/*
   *	Copyright (C) 2002 Motorola GSG-China
   *
   *	This program is free software; you can redistribute it and/or
   *	modify it under the terms of the GNU General Public License
   *	as published by the Free Software Foundation; either version 2
   *	of the License, or (at your option) any later version.
   *
   *	This program is distributed in the hope that it will be useful,
   *	but WITHOUT ANY WARRANTY; without even the implied warranty of
   *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *	GNU General Public License for more details.
   *
   *	You should have received a copy of the GNU General Public License
   *	along with this program; if not, write to the Free Software
   *	Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
   *	USA.
   *
   * Author:
   *	Darius Augulis, Teltonika Inc.
   *
   * Desc.:
   *	Implementation of I2C Adapter/Algorithm Driver
   *	for I2C Bus integrated in Freescale i.MX/MXC processors
   *
   *	Derived from Motorola GSG China I2C example driver
   *
   *	Copyright (C) 2005 Torsten Koschorrek <koschorrek at synertronixx.de
   *	Copyright (C) 2005 Matthias Blaschke <blaschke at synertronixx.de
   *	Copyright (C) 2007 RightHand Technologies, Inc.
   *	Copyright (C) 2008 Darius Augulis <darius.augulis at teltonika.lt>
   *
   *	Copyright 2013 Freescale Semiconductor, Inc.
   *
   */
  
  /** Includes *******************************************************************
  *******************************************************************************/
  
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/err.h>
  #include <linux/interrupt.h>
  #include <linux/delay.h>
  #include <linux/i2c.h>
  #include <linux/io.h>
  #include <linux/sched.h>
  #include <linux/platform_device.h>
  #include <linux/clk.h>
  #include <linux/slab.h>
  #include <linux/of.h>
  #include <linux/of_device.h>
  #include <linux/platform_data/i2c-imx.h>
  
  /** Defines ********************************************************************
  *******************************************************************************/
  
  /* This will be the driver name the kernel reports */
  #define DRIVER_NAME "imx-i2c"
  
  /* Default value */
  #define IMX_I2C_BIT_RATE	100000	/* 100kHz */
  
  /* IMX I2C registers:
   * the I2C register offset is different between SoCs,
   * to provid support for all these chips, split the
   * register offset into a fixed base address and a
   * variable shift value, then the full register offset
   * will be calculated by
   * reg_off = ( reg_base_addr << reg_shift)
   */
  #define IMX_I2C_IADR	0x00	/* i2c slave address */
  #define IMX_I2C_IFDR	0x01	/* i2c frequency divider */
  #define IMX_I2C_I2CR	0x02	/* i2c control */
  #define IMX_I2C_I2SR	0x03	/* i2c status */
  #define IMX_I2C_I2DR	0x04	/* i2c transfer data */
  
  #define IMX_I2C_REGSHIFT	2
  #define VF610_I2C_REGSHIFT	0
  
  /* Bits of IMX I2C registers */
  #define I2SR_RXAK	0x01
  #define I2SR_IIF	0x02
  #define I2SR_SRW	0x04
  #define I2SR_IAL	0x10
  #define I2SR_IBB	0x20
  #define I2SR_IAAS	0x40
  #define I2SR_ICF	0x80
  #define I2CR_RSTA	0x04
  #define I2CR_TXAK	0x08
  #define I2CR_MTX	0x10
  #define I2CR_MSTA	0x20
  #define I2CR_IIEN	0x40
  #define I2CR_IEN	0x80
  
  /* register bits different operating codes definition:
   * 1) I2SR: Interrupt flags clear operation differ between SoCs:
   * - write zero to clear(w0c) INT flag on i.MX,
   * - but write one to clear(w1c) INT flag on Vybrid.
   * 2) I2CR: I2C module enable operation also differ between SoCs:
   * - set I2CR_IEN bit enable the module on i.MX,
   * - but clear I2CR_IEN bit enable the module on Vybrid.
   */
  #define I2SR_CLR_OPCODE_W0C	0x0
  #define I2SR_CLR_OPCODE_W1C	(I2SR_IAL | I2SR_IIF)
  #define I2CR_IEN_OPCODE_0	0x0
  #define I2CR_IEN_OPCODE_1	I2CR_IEN
  
