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

 /*
  * I2C bus driver for Kontron COM modules
  *
  * Copyright (c) 2010-2013 Kontron Europe GmbH
  * Author: Michael Brunner <michael.brunner@kontron.com>
  *
  * The driver is based on the i2c-ocores driver by Peter Korsgaard.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License 2 as published
  * by the Free Software Foundation.
  *
  * 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.
  */

 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/i2c.h>
 #include <linux/delay.h>
 #include <linux/mfd/kempld.h>

 #define KEMPLD_I2C_PRELOW	0x0b
 #define KEMPLD_I2C_PREHIGH	0x0c
 #define KEMPLD_I2C_DATA		0x0e

 #define KEMPLD_I2C_CTRL		0x0d
 #define I2C_CTRL_IEN		0x40
 #define I2C_CTRL_EN		0x80

 #define KEMPLD_I2C_STAT		0x0f
 #define I2C_STAT_IF		0x01
 #define I2C_STAT_TIP		0x02
 #define I2C_STAT_ARBLOST	0x20
 #define I2C_STAT_BUSY		0x40
 #define I2C_STAT_NACK		0x80

 #define KEMPLD_I2C_CMD		0x0f
 #define I2C_CMD_START		0x91
 #define I2C_CMD_STOP		0x41
 #define I2C_CMD_READ		0x21
 #define I2C_CMD_WRITE		0x11
 #define I2C_CMD_READ_ACK	0x21
 #define I2C_CMD_READ_NACK	0x29
 #define I2C_CMD_IACK		0x01

 #define KEMPLD_I2C_FREQ_MAX	2700	/* 2.7 mHz */
 #define KEMPLD_I2C_FREQ_STD	100	/* 100 kHz */

 enum {
 	STATE_DONE = 0,
 	STATE_INIT,
 	STATE_ADDR,
 	STATE_ADDR10,
 	STATE_START,
 	STATE_WRITE,
 	STATE_READ,
 	STATE_ERROR,
 };

 struct kempld_i2c_data {
 	struct device			*dev;
 	struct kempld_device_data	*pld;
 	struct i2c_adapter		adap;
 	struct i2c_msg			*msg;
 	int				pos;
 	int				nmsgs;
 	int				state;
 	bool				was_active;
 };

 static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;
 module_param(bus_frequency, uint, 0);
 MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="
 				__MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");

 static int i2c_bus = -1;
 module_param(i2c_bus, int, 0);
 MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");

 static bool i2c_gpio_mux;
 module_param(i2c_gpio_mux, bool, 0);
 MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");

 /*
  * kempld_get_mutex must be called prior to calling this function.
  */
 static int kempld_i2c_process(struct kempld_i2c_data *i2c)
 {
 	struct kempld_device_data *pld = i2c->pld;
 	u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);
 	struct i2c_msg *msg = i2c->msg;
 	u8 addr;

 	/* Ready? */
 	if (stat & I2C_STAT_TIP)
 		return -EBUSY;

 	if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {
 		/* Stop has been sent */
 		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
 		if (i2c->state == STATE_ERROR)
 			return -EIO;
 		return 0;
 	}

 	/* Error? */
 	if (stat & I2C_STAT_ARBLOST) {
 		i2c->state = STATE_ERROR;
 		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 		return -EAGAIN;
 	}

 	if (i2c->state == STATE_INIT) {
 		if (stat & I2C_STAT_BUSY)
 			return -EBUSY;

 		i2c->state = STATE_ADDR;
 	}

 	if (i2c->state == STATE_ADDR) {
 		/* 10 bit address? */
 		if (i2c->msg->flags & I2C_M_TEN) {
 			addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6);
 			i2c->state = STATE_ADDR10;
 		} else {
 			addr = (i2c->msg->addr << 1);
 			i2c->state = STATE_START;
 		}

