/*
 * Support for Moorestown/Medfield I2C chip
 *
 * Copyright (c) 2009 Intel Corporation.
 * Copyright (c) 2009 Synopsys. Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License, version
 * 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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., 51
 * Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/pm_runtime.h>
#include <linux/io.h>

#define DRIVER_NAME	"i2c-intel-mid"
#define VERSION		"Version 0.5ac2"
#define PLATFORM	"Moorestown/Medfield"

/* Tables use: 0 Moorestown, 1 Medfield */
#define NUM_PLATFORMS	2
enum platform_enum {
	MOORESTOWN = 0,
	MEDFIELD = 1,
};

enum mid_i2c_status {
	STATUS_IDLE = 0,
	STATUS_READ_START,
	STATUS_READ_IN_PROGRESS,
	STATUS_READ_SUCCESS,
	STATUS_WRITE_START,
	STATUS_WRITE_SUCCESS,
	STATUS_XFER_ABORT,
	STATUS_STANDBY
};

/**
 * struct intel_mid_i2c_private	- per device I²C context
 * @adap: core i2c layer adapter information
 * @dev: device reference for power management
 * @base: register base
 * @speed: speed mode for this port
 * @complete: completion object for transaction wait
 * @abort: reason for last abort
 * @rx_buf: pointer into working receive buffer
 * @rx_buf_len: receive buffer length
 * @status: adapter state machine
 * @msg: the message we are currently processing
 * @platform: the MID device type we are part of
 * @lock: transaction serialization
 *
 * We allocate one of these per device we discover, it holds the core
 * i2c layer objects and the data we need to track privately.
 */
struct intel_mid_i2c_private {
	struct i2c_adapter adap;
	struct device *dev;
	void __iomem *base;
	int speed;
	struct completion complete;
	int abort;
	u8 *rx_buf;
	int rx_buf_len;
	enum mid_i2c_status status;
	struct i2c_msg *msg;
	enum platform_enum platform;
	struct mutex lock;
};

#define NUM_SPEEDS		3

#define ACTIVE			0
#define STANDBY			1


/* Control register */
#define IC_CON			0x00
#define SLV_DIS			(1 << 6)	/* Disable slave mode */
#define RESTART			(1 << 5)	/* Send a Restart condition */
#define	ADDR_10BIT		(1 << 4)	/* 10-bit addressing */
#define	STANDARD_MODE		(1 << 1)	/* standard mode */
#define FAST_MODE		(2 << 1)	/* fast mode */
#define HIGH_MODE		(3 << 1)	/* high speed mode */
#define	MASTER_EN		(1 << 0)	/* Master mode */

/* Target address register */
#define IC_TAR			0x04
#define IC_TAR_10BIT_ADDR	(1 << 12)	/* 10-bit addressing */
#define IC_TAR_SPECIAL		(1 << 11)	/* Perform special I2C cmd */
#define IC_TAR_GC_OR_START	(1 << 10)	/* 0: Gerneral Call Address */
						/* 1: START BYTE */
/* Slave Address Register */
#define IC_SAR			0x08		/* Not used in Master mode */

/* High Speed Master Mode Code Address Register */
#define IC_HS_MADDR		0x0c

/* Rx/Tx Data Buffer and Command Register */
#define IC_DATA_CMD		0x10
#define IC_RD			(1 << 8)	/* 1: Read 0: Write */

/* Standard Speed Clock SCL High Count Register */
#define IC_SS_SCL_HCNT		0x14

/* Standard Speed Clock SCL Low Count Register */
#define IC_SS_SCL_LCNT		0x18

/* Fast Speed Clock SCL High Count Register */
#define IC_FS_SCL_HCNT		0x1c

/* Fast Spedd Clock SCL Low Count Register */
#define IC_FS_SCL_LCNT		0x20

/* High Speed Clock SCL High Count Register */
#define IC_HS_SCL_HCNT		0x24

/* High Speed Clock SCL Low Count Register */
#define IC_HS_SCL_LCNT		0x28

/* Interrupt Status Register */
#define IC_INTR_STAT		0x2c		/* Read only */
#define R_GEN_CALL		(1 << 11)
#define R_START_DET		(1 << 10)
#define R_STOP_DET		(1 << 9)
#define R_ACTIVITY		(1 << 8)
#define R_RX_DONE		(1 << 7)
#define	R_TX_ABRT		(1 << 6)
#define R_RD_REQ		(1 << 5)
#define R_TX_EMPTY		(1 << 4)
#define R_TX_OVER		(1 << 3)
#define	R_RX_FULL		(1 << 2)
#define	R_RX_OVER		(1 << 1)
#define R_RX_UNDER		(1 << 0)

/* Interrupt Mask Register */
#define IC_INTR_MASK		0x30		/* Read and Write */
#define M_GEN_CALL		(1 << 11)
#define M_START_DET		(1 << 10)
#define M_STOP_DET		(1 << 9)
#define M_ACTIVITY		(1 << 8)
#define M_RX_DONE		(1 << 7)
#define	M_TX_ABRT		(1 << 6)
#define M_RD_REQ		(1 << 5)
#define M_TX_EMPTY		(1 << 4)
#define M_TX_OVER		(1 << 3)
#define	M_RX_FULL		(1 << 2)
#define	M_RX_OVER		(1 << 1)
#define M_RX_UNDER		(1 << 0)