  /** Variables ******************************************************************
  *******************************************************************************/
  
  /*
   * sorted list of clock divider, register value pairs
   * taken from table 26-5, p.26-9, Freescale i.MX
   * Integrated Portable System Processor Reference Manual
   * Document Number: MC9328MXLRM, Rev. 5.1, 06/2007
   *
   * Duplicated divider values removed from list
   */
  struct imx_i2c_clk_pair {
  	u16	div;
  	u16	val;
  };
  
  static struct imx_i2c_clk_pair imx_i2c_clk_div[] = {
  	{ 22,	0x20 }, { 24,	0x21 }, { 26,	0x22 }, { 28,	0x23 },
  	{ 30,	0x00 },	{ 32,	0x24 }, { 36,	0x25 }, { 40,	0x26 },
  	{ 42,	0x03 }, { 44,	0x27 },	{ 48,	0x28 }, { 52,	0x05 },
  	{ 56,	0x29 }, { 60,	0x06 }, { 64,	0x2A },	{ 72,	0x2B },
  	{ 80,	0x2C }, { 88,	0x09 }, { 96,	0x2D }, { 104,	0x0A },
  	{ 112,	0x2E }, { 128,	0x2F }, { 144,	0x0C }, { 160,	0x30 },
  	{ 192,	0x31 },	{ 224,	0x32 }, { 240,	0x0F }, { 256,	0x33 },
  	{ 288,	0x10 }, { 320,	0x34 },	{ 384,	0x35 }, { 448,	0x36 },
  	{ 480,	0x13 }, { 512,	0x37 }, { 576,	0x14 },	{ 640,	0x38 },
  	{ 768,	0x39 }, { 896,	0x3A }, { 960,	0x17 }, { 1024,	0x3B },
  	{ 1152,	0x18 }, { 1280,	0x3C }, { 1536,	0x3D }, { 1792,	0x3E },
  	{ 1920,	0x1B },	{ 2048,	0x3F }, { 2304,	0x1C }, { 2560,	0x1D },
  	{ 3072,	0x1E }, { 3840,	0x1F }
  };
  
  /* Vybrid VF610 clock divider, register value pairs */
  static struct imx_i2c_clk_pair vf610_i2c_clk_div[] = {
  	{ 20,   0x00 }, { 22,   0x01 }, { 24,   0x02 }, { 26,   0x03 },
  	{ 28,   0x04 }, { 30,   0x05 }, { 32,   0x09 }, { 34,   0x06 },
  	{ 36,   0x0A }, { 40,   0x07 }, { 44,   0x0C }, { 48,   0x0D },
  	{ 52,   0x43 }, { 56,   0x0E }, { 60,   0x45 }, { 64,   0x12 },
  	{ 68,   0x0F }, { 72,   0x13 }, { 80,   0x14 }, { 88,   0x15 },
  	{ 96,   0x19 }, { 104,  0x16 }, { 112,  0x1A }, { 128,  0x17 },
  	{ 136,  0x4F }, { 144,  0x1C }, { 160,  0x1D }, { 176,  0x55 },
  	{ 192,  0x1E }, { 208,  0x56 }, { 224,  0x22 }, { 228,  0x24 },
  	{ 240,  0x1F }, { 256,  0x23 }, { 288,  0x5C }, { 320,  0x25 },
  	{ 384,  0x26 }, { 448,  0x2A }, { 480,  0x27 }, { 512,  0x2B },
  	{ 576,  0x2C }, { 640,  0x2D }, { 768,  0x31 }, { 896,  0x32 },
  	{ 960,  0x2F }, { 1024, 0x33 }, { 1152, 0x34 }, { 1280, 0x35 },
  	{ 1536, 0x36 }, { 1792, 0x3A }, { 1920, 0x37 }, { 2048, 0x3B },
  	{ 2304, 0x3C }, { 2560, 0x3D }, { 3072, 0x3E }, { 3584, 0x7A },
  	{ 3840, 0x3F }, { 4096, 0x7B }, { 5120, 0x7D }, { 6144, 0x7E },
  };
  