 		/* Set read bit if necessary */
 		addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;

 		kempld_write8(pld, KEMPLD_I2C_DATA, addr);
 		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);

 		return 0;
 	}

 	/* Second part of 10 bit addressing */
 	if (i2c->state == STATE_ADDR10) {
 		kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);
 		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);

 		i2c->state = STATE_START;
 		return 0;
 	}

 	if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {
 		i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;

 		if (stat & I2C_STAT_NACK) {
 			i2c->state = STATE_ERROR;
 			kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 			return -ENXIO;
 		}
 	} else {
 		msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);
 	}

 	if (i2c->pos >= msg->len) {
 		i2c->nmsgs--;
 		i2c->msg++;
 		i2c->pos = 0;
 		msg = i2c->msg;

 		if (i2c->nmsgs) {
 			if (!(msg->flags & I2C_M_NOSTART)) {
 				i2c->state = STATE_ADDR;
 				return 0;
 			} else {
 				i2c->state = (msg->flags & I2C_M_RD)
 					? STATE_READ : STATE_WRITE;
 			}
 		} else {
 			i2c->state = STATE_DONE;
 			kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 			return 0;
 		}
 	}

 	if (i2c->state == STATE_READ) {
 		kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?
 			      I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);
 	} else {
 		kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);
 		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
 	}

 	return 0;
 }

 static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 				int num)
 {
 	struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);
 	struct kempld_device_data *pld = i2c->pld;
 	unsigned long timeout = jiffies + HZ;
 	int ret;

 	i2c->msg = msgs;
 	i2c->pos = 0;
 	i2c->nmsgs = num;
 	i2c->state = STATE_INIT;

 	/* Handle the transfer */
 	while (time_before(jiffies, timeout)) {
 		kempld_get_mutex(pld);
 		ret = kempld_i2c_process(i2c);
 		kempld_release_mutex(pld);

 		if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
 			return (i2c->state == STATE_DONE) ? num : ret;

 		if (ret == 0)
 			timeout = jiffies + HZ;

 		usleep_range(5, 15);
 	}

 	i2c->state = STATE_ERROR;

 	return -ETIMEDOUT;
 }

 /*
  * kempld_get_mutex must be called prior to calling this function.
  */
 static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)
 {
 	struct kempld_device_data *pld = i2c->pld;
 	u16 prescale_corr;
 	long prescale;
 	u8 ctrl;
 	u8 stat;
 	u8 cfg;

 	/* Make sure the device is disabled */
 	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 	ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);
 	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);

 	if (bus_frequency > KEMPLD_I2C_FREQ_MAX)
 		bus_frequency = KEMPLD_I2C_FREQ_MAX;

 	if (pld->info.spec_major == 1)
 		prescale = pld->pld_clock / (bus_frequency * 5) - 1000;
 	else
 		prescale = pld->pld_clock / (bus_frequency * 4) - 3000;

 	if (prescale < 0)
 		prescale = 0;

 	/* Round to the best matching value */
 	prescale_corr = prescale / 1000;
 	if (prescale % 1000 >= 500)
 		prescale_corr++;

 	kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);
 	kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);

 	/* Activate I2C bus output on GPIO pins */
 	cfg = kempld_read8(pld, KEMPLD_CFG);
 	if (i2c_gpio_mux)
 		cfg |= KEMPLD_CFG_GPIO_I2C_MUX;
 	else
 		cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;
 	kempld_write8(pld, KEMPLD_CFG, cfg);

 	/* Enable the device */
 	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
 	ctrl |= I2C_CTRL_EN;
 	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);

 	stat = kempld_read8(pld, KEMPLD_I2C_STAT);
 	if (stat & I2C_STAT_BUSY)
 		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
 }

 static u32 kempld_i2c_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
 }

 static const struct i2c_algorithm kempld_i2c_algorithm = {
 	.master_xfer	= kempld_i2c_xfer,
 	.functionality	= kempld_i2c_func,
 };

 static struct i2c_adapter kempld_i2c_adapter = {
 	.owner		= THIS_MODULE,
 	.name		= "i2c-kempld",
 	.class		= I2C_CLASS_HWMON | I2C_CLASS_SPD,
 	.algo		= &kempld_i2c_algorithm,
 };

 static int kempld_i2c_probe(struct platform_device *pdev)
 {
 	struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
 	struct kempld_i2c_data *i2c;
 	int ret;
 	u8 ctrl;

 	i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
 	if (!i2c)
 		return -ENOMEM;

 	i2c->pld = pld;
 	i2c->dev = &pdev->dev;
 	i2c->adap = kempld_i2c_adapter;
 	i2c->adap.dev.parent = i2c->dev;
 	i2c_set_adapdata(&i2c->adap, i2c);
 	platform_set_drvdata(pdev, i2c);

 	kempld_get_mutex(pld);
 	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);

 	if (ctrl & I2C_CTRL_EN)
 		i2c->was_active = true;

 	kempld_i2c_device_init(i2c);
 	kempld_release_mutex(pld);