/* Raw Interrupt Status Register */
#define IC_RAW_INTR_STAT	0x34		/* Read Only */
#define GEN_CALL		(1 << 11)	/* General call */
#define START_DET		(1 << 10)	/* (RE)START occurred */
#define STOP_DET		(1 << 9)	/* STOP occurred */
#define ACTIVITY		(1 << 8)	/* Bus busy */
#define RX_DONE			(1 << 7)	/* Not used in Master mode */
#define	TX_ABRT			(1 << 6)	/* Transmit Abort */
#define RD_REQ			(1 << 5)	/* Not used in Master mode */
#define TX_EMPTY		(1 << 4)	/* TX FIFO <= threshold */
#define TX_OVER			(1 << 3)	/* TX FIFO overflow */
#define	RX_FULL			(1 << 2)	/* RX FIFO >= threshold */
#define	RX_OVER			(1 << 1)	/* RX FIFO overflow */
#define RX_UNDER		(1 << 0)	/* RX FIFO empty */

/* Receive FIFO Threshold Register */
#define IC_RX_TL		0x38

/* Transmit FIFO Treshold Register */
#define IC_TX_TL		0x3c

/* Clear Combined and Individual Interrupt Register */
#define IC_CLR_INTR		0x40
#define CLR_INTR		(1 << 0)

/* Clear RX_UNDER Interrupt Register */
#define IC_CLR_RX_UNDER		0x44
#define CLR_RX_UNDER		(1 << 0)

/* Clear RX_OVER Interrupt Register */
#define IC_CLR_RX_OVER		0x48
#define CLR_RX_OVER		(1 << 0)

/* Clear TX_OVER Interrupt Register */
#define IC_CLR_TX_OVER		0x4c
#define CLR_TX_OVER		(1 << 0)

#define IC_CLR_RD_REQ		0x50

/* Clear TX_ABRT Interrupt Register */
#define IC_CLR_TX_ABRT		0x54
#define CLR_TX_ABRT		(1 << 0)
#define IC_CLR_RX_DONE		0x58

/* Clear ACTIVITY Interrupt Register */
#define IC_CLR_ACTIVITY		0x5c
#define CLR_ACTIVITY		(1 << 0)

/* Clear STOP_DET Interrupt Register */
#define IC_CLR_STOP_DET		0x60
#define CLR_STOP_DET		(1 << 0)

/* Clear START_DET Interrupt Register */
#define IC_CLR_START_DET	0x64
#define CLR_START_DET		(1 << 0)

/* Clear GEN_CALL Interrupt Register */
#define IC_CLR_GEN_CALL		0x68
#define CLR_GEN_CALL		(1 << 0)

/* Enable Register */
#define IC_ENABLE		0x6c
#define ENABLE			(1 << 0)

/* Status Register */
#define IC_STATUS		0x70		/* Read Only */
#define STAT_SLV_ACTIVITY	(1 << 6)	/* Slave not in idle */
#define STAT_MST_ACTIVITY	(1 << 5)	/* Master not in idle */
#define STAT_RFF		(1 << 4)	/* RX FIFO Full */
#define STAT_RFNE		(1 << 3)	/* RX FIFO Not Empty */
#define STAT_TFE		(1 << 2)	/* TX FIFO Empty */
#define STAT_TFNF		(1 << 1)	/* TX FIFO Not Full */
#define STAT_ACTIVITY		(1 << 0)	/* Activity Status */

/* Transmit FIFO Level Register */
#define IC_TXFLR		0x74		/* Read Only */
#define TXFLR			(1 << 0)	/* TX FIFO level */

/* Receive FIFO Level Register */
#define IC_RXFLR		0x78		/* Read Only */
#define RXFLR			(1 << 0)	/* RX FIFO level */

/* Transmit Abort Source Register */
#define IC_TX_ABRT_SOURCE	0x80
#define ABRT_SLVRD_INTX		(1 << 15)
#define ABRT_SLV_ARBLOST	(1 << 14)
#define ABRT_SLVFLUSH_TXFIFO	(1 << 13)
#define	ARB_LOST		(1 << 12)
#define ABRT_MASTER_DIS		(1 << 11)
#define ABRT_10B_RD_NORSTRT	(1 << 10)
#define ABRT_SBYTE_NORSTRT	(1 << 9)
#define ABRT_HS_NORSTRT		(1 << 8)
#define ABRT_SBYTE_ACKDET	(1 << 7)
#define ABRT_HS_ACKDET		(1 << 6)
#define ABRT_GCALL_READ		(1 << 5)
#define ABRT_GCALL_NOACK	(1 << 4)
#define ABRT_TXDATA_NOACK	(1 << 3)
#define ABRT_10ADDR2_NOACK	(1 << 2)
#define ABRT_10ADDR1_NOACK	(1 << 1)
#define ABRT_7B_ADDR_NOACK	(1 << 0)