  enum imx_i2c_type {
  	IMX1_I2C,
  	IMX21_I2C,
  	VF610_I2C,
  };
  
  struct imx_i2c_hwdata {
  	enum imx_i2c_type	devtype;
  	unsigned		regshift;
  	struct imx_i2c_clk_pair	*clk_div;
  	unsigned		ndivs;
  	unsigned		i2sr_clr_opcode;
  	unsigned		i2cr_ien_opcode;
  };
  
  struct imx_i2c_struct {
  	struct i2c_adapter	adapter;
  	struct clk		*clk;
  	void __iomem		*base;
  	wait_queue_head_t	queue;
  	unsigned long		i2csr;
  	unsigned int 		disable_delay;
  	int			stopped;
  	unsigned int		ifdr; /* IMX_I2C_IFDR */
  	const struct imx_i2c_hwdata	*hwdata;
  };
  
  static const struct imx_i2c_hwdata imx1_i2c_hwdata  = {
  	.devtype		= IMX1_I2C,
  	.regshift		= IMX_I2C_REGSHIFT,
  	.clk_div		= imx_i2c_clk_div,
  	.ndivs			= ARRAY_SIZE(imx_i2c_clk_div),
  	.i2sr_clr_opcode	= I2SR_CLR_OPCODE_W0C,
  	.i2cr_ien_opcode	= I2CR_IEN_OPCODE_1,
  
  };
  
  static const struct imx_i2c_hwdata imx21_i2c_hwdata  = {
  	.devtype		= IMX21_I2C,
  	.regshift		= IMX_I2C_REGSHIFT,
  	.clk_div		= imx_i2c_clk_div,
  	.ndivs			= ARRAY_SIZE(imx_i2c_clk_div),
  	.i2sr_clr_opcode	= I2SR_CLR_OPCODE_W0C,
  	.i2cr_ien_opcode	= I2CR_IEN_OPCODE_1,
  
  };
  
  static struct imx_i2c_hwdata vf610_i2c_hwdata = {
  	.devtype		= VF610_I2C,
  	.regshift		= VF610_I2C_REGSHIFT,
  	.clk_div		= vf610_i2c_clk_div,
  	.ndivs			= ARRAY_SIZE(vf610_i2c_clk_div),
  	.i2sr_clr_opcode	= I2SR_CLR_OPCODE_W1C,
  	.i2cr_ien_opcode	= I2CR_IEN_OPCODE_0,
  
  };
  
  static struct platform_device_id imx_i2c_devtype[] = {
  	{
  		.name = "imx1-i2c",
  		.driver_data = (kernel_ulong_t)&imx1_i2c_hwdata,
  	}, {
  		.name = "imx21-i2c",
  		.driver_data = (kernel_ulong_t)&imx21_i2c_hwdata,
  	}, {
  		/* sentinel */
  	}
  };
  MODULE_DEVICE_TABLE(platform, imx_i2c_devtype);
  
  static const struct of_device_id i2c_imx_dt_ids[] = {
  	{ .compatible = "fsl,imx1-i2c", .data = &imx1_i2c_hwdata, },
  	{ .compatible = "fsl,imx21-i2c", .data = &imx21_i2c_hwdata, },
  	{ .compatible = "fsl,vf610-i2c", .data = &vf610_i2c_hwdata, },
  	{ /* sentinel */ }
  };
  MODULE_DEVICE_TABLE(of, i2c_imx_dt_ids);
  
