drivers/i2c/busses/i2c-exynos5.c - kernel/msm-5.4 - Gitiles

 /**
  * i2c-exynos5.c - Samsung Exynos5 I2C Controller Driver
  *
  * Copyright (C) 2013 Samsung Electronics Co., Ltd.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
 */

 #include <linux/kernel.h>
 #include <linux/module.h>

 #include <linux/i2c.h>
 #include <linux/time.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/platform_device.h>
 #include <linux/clk.h>
 #include <linux/slab.h>
 #include <linux/io.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/spinlock.h>

 /*
  * HSI2C controller from Samsung supports 2 modes of operation
  * 1. Auto mode: Where in master automatically controls the whole transaction
  * 2. Manual mode: Software controls the transaction by issuing commands
  *    START, READ, WRITE, STOP, RESTART in I2C_MANUAL_CMD register.
  *
  * Operation mode can be selected by setting AUTO_MODE bit in I2C_CONF register
  *
  * Special bits are available for both modes of operation to set commands
  * and for checking transfer status
  */

 /* Register Map */
 #define HSI2C_CTL		0x00
 #define HSI2C_FIFO_CTL		0x04
 #define HSI2C_TRAILIG_CTL	0x08
 #define HSI2C_CLK_CTL		0x0C
 #define HSI2C_CLK_SLOT		0x10
 #define HSI2C_INT_ENABLE	0x20
 #define HSI2C_INT_STATUS	0x24
 #define HSI2C_ERR_STATUS	0x2C
 #define HSI2C_FIFO_STATUS	0x30
 #define HSI2C_TX_DATA		0x34
 #define HSI2C_RX_DATA		0x38
 #define HSI2C_CONF		0x40
 #define HSI2C_AUTO_CONF		0x44
 #define HSI2C_TIMEOUT		0x48
 #define HSI2C_MANUAL_CMD	0x4C
 #define HSI2C_TRANS_STATUS	0x50
 #define HSI2C_TIMING_HS1	0x54
 #define HSI2C_TIMING_HS2	0x58
 #define HSI2C_TIMING_HS3	0x5C
 #define HSI2C_TIMING_FS1	0x60
 #define HSI2C_TIMING_FS2	0x64
 #define HSI2C_TIMING_FS3	0x68
 #define HSI2C_TIMING_SLA	0x6C
 #define HSI2C_ADDR		0x70

 /* I2C_CTL Register bits */
 #define HSI2C_FUNC_MODE_I2C			(1u << 0)
 #define HSI2C_MASTER				(1u << 3)
 #define HSI2C_RXCHON				(1u << 6)
 #define HSI2C_TXCHON				(1u << 7)
 #define HSI2C_SW_RST				(1u << 31)

 /* I2C_FIFO_CTL Register bits */
 #define HSI2C_RXFIFO_EN				(1u << 0)
 #define HSI2C_TXFIFO_EN				(1u << 1)
 #define HSI2C_RXFIFO_TRIGGER_LEVEL(x)		((x) << 4)
 #define HSI2C_TXFIFO_TRIGGER_LEVEL(x)		((x) << 16)

 /* I2C_TRAILING_CTL Register bits */
 #define HSI2C_TRAILING_COUNT			(0xf)

 /* I2C_INT_EN Register bits */
 #define HSI2C_INT_TX_ALMOSTEMPTY_EN		(1u << 0)
 #define HSI2C_INT_RX_ALMOSTFULL_EN		(1u << 1)
 #define HSI2C_INT_TRAILING_EN			(1u << 6)
 #define HSI2C_INT_I2C_EN			(1u << 9)

 /* I2C_INT_STAT Register bits */
 #define HSI2C_INT_TX_ALMOSTEMPTY		(1u << 0)
 #define HSI2C_INT_RX_ALMOSTFULL			(1u << 1)
 #define HSI2C_INT_TX_UNDERRUN			(1u << 2)
 #define HSI2C_INT_TX_OVERRUN			(1u << 3)
 #define HSI2C_INT_RX_UNDERRUN			(1u << 4)
 #define HSI2C_INT_RX_OVERRUN			(1u << 5)
 #define HSI2C_INT_TRAILING			(1u << 6)
 #define HSI2C_INT_I2C				(1u << 9)

 /* I2C_FIFO_STAT Register bits */
 #define HSI2C_RX_FIFO_EMPTY			(1u << 24)
 #define HSI2C_RX_FIFO_FULL			(1u << 23)
 #define HSI2C_RX_FIFO_LVL(x)			((x >> 16) & 0x7f)
 #define HSI2C_TX_FIFO_EMPTY			(1u << 8)
 #define HSI2C_TX_FIFO_FULL			(1u << 7)
 #define HSI2C_TX_FIFO_LVL(x)			((x >> 0) & 0x7f)

 /* I2C_CONF Register bits */
 #define HSI2C_AUTO_MODE				(1u << 31)
 #define HSI2C_10BIT_ADDR_MODE			(1u << 30)
 #define HSI2C_HS_MODE				(1u << 29)

 /* I2C_AUTO_CONF Register bits */
 #define HSI2C_READ_WRITE			(1u << 16)
 #define HSI2C_STOP_AFTER_TRANS			(1u << 17)
 #define HSI2C_MASTER_RUN			(1u << 31)

 /* I2C_TIMEOUT Register bits */
 #define HSI2C_TIMEOUT_EN			(1u << 31)
 #define HSI2C_TIMEOUT_MASK			0xff

 /* I2C_TRANS_STATUS register bits */
 #define HSI2C_MASTER_BUSY			(1u << 17)
 #define HSI2C_SLAVE_BUSY			(1u << 16)
 #define HSI2C_TIMEOUT_AUTO			(1u << 4)
 #define HSI2C_NO_DEV				(1u << 3)
 #define HSI2C_NO_DEV_ACK			(1u << 2)
 #define HSI2C_TRANS_ABORT			(1u << 1)
 #define HSI2C_TRANS_DONE			(1u << 0)

 /* I2C_ADDR register bits */
 #define HSI2C_SLV_ADDR_SLV(x)			((x & 0x3ff) << 0)
 #define HSI2C_SLV_ADDR_MAS(x)			((x & 0x3ff) << 10)
 #define HSI2C_MASTER_ID(x)			((x & 0xff) << 24)
 #define MASTER_ID(x)				((x & 0x7) + 0x08)

 /*
  * Controller operating frequency, timing values for operation
  * are calculated against this frequency
  */
 #define HSI2C_HS_TX_CLOCK	1000000
 #define HSI2C_FS_TX_CLOCK	100000
 #define HSI2C_HIGH_SPD		1
 #define HSI2C_FAST_SPD		0

 #define EXYNOS5_I2C_TIMEOUT (msecs_to_jiffies(1000))

 struct exynos5_i2c {
 	struct i2c_adapter	adap;
 	unsigned int		suspended:1;

 	struct i2c_msg		*msg;
 	struct completion	msg_complete;
 	unsigned int		msg_ptr;

 	unsigned int		irq;

 	void __iomem		*regs;
 	struct clk		*clk;
 	struct device		*dev;
 	int			state;

 	spinlock_t		lock;		/* IRQ synchronization */

 	/*
 	 * Since the TRANS_DONE bit is cleared on read, and we may read it
 	 * either during an IRQ or after a transaction, keep track of its
 	 * state here.
 	 */
 	int			trans_done;

 	/* Controller operating frequency */
 	unsigned int		fs_clock;
 	unsigned int		hs_clock;

 	/*
 	 * HSI2C Controller can operate in
 	 * 1. High speed upto 3.4Mbps
 	 * 2. Fast speed upto 1Mbps
 	 */
 	int			speed_mode;