/* Enable Status Register */
#define IC_ENABLE_STATUS	0x9c
#define IC_EN			(1 << 0)	/* I2C in an enabled state */

/* Component Parameter Register 1*/
#define IC_COMP_PARAM_1		0xf4
#define APB_DATA_WIDTH		(0x3 << 0)

/* added by xiaolin --begin */
#define SS_MIN_SCL_HIGH         4000
#define SS_MIN_SCL_LOW          4700
#define FS_MIN_SCL_HIGH         600
#define FS_MIN_SCL_LOW          1300
#define HS_MIN_SCL_HIGH_100PF   60
#define HS_MIN_SCL_LOW_100PF    120

#define STANDARD		0
#define FAST			1
#define HIGH			2

#define NUM_SPEEDS		3

static int speed_mode[6] = {
	FAST,
	FAST,
	FAST,
	STANDARD,
	FAST,
	FAST
};

static int ctl_num = 6;
module_param_array(speed_mode, int, &ctl_num, S_IRUGO);
MODULE_PARM_DESC(speed_mode, "Set the speed of the i2c interface (0-2)");

/**
 * intel_mid_i2c_disable - Disable I2C controller
 * @adap: struct pointer to i2c_adapter
 *
 * Return Value:
 * 0		success
 * -EBUSY	if device is busy
 * -ETIMEDOUT	if i2c cannot be disabled within the given time
 *
 * I2C bus state should be checked prior to disabling the hardware. If bus is
 * not in idle state, an errno is returned. Write "0" to IC_ENABLE to disable
 * I2C controller.
 */
static int intel_mid_i2c_disable(struct i2c_adapter *adap)
{
	struct intel_mid_i2c_private *i2c = i2c_get_adapdata(adap);
	int err = 0;
	int count = 0;
	int ret1, ret2;
	static const u16 delay[NUM_SPEEDS] = {100, 25, 3};

	/* Set IC_ENABLE to 0 */
	writel(0, i2c->base + IC_ENABLE);

	/* Check if device is busy */
	dev_dbg(&adap->dev, "mrst i2c disable\n");
	while ((ret1 = readl(i2c->base + IC_ENABLE_STATUS) & 0x1)
		|| (ret2 = readl(i2c->base + IC_STATUS) & 0x1)) {
		udelay(delay[i2c->speed]);
		writel(0, i2c->base + IC_ENABLE);
		dev_dbg(&adap->dev, "i2c is busy, count is %d speed %d\n",
			count, i2c->speed);
		if (count++ > 10) {
			err = -ETIMEDOUT;
			break;
		}
	}

	/* Clear all interrupts */
	readl(i2c->base + IC_CLR_INTR);
	readl(i2c->base + IC_CLR_STOP_DET);
	readl(i2c->base + IC_CLR_START_DET);
	readl(i2c->base + IC_CLR_ACTIVITY);
	readl(i2c->base + IC_CLR_TX_ABRT);
	readl(i2c->base + IC_CLR_RX_OVER);
	readl(i2c->base + IC_CLR_RX_UNDER);
	readl(i2c->base + IC_CLR_TX_OVER);
	readl(i2c->base + IC_CLR_RX_DONE);
	readl(i2c->base + IC_CLR_GEN_CALL);

	/* Disable all interupts */
	writel(0x0000, i2c->base + IC_INTR_MASK);

	return err;
}

/**
 * intel_mid_i2c_hwinit - Initialize the I2C hardware registers
 * @dev: pci device struct pointer
 *
 * This function will be called in intel_mid_i2c_probe() before device
 * registration.
 *
 * Return Values:
 * 0		success
 * -EBUSY	i2c cannot be disabled
 * -ETIMEDOUT	i2c cannot be disabled
 * -EFAULT	If APB data width is not 32-bit wide
 *
 * I2C should be disabled prior to other register operation. If failed, an
 * errno is returned. Mask and Clear all interrpts, this should be done at
 * first.  Set common registers which will not be modified during normal
 * transfers, including: control register, FIFO threshold and clock freq.
 * Check APB data width at last.
 */
static int intel_mid_i2c_hwinit(struct intel_mid_i2c_private *i2c)
{
	int err;

	static const u16 hcnt[NUM_PLATFORMS][NUM_SPEEDS] = {
		{ 0x75,  0x15, 0x07 },
		{ 0x04c,  0x10, 0x06 }
	};
	static const u16 lcnt[NUM_PLATFORMS][NUM_SPEEDS] = {
		{ 0x7C,  0x21, 0x0E },
		{ 0x053, 0x19, 0x0F }
	};

	/* Disable i2c first */
	err = intel_mid_i2c_disable(&i2c->adap);
	if (err)
		return err;

	/*
	 * Setup clock frequency and speed mode
	 * Enable restart condition,
	 * enable master FSM, disable slave FSM,
	 * use target address when initiating transfer
	 */

	writel((i2c->speed + 1) << 1 | SLV_DIS | RESTART | MASTER_EN,
		i2c->base + IC_CON);
	writel(hcnt[i2c->platform][i2c->speed],
		i2c->base + (IC_SS_SCL_HCNT + (i2c->speed << 3)));
	writel(lcnt[i2c->platform][i2c->speed],
		i2c->base + (IC_SS_SCL_LCNT + (i2c->speed << 3)));