  static inline int is_imx1_i2c(struct imx_i2c_struct *i2c_imx)
  {
  	return i2c_imx->hwdata->devtype == IMX1_I2C;
  }
  
  static inline void imx_i2c_write_reg(unsigned int val,
  		struct imx_i2c_struct *i2c_imx, unsigned int reg)
  {
  	writeb(val, i2c_imx->base + (reg << i2c_imx->hwdata->regshift));
  }
  
  static inline unsigned char imx_i2c_read_reg(struct imx_i2c_struct *i2c_imx,
  		unsigned int reg)
  {
  	return readb(i2c_imx->base + (reg << i2c_imx->hwdata->regshift));
  }
  
  /** Functions for IMX I2C adapter driver ***************************************
  *******************************************************************************/
  
  static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
  {
  	unsigned long orig_jiffies = jiffies;
  	unsigned int temp;
  
  	dev_dbg(&i2c_imx->adapter.dev, "<%s>
  ", __func__);
  
  	while (1) {
  		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
  		if (for_busy && (temp & I2SR_IBB))
  			break;
  		if (!for_busy && !(temp & I2SR_IBB))
  			break;
  		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
  			dev_dbg(&i2c_imx->adapter.dev,
  				"<%s> I2C bus is busy
  ", __func__);
  			return -ETIMEDOUT;
  		}
  		schedule();
  	}
  
  	return 0;
  }
  
  static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx)
  {
  	wait_event_timeout(i2c_imx->queue, i2c_imx->i2csr & I2SR_IIF, HZ / 10);
  
  	if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
  		dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout
  ", __func__);
  		return -ETIMEDOUT;
  	}
  	dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete
  ", __func__);
  	i2c_imx->i2csr = 0;
  	return 0;
  }
  
  static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
  {
  	if (imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR) & I2SR_RXAK) {
  		dev_dbg(&i2c_imx->adapter.dev, "<%s> No ACK
  ", __func__);
  		return -EIO;  /* No ACK */
  	}
  
  	dev_dbg(&i2c_imx->adapter.dev, "<%s> ACK received
  ", __func__);
  	return 0;
  }
  
  static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
  {
  	unsigned int temp = 0;
  	int result;
  
  	dev_dbg(&i2c_imx->adapter.dev, "<%s>
  ", __func__);
  
  	result = clk_prepare_enable(i2c_imx->clk);
  	if (result)
  		return result;
  	imx_i2c_write_reg(i2c_imx->ifdr, i2c_imx, IMX_I2C_IFDR);
  	/* Enable I2C controller */
  	imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);
  	imx_i2c_write_reg(i2c_imx->hwdata->i2cr_ien_opcode, i2c_imx, IMX_I2C_I2CR);
  
  	/* Wait controller to be stable */
  	udelay(50);
  
  	/* Start I2C transaction */
  	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
  	temp |= I2CR_MSTA;
  	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
  	result = i2c_imx_bus_busy(i2c_imx, 1);
  	if (result)
  		return result;
  	i2c_imx->stopped = 0;
  
  	temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
  	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
  	return result;
  }
  
  static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
  {
  	unsigned int temp = 0;
  
  	if (!i2c_imx->stopped) {
  		/* Stop I2C transaction */
  		dev_dbg(&i2c_imx->adapter.dev, "<%s>
  ", __func__);
  		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
  		temp &= ~(I2CR_MSTA | I2CR_MTX);
  		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
  	}
  	if (is_imx1_i2c(i2c_imx)) {
  		/*
  		 * This delay caused by an i.MXL hardware bug.
  		 * If no (or too short) delay, no "STOP" bit will be generated.
  		 */
  		udelay(i2c_imx->disable_delay);
  	}
  
  	if (!i2c_imx->stopped) {
  		i2c_imx_bus_busy(i2c_imx, 0);
  		i2c_imx->stopped = 1;
  	}
  