 	/* Version of HS-I2C Hardware */
 	struct exynos_hsi2c_variant	*variant;
 };

 /**
  * struct exynos_hsi2c_variant - platform specific HSI2C driver data
  * @fifo_depth: the fifo depth supported by the HSI2C module
  *
  * Specifies platform specific configuration of HSI2C module.
  * Note: A structure for driver specific platform data is used for future
  * expansion of its usage.
  */
 struct exynos_hsi2c_variant {
 	unsigned int	fifo_depth;
 };

 static const struct exynos_hsi2c_variant exynos5250_hsi2c_data = {
 	.fifo_depth	= 64,
 };

 static const struct exynos_hsi2c_variant exynos5260_hsi2c_data = {
 	.fifo_depth	= 16,
 };

 static const struct of_device_id exynos5_i2c_match[] = {
 	{
 		.compatible = "samsung,exynos5-hsi2c",
 		.data = &exynos5250_hsi2c_data
 	}, {
 		.compatible = "samsung,exynos5250-hsi2c",
 		.data = &exynos5250_hsi2c_data
 	}, {
 		.compatible = "samsung,exynos5260-hsi2c",
 		.data = &exynos5260_hsi2c_data
 	}, {},
 };
 MODULE_DEVICE_TABLE(of, exynos5_i2c_match);

 static inline struct exynos_hsi2c_variant *exynos5_i2c_get_variant
 					(struct platform_device *pdev)
 {
 	const struct of_device_id *match;

 	match = of_match_node(exynos5_i2c_match, pdev->dev.of_node);
 	return (struct exynos_hsi2c_variant *)match->data;
 }

 static void exynos5_i2c_clr_pend_irq(struct exynos5_i2c *i2c)
 {
 	writel(readl(i2c->regs + HSI2C_INT_STATUS),
 				i2c->regs + HSI2C_INT_STATUS);
 }

 /*
  * exynos5_i2c_set_timing: updates the registers with appropriate
  * timing values calculated
  *
  * Returns 0 on success, -EINVAL if the cycle length cannot
  * be calculated.
  */
 static int exynos5_i2c_set_timing(struct exynos5_i2c *i2c, int mode)
 {
 	u32 i2c_timing_s1;
 	u32 i2c_timing_s2;
 	u32 i2c_timing_s3;
 	u32 i2c_timing_sla;
 	unsigned int t_start_su, t_start_hd;
 	unsigned int t_stop_su;
 	unsigned int t_data_su, t_data_hd;
 	unsigned int t_scl_l, t_scl_h;
 	unsigned int t_sr_release;
 	unsigned int t_ftl_cycle;
 	unsigned int clkin = clk_get_rate(i2c->clk);
 	unsigned int div, utemp0 = 0, utemp1 = 0, clk_cycle;
 	unsigned int op_clk = (mode == HSI2C_HIGH_SPD) ?
 				i2c->hs_clock : i2c->fs_clock;

 	/*
 	 * FPCLK / FI2C =
 	 * (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2) + 8 + 2 * FLT_CYCLE
 	 * utemp0 = (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2)
 	 * utemp1 = (TSCLK_L + TSCLK_H + 2)
 	 */
 	t_ftl_cycle = (readl(i2c->regs + HSI2C_CONF) >> 16) & 0x7;
 	utemp0 = (clkin / op_clk) - 8 - 2 * t_ftl_cycle;

 	/* CLK_DIV max is 256 */
 	for (div = 0; div < 256; div++) {
 		utemp1 = utemp0 / (div + 1);

 		/*
 		 * SCL_L and SCL_H each has max value of 255
 		 * Hence, For the clk_cycle to the have right value
 		 * utemp1 has to be less then 512 and more than 4.
 		 */
 		if ((utemp1 < 512) && (utemp1 > 4)) {
 			clk_cycle = utemp1 - 2;
 			break;
 		} else if (div == 255) {
 			dev_warn(i2c->dev, "Failed to calculate divisor");
 			return -EINVAL;
 		}
 	}

 	t_scl_l = clk_cycle / 2;
 	t_scl_h = clk_cycle / 2;
 	t_start_su = t_scl_l;
 	t_start_hd = t_scl_l;
 	t_stop_su = t_scl_l;
 	t_data_su = t_scl_l / 2;
 	t_data_hd = t_scl_l / 2;
 	t_sr_release = clk_cycle;

 	i2c_timing_s1 = t_start_su << 24 | t_start_hd << 16 | t_stop_su << 8;
 	i2c_timing_s2 = t_data_su << 24 | t_scl_l << 8 | t_scl_h << 0;
 	i2c_timing_s3 = div << 16 | t_sr_release << 0;
 	i2c_timing_sla = t_data_hd << 0;

 	dev_dbg(i2c->dev, "tSTART_SU: %X, tSTART_HD: %X, tSTOP_SU: %X\n",
 		t_start_su, t_start_hd, t_stop_su);
 	dev_dbg(i2c->dev, "tDATA_SU: %X, tSCL_L: %X, tSCL_H: %X\n",
 		t_data_su, t_scl_l, t_scl_h);
 	dev_dbg(i2c->dev, "nClkDiv: %X, tSR_RELEASE: %X\n",
 		div, t_sr_release);
 	dev_dbg(i2c->dev, "tDATA_HD: %X\n", t_data_hd);

 	if (mode == HSI2C_HIGH_SPD) {
 		writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_HS1);
 		writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_HS2);
 		writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_HS3);
 	} else {
 		writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_FS1);
 		writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_FS2);
 		writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_FS3);
 	}
 	writel(i2c_timing_sla, i2c->regs + HSI2C_TIMING_SLA);

 	return 0;
 }

 static int exynos5_hsi2c_clock_setup(struct exynos5_i2c *i2c)
 {
 	/*
 	 * Configure the Fast speed timing values
 	 * Even the High Speed mode initially starts with Fast mode
 	 */
 	if (exynos5_i2c_set_timing(i2c, HSI2C_FAST_SPD)) {
 		dev_err(i2c->dev, "HSI2C FS Clock set up failed\n");
 		return -EINVAL;
 	}

 	/* configure the High speed timing values */
 	if (i2c->speed_mode == HSI2C_HIGH_SPD) {
 		if (exynos5_i2c_set_timing(i2c, HSI2C_HIGH_SPD)) {
 			dev_err(i2c->dev, "HSI2C HS Clock set up failed\n");
 			return -EINVAL;
 		}
 	}

 	return 0;
 }

 /*
  * exynos5_i2c_init: configures the controller for I2C functionality
  * Programs I2C controller for Master mode operation
  */
 static void exynos5_i2c_init(struct exynos5_i2c *i2c)
 {
 	u32 i2c_conf = readl(i2c->regs + HSI2C_CONF);
 	u32 i2c_timeout = readl(i2c->regs + HSI2C_TIMEOUT);

 	/* Clear to disable Timeout */
 	i2c_timeout &= ~HSI2C_TIMEOUT_EN;
 	writel(i2c_timeout, i2c->regs + HSI2C_TIMEOUT);

 	writel((HSI2C_FUNC_MODE_I2C | HSI2C_MASTER),
 					i2c->regs + HSI2C_CTL);
 	writel(HSI2C_TRAILING_COUNT, i2c->regs + HSI2C_TRAILIG_CTL);

 	if (i2c->speed_mode == HSI2C_HIGH_SPD) {
 		writel(HSI2C_MASTER_ID(MASTER_ID(i2c->adap.nr)),
 					i2c->regs + HSI2C_ADDR);
 		i2c_conf |= HSI2C_HS_MODE;
 	}

 	writel(i2c_conf | HSI2C_AUTO_MODE, i2c->regs + HSI2C_CONF);
 }

 static void exynos5_i2c_reset(struct exynos5_i2c *i2c)
 {
 	u32 i2c_ctl;