	/* Set tranmit & receive FIFO threshold to zero */
	writel(0x0, i2c->base + IC_RX_TL);
	writel(0x0, i2c->base + IC_TX_TL);

	return 0;
}

/**
 * intel_mid_i2c_func - Return the supported three I2C operations.
 * @adapter: i2c_adapter struct pointer
 */
static u32 intel_mid_i2c_func(struct i2c_adapter *adapter)
{
	return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
}

/**
 * intel_mid_i2c_address_neq - To check if the addresses for different i2c messages
 * are equal.
 * @p1: first i2c_msg
 * @p2: second i2c_msg
 *
 * Return Values:
 * 0	 if addresses are equal
 * 1	 if not equal
 *
 * Within a single transfer, the I2C client may need to send its address more
 * than once. So a check if the addresses match is needed.
 */
static inline bool intel_mid_i2c_address_neq(const struct i2c_msg *p1,
				       const struct i2c_msg *p2)
{
	if (p1->addr != p2->addr)
		return 1;
	if ((p1->flags ^ p2->flags) & I2C_M_TEN)
		return 1;
	return 0;
}

/**
 * intel_mid_i2c_abort - To handle transfer abortions and print error messages.
 * @adap: i2c_adapter struct pointer
 *
 * By reading register IC_TX_ABRT_SOURCE, various transfer errors can be
 * distingushed. At present, no circumstances have been found out that
 * multiple errors would be occurred simutaneously, so we simply use the
 * register value directly.
 *
 * At last the error bits are cleared. (Note clear ABRT_SBYTE_NORSTRT bit need
 * a few extra steps)
 */
static void intel_mid_i2c_abort(struct intel_mid_i2c_private *i2c)
{
	/* Read about source register */
	int abort = i2c->abort;
	struct i2c_adapter *adap = &i2c->adap;

	/* Single transfer error check:
	 * According to databook, TX/RX FIFOs would be flushed when
	 * the abort interrupt occurred.
	 */
	if (abort & ABRT_MASTER_DIS)
		dev_err(&adap->dev,
		"initiate master operation with master mode disabled.\n");
	if (abort & ABRT_10B_RD_NORSTRT)
		dev_err(&adap->dev,
	"RESTART disabled and master sent READ cmd in 10-bit addressing.\n");

	if (abort & ABRT_SBYTE_NORSTRT) {
		dev_err(&adap->dev,
		"RESTART disabled and user is trying to send START byte.\n");
		writel(~ABRT_SBYTE_NORSTRT, i2c->base + IC_TX_ABRT_SOURCE);
		writel(RESTART, i2c->base + IC_CON);
		writel(~IC_TAR_SPECIAL, i2c->base + IC_TAR);
	}

	if (abort & ABRT_SBYTE_ACKDET)
		dev_err(&adap->dev,
			"START byte was not acknowledged.\n");
	if (abort & ABRT_TXDATA_NOACK)
		dev_dbg(&adap->dev,
			"No acknowledgement received from slave.\n");
	if (abort & ABRT_10ADDR2_NOACK)
		dev_dbg(&adap->dev,
	"The 2nd address byte of the 10-bit address was not acknowledged.\n");
	if (abort & ABRT_10ADDR1_NOACK)
		dev_dbg(&adap->dev,
	"The 1st address byte of 10-bit address was not acknowledged.\n");
	if (abort & ABRT_7B_ADDR_NOACK)
		dev_dbg(&adap->dev,
			"I2C slave device not acknowledged.\n");

	/* Clear TX_ABRT bit */
	readl(i2c->base + IC_CLR_TX_ABRT);
	i2c->status = STATUS_XFER_ABORT;
}

/**
 * xfer_read - Internal function to implement master read transfer.
 * @adap: i2c_adapter struct pointer
 * @buf: buffer in i2c_msg
 * @length: number of bytes to be read
 *
 * Return Values:
 * 0		if the read transfer succeeds
 * -ETIMEDOUT	if cannot read the "raw" interrupt register
 * -EINVAL	if a transfer abort occurred
 *
 * For every byte, a "READ" command will be loaded into IC_DATA_CMD prior to
 * data transfer. The actual "read" operation will be performed if an RX_FULL
 * interrupt occurred.
 *
 * Note there may be two interrupt signals captured, one should read
 * IC_RAW_INTR_STAT to separate between errors and actual data.
 */
static int xfer_read(struct i2c_adapter *adap, unsigned char *buf, int length)
{
	struct intel_mid_i2c_private *i2c = i2c_get_adapdata(adap);
	int i = length;
	int err;

	if (length >= 256) {
		dev_err(&adap->dev,
			"I2C FIFO cannot support larger than 256 bytes\n");
		return -EMSGSIZE;
	}