  	/* Disable I2C controller */
  	temp = i2c_imx->hwdata->i2cr_ien_opcode ^ I2CR_IEN,
  	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
  	clk_disable_unprepare(i2c_imx->clk);
  }
  
  static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
  							unsigned int rate)
  {
  	struct imx_i2c_clk_pair *i2c_clk_div = i2c_imx->hwdata->clk_div;
  	unsigned int i2c_clk_rate;
  	unsigned int div;
  	int i;
  
  	/* Divider value calculation */
  	i2c_clk_rate = clk_get_rate(i2c_imx->clk);
  	div = (i2c_clk_rate + rate - 1) / rate;
  	if (div < i2c_clk_div[0].div)
  		i = 0;
  	else if (div > i2c_clk_div[i2c_imx->hwdata->ndivs - 1].div)
  		i = i2c_imx->hwdata->ndivs - 1;
  	else
  		for (i = 0; i2c_clk_div[i].div < div; i++);
  
  	/* Store divider value */
  	i2c_imx->ifdr = i2c_clk_div[i].val;
  
  	/*
  	 * There dummy delay is calculated.
  	 * It should be about one I2C clock period long.
  	 * This delay is used in I2C bus disable function
  	 * to fix chip hardware bug.
  	 */
  	i2c_imx->disable_delay = (500000U * i2c_clk_div[i].div
  		+ (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
  
  	/* dev_dbg() can't be used, because adapter is not yet registered */
  #ifdef CONFIG_I2C_DEBUG_BUS
  	dev_dbg(&i2c_imx->adapter.dev, "<%s> I2C_CLK=%d, REQ DIV=%d
  ",
  		__func__, i2c_clk_rate, div);
  	dev_dbg(&i2c_imx->adapter.dev, "<%s> IFDR[IC]=0x%x, REAL DIV=%d
  ",
  		__func__, i2c_clk_div[i].val, i2c_clk_div[i].div);
  #endif
  }
  
  static irqreturn_t i2c_imx_isr(int irq, void *dev_id)
  {
  	struct imx_i2c_struct *i2c_imx = dev_id;
  	unsigned int temp;
  
  	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
  	if (temp & I2SR_IIF) {
  		/* save status register */
  		i2c_imx->i2csr = temp;
  		temp &= ~I2SR_IIF;
  		temp |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF);
  		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
  		wake_up(&i2c_imx->queue);
  		return IRQ_HANDLED;
  	}
  
  	return IRQ_NONE;
  }
  
  static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
  {
  	int i, result;
  
  	dev_dbg(&i2c_imx->adapter.dev, "<%s> write slave address: addr=0x%x
  ",
  		__func__, msgs->addr << 1);
  
  	/* write slave address */
  	imx_i2c_write_reg(msgs->addr << 1, i2c_imx, IMX_I2C_I2DR);
  	result = i2c_imx_trx_complete(i2c_imx);
  	if (result)
  		return result;
  	result = i2c_imx_acked(i2c_imx);
  	if (result)
  		return result;
  	dev_dbg(&i2c_imx->adapter.dev, "<%s> write data
  ", __func__);
  
  	/* write data */
  	for (i = 0; i < msgs->len; i++) {
  		dev_dbg(&i2c_imx->adapter.dev,
  			"<%s> write byte: B%d=0x%X
  ",
  			__func__, i, msgs->buf[i]);
  		imx_i2c_write_reg(msgs->buf[i], i2c_imx, IMX_I2C_I2DR);
  		result = i2c_imx_trx_complete(i2c_imx);
  		if (result)
  			return result;
  		result = i2c_imx_acked(i2c_imx);
  		if (result)
  			return result;
  	}
  	return 0;
  }
  
  static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bool is_lastmsg)
  {
  	int i, result;
  	unsigned int temp;
  
  	dev_dbg(&i2c_imx->adapter.dev,
  		"<%s> write slave address: addr=0x%x
  ",
  		__func__, (msgs->addr << 1) | 0x01);
  