 	/* Add I2C adapter to I2C tree */
 	if (i2c_bus >= -1)
 		i2c->adap.nr = i2c_bus;
 	ret = i2c_add_numbered_adapter(&i2c->adap);
 	if (ret)
 		return ret;

 	dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",
 		 bus_frequency);

 	return 0;
 }

 static int kempld_i2c_remove(struct platform_device *pdev)
 {
 	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
 	struct kempld_device_data *pld = i2c->pld;
 	u8 ctrl;

 	kempld_get_mutex(pld);
 	/*
 	 * Disable I2C logic if it was not activated before the
 	 * driver loaded
 	 */
 	if (!i2c->was_active) {
 		ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 		ctrl &= ~I2C_CTRL_EN;
 		kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
 	}
 	kempld_release_mutex(pld);

 	i2c_del_adapter(&i2c->adap);

 	return 0;
 }

 #ifdef CONFIG_PM
 static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)
 {
 	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
 	struct kempld_device_data *pld = i2c->pld;
 	u8 ctrl;

 	kempld_get_mutex(pld);
 	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
 	ctrl &= ~I2C_CTRL_EN;
 	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
 	kempld_release_mutex(pld);

 	return 0;
 }

 static int kempld_i2c_resume(struct platform_device *pdev)
 {
 	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
 	struct kempld_device_data *pld = i2c->pld;

 	kempld_get_mutex(pld);
 	kempld_i2c_device_init(i2c);
 	kempld_release_mutex(pld);

 	return 0;
 }
 #else
 #define kempld_i2c_suspend	NULL
 #define kempld_i2c_resume	NULL
 #endif

 static struct platform_driver kempld_i2c_driver = {
 	.driver = {
 		.name = "kempld-i2c",
 	},
 	.probe		= kempld_i2c_probe,
 	.remove		= kempld_i2c_remove,
 	.suspend	= kempld_i2c_suspend,
 	.resume		= kempld_i2c_resume,
 };

 module_platform_driver(kempld_i2c_driver);

 MODULE_DESCRIPTION("KEM PLD I2C Driver");
 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:kempld_i2c");
	/*
	* I2C bus driver for Kontron COM modules
	*
	* Copyright (c) 2010-2013 Kontron Europe GmbH
	* Author: Michael Brunner <michael.brunner@kontron.com>
	*
	* The driver is based on the i2c-ocores driver by Peter Korsgaard.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License 2 as published
	* by the Free Software Foundation.
	*
	* 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.
	*/

	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/i2c.h>
	#include <linux/delay.h>
	#include <linux/mfd/kempld.h>

	#define KEMPLD_I2C_PRELOW 0x0b
	#define KEMPLD_I2C_PREHIGH 0x0c
	#define KEMPLD_I2C_DATA 0x0e

	#define KEMPLD_I2C_CTRL 0x0d
	#define I2C_CTRL_IEN 0x40
	#define I2C_CTRL_EN 0x80

	#define KEMPLD_I2C_STAT 0x0f
	#define I2C_STAT_IF 0x01
	#define I2C_STAT_TIP 0x02
	#define I2C_STAT_ARBLOST 0x20
	#define I2C_STAT_BUSY 0x40
	#define I2C_STAT_NACK 0x80

	#define KEMPLD_I2C_CMD 0x0f
	#define I2C_CMD_START 0x91
	#define I2C_CMD_STOP 0x41
	#define I2C_CMD_READ 0x21
	#define I2C_CMD_WRITE 0x11
	#define I2C_CMD_READ_ACK 0x21
	#define I2C_CMD_READ_NACK 0x29
	#define I2C_CMD_IACK 0x01