	INIT_COMPLETION(i2c->complete);

	readl(i2c->base + IC_CLR_INTR);
	writel(0x0044, i2c->base + IC_INTR_MASK);

	i2c->status = STATUS_READ_START;

	while (i--)
		writel(IC_RD, i2c->base + IC_DATA_CMD);

	i2c->status = STATUS_READ_START;
	err = wait_for_completion_interruptible_timeout(&i2c->complete, HZ);
	if (!err) {
		dev_err(&adap->dev, "Timeout for ACK from I2C slave device\n");
		intel_mid_i2c_hwinit(i2c);
		return -ETIMEDOUT;
	}
	if (i2c->status == STATUS_READ_SUCCESS)
		return 0;
	else
		return -EIO;
}

/**
 * xfer_write - Internal function to implement master write transfer.
 * @adap: i2c_adapter struct pointer
 * @buf: buffer in i2c_msg
 * @length: number of bytes to be read
 *
 * Return Values:
 * 0	if the read transfer succeeds
 * -ETIMEDOUT	if we cannot read the "raw" interrupt register
 * -EINVAL	if a transfer abort occurred
 *
 * For every byte, a "WRITE" command will be loaded into IC_DATA_CMD prior to
 * data transfer. The actual "write" operation will be performed when the
 * RX_FULL interrupt signal occurs.
 *
 * Note there may be two interrupt signals captured, one should read
 * IC_RAW_INTR_STAT to separate between errors and actual data.
 */
static int xfer_write(struct i2c_adapter *adap,
		      unsigned char *buf, int length)
{
	struct intel_mid_i2c_private *i2c = i2c_get_adapdata(adap);
	int i, err;

	if (length >= 256) {
		dev_err(&adap->dev,
			"I2C FIFO cannot support larger than 256 bytes\n");
		return -EMSGSIZE;
	}

	INIT_COMPLETION(i2c->complete);

	readl(i2c->base + IC_CLR_INTR);
	writel(0x0050, i2c->base + IC_INTR_MASK);

	i2c->status = STATUS_WRITE_START;
	for (i = 0; i < length; i++)
		writel((u16)(*(buf + i)), i2c->base + IC_DATA_CMD);

	i2c->status = STATUS_WRITE_START;
	err = wait_for_completion_interruptible_timeout(&i2c->complete, HZ);
	if (!err) {
		dev_err(&adap->dev, "Timeout for ACK from I2C slave device\n");
		intel_mid_i2c_hwinit(i2c);
		return -ETIMEDOUT;
	} else {
		if (i2c->status == STATUS_WRITE_SUCCESS)
			return 0;
		else
			return -EIO;
	}
}

static int intel_mid_i2c_setup(struct i2c_adapter *adap,  struct i2c_msg *pmsg)
{
	struct intel_mid_i2c_private *i2c = i2c_get_adapdata(adap);
	int err;
	u32 reg;
	u32 bit_mask;
	u32 mode;

	/* Disable device first */
	err = intel_mid_i2c_disable(adap);
	if (err) {
		dev_err(&adap->dev,
			"Cannot disable i2c controller, timeout\n");
		return err;
	}

	mode = (1 + i2c->speed) << 1;
	/* set the speed mode */
	reg = readl(i2c->base + IC_CON);
	if ((reg & 0x06) != mode) {
		dev_dbg(&adap->dev, "set mode %d\n", i2c->speed);
		writel((reg & ~0x6) | mode, i2c->base + IC_CON);
	}

	reg = readl(i2c->base + IC_CON);
	/* use 7-bit addressing */
	if (pmsg->flags & I2C_M_TEN) {
		if ((reg & ADDR_10BIT) != ADDR_10BIT) {
			dev_dbg(&adap->dev, "set i2c 10 bit address mode\n");
			writel(reg | ADDR_10BIT, i2c->base + IC_CON);
		}
	} else {
		if ((reg & ADDR_10BIT) != 0x0) {
			dev_dbg(&adap->dev, "set i2c 7 bit address mode\n");
			writel(reg & ~ADDR_10BIT, i2c->base + IC_CON);
		}
	}
	/* enable restart conditions */
	reg = readl(i2c->base + IC_CON);
	if ((reg & RESTART) != RESTART) {
		dev_dbg(&adap->dev, "enable restart conditions\n");
		writel(reg | RESTART, i2c->base + IC_CON);
	}

	/* enable master FSM */
	reg = readl(i2c->base + IC_CON);
	dev_dbg(&adap->dev, "ic_con reg is 0x%x\n", reg);
	writel(reg | MASTER_EN, i2c->base + IC_CON);
	if ((reg & SLV_DIS) != SLV_DIS) {
		dev_dbg(&adap->dev, "enable master FSM\n");
		writel(reg | SLV_DIS, i2c->base + IC_CON);
		dev_dbg(&adap->dev, "ic_con reg is 0x%x\n", reg);
	}

	/* use target address when initiating transfer */
	reg = readl(i2c->base + IC_TAR);
	bit_mask = IC_TAR_SPECIAL | IC_TAR_GC_OR_START;

	if ((reg & bit_mask) != 0x0) {
		dev_dbg(&adap->dev,
	 "WR: use target address when intiating transfer, i2c_tx_target\n");
		writel(reg & ~bit_mask, i2c->base + IC_TAR);
	}