  	/* write slave address */
  	imx_i2c_write_reg((msgs->addr << 1) | 0x01, i2c_imx, IMX_I2C_I2DR);
  	result = i2c_imx_trx_complete(i2c_imx);
  	if (result)
  		return result;
  	result = i2c_imx_acked(i2c_imx);
  	if (result)
  		return result;
  
  	dev_dbg(&i2c_imx->adapter.dev, "<%s> setup bus
  ", __func__);
  
  	/* setup bus to read data */
  	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
  	temp &= ~I2CR_MTX;
  	if (msgs->len - 1)
  		temp &= ~I2CR_TXAK;
  	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
  	imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */
  
  	dev_dbg(&i2c_imx->adapter.dev, "<%s> read data
  ", __func__);
  
  	/* read data */
  	for (i = 0; i < msgs->len; i++) {
  		result = i2c_imx_trx_complete(i2c_imx);
  		if (result)
  			return result;
  		if (i == (msgs->len - 1)) {
  			if (is_lastmsg) {
  				/*
  				 * It must generate STOP before read I2DR to prevent
  				 * controller from generating another clock cycle
  				 */
  				dev_dbg(&i2c_imx->adapter.dev,
  					"<%s> clear MSTA
  ", __func__);
  				temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
  				temp &= ~(I2CR_MSTA | I2CR_MTX);
  				imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
  				i2c_imx_bus_busy(i2c_imx, 0);
  				i2c_imx->stopped = 1;
  			} else {
  				/*
  				 * For i2c master receiver repeat restart operation like:
  				 * read -> repeat MSTA -> read/write
  				 * The controller must set MTX before read the last byte in
  				 * the first read operation, otherwise the first read cost
  				 * one extra clock cycle.
  				 */
  				temp = readb(i2c_imx->base + IMX_I2C_I2CR);
  				temp |= I2CR_MTX;
  				writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
  			}
  		} else if (i == (msgs->len - 2)) {
  			dev_dbg(&i2c_imx->adapter.dev,
  				"<%s> set TXAK
  ", __func__);
  			temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
  			temp |= I2CR_TXAK;
  			imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
  		}
  		msgs->buf[i] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
  		dev_dbg(&i2c_imx->adapter.dev,
  			"<%s> read byte: B%d=0x%X
  ",
  			__func__, i, msgs->buf[i]);
  	}
  	return 0;
  }
  
  static int i2c_imx_xfer(struct i2c_adapter *adapter,
  						struct i2c_msg *msgs, int num)
  {
  	unsigned int i, temp;
  	int result;
  	bool is_lastmsg = false;
  	struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(adapter);
  
  	dev_dbg(&i2c_imx->adapter.dev, "<%s>
  ", __func__);
  
  	/* Start I2C transfer */
  	result = i2c_imx_start(i2c_imx);
  	if (result)
  		goto fail0;
  
  	/* read/write data */
  	for (i = 0; i < num; i++) {
  		if (i == num - 1)
  			is_lastmsg = true;
  
