(readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) &
	OWL_I2C_FIFOSTAT_TFF) && i2c_dev->msg_ptr < msg->len) {
	writel(msg->buf[i2c_dev->msg_ptr++],
	i2c_dev->base + OWL_I2C_REG_TXDAT);
	}
	}

	stop:
	/* Clear pending interrupts */
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_STAT,
	OWL_I2C_STAT_IRQP, true);

	complete_all(&i2c_dev->msg_complete);
	spin_unlock_irqrestore(&i2c_dev->lock, flags);

	return IRQ_HANDLED;
	}

	static u32 owl_i2c_func(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL;
	}

	static int owl_i2c_check_bus_busy(struct i2c_adapter *adap)
	{
	struct owl_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
	unsigned long timeout;

	/* Check for Bus busy */
	timeout = jiffies + OWL_I2C_TIMEOUT;
	while (readl(i2c_dev->base + OWL_I2C_REG_STAT) & OWL_I2C_STAT_BBB) {
	if (time_after(jiffies, timeout)) {
	dev_err(&adap->dev, "Bus busy timeout\n");
	return -ETIMEDOUT;
	}
	}

	return 0;
	}

	static int owl_i2c_master_xfer(struct i2c_adapter adap, struct i2c_msg msgs,
	int num)
	{
	struct owl_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
	struct i2c_msg *msg;
	unsigned long time_left, flags;
	unsigned int i2c_cmd, val;
	unsigned int addr;
	int ret, idx;

	spin_lock_irqsave(&i2c_dev->lock, flags);

	/* Reset I2C controller */
	owl_i2c_reset(i2c_dev);

	/* Set bus frequency */
	owl_i2c_set_freq(i2c_dev);

	/*
	* Spinlock should be released before calling reset FIFO and
	* bus busy check since those functions may sleep
	*/
	spin_unlock_irqrestore(&i2c_dev->lock, flags);

	/* Reset FIFO */
	ret = owl_i2c_reset_fifo(i2c_dev);
	if (ret)
	goto unlocked_err_exit;

	/* Check for bus busy */
	ret = owl_i2c_check_bus_busy(adap);
	if (ret)
	goto unlocked_err_exit;

	spin_lock_irqsave(&i2c_dev->lock, flags);

	/* Check for Arbitration lost */
	val = readl(i2c_dev->base + OWL_I2C_REG_STAT);
	if (val & OWL_I2C_STAT_LAB) {
	val &= ~OWL_I2C_STAT_LAB;
	writel(val, i2c_dev->base + OWL_I2C_REG_STAT);
	ret = -EAGAIN;
	goto err_exit;
	}

	reinit_completion(&i2c_dev->msg_complete);

	/* Enable I2C controller interrupt */
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
	OWL_I2C_CTL_IRQE, true);

	/*
	* Select: FIFO enable, Master mode, Stop enable, Data count enable,
	* Send start bit
	*/
	i2c_cmd = OWL_I2C_CMD_SECL \| OWL_I2C_CMD_MSS \| OWL_I2C_CMD_SE \|
	OWL_I2C_CMD_NS \| OWL_I2C_CMD_DE \| OWL_I2C_CMD_SBE;

	/* Handle repeated start condition */
	if (num > 1) {
	/* Set internal address length and enable repeated start */
	i2c_cmd \|= OWL_I2C_CMD_AS(msgs[0].len + 1) \|
	OWL_I2C_CMD_SAS(1) \| OWL_I2C_CMD_RBE;

	/* Write slave address */
	addr = i2c_8bit_addr_from_msg(&msgs[0]);
	writel(addr, i2c_dev->base + OWL_I2C_REG_TXDAT);

	/* Write internal register address */
	for (idx = 0; idx < msgs[0].len; idx++)
	writel(msgs[0].buf[idx],
	i2c_dev->base + OWL_I2C_REG_TXDAT);

	msg = &msgs[1];
	} else {
	/* Set address length */
	i2c_cmd \|= OWL_I2C_CMD_AS(1);
	msg = &msgs[0];
	}

	i2c_dev->msg = msg;
	i2c_dev->msg_ptr = 0;

	/* Set data count for the message */
	writel(msg->len, i2c_dev->base + OWL_I2C_REG_DATCNT);

	addr = i2c_8bit_addr_from_msg(msg);
	writel(addr, i2c_dev->base + OWL_I2C_REG_TXDAT);

	if (!(msg->flags & I2C_M_RD)) {
	/* Write data to FIFO */
	for (idx = 0; idx < msg->len; idx++) {
	/* Check for FIFO full */
	if (readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) &
	OWL_I2C_FIFOSTAT_TFF)
	break;

	writel(msg->buf[idx],
	i2c_dev->base + OWL_I2C_REG_TXDAT);
	}

	i2c_dev->msg_ptr = idx;
	}

	/* Ignore the NACK if needed */
	if (msg->flags & I2C_M_IGNORE_NAK)
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
	OWL_I2C_FIFOCTL_NIB, true);
	else
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
	OWL_I2C_FIFOCTL_NIB, false);