	/* set target address to the I2C slave address */
	dev_dbg(&adap->dev,
		"set target address to the I2C slave address, addr is %x\n",
			pmsg->addr);
	writel(pmsg->addr | (pmsg->flags & I2C_M_TEN ? IC_TAR_10BIT_ADDR : 0),
		i2c->base + IC_TAR);

	/* Enable I2C controller */
	writel(ENABLE, i2c->base + IC_ENABLE);

	return 0;
}

/**
 * intel_mid_i2c_xfer - Main master transfer routine.
 * @adap: i2c_adapter struct pointer
 * @pmsg: i2c_msg struct pointer
 * @num: number of i2c_msg
 *
 * Return Values:
 * +		number of messages transferred
 * -ETIMEDOUT	If cannot disable I2C controller or read IC_STATUS
 * -EINVAL	If the address in i2c_msg is invalid
 *
 * This function will be registered in i2c-core and exposed to external
 * I2C clients.
 * 1. Disable I2C controller
 * 2. Unmask three interrupts: RX_FULL, TX_EMPTY, TX_ABRT
 * 3. Check if address in i2c_msg is valid
 * 4. Enable I2C controller
 * 5. Perform real transfer (call xfer_read or xfer_write)
 * 6. Wait until the current transfer is finished (check bus state)
 * 7. Mask and clear all interrupts
 */
static int intel_mid_i2c_xfer(struct i2c_adapter *adap,
			 struct i2c_msg *pmsg,
			 int num)
{
	struct intel_mid_i2c_private *i2c = i2c_get_adapdata(adap);
	int i, err = 0;

	/* if number of messages equal 0*/
	if (num == 0)
		return 0;

	pm_runtime_get(i2c->dev);

	mutex_lock(&i2c->lock);
	dev_dbg(&adap->dev, "intel_mid_i2c_xfer, process %d msg(s)\n", num);
	dev_dbg(&adap->dev, "slave address is %x\n", pmsg->addr);


	if (i2c->status != STATUS_IDLE) {
		dev_err(&adap->dev, "Adapter %d in transfer/standby\n",
								adap->nr);
		mutex_unlock(&i2c->lock);
		pm_runtime_put(i2c->dev);
		return -1;
	}


	for (i = 1; i < num; i++) {
		/* Message address equal? */
		if (unlikely(intel_mid_i2c_address_neq(&pmsg[0], &pmsg[i]))) {
			dev_err(&adap->dev, "Invalid address in msg[%d]\n", i);
			mutex_unlock(&i2c->lock);
			pm_runtime_put(i2c->dev);
			return -EINVAL;
		}
	}

	if (intel_mid_i2c_setup(adap, pmsg)) {
		mutex_unlock(&i2c->lock);
		pm_runtime_put(i2c->dev);
		return -EINVAL;
	}

	for (i = 0; i < num; i++) {
		i2c->msg = pmsg;
		i2c->status = STATUS_IDLE;
		/* Read or Write */
		if (pmsg->flags & I2C_M_RD) {
			dev_dbg(&adap->dev, "I2C_M_RD\n");
			err = xfer_read(adap, pmsg->buf, pmsg->len);
		} else {
			dev_dbg(&adap->dev, "I2C_M_WR\n");
			err = xfer_write(adap, pmsg->buf, pmsg->len);
		}
		if (err < 0)
			break;
		dev_dbg(&adap->dev, "msg[%d] transfer complete\n", i);
		pmsg++;		/* next message */
	}

	/* Mask interrupts */
	writel(0x0000, i2c->base + IC_INTR_MASK);
	/* Clear all interrupts */
	readl(i2c->base + IC_CLR_INTR);

	i2c->status = STATUS_IDLE;
	mutex_unlock(&i2c->lock);
	pm_runtime_put(i2c->dev);

	return err;
}

static int intel_mid_i2c_runtime_suspend(struct device *dev)
{
	struct pci_dev *pdev = to_pci_dev(dev);
	struct intel_mid_i2c_private *i2c = pci_get_drvdata(pdev);
	struct i2c_adapter *adap = to_i2c_adapter(dev);
	int err;

	if (i2c->status != STATUS_IDLE)
		return -1;

	intel_mid_i2c_disable(adap);

	err = pci_save_state(pdev);
	if (err) {
		dev_err(dev, "pci_save_state failed\n");
		return err;
	}

	err = pci_set_power_state(pdev, PCI_D3hot);
	if (err) {
		dev_err(dev, "pci_set_power_state failed\n");
		return err;
	}
	i2c->status = STATUS_STANDBY;

	return 0;
}

static int intel_mid_i2c_runtime_resume(struct device *dev)
{
	struct pci_dev *pdev = to_pci_dev(dev);
	struct intel_mid_i2c_private *i2c = pci_get_drvdata(pdev);
	int err;

	if (i2c->status != STATUS_STANDBY)
		return 0;

	pci_set_power_state(pdev, PCI_D0);
	pci_restore_state(pdev);
	err = pci_enable_device(pdev);
	if (err) {
		dev_err(dev, "pci_enable_device failed\n");
		return err;
	}

	i2c->status = STATUS_IDLE;

	intel_mid_i2c_hwinit(i2c);
	return err;
}

static void i2c_isr_read(struct intel_mid_i2c_private *i2c)
{
	struct i2c_msg *msg = i2c->msg;
	int rx_num;
	u32 len;
	u8 *buf;