	#define KEMPLD_I2C_FREQ_MAX 2700 /* 2.7 mHz */
	#define KEMPLD_I2C_FREQ_STD 100 /* 100 kHz */

	enum {
	STATE_DONE = 0,
	STATE_INIT,
	STATE_ADDR,
	STATE_ADDR10,
	STATE_START,
	STATE_WRITE,
	STATE_READ,
	STATE_ERROR,
	};

	struct kempld_i2c_data {
	struct device *dev;
	struct kempld_device_data *pld;
	struct i2c_adapter adap;
	struct i2c_msg *msg;
	int pos;
	int nmsgs;
	int state;
	bool was_active;
	};

	static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;
	module_param(bus_frequency, uint, 0);
	MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="
	__MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");

	static int i2c_bus = -1;
	module_param(i2c_bus, int, 0);
	MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");

	static bool i2c_gpio_mux;
	module_param(i2c_gpio_mux, bool, 0);
	MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");

	/*
	* kempld_get_mutex must be called prior to calling this function.
	*/
	static int kempld_i2c_process(struct kempld_i2c_data *i2c)
	{
	struct kempld_device_data *pld = i2c->pld;
	u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);
	struct i2c_msg *msg = i2c->msg;
	u8 addr;

	/* Ready? */
	if (stat & I2C_STAT_TIP)
	return -EBUSY;

	if (i2c->state == STATE_DONE \|\| i2c->state == STATE_ERROR) {
	/* Stop has been sent */
	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
	if (i2c->state == STATE_ERROR)
	return -EIO;
	return 0;
	}

	/* Error? */
	if (stat & I2C_STAT_ARBLOST) {
	i2c->state = STATE_ERROR;
	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
	return -EAGAIN;
	}

	if (i2c->state == STATE_INIT) {
	if (stat & I2C_STAT_BUSY)
	return -EBUSY;

	i2c->state = STATE_ADDR;
	}

	if (i2c->state == STATE_ADDR) {
	/* 10 bit address? */
	if (i2c->msg->flags & I2C_M_TEN) {
	addr = 0xf0 \| ((i2c->msg->addr >> 7) & 0x6);
	i2c->state = STATE_ADDR10;
	} else {
	addr = (i2c->msg->addr << 1);
	i2c->state = STATE_START;
	}

	/* Set read bit if necessary */
	addr \|= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;

	kempld_write8(pld, KEMPLD_I2C_DATA, addr);
	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);

	return 0;
	}

	/* Second part of 10 bit addressing */
	if (i2c->state == STATE_ADDR10) {
	kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);
	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);

	i2c->state = STATE_START;
	return 0;
	}

	if (i2c->state == STATE_START \|\| i2c->state == STATE_WRITE) {
	i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;

	if (stat & I2C_STAT_NACK) {
	i2c->state = STATE_ERROR;
	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
	return -ENXIO;
	}
	} else {
	msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);
	}

	if (i2c->pos >= msg->len) {
	i2c->nmsgs--;
	i2c->msg++;
	i2c->pos = 0;
	msg = i2c->msg;

	if (i2c->nmsgs) {
	if (!(msg->flags & I2C_M_NOSTART)) {
	i2c->state = STATE_ADDR;
	return 0;
	} else {
	i2c->state = (msg->flags & I2C_M_RD)
	? STATE_READ : STATE_WRITE;
	}
	} else {
	i2c->state = STATE_DONE;
	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
	return 0;
	}
	}

	if (i2c->state == STATE_READ) {
	kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?
	I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);
	} else {
	kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);
	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
	}

	return 0;
	}

	static int kempld_i2c_xfer(struct i2c_adapter adap, struct i2c_msg msgs,
	int num)
	{
	struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);
	struct kempld_device_data *pld = i2c->pld;
	unsigned long timeout = jiffies + HZ;
	int ret;

	i2c->msg = msgs;
	i2c->pos = 0;
	i2c->nmsgs = num;
	i2c->state = STATE_INIT;

	/* Handle the transfer */
	while (time_before(jiffies, timeout)) {
	kempld_get_mutex(pld);
	ret = kempld_i2c_process(i2c);
	kempld_release_mutex(pld);

	if (i2c->state == STATE_DONE \|\| i2c->state == STATE_ERROR)
	return (i2c->state == STATE_DONE) ? num : ret;

	if (ret == 0)
	timeout = jiffies + HZ;

	usleep_range(5, 15);
	}

	i2c->state = STATE_ERROR;

	return -ETIMEDOUT;
	}

	/*
	* kempld_get_mutex must be called prior to calling this function.
	*/
	static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)
	{
	struct kempld_device_data *pld = i2c->pld;
	u16 prescale_corr;
	long prescale;
	u8 ctrl;
	u8 stat;
	u8 cfg;