 	/* Set and clear the bit for reset */
 	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
 	i2c_ctl |= HSI2C_SW_RST;
 	writel(i2c_ctl, i2c->regs + HSI2C_CTL);

 	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
 	i2c_ctl &= ~HSI2C_SW_RST;
 	writel(i2c_ctl, i2c->regs + HSI2C_CTL);

 	/* We don't expect calculations to fail during the run */
 	exynos5_hsi2c_clock_setup(i2c);
 	/* Initialize the configure registers */
 	exynos5_i2c_init(i2c);
 }

 /*
  * exynos5_i2c_irq: top level IRQ servicing routine
  *
  * INT_STATUS registers gives the interrupt details. Further,
  * FIFO_STATUS or TRANS_STATUS registers are to be check for detailed
  * state of the bus.
  */
 static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id)
 {
 	struct exynos5_i2c *i2c = dev_id;
 	u32 fifo_level, int_status, fifo_status, trans_status;
 	unsigned char byte;
 	int len = 0;

 	i2c->state = -EINVAL;

 	spin_lock(&i2c->lock);

 	int_status = readl(i2c->regs + HSI2C_INT_STATUS);
 	writel(int_status, i2c->regs + HSI2C_INT_STATUS);
 	fifo_status = readl(i2c->regs + HSI2C_FIFO_STATUS);

 	/* handle interrupt related to the transfer status */
 	if (int_status & HSI2C_INT_I2C) {
 		trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
 		if (trans_status & HSI2C_NO_DEV_ACK) {
 			dev_dbg(i2c->dev, "No ACK from device\n");
 			i2c->state = -ENXIO;
 			goto stop;
 		} else if (trans_status & HSI2C_NO_DEV) {
 			dev_dbg(i2c->dev, "No device\n");
 			i2c->state = -ENXIO;
 			goto stop;
 		} else if (trans_status & HSI2C_TRANS_ABORT) {
 			dev_dbg(i2c->dev, "Deal with arbitration lose\n");
 			i2c->state = -EAGAIN;
 			goto stop;
 		} else if (trans_status & HSI2C_TIMEOUT_AUTO) {
 			dev_dbg(i2c->dev, "Accessing device timed out\n");
 			i2c->state = -EAGAIN;
 			goto stop;
 		} else if (trans_status & HSI2C_TRANS_DONE) {
 			i2c->trans_done = 1;
 			i2c->state = 0;
 		}
 	}

 	if ((i2c->msg->flags & I2C_M_RD) && (int_status &
 			(HSI2C_INT_TRAILING | HSI2C_INT_RX_ALMOSTFULL))) {
 		fifo_status = readl(i2c->regs + HSI2C_FIFO_STATUS);
 		fifo_level = HSI2C_RX_FIFO_LVL(fifo_status);
 		len = min(fifo_level, i2c->msg->len - i2c->msg_ptr);

 		while (len > 0) {
 			byte = (unsigned char)
 				readl(i2c->regs + HSI2C_RX_DATA);
 			i2c->msg->buf[i2c->msg_ptr++] = byte;
 			len--;
 		}
 		i2c->state = 0;
 	} else if (int_status & HSI2C_INT_TX_ALMOSTEMPTY) {
 		fifo_status = readl(i2c->regs + HSI2C_FIFO_STATUS);
 		fifo_level = HSI2C_TX_FIFO_LVL(fifo_status);

 		len = i2c->variant->fifo_depth - fifo_level;
 		if (len > (i2c->msg->len - i2c->msg_ptr))
 			len = i2c->msg->len - i2c->msg_ptr;

 		while (len > 0) {
 			byte = i2c->msg->buf[i2c->msg_ptr++];
 			writel(byte, i2c->regs + HSI2C_TX_DATA);
 			len--;
 		}
 		i2c->state = 0;
 	}

  stop:
 	if ((i2c->trans_done && (i2c->msg->len == i2c->msg_ptr)) ||
 	    (i2c->state < 0)) {
 		writel(0, i2c->regs + HSI2C_INT_ENABLE);
 		exynos5_i2c_clr_pend_irq(i2c);
 		complete(&i2c->msg_complete);
 	}

 	spin_unlock(&i2c->lock);

 	return IRQ_HANDLED;
 }

 /*
  * exynos5_i2c_wait_bus_idle
  *
  * Wait for the bus to go idle, indicated by the MASTER_BUSY bit being
  * cleared.
  *
  * Returns -EBUSY if the bus cannot be bought to idle
  */
 static int exynos5_i2c_wait_bus_idle(struct exynos5_i2c *i2c)
 {
 	unsigned long stop_time;
 	u32 trans_status;

 	/* wait for 100 milli seconds for the bus to be idle */
 	stop_time = jiffies + msecs_to_jiffies(100) + 1;
 	do {
 		trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
 		if (!(trans_status & HSI2C_MASTER_BUSY))
 			return 0;

 		usleep_range(50, 200);
 	} while (time_before(jiffies, stop_time));

 	return -EBUSY;
 }

 /*
  * exynos5_i2c_message_start: Configures the bus and starts the xfer
  * i2c: struct exynos5_i2c pointer for the current bus
  * stop: Enables stop after transfer if set. Set for last transfer of
  *       in the list of messages.
  *
  * Configures the bus for read/write function
  * Sets chip address to talk to, message length to be sent.
  * Enables appropriate interrupts and sends start xfer command.
  */
 static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)
 {
 	u32 i2c_ctl;
 	u32 int_en = HSI2C_INT_I2C_EN;
 	u32 i2c_auto_conf = 0;
 	u32 fifo_ctl;
 	unsigned long flags;
 	unsigned short trig_lvl;

 	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
 	i2c_ctl &= ~(HSI2C_TXCHON | HSI2C_RXCHON);
 	fifo_ctl = HSI2C_RXFIFO_EN | HSI2C_TXFIFO_EN;

 	if (i2c->msg->flags & I2C_M_RD) {
 		i2c_ctl |= HSI2C_RXCHON;

 		i2c_auto_conf = HSI2C_READ_WRITE;

 		trig_lvl = (i2c->msg->len > i2c->variant->fifo_depth) ?
 			(i2c->variant->fifo_depth * 3 / 4) : i2c->msg->len;
 		fifo_ctl |= HSI2C_RXFIFO_TRIGGER_LEVEL(trig_lvl);

 		int_en |= (HSI2C_INT_RX_ALMOSTFULL_EN |
 			HSI2C_INT_TRAILING_EN);
 	} else {
 		i2c_ctl |= HSI2C_TXCHON;

 		trig_lvl = (i2c->msg->len > i2c->variant->fifo_depth) ?
 			(i2c->variant->fifo_depth * 1 / 4) : i2c->msg->len;
 		fifo_ctl |= HSI2C_TXFIFO_TRIGGER_LEVEL(trig_lvl);

 		int_en |= HSI2C_INT_TX_ALMOSTEMPTY_EN;
 	}

 	writel(HSI2C_SLV_ADDR_MAS(i2c->msg->addr), i2c->regs + HSI2C_ADDR);

 	writel(fifo_ctl, i2c->regs + HSI2C_FIFO_CTL);
 	writel(i2c_ctl, i2c->regs + HSI2C_CTL);