	if (!(msg->flags & I2C_M_RD))
		return;

	if (i2c->status != STATUS_READ_IN_PROGRESS) {
		len = msg->len;
		buf = msg->buf;
	} else {
		len = i2c->rx_buf_len;
		buf = i2c->rx_buf;
	}

	rx_num = readl(i2c->base + IC_RXFLR);

	for (; len > 0 && rx_num > 0; len--, rx_num--)
		*buf++ = readl(i2c->base + IC_DATA_CMD);

	if (len > 0) {
		i2c->status = STATUS_READ_IN_PROGRESS;
		i2c->rx_buf_len = len;
		i2c->rx_buf = buf;
	} else
		i2c->status = STATUS_READ_SUCCESS;

	return;
}

static irqreturn_t intel_mid_i2c_isr(int this_irq, void *dev)
{
	struct intel_mid_i2c_private *i2c = dev;
	u32 stat = readl(i2c->base + IC_INTR_STAT);

	if (!stat)
		return IRQ_NONE;

	dev_dbg(&i2c->adap.dev, "%s, stat = 0x%x\n", __func__, stat);
	stat &= 0x54;

	if (i2c->status != STATUS_WRITE_START &&
	    i2c->status != STATUS_READ_START &&
	    i2c->status != STATUS_READ_IN_PROGRESS)
		goto err;

	if (stat & TX_ABRT)
		i2c->abort = readl(i2c->base + IC_TX_ABRT_SOURCE);

	readl(i2c->base + IC_CLR_INTR);

	if (stat & TX_ABRT) {
		intel_mid_i2c_abort(i2c);
		goto exit;
	}

	if (stat & RX_FULL) {
		i2c_isr_read(i2c);
		goto exit;
	}

	if (stat & TX_EMPTY) {
		if (readl(i2c->base + IC_STATUS) & 0x4)
			i2c->status = STATUS_WRITE_SUCCESS;
	}

exit:
	if (i2c->status == STATUS_READ_SUCCESS ||
	    i2c->status == STATUS_WRITE_SUCCESS ||
	    i2c->status == STATUS_XFER_ABORT) {
		/* Clear all interrupts */
		readl(i2c->base + IC_CLR_INTR);
		/* Mask interrupts */
		writel(0, i2c->base + IC_INTR_MASK);
		complete(&i2c->complete);
	}
err:
	return IRQ_HANDLED;
}

static struct i2c_algorithm intel_mid_i2c_algorithm = {
	.master_xfer	= intel_mid_i2c_xfer,
	.functionality	= intel_mid_i2c_func,
};


static const struct dev_pm_ops intel_mid_i2c_pm_ops = {
	.runtime_suspend = intel_mid_i2c_runtime_suspend,
	.runtime_resume = intel_mid_i2c_runtime_resume,
};

/**
 * intel_mid_i2c_probe - I2C controller initialization routine
 * @dev: pci device
 * @id: device id
 *
 * Return Values:
 * 0		success
 * -ENODEV	If cannot allocate pci resource
 * -ENOMEM	If the register base remapping failed, or
 *		if kzalloc failed
 *
 * Initialization steps:
 * 1. Request for PCI resource
 * 2. Remap the start address of PCI resource to register base
 * 3. Request for device memory region
 * 4. Fill in the struct members of intel_mid_i2c_private
 * 5. Call intel_mid_i2c_hwinit() for hardware initialization
 * 6. Register I2C adapter in i2c-core
 */
static int __devinit intel_mid_i2c_probe(struct pci_dev *dev,
				    const struct pci_device_id *id)
{
	struct intel_mid_i2c_private *mrst;
	unsigned long start, len;
	int err, busnum;
	void __iomem *base = NULL;

	dev_dbg(&dev->dev, "Get into probe function for I2C\n");
	err = pci_enable_device(dev);
	if (err) {
		dev_err(&dev->dev, "Failed to enable I2C PCI device (%d)\n",
			err);
		goto exit;
	}

	/* Determine the address of the I2C area */
	start = pci_resource_start(dev, 0);
	len = pci_resource_len(dev, 0);
	if (!start || len == 0) {
		dev_err(&dev->dev, "base address not set\n");
		err = -ENODEV;
		goto exit;
	}
	dev_dbg(&dev->dev, "%s i2c resource start 0x%lx, len=%ld\n",
		PLATFORM, start, len);

	err = pci_request_region(dev, 0, DRIVER_NAME);
	if (err) {
		dev_err(&dev->dev, "failed to request I2C region "
			"0x%lx-0x%lx\n", start,
			(unsigned long)pci_resource_end(dev, 0));
		goto exit;
	}

	base = ioremap_nocache(start, len);
	if (!base) {
		dev_err(&dev->dev, "I/O memory remapping failed\n");
		err = -ENOMEM;
		goto fail0;
	}

	/* Allocate the per-device data structure, intel_mid_i2c_private */
	mrst = kzalloc(sizeof(struct intel_mid_i2c_private), GFP_KERNEL);
	if (mrst == NULL) {
		dev_err(&dev->dev, "can't allocate interface\n");
		err = -ENOMEM;
		goto fail1;
	}