  		if (i) {
  			dev_dbg(&i2c_imx->adapter.dev,
  				"<%s> repeated start
  ", __func__);
  			temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
  			temp |= I2CR_RSTA;
  			imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
  			result =  i2c_imx_bus_busy(i2c_imx, 1);
  			if (result)
  				goto fail0;
  		}
  		dev_dbg(&i2c_imx->adapter.dev,
  			"<%s> transfer message: %d
  ", __func__, i);
  		/* write/read data */
  #ifdef CONFIG_I2C_DEBUG_BUS
  		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
  		dev_dbg(&i2c_imx->adapter.dev, "<%s> CONTROL: IEN=%d, IIEN=%d, "
  			"MSTA=%d, MTX=%d, TXAK=%d, RSTA=%d
  ", __func__,
  			(temp & I2CR_IEN ? 1 : 0), (temp & I2CR_IIEN ? 1 : 0),
  			(temp & I2CR_MSTA ? 1 : 0), (temp & I2CR_MTX ? 1 : 0),
  			(temp & I2CR_TXAK ? 1 : 0), (temp & I2CR_RSTA ? 1 : 0));
  		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
  		dev_dbg(&i2c_imx->adapter.dev,
  			"<%s> STATUS: ICF=%d, IAAS=%d, IBB=%d, "
  			"IAL=%d, SRW=%d, IIF=%d, RXAK=%d
  ", __func__,
  			(temp & I2SR_ICF ? 1 : 0), (temp & I2SR_IAAS ? 1 : 0),
  			(temp & I2SR_IBB ? 1 : 0), (temp & I2SR_IAL ? 1 : 0),
  			(temp & I2SR_SRW ? 1 : 0), (temp & I2SR_IIF ? 1 : 0),
  			(temp & I2SR_RXAK ? 1 : 0));
  #endif
  		if (msgs[i].flags & I2C_M_RD)
  			result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg);
  		else
  			result = i2c_imx_write(i2c_imx, &msgs[i]);
  		if (result)
  			goto fail0;
  	}
  
  fail0:
  	/* Stop I2C transfer */
  	i2c_imx_stop(i2c_imx);
  
  	dev_dbg(&i2c_imx->adapter.dev, "<%s> exit with: %s: %d
  ", __func__,
  		(result < 0) ? "error" : "success msg",
  			(result < 0) ? result : num);
  	return (result < 0) ? result : num;
  }
  
  static u32 i2c_imx_func(struct i2c_adapter *adapter)
  {
  	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
  }
  
  static struct i2c_algorithm i2c_imx_algo = {
  	.master_xfer	= i2c_imx_xfer,
  	.functionality	= i2c_imx_func,
  };
  
  static int i2c_imx_probe(struct platform_device *pdev)
  {
  	const struct of_device_id *of_id = of_match_device(i2c_imx_dt_ids,
  							   &pdev->dev);
  	struct imx_i2c_struct *i2c_imx;
  	struct resource *res;
  	struct imxi2c_platform_data *pdata = dev_get_platdata(&pdev->dev);
  	void __iomem *base;
  	int irq, ret;
  	u32 bitrate;
  
  	dev_dbg(&pdev->dev, "<%s>
  ", __func__);
  
  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0) {
  		dev_err(&pdev->dev, "can't get irq number
  ");
  		return irq;
  	}
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	base = devm_ioremap_resource(&pdev->dev, res);
  	if (IS_ERR(base))
  		return PTR_ERR(base);
  
  	i2c_imx = devm_kzalloc(&pdev->dev, sizeof(struct imx_i2c_struct),
  				GFP_KERNEL);
  	if (!i2c_imx) {
  		dev_err(&pdev->dev, "can't allocate interface
  ");
  		return -ENOMEM;
  	}
  
  	if (of_id)
  		i2c_imx->hwdata = of_id->data;
  	else
  		i2c_imx->hwdata = (struct imx_i2c_hwdata *)
  				platform_get_device_id(pdev)->driver_data;
  
  	/* Setup i2c_imx driver structure */
  	strlcpy(i2c_imx->adapter.name, pdev->name, sizeof(i2c_imx->adapter.name));
  	i2c_imx->adapter.owner		= THIS_MODULE;
  	i2c_imx->adapter.algo		= &i2c_imx_algo;
  	i2c_imx->adapter.dev.parent	= &pdev->dev;
  	i2c_imx->adapter.nr 		= pdev->id;
  	i2c_imx->adapter.dev.of_node	= pdev->dev.of_node;
  	i2c_imx->base			= base;
  