 	/*
 	 * Enable interrupts before starting the transfer so that we don't
 	 * miss any INT_I2C interrupts.
 	 */
 	spin_lock_irqsave(&i2c->lock, flags);
 	writel(int_en, i2c->regs + HSI2C_INT_ENABLE);

 	if (stop == 1)
 		i2c_auto_conf |= HSI2C_STOP_AFTER_TRANS;
 	i2c_auto_conf |= i2c->msg->len;
 	i2c_auto_conf |= HSI2C_MASTER_RUN;
 	writel(i2c_auto_conf, i2c->regs + HSI2C_AUTO_CONF);
 	spin_unlock_irqrestore(&i2c->lock, flags);
 }

 static int exynos5_i2c_xfer_msg(struct exynos5_i2c *i2c,
 			      struct i2c_msg *msgs, int stop)
 {
 	unsigned long timeout;
 	int ret;

 	i2c->msg = msgs;
 	i2c->msg_ptr = 0;
 	i2c->trans_done = 0;

 	reinit_completion(&i2c->msg_complete);

 	exynos5_i2c_message_start(i2c, stop);

 	timeout = wait_for_completion_timeout(&i2c->msg_complete,
 					      EXYNOS5_I2C_TIMEOUT);
 	if (timeout == 0)
 		ret = -ETIMEDOUT;
 	else
 		ret = i2c->state;

 	/*
 	 * If this is the last message to be transfered (stop == 1)
 	 * Then check if the bus can be brought back to idle.
 	 */
 	if (ret == 0 && stop)
 		ret = exynos5_i2c_wait_bus_idle(i2c);

 	if (ret < 0) {
 		exynos5_i2c_reset(i2c);
 		if (ret == -ETIMEDOUT)
 			dev_warn(i2c->dev, "%s timeout\n",
 				 (msgs->flags & I2C_M_RD) ? "rx" : "tx");
 	}

 	/* Return the state as in interrupt routine */
 	return ret;
 }

 static int exynos5_i2c_xfer(struct i2c_adapter *adap,
 			struct i2c_msg *msgs, int num)
 {
 	struct exynos5_i2c *i2c = adap->algo_data;
 	int i = 0, ret = 0, stop = 0;

 	if (i2c->suspended) {
 		dev_err(i2c->dev, "HS-I2C is not initialized.\n");
 		return -EIO;
 	}

 	clk_prepare_enable(i2c->clk);

 	for (i = 0; i < num; i++, msgs++) {
 		stop = (i == num - 1);

 		ret = exynos5_i2c_xfer_msg(i2c, msgs, stop);

 		if (ret < 0)
 			goto out;
 	}

 	if (i == num) {
 		ret = num;
 	} else {
 		/* Only one message, cannot access the device */
 		if (i == 1)
 			ret = -EREMOTEIO;
 		else
 			ret = i;

 		dev_warn(i2c->dev, "xfer message failed\n");
 	}

  out:
 	clk_disable_unprepare(i2c->clk);
 	return ret;
 }

 static u32 exynos5_i2c_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
 }

 static const struct i2c_algorithm exynos5_i2c_algorithm = {
 	.master_xfer		= exynos5_i2c_xfer,
 	.functionality		= exynos5_i2c_func,
 };

 static int exynos5_i2c_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct exynos5_i2c *i2c;
 	struct resource *mem;
 	unsigned int op_clock;
 	int ret;

 	i2c = devm_kzalloc(&pdev->dev, sizeof(struct exynos5_i2c), GFP_KERNEL);
 	if (!i2c) {
 		dev_err(&pdev->dev, "no memory for state\n");
 		return -ENOMEM;
 	}

 	if (of_property_read_u32(np, "clock-frequency", &op_clock)) {
 		i2c->speed_mode = HSI2C_FAST_SPD;
 		i2c->fs_clock = HSI2C_FS_TX_CLOCK;
 	} else {
 		if (op_clock >= HSI2C_HS_TX_CLOCK) {
 			i2c->speed_mode = HSI2C_HIGH_SPD;
 			i2c->fs_clock = HSI2C_FS_TX_CLOCK;
 			i2c->hs_clock = op_clock;
 		} else {
 			i2c->speed_mode = HSI2C_FAST_SPD;
 			i2c->fs_clock = op_clock;
 		}
 	}

 	strlcpy(i2c->adap.name, "exynos5-i2c", sizeof(i2c->adap.name));
 	i2c->adap.owner   = THIS_MODULE;
 	i2c->adap.algo    = &exynos5_i2c_algorithm;
 	i2c->adap.retries = 3;

 	i2c->dev = &pdev->dev;
 	i2c->clk = devm_clk_get(&pdev->dev, "hsi2c");
 	if (IS_ERR(i2c->clk)) {
 		dev_err(&pdev->dev, "cannot get clock\n");
 		return -ENOENT;
 	}

 	clk_prepare_enable(i2c->clk);

 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
 	if (IS_ERR(i2c->regs)) {
 		ret = PTR_ERR(i2c->regs);
 		goto err_clk;
 	}

 	i2c->adap.dev.of_node = np;
 	i2c->adap.algo_data = i2c;
 	i2c->adap.dev.parent = &pdev->dev;

 	/* Clear pending interrupts from u-boot or misc causes */
 	exynos5_i2c_clr_pend_irq(i2c);

 	spin_lock_init(&i2c->lock);
 	init_completion(&i2c->msg_complete);

 	i2c->irq = ret = platform_get_irq(pdev, 0);
 	if (ret <= 0) {
 		dev_err(&pdev->dev, "cannot find HS-I2C IRQ\n");
 		ret = -EINVAL;
 		goto err_clk;
 	}

 	ret = devm_request_irq(&pdev->dev, i2c->irq, exynos5_i2c_irq,
 				IRQF_NO_SUSPEND | IRQF_ONESHOT,
 				dev_name(&pdev->dev), i2c);

 	if (ret != 0) {
 		dev_err(&pdev->dev, "cannot request HS-I2C IRQ %d\n", i2c->irq);
 		goto err_clk;
 	}

 	ret = exynos5_hsi2c_clock_setup(i2c);
 	if (ret)
 		goto err_clk;

 	i2c->variant = exynos5_i2c_get_variant(pdev);

 	exynos5_i2c_reset(i2c);

 	ret = i2c_add_adapter(&i2c->adap);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to add bus to i2c core\n");
 		goto err_clk;
 	}

 	platform_set_drvdata(pdev, i2c);

  err_clk:
 	clk_disable_unprepare(i2c->clk);
 	return ret;
 }

 static int exynos5_i2c_remove(struct platform_device *pdev)
 {
 	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);

 	i2c_del_adapter(&i2c->adap);

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static int exynos5_i2c_suspend_noirq(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);

 	i2c->suspended = 1;

 	return 0;
 }

 static int exynos5_i2c_resume_noirq(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
 	int ret = 0;

 	clk_prepare_enable(i2c->clk);

 	ret = exynos5_hsi2c_clock_setup(i2c);
 	if (ret) {
 		clk_disable_unprepare(i2c->clk);
 		return ret;
 	}

 	exynos5_i2c_init(i2c);
 	clk_disable_unprepare(i2c->clk);
 	i2c->suspended = 0;

 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(exynos5_i2c_dev_pm_ops, exynos5_i2c_suspend_noirq,
 			 exynos5_i2c_resume_noirq);

 static struct platform_driver exynos5_i2c_driver = {
 	.probe		= exynos5_i2c_probe,
 	.remove		= exynos5_i2c_remove,
 	.driver		= {
 		.owner	= THIS_MODULE,
 		.name	= "exynos5-hsi2c",
 		.pm	= &exynos5_i2c_dev_pm_ops,
 		.of_match_table = exynos5_i2c_match,
 	},
 };

 module_platform_driver(exynos5_i2c_driver);