	/* Initialize struct members */
	snprintf(mrst->adap.name, sizeof(mrst->adap.name),
		"Intel MID I2C at %lx", start);
	mrst->adap.owner = THIS_MODULE;
	mrst->adap.algo = &intel_mid_i2c_algorithm;
	mrst->adap.dev.parent = &dev->dev;
	mrst->dev = &dev->dev;
	mrst->base = base;
	mrst->speed = STANDARD;
	mrst->abort = 0;
	mrst->rx_buf_len = 0;
	mrst->status = STATUS_IDLE;

	pci_set_drvdata(dev, mrst);
	i2c_set_adapdata(&mrst->adap, mrst);

	mrst->adap.nr = busnum = id->driver_data;
	if (dev->device <= 0x0804)
		mrst->platform = MOORESTOWN;
	else
		mrst->platform = MEDFIELD;

	dev_dbg(&dev->dev, "I2C%d\n", busnum);

	if (ctl_num > busnum) {
		if (speed_mode[busnum] < 0 || speed_mode[busnum] >= NUM_SPEEDS)
			dev_warn(&dev->dev, "invalid speed %d ignored.\n",
							speed_mode[busnum]);
		else
			mrst->speed = speed_mode[busnum];
	}

	/* Initialize i2c controller */
	err = intel_mid_i2c_hwinit(mrst);
	if (err < 0) {
		dev_err(&dev->dev, "I2C interface initialization failed\n");
		goto fail2;
	}

	mutex_init(&mrst->lock);
	init_completion(&mrst->complete);

	/* Clear all interrupts */
	readl(mrst->base + IC_CLR_INTR);
	writel(0x0000, mrst->base + IC_INTR_MASK);

	err = request_irq(dev->irq, intel_mid_i2c_isr, IRQF_SHARED,
					mrst->adap.name, mrst);
	if (err) {
		dev_err(&dev->dev, "Failed to request IRQ for I2C controller: "
			"%s", mrst->adap.name);
		goto fail2;
	}

	/* Adapter registration */
	err = i2c_add_numbered_adapter(&mrst->adap);
	if (err) {
		dev_err(&dev->dev, "Adapter %s registration failed\n",
			mrst->adap.name);
		goto fail3;
	}

	dev_dbg(&dev->dev, "%s I2C bus %d driver bind success.\n",
		(mrst->platform == MOORESTOWN) ? "Moorestown" : "Medfield",
		busnum);

	pm_runtime_enable(&dev->dev);
	return 0;

fail3:
	free_irq(dev->irq, mrst);
fail2:
	pci_set_drvdata(dev, NULL);
	kfree(mrst);
fail1:
	iounmap(base);
fail0:
	pci_release_region(dev, 0);
exit:
	return err;
}

static void __devexit intel_mid_i2c_remove(struct pci_dev *dev)
{
	struct intel_mid_i2c_private *mrst = pci_get_drvdata(dev);
	intel_mid_i2c_disable(&mrst->adap);
	if (i2c_del_adapter(&mrst->adap))
		dev_err(&dev->dev, "Failed to delete i2c adapter");

	free_irq(dev->irq, mrst);
	pci_set_drvdata(dev, NULL);
	iounmap(mrst->base);
	kfree(mrst);
	pci_release_region(dev, 0);
}

static struct pci_device_id intel_mid_i2c_ids[] = {
	/* Moorestown */
	{ PCI_VDEVICE(INTEL, 0x0802), 0 },
	{ PCI_VDEVICE(INTEL, 0x0803), 1 },
	{ PCI_VDEVICE(INTEL, 0x0804), 2 },
	/* Medfield */
	{ PCI_VDEVICE(INTEL, 0x0817), 3,},
	{ PCI_VDEVICE(INTEL, 0x0818), 4 },
	{ PCI_VDEVICE(INTEL, 0x0819), 5 },
	{ PCI_VDEVICE(INTEL, 0x082C), 0 },
	{ PCI_VDEVICE(INTEL, 0x082D), 1 },
	{ PCI_VDEVICE(INTEL, 0x082E), 2 },
	{ 0,}
};
MODULE_DEVICE_TABLE(pci, intel_mid_i2c_ids);

static struct pci_driver intel_mid_i2c_driver = {
	.name		= DRIVER_NAME,
	.id_table	= intel_mid_i2c_ids,
	.probe		= intel_mid_i2c_probe,
	.remove		= __devexit_p(intel_mid_i2c_remove),
};

static int __init intel_mid_i2c_init(void)
{
	return pci_register_driver(&intel_mid_i2c_driver);
}

static void __exit intel_mid_i2c_exit(void)
{
	pci_unregister_driver(&intel_mid_i2c_driver);
}

module_init(intel_mid_i2c_init);
module_exit(intel_mid_i2c_exit);

MODULE_AUTHOR("Ba Zheng <zheng.ba@intel.com>");
MODULE_DESCRIPTION("I2C driver for Moorestown Platform");
MODULE_LICENSE("GPL");
MODULE_VERSION(VERSION);