	/* Start the transfer */
	writel(i2c_cmd, i2c_dev->base + OWL_I2C_REG_CMD);

	spin_unlock_irqrestore(&i2c_dev->lock, flags);

	time_left = wait_for_completion_timeout(&i2c_dev->msg_complete,
	adap->timeout);

	spin_lock_irqsave(&i2c_dev->lock, flags);
	if (time_left == 0) {
	dev_err(&adap->dev, "Transaction timed out\n");
	/* Send stop condition and release the bus */
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
	OWL_I2C_CTL_GBCC_STOP \| OWL_I2C_CTL_RB,
	true);
	ret = -ETIMEDOUT;
	goto err_exit;
	}

	ret = i2c_dev->err < 0 ? i2c_dev->err : num;

	err_exit:
	spin_unlock_irqrestore(&i2c_dev->lock, flags);

	unlocked_err_exit:
	/* Disable I2C controller */
	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
	OWL_I2C_CTL_EN, false);

	return ret;
	}

	static const struct i2c_algorithm owl_i2c_algorithm = {
	.master_xfer = owl_i2c_master_xfer,
	.functionality = owl_i2c_func,
	};

	static const struct i2c_adapter_quirks owl_i2c_quirks = {
	.flags = I2C_AQ_COMB \| I2C_AQ_COMB_WRITE_FIRST,
	.max_read_len = 240,
	.max_write_len = 240,
	.max_comb_1st_msg_len = 6,
	.max_comb_2nd_msg_len = 240,
	};

	static int owl_i2c_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct owl_i2c_dev *i2c_dev;
	struct resource *res;
	int ret, irq;

	i2c_dev = devm_kzalloc(dev, sizeof(*i2c_dev), GFP_KERNEL);
	if (!i2c_dev)
	return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	i2c_dev->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(i2c_dev->base))
	return PTR_ERR(i2c_dev->base);

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	dev_err(dev, "failed to get IRQ number\n");
	return irq;
	}

	if (of_property_read_u32(dev->of_node, "clock-frequency",
	&i2c_dev->bus_freq))
	i2c_dev->bus_freq = I2C_MAX_STANDARD_MODE_FREQ;

	/* We support only frequencies of 100k and 400k for now */
	if (i2c_dev->bus_freq != I2C_MAX_STANDARD_MODE_FREQ &&
	i2c_dev->bus_freq != I2C_MAX_FAST_MODE_FREQ) {
	dev_err(dev, "invalid clock-frequency %d\n", i2c_dev->bus_freq);
	return -EINVAL;
	}

	i2c_dev->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(i2c_dev->clk)) {
	dev_err(dev, "failed to get clock\n");
	return PTR_ERR(i2c_dev->clk);
	}

	ret = clk_prepare_enable(i2c_dev->clk);
	if (ret)
	return ret;

	i2c_dev->clk_rate = clk_get_rate(i2c_dev->clk);
	if (!i2c_dev->clk_rate) {
	dev_err(dev, "input clock rate should not be zero\n");
	ret = -EINVAL;
	goto disable_clk;
	}

	init_completion(&i2c_dev->msg_complete);
	spin_lock_init(&i2c_dev->lock);
	i2c_dev->adap.owner = THIS_MODULE;
	i2c_dev->adap.algo = &owl_i2c_algorithm;
	i2c_dev->adap.timeout = OWL_I2C_TIMEOUT;
	i2c_dev->adap.quirks = &owl_i2c_quirks;
	i2c_dev->adap.dev.parent = dev;
	i2c_dev->adap.dev.of_node = dev->of_node;
	snprintf(i2c_dev->adap.name, sizeof(i2c_dev->adap.name),
	"%s", "OWL I2C adapter");
	i2c_set_adapdata(&i2c_dev->adap, i2c_dev);

	platform_set_drvdata(pdev, i2c_dev);

	ret = devm_request_irq(dev, irq, owl_i2c_interrupt, 0, pdev->name,
	i2c_dev);
	if (ret) {
	dev_err(dev, "failed to request irq %d\n", irq);
	goto disable_clk;
	}

	return i2c_add_adapter(&i2c_dev->adap);

	disable_clk:
	clk_disable_unprepare(i2c_dev->clk);

	return ret;
	}

	static const struct of_device_id owl_i2c_of_match[] = {
	{ .compatible = "actions,s700-i2c" },
	{ .compatible = "actions,s900-i2c" },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, owl_i2c_of_match);

	static struct platform_driver owl_i2c_driver = {
	.probe = owl_i2c_probe,
	.driver = {
	.name = "owl-i2c",
	.of_match_table = of_match_ptr(owl_i2c_of_match),
	},
	};
	module_platform_driver(owl_i2c_driver);

	MODULE_AUTHOR("David Liu <liuwei@actions-semi.com>");
	MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
	MODULE_DESCRIPTION("Actions Semiconductor Owl SoC's I2C driver");
	MODULE_LICENSE("GPL");