 MODULE_DESCRIPTION("Exynos5 HS-I2C Bus driver");
 MODULE_AUTHOR("Naveen Krishna Chatradhi, <ch.naveen@samsung.com>");
 MODULE_AUTHOR("Taekgyun Ko, <taeggyun.ko@samsung.com>");
 MODULE_LICENSE("GPL v2");
	/**
	* i2c-exynos5.c - Samsung Exynos5 I2C Controller Driver
	*
	* Copyright (C) 2013 Samsung Electronics Co., Ltd.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>

	#include <linux/i2c.h>
	#include <linux/time.h>
	#include <linux/interrupt.h>
	#include <linux/delay.h>
	#include <linux/errno.h>
	#include <linux/err.h>
	#include <linux/platform_device.h>
	#include <linux/clk.h>
	#include <linux/slab.h>
	#include <linux/io.h>
	#include <linux/of_address.h>
	#include <linux/of_irq.h>
	#include <linux/spinlock.h>

	/*
	* HSI2C controller from Samsung supports 2 modes of operation
	* 1. Auto mode: Where in master automatically controls the whole transaction
	* 2. Manual mode: Software controls the transaction by issuing commands
	* START, READ, WRITE, STOP, RESTART in I2C_MANUAL_CMD register.
	*
	* Operation mode can be selected by setting AUTO_MODE bit in I2C_CONF register
	*
	* Special bits are available for both modes of operation to set commands
	* and for checking transfer status
	*/

	/* Register Map */
	#define HSI2C_CTL 0x00
	#define HSI2C_FIFO_CTL 0x04
	#define HSI2C_TRAILIG_CTL 0x08
	#define HSI2C_CLK_CTL 0x0C
	#define HSI2C_CLK_SLOT 0x10
	#define HSI2C_INT_ENABLE 0x20
	#define HSI2C_INT_STATUS 0x24
	#define HSI2C_ERR_STATUS 0x2C
	#define HSI2C_FIFO_STATUS 0x30
	#define HSI2C_TX_DATA 0x34
	#define HSI2C_RX_DATA 0x38
	#define HSI2C_CONF 0x40
	#define HSI2C_AUTO_CONF 0x44
	#define HSI2C_TIMEOUT 0x48
	#define HSI2C_MANUAL_CMD 0x4C
	#define HSI2C_TRANS_STATUS 0x50
	#define HSI2C_TIMING_HS1 0x54
	#define HSI2C_TIMING_HS2 0x58
	#define HSI2C_TIMING_HS3 0x5C
	#define HSI2C_TIMING_FS1 0x60
	#define HSI2C_TIMING_FS2 0x64
	#define HSI2C_TIMING_FS3 0x68
	#define HSI2C_TIMING_SLA 0x6C
	#define HSI2C_ADDR 0x70

	/* I2C_CTL Register bits */
	#define HSI2C_FUNC_MODE_I2C (1u << 0)
	#define HSI2C_MASTER (1u << 3)
	#define HSI2C_RXCHON (1u << 6)
	#define HSI2C_TXCHON (1u << 7)
	#define HSI2C_SW_RST (1u << 31)

	/* I2C_FIFO_CTL Register bits */
	#define HSI2C_RXFIFO_EN (1u << 0)
	#define HSI2C_TXFIFO_EN (1u << 1)
	#define HSI2C_RXFIFO_TRIGGER_LEVEL(x) ((x) << 4)
	#define HSI2C_TXFIFO_TRIGGER_LEVEL(x) ((x) << 16)

	/* I2C_TRAILING_CTL Register bits */
	#define HSI2C_TRAILING_COUNT (0xf)

	/* I2C_INT_EN Register bits */
	#define HSI2C_INT_TX_ALMOSTEMPTY_EN (1u << 0)
	#define HSI2C_INT_RX_ALMOSTFULL_EN (1u << 1)
	#define HSI2C_INT_TRAILING_EN (1u << 6)
	#define HSI2C_INT_I2C_EN (1u << 9)

	/* I2C_INT_STAT Register bits */
	#define HSI2C_INT_TX_ALMOSTEMPTY (1u << 0)
	#define HSI2C_INT_RX_ALMOSTFULL (1u << 1)
	#define HSI2C_INT_TX_UNDERRUN (1u << 2)
	#define HSI2C_INT_TX_OVERRUN (1u << 3)
	#define HSI2C_INT_RX_UNDERRUN (1u << 4)
	#define HSI2C_INT_RX_OVERRUN (1u << 5)
	#define HSI2C_INT_TRAILING (1u << 6)
	#define HSI2C_INT_I2C (1u << 9)

	/* I2C_FIFO_STAT Register bits */
	#define HSI2C_RX_FIFO_EMPTY (1u << 24)
	#define HSI2C_RX_FIFO_FULL (1u << 23)
	#define HSI2C_RX_FIFO_LVL(x) ((x >> 16) & 0x7f)
	#define HSI2C_TX_FIFO_EMPTY (1u << 8)
	#define HSI2C_TX_FIFO_FULL (1u << 7)
	#define HSI2C_TX_FIFO_LVL(x) ((x >> 0) & 0x7f)

	/* I2C_CONF Register bits */
	#define HSI2C_AUTO_MODE (1u << 31)
	#define HSI2C_10BIT_ADDR_MODE (1u << 30)
	#define HSI2C_HS_MODE (1u << 29)

	/* I2C_AUTO_CONF Register bits */
	#define HSI2C_READ_WRITE (1u << 16)
	#define HSI2C_STOP_AFTER_TRANS (1u << 17)
	#define HSI2C_MASTER_RUN (1u << 31)

	/* I2C_TIMEOUT Register bits */
	#define HSI2C_TIMEOUT_EN (1u << 31)
	#define HSI2C_TIMEOUT_MASK 0xff

	/* I2C_TRANS_STATUS register bits */
	#define HSI2C_MASTER_BUSY (1u << 17)
	#define HSI2C_SLAVE_BUSY (1u << 16)
	#define HSI2C_TIMEOUT_AUTO (1u << 4)
	#define HSI2C_NO_DEV (1u << 3)
	#define HSI2C_NO_DEV_ACK (1u << 2)
	#define HSI2C_TRANS_ABORT (1u << 1)
	#define HSI2C_TRANS_DONE (1u << 0)

	/* I2C_ADDR register bits */
	#define HSI2C_SLV_ADDR_SLV(x) ((x & 0x3ff) << 0)
	#define HSI2C_SLV_ADDR_MAS(x) ((x & 0x3ff) << 10)
	#define HSI2C_MASTER_ID(x) ((x & 0xff) << 24)
	#define MASTER_ID(x) ((x & 0x7) + 0x08)

	/*
	* Controller operating frequency, timing values for operation
	* are calculated against this frequency
	*/
	#define HSI2C_HS_TX_CLOCK 1000000
	#define HSI2C_FS_TX_CLOCK 100000
	#define HSI2C_HIGH_SPD 1
	#define HSI2C_FAST_SPD 0

	#define EXYNOS5_I2C_TIMEOUT (msecs_to_jiffies(1000))

	struct exynos5_i2c {
	struct i2c_adapter adap;
	unsigned int suspended:1;

	struct i2c_msg *msg;
	struct completion msg_complete;
	unsigned int msg_ptr;

	unsigned int irq;

	void __iomem *regs;
	struct clk *clk;
	struct device *dev;
	int state;

	spinlock_t lock; /* IRQ synchronization */

	/*
	* Since the TRANS_DONE bit is cleared on read, and we may read it
	* either during an IRQ or after a transaction, keep track of its
	* state here.
	*/
	int trans_done;