  	/* Get I2C clock */
  	i2c_imx->clk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(i2c_imx->clk)) {
  		dev_err(&pdev->dev, "can't get I2C clock
  ");
  		return PTR_ERR(i2c_imx->clk);
  	}
  
  	ret = clk_prepare_enable(i2c_imx->clk);
  	if (ret) {
  		dev_err(&pdev->dev, "can't enable I2C clock
  ");
  		return ret;
  	}
  	/* Request IRQ */
  	ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, 0,
  				pdev->name, i2c_imx);
  	if (ret) {
  		dev_err(&pdev->dev, "can't claim irq %d
  ", irq);
  		return ret;
  	}
  
  	/* Init queue */
  	init_waitqueue_head(&i2c_imx->queue);
  
  	/* Set up adapter data */
  	i2c_set_adapdata(&i2c_imx->adapter, i2c_imx);
  
  	/* Set up clock divider */
  	bitrate = IMX_I2C_BIT_RATE;
  	ret = of_property_read_u32(pdev->dev.of_node,
  				   "clock-frequency", &bitrate);
  	if (ret < 0 && pdata && pdata->bitrate)
  		bitrate = pdata->bitrate;
  	i2c_imx_set_clk(i2c_imx, bitrate);
  
  	/* Set up chip registers to defaults */
  	imx_i2c_write_reg(i2c_imx->hwdata->i2cr_ien_opcode ^ I2CR_IEN,
  			i2c_imx, IMX_I2C_I2CR);
  	imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);
  
  	/* Add I2C adapter */
  	ret = i2c_add_numbered_adapter(&i2c_imx->adapter);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "registration failed
  ");
  		return ret;
  	}
  
  	/* Set up platform driver data */
  	platform_set_drvdata(pdev, i2c_imx);
  	clk_disable_unprepare(i2c_imx->clk);
  
  	dev_dbg(&i2c_imx->adapter.dev, "claimed irq %d
  ", irq);
  	dev_dbg(&i2c_imx->adapter.dev, "device resources from 0x%x to 0x%x
  ",
  		res->start, res->end);
  	dev_dbg(&i2c_imx->adapter.dev, "allocated %d bytes at 0x%x
  ",
  		resource_size(res), res->start);
  	dev_dbg(&i2c_imx->adapter.dev, "adapter name: \"%s\"
  ",
  		i2c_imx->adapter.name);
  	dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered
  ");
  
  	return 0;   /* Return OK */
  }
  
  static int i2c_imx_remove(struct platform_device *pdev)
  {
  	struct imx_i2c_struct *i2c_imx = platform_get_drvdata(pdev);
  
  	/* remove adapter */
  	dev_dbg(&i2c_imx->adapter.dev, "adapter removed
  ");
  	i2c_del_adapter(&i2c_imx->adapter);
  
  	/* setup chip registers to defaults */
  	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IADR);
  	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IFDR);
  	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2CR);
  	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2SR);
  
  	return 0;
  }
  
  static struct platform_driver i2c_imx_driver = {
  	.probe = i2c_imx_probe,
  	.remove = i2c_imx_remove,
  	.driver	= {
  		.name	= DRIVER_NAME,
  		.owner	= THIS_MODULE,
  		.of_match_table = i2c_imx_dt_ids,
  	},
  	.id_table	= imx_i2c_devtype,
  };
  
  static int __init i2c_adap_imx_init(void)
  {
  	return platform_driver_register(&i2c_imx_driver);
  }
  subsys_initcall(i2c_adap_imx_init);
  
  static void __exit i2c_adap_imx_exit(void)
  {
  	platform_driver_unregister(&i2c_imx_driver);
  }
  module_exit(i2c_adap_imx_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Darius Augulis");
  MODULE_DESCRIPTION("I2C adapter driver for IMX I2C bus");
  MODULE_ALIAS("platform:" DRIVER_NAME);