	/* Controller operating frequency */
	unsigned int fs_clock;
	unsigned int hs_clock;

	/*
	* HSI2C Controller can operate in
	* 1. High speed upto 3.4Mbps
	* 2. Fast speed upto 1Mbps
	*/
	int speed_mode;

	/* Version of HS-I2C Hardware */
	struct exynos_hsi2c_variant *variant;
	};

	/**
	* struct exynos_hsi2c_variant - platform specific HSI2C driver data
	* @fifo_depth: the fifo depth supported by the HSI2C module
	*
	* Specifies platform specific configuration of HSI2C module.
	* Note: A structure for driver specific platform data is used for future
	* expansion of its usage.
	*/
	struct exynos_hsi2c_variant {
	unsigned int fifo_depth;
	};

	static const struct exynos_hsi2c_variant exynos5250_hsi2c_data = {
	.fifo_depth = 64,
	};

	static const struct exynos_hsi2c_variant exynos5260_hsi2c_data = {
	.fifo_depth = 16,
	};

	static const struct of_device_id exynos5_i2c_match[] = {
	{
	.compatible = "samsung,exynos5-hsi2c",
	.data = &exynos5250_hsi2c_data
	}, {
	.compatible = "samsung,exynos5250-hsi2c",
	.data = &exynos5250_hsi2c_data
	}, {
	.compatible = "samsung,exynos5260-hsi2c",
	.data = &exynos5260_hsi2c_data
	}, {},
	};
	MODULE_DEVICE_TABLE(of, exynos5_i2c_match);

	static inline struct exynos_hsi2c_variant *exynos5_i2c_get_variant
	(struct platform_device *pdev)
	{
	const struct of_device_id *match;

	match = of_match_node(exynos5_i2c_match, pdev->dev.of_node);
	return (struct exynos_hsi2c_variant *)match->data;
	}

	static void exynos5_i2c_clr_pend_irq(struct exynos5_i2c *i2c)
	{
	writel(readl(i2c->regs + HSI2C_INT_STATUS),
	i2c->regs + HSI2C_INT_STATUS);
	}

	/*
	* exynos5_i2c_set_timing: updates the registers with appropriate
	* timing values calculated
	*
	* Returns 0 on success, -EINVAL if the cycle length cannot
	* be calculated.
	*/
	static int exynos5_i2c_set_timing(struct exynos5_i2c *i2c, int mode)
	{
	u32 i2c_timing_s1;
	u32 i2c_timing_s2;
	u32 i2c_timing_s3;
	u32 i2c_timing_sla;
	unsigned int t_start_su, t_start_hd;
	unsigned int t_stop_su;
	unsigned int t_data_su, t_data_hd;
	unsigned int t_scl_l, t_scl_h;
	unsigned int t_sr_release;
	unsigned int t_ftl_cycle;
	unsigned int clkin = clk_get_rate(i2c->clk);
	unsigned int div, utemp0 = 0, utemp1 = 0, clk_cycle;
	unsigned int op_clk = (mode == HSI2C_HIGH_SPD) ?
	i2c->hs_clock : i2c->fs_clock;

	/*
	* FPCLK / FI2C =
	* (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2) + 8 + 2 * FLT_CYCLE
	* utemp0 = (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2)
	* utemp1 = (TSCLK_L + TSCLK_H + 2)
	*/
	t_ftl_cycle = (readl(i2c->regs + HSI2C_CONF) >> 16) & 0x7;
	utemp0 = (clkin / op_clk) - 8 - 2 * t_ftl_cycle;

	/* CLK_DIV max is 256 */
	for (div = 0; div < 256; div++) {
	utemp1 = utemp0 / (div + 1);

	/*
	* SCL_L and SCL_H each has max value of 255
	* Hence, For the clk_cycle to the have right value
	* utemp1 has to be less then 512 and more than 4.
	*/
	if ((utemp1 < 512) && (utemp1 > 4)) {
	clk_cycle = utemp1 - 2;
	break;
	} else if (div == 255) {
	dev_warn(i2c->dev, "Failed to calculate divisor");
	return -EINVAL;
	}
	}

	t_scl_l = clk_cycle / 2;
	t_scl_h = clk_cycle / 2;
	t_start_su = t_scl_l;
	t_start_hd = t_scl_l;
	t_stop_su = t_scl_l;
	t_data_su = t_scl_l / 2;
	t_data_hd = t_scl_l / 2;
	t_sr_release = clk_cycle;

	i2c_timing_s1 = t_start_su << 24 \| t_start_hd << 16 \| t_stop_su << 8;
	i2c_timing_s2 = t_data_su << 24 \| t_scl_l << 8 \| t_scl_h << 0;
	i2c_timing_s3 = div << 16 \| t_sr_release << 0;
	i2c_timing_sla = t_data_hd << 0;

	dev_dbg(i2c->dev, "tSTART_SU: %X, tSTART_HD: %X, tSTOP_SU: %X\n",
	t_start_su, t_start_hd, t_stop_su);
	dev_dbg(i2c->dev, "tDATA_SU: %X, tSCL_L: %X, tSCL_H: %X\n",
	t_data_su, t_scl_l, t_scl_h);
	dev_dbg(i2c->dev, "nClkDiv: %X, tSR_RELEASE: %X\n",
	div, t_sr_release);
	dev_dbg(i2c->dev, "tDATA_HD: %X\n", t_data_hd);

	if (mode == HSI2C_HIGH_SPD) {
	writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_HS1);
	writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_HS2);
	writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_HS3);
	} else {
	writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_FS1);
	writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_FS2);
	writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_FS3);
	}
	writel(i2c_timing_sla, i2c->regs + HSI2C_TIMING_SLA);

	return 0;
	}

	static int exynos5_hsi2c_clock_setup(struct exynos5_i2c *i2c)
	{
	/*
	* Configure the Fast speed timing values
	* Even the High Speed mode initially starts with Fast mode
	*/
	if (exynos5_i2c_set_timing(i2c, HSI2C_FAST_SPD)) {
	dev_err(i2c->dev, "HSI2C FS Clock set up failed\n");
	return -EINVAL;
	}

	/* configure the High speed timing values */
	if (i2c->speed_mode == HSI2C_HIGH_SPD) {
	if (exynos5_i2c_set_timing(i2c, HSI2C_HIGH_SPD)) {
	dev_err(i2c->dev, "HSI2C HS Clock set up failed\n");
	return -EINVAL;
	}
	}

	return 0;
	}

	/*
	* exynos5_i2c_init: configures the controller for I2C functionality
	* Programs I2C controller for Master mode operation
	*/
	static void exynos5_i2c_init(struct exynos5_i2c *i2c)
	{
	u32 i2c_conf = readl(i2c->regs + HSI2C_CONF);
	u32 i2c_timeout = readl(i2c->regs + HSI2C_TIMEOUT);

	/* Clear to disable Timeout */
	i2c_timeout &= ~HSI2C_TIMEOUT_EN;
	writel(i2c_timeout, i2c->regs + HSI2C_TIMEOUT);

	writel((HSI2C_FUNC_MODE_I2C \| HSI2C_MASTER),
	i2c->regs + HSI2C_CTL);
	writel(HSI2C_TRAILING_COUNT, i2c->regs + HSI2C_TRAILIG_CTL);

	if (i2c->speed_mode == HSI2C_HIGH_SPD) {
	writel(HSI2C_MASTER_ID(MASTER_ID(i2c->adap.nr)),
	i2c->regs + HSI2C_ADDR);
	i2c_conf \|= HSI2C_HS_MODE;
	}

	writel(i2c_conf \| HSI2C_AUTO_MODE, i2c->regs + HSI2C_CONF);
	}

	static void exynos5_i2c_reset(struct exynos5_i2c *i2c)
	{
	u32 i2c_ctl;

	/* Set and clear the bit for reset */
	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
	i2c_ctl \|= HSI2C_SW_RST;
	writel(i2c_ctl, i2c->regs + HSI2C_CTL);

	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
	i2c_ctl &= ~HSI2C_SW_RST;
	writel(i2c_ctl, i2c->regs + HSI2C_CTL);

	/* We don't expect calculations to fail during the run */
	exynos5_hsi2c_clock_setup(i2c);
	/* Initialize the configure registers */
	exynos5_i2c_init(i2c);
	}

	/*
	* exynos5_i2c_irq: top level IRQ servicing routine
	*
	* INT_STATUS registers gives the interrupt details. Further,
	* FIFO_STATUS or TRANS_STATUS registers are to be check for detailed
	* state of the bus.
	*/
	static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id)
	{
	struct exynos5_i2c *i2c = dev_id;
	u32 fifo_level, int_status, fifo_status, trans_status;
	unsigned char byte;
	int len = 0;

	i2c->state = -EINVAL;

	spin_lock(&i2c->lock);

	int_status = readl(i2c->regs + HSI2C_INT_STATUS);
	writel(int_status, i2c->regs + HSI2C_INT_STATUS);
	fifo_status = readl(i2c->regs + HSI2C_FIFO_STATUS);

	/* handle interrupt related to the transfer status */
	if (int_status & HSI2C_INT_I2C) {
	trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
	if (trans_status & HSI2C_NO_DEV_ACK) {
	dev_dbg(i2c->dev, "No ACK from device\n");
	i2c->state = -ENXIO;
	goto stop;
	} else if (trans_status & HSI2C_NO_DEV) {
	dev_dbg(i2c->dev, "No device\n");
	i2c->state = -ENXIO;
	goto stop;
	} else if (trans_status & HSI2C_TRANS_ABORT) {
	dev_dbg(i2c->dev, "Deal with arbitration lose\n");
	i2c->state = -EAGAIN;
	goto stop;
	} else if (trans_status & HSI2C_TIMEOUT_AUTO) {
	dev_dbg(i2c->dev, "Accessing device timed out\n");
	i2c->state = -EAGAIN;
	goto stop;
	} else if (trans_status & HSI2C_TRANS_DONE) {
	i2c->trans_done = 1;
	i2c->state = 0;
	}
	}

	if ((i2c->msg->flags & I2C_M_RD) && (int_status &
	(HSI2C_INT_TRAILING \| HSI2C_INT_RX_ALMOSTFULL))) {
	fifo_status = readl(i2c->regs + HSI2C_FIFO_STATUS);
	fifo_level = HSI2C_RX_FIFO_LVL(fifo_status);
	len = min(fifo_level, i2c->msg->len - i2c->msg_ptr);

	while (len > 0) {
	byte = (unsigned char)
	readl(i2c->regs + HSI2C_RX_DATA);
	i2c->msg->buf[i2c->msg_ptr++] = byte;
	len--;
	}
	i2c->state = 0;
	} else if (int_status & HSI2C_INT_TX_ALMOSTEMPTY) {
	fifo_status = readl(i2c->regs + HSI2C_FIFO_STATUS);
	fifo_level = HSI2C_TX_FIFO_LVL(fifo_status);

	len = i2c->variant->fifo_depth - fifo_level;
	if (len > (i2c->msg->len - i2c->msg_ptr))
	len = i2c->msg->len - i2c->msg_ptr;

	while (len > 0) {
	byte = i2c->msg->buf[i2c->msg_ptr++];
	writel(byte, i2c->regs + HSI2C_TX_DATA);
	len--;
	}
	i2c->state = 0;
	}

	stop:
	if ((i2c->trans_done && (i2c->msg->len == i2c->msg_ptr)) \|\|
	(i2c->state < 0)) {
	writel(0, i2c->regs + HSI2C_INT_ENABLE);
	exynos5_i2c_clr_pend_irq(i2c);
	complete(&i2c->msg_complete);
	}

	spin_unlock(&i2c->lock);

	return IRQ_HANDLED;
	}

	/*
	* exynos5_i2c_wait_bus_idle
	*
	* Wait for the bus to go idle, indicated by the MASTER_BUSY bit being
	* cleared.
	*
	* Returns -EBUSY if the bus cannot be bought to idle
	*/
	static int exynos5_i2c_wait_bus_idle(struct exynos5_i2c *i2c)
	{
	unsigned long stop_time;
	u32 trans_status;

	/* wait for 100 milli seconds for the bus to be idle */
	stop_time = jiffies + msecs_to_jiffies(100) + 1;
	do {
	trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
	if (!(trans_status & HSI2C_MASTER_BUSY))
	return 0;

	usleep_range(50, 200);
	} while (time_before(jiffies, stop_time));

	return -EBUSY;
	}

	/*
	* exynos5_i2c_message_start: Configures the bus and starts the xfer
	* i2c: struct exynos5_i2c pointer for the current bus
	* stop: Enables stop after transfer if set. Set for last transfer of
	* in the list of messages.
	*
	* Configures the bus for read/write function
	* Sets chip address to talk to, message length to be sent.
	* Enables appropriate interrupts and sends start xfer command.
	*/
	static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)
	{
	u32 i2c_ctl;
	u32 int_en = HSI2C_INT_I2C_EN;
	u32 i2c_auto_conf = 0;
	u32 fifo_ctl;
	unsigned long flags;
	unsigned short trig_lvl;

	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
	i2c_ctl &= ~(HSI2C_TXCHON \| HSI2C_RXCHON);
	fifo_ctl = HSI2C_RXFIFO_EN \| HSI2C_TXFIFO_EN;

	if (i2c->msg->flags & I2C_M_RD) {
	i2c_ctl \|= HSI2C_RXCHON;

	i2c_auto_conf = HSI2C_READ_WRITE;

	trig_lvl = (i2c->msg->len > i2c->variant->fifo_depth) ?
	(i2c->variant->fifo_depth * 3 / 4) : i2c->msg->len;
	fifo_ctl \|= HSI2C_RXFIFO_TRIGGER_LEVEL(trig_lvl);

	int_en \|= (HSI2C_INT_RX_ALMOSTFULL_EN \|
	HSI2C_INT_TRAILING_EN);
	} else {
	i2c_ctl \|= HSI2C_TXCHON;

	trig_lvl = (i2c->msg->len > i2c->variant->fifo_depth) ?
	(i2c->variant->fifo_depth * 1 / 4) : i2c->msg->len;
	fifo_ctl \|= HSI2C_TXFIFO_TRIGGER_LEVEL(trig_lvl);

	int_en \|= HSI2C_INT_TX_ALMOSTEMPTY_EN;
	}

	writel(HSI2C_SLV_ADDR_MAS(i2c->msg->addr), i2c->regs + HSI2C_ADDR);

	writel(fifo_ctl, i2c->regs + HSI2C_FIFO_CTL);
	writel(i2c_ctl, i2c->regs + HSI2C_CTL);


	/*
	* Enable interrupts before starting the transfer so that we don't
	* miss any INT_I2C interrupts.
	*/
	spin_lock_irqsave(&i2c->lock, flags);
	writel(int_en, i2c->regs + HSI2C_INT_ENABLE);

	if (stop == 1)
	i2c_auto_conf \|= HSI2C_STOP_AFTER_TRANS;
	i2c_auto_conf \|= i2c->msg->len;
	i2c_auto_conf \|= HSI2C_MASTER_RUN;
	writel(i2c_auto_conf, i2c->regs + HSI2C_AUTO_CONF);
	spin_unlock_irqrestore(&i2c->lock, flags);
	}

	static int exynos5_i2c_xfer_msg(struct exynos5_i2c *i2c,
	struct i2c_msg *msgs, int stop)
	{
	unsigned long timeout;
	int ret;

	i2c->msg = msgs;
	i2c->msg_ptr = 0;
	i2c->trans_done = 0;

	reinit_completion(&i2c->msg_complete);

	exynos5_i2c_message_start(i2c, stop);

	timeout = wait_for_completion_timeout(&i2c->msg_complete,
	EXYNOS5_I2C_TIMEOUT);
	if (timeout == 0)
	ret = -ETIMEDOUT;
	else
	ret = i2c->state;

	/*
	* If this is the last message to be transfered (stop == 1)
	* Then check if the bus can be brought back to idle.
	*/
	if (ret == 0 && stop)
	ret = exynos5_i2c_wait_bus_idle(i2c);

	if (ret < 0) {
	exynos5_i2c_reset(i2c);
	if (ret == -ETIMEDOUT)
	dev_warn(i2c->dev, "%s timeout\n",
	(msgs->flags & I2C_M_RD) ? "rx" : "tx");
	}

	/* Return the state as in interrupt routine */
	return ret;
	}

	static int exynos5_i2c_xfer(struct i2c_adapter *adap,
	struct i2c_msg *msgs, int num)
	{
	struct exynos5_i2c *i2c = adap->algo_data;
	int i = 0, ret = 0, stop = 0;

	if (i2c->suspended) {
	dev_err(i2c->dev, "HS-I2C is not initialized.\n");
	return -EIO;
	}

	clk_prepare_enable(i2c->clk);

	for (i = 0; i < num; i++, msgs++) {
	stop = (i == num - 1);

	ret = exynos5_i2c_xfer_msg(i2c, msgs, stop);

	if (ret < 0)
	goto out;
	}

	if (i == num) {
	ret = num;
	} else {
	/* Only one message, cannot access the device */
	if (i == 1)
	ret = -EREMOTEIO;
	else
	ret = i;

	dev_warn(i2c->dev, "xfer message failed\n");
	}

	out:
	clk_disable_unprepare(i2c->clk);
	return ret;
	}

	static u32 exynos5_i2c_func(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
	}

	static const struct i2c_algorithm exynos5_i2c_algorithm = {
	.master_xfer = exynos5_i2c_xfer,
	.functionality = exynos5_i2c_func,
	};

	static int exynos5_i2c_probe(struct platform_device *pdev)
	{
	struct device_node *np = pdev->dev.of_node;
	struct exynos5_i2c *i2c;
	struct resource *mem;
	unsigned int op_clock;
	int ret;

	i2c = devm_kzalloc(&pdev->dev, sizeof(struct exynos5_i2c), GFP_KERNEL);
	if (!i2c) {
	dev_err(&pdev->dev, "no memory for state\n");
	return -ENOMEM;
	}

	if (of_property_read_u32(np, "clock-frequency", &op_clock)) {
	i2c->speed_mode = HSI2C_FAST_SPD;
	i2c->fs_clock = HSI2C_FS_TX_CLOCK;
	} else {
	if (op_clock >= HSI2C_HS_TX_CLOCK) {
	i2c->speed_mode = HSI2C_HIGH_SPD;
	i2c->fs_clock = HSI2C_FS_TX_CLOCK;
	i2c->hs_clock = op_clock;
	} else {
	i2c->speed_mode = HSI2C_FAST_SPD;
	i2c->fs_clock = op_clock;
	}
	}

	strlcpy(i2c->adap.name, "exynos5-i2c", sizeof(i2c->adap.name));
	i2c->adap.owner = THIS_MODULE;
	i2c->adap.algo = &exynos5_i2c_algorithm;
	i2c->adap.retries = 3;

	i2c->dev = &pdev->dev;
	i2c->clk = devm_clk_get(&pdev->dev, "hsi2c");
	if (IS_ERR(i2c->clk)) {
	dev_err(&pdev->dev, "cannot get clock\n");
	return -ENOENT;
	}

	clk_prepare_enable(i2c->clk);

	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
	if (IS_ERR(i2c->regs)) {
	ret = PTR_ERR(i2c->regs);
	goto err_clk;
	}

	i2c->adap.dev.of_node = np;
	i2c->adap.algo_data = i2c;
	i2c->adap.dev.parent = &pdev->dev;

	/* Clear pending interrupts from u-boot or misc causes */
	exynos5_i2c_clr_pend_irq(i2c);

	spin_lock_init(&i2c->lock);
	init_completion(&i2c->msg_complete);

	i2c->irq = ret = platform_get_irq(pdev, 0);
	if (ret <= 0) {
	dev_err(&pdev->dev, "cannot find HS-I2C IRQ\n");
	ret = -EINVAL;
	goto err_clk;
	}

	ret = devm_request_irq(&pdev->dev, i2c->irq, exynos5_i2c_irq,
	IRQF_NO_SUSPEND \| IRQF_ONESHOT,
	dev_name(&pdev->dev), i2c);

	if (ret != 0) {
	dev_err(&pdev->dev, "cannot request HS-I2C IRQ %d\n", i2c->irq);
	goto err_clk;
	}

	ret = exynos5_hsi2c_clock_setup(i2c);
	if (ret)
	goto err_clk;

	i2c->variant = exynos5_i2c_get_variant(pdev);

	exynos5_i2c_reset(i2c);

	ret = i2c_add_adapter(&i2c->adap);
	if (ret < 0) {
	dev_err(&pdev->dev, "failed to add bus to i2c core\n");
	goto err_clk;
	}

	platform_set_drvdata(pdev, i2c);

	err_clk:
	clk_disable_unprepare(i2c->clk);
	return ret;
	}

	static int exynos5_i2c_remove(struct platform_device *pdev)
	{
	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);

	i2c_del_adapter(&i2c->adap);

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static int exynos5_i2c_suspend_noirq(struct device *dev)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);

	i2c->suspended = 1;

	return 0;
	}

	static int exynos5_i2c_resume_noirq(struct device *dev)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
	int ret = 0;

	clk_prepare_enable(i2c->clk);

	ret = exynos5_hsi2c_clock_setup(i2c);
	if (ret) {
	clk_disable_unprepare(i2c->clk);
	return ret;
	}

	exynos5_i2c_init(i2c);
	clk_disable_unprepare(i2c->clk);
	i2c->suspended = 0;

	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(exynos5_i2c_dev_pm_ops, exynos5_i2c_suspend_noirq,
	exynos5_i2c_resume_noirq);

	static struct platform_driver exynos5_i2c_driver = {
	.probe = exynos5_i2c_probe,
	.remove = exynos5_i2c_remove,
	.driver = {
	.owner = THIS_MODULE,
	.name = "exynos5-hsi2c",
	.pm = &exynos5_i2c_dev_pm_ops,
	.of_match_table = exynos5_i2c_match,
	},
	};

	module_platform_driver(exynos5_i2c_driver);

	MODULE_DESCRIPTION("Exynos5 HS-I2C Bus driver");
	MODULE_AUTHOR("Naveen Krishna Chatradhi, <ch.naveen@samsung.com>");
	MODULE_AUTHOR("Taekgyun Ko, <taeggyun.ko@samsung.com>");
	MODULE_LICENSE("GPL v2");