	/* Make sure the device is disabled */
	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
	ctrl &= ~(I2C_CTRL_EN \| I2C_CTRL_IEN);
	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);

	if (bus_frequency > KEMPLD_I2C_FREQ_MAX)
	bus_frequency = KEMPLD_I2C_FREQ_MAX;

	if (pld->info.spec_major == 1)
	prescale = pld->pld_clock / (bus_frequency * 5) - 1000;
	else
	prescale = pld->pld_clock / (bus_frequency * 4) - 3000;

	if (prescale < 0)
	prescale = 0;

	/* Round to the best matching value */
	prescale_corr = prescale / 1000;
	if (prescale % 1000 >= 500)
	prescale_corr++;

	kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);
	kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);

	/* Activate I2C bus output on GPIO pins */
	cfg = kempld_read8(pld, KEMPLD_CFG);
	if (i2c_gpio_mux)
	cfg \|= KEMPLD_CFG_GPIO_I2C_MUX;
	else
	cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;
	kempld_write8(pld, KEMPLD_CFG, cfg);

	/* Enable the device */
	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
	ctrl \|= I2C_CTRL_EN;
	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);

	stat = kempld_read8(pld, KEMPLD_I2C_STAT);
	if (stat & I2C_STAT_BUSY)
	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
	}

	static u32 kempld_i2c_func(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_10BIT_ADDR \| I2C_FUNC_SMBUS_EMUL;
	}

	static const struct i2c_algorithm kempld_i2c_algorithm = {
	.master_xfer = kempld_i2c_xfer,
	.functionality = kempld_i2c_func,
	};

	static struct i2c_adapter kempld_i2c_adapter = {
	.owner = THIS_MODULE,
	.name = "i2c-kempld",
	.class = I2C_CLASS_HWMON \| I2C_CLASS_SPD,
	.algo = &kempld_i2c_algorithm,
	};

	static int kempld_i2c_probe(struct platform_device *pdev)
	{
	struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
	struct kempld_i2c_data *i2c;
	int ret;
	u8 ctrl;

	i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
	if (!i2c)
	return -ENOMEM;

	i2c->pld = pld;
	i2c->dev = &pdev->dev;
	i2c->adap = kempld_i2c_adapter;
	i2c->adap.dev.parent = i2c->dev;
	i2c_set_adapdata(&i2c->adap, i2c);
	platform_set_drvdata(pdev, i2c);

	kempld_get_mutex(pld);
	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);

	if (ctrl & I2C_CTRL_EN)
	i2c->was_active = true;

	kempld_i2c_device_init(i2c);
	kempld_release_mutex(pld);

	/* Add I2C adapter to I2C tree */
	if (i2c_bus >= -1)
	i2c->adap.nr = i2c_bus;
	ret = i2c_add_numbered_adapter(&i2c->adap);
	if (ret)
	return ret;

	dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",
	bus_frequency);

	return 0;
	}

	static int kempld_i2c_remove(struct platform_device *pdev)
	{
	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
	struct kempld_device_data *pld = i2c->pld;
	u8 ctrl;

	kempld_get_mutex(pld);
	/*
	* Disable I2C logic if it was not activated before the
	* driver loaded
	*/
	if (!i2c->was_active) {
	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
	ctrl &= ~I2C_CTRL_EN;
	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
	}
	kempld_release_mutex(pld);

	i2c_del_adapter(&i2c->adap);

	return 0;
	}

	#ifdef CONFIG_PM
	static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)
	{
	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
	struct kempld_device_data *pld = i2c->pld;
	u8 ctrl;

	kempld_get_mutex(pld);
	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
	ctrl &= ~I2C_CTRL_EN;
	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
	kempld_release_mutex(pld);

	return 0;
	}

	static int kempld_i2c_resume(struct platform_device *pdev)
	{
	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
	struct kempld_device_data *pld = i2c->pld;

	kempld_get_mutex(pld);
	kempld_i2c_device_init(i2c);
	kempld_release_mutex(pld);

	return 0;
	}
	#else
	#define kempld_i2c_suspend NULL
	#define kempld_i2c_resume NULL
	#endif

	static struct platform_driver kempld_i2c_driver = {
	.driver = {
	.name = "kempld-i2c",
	},
	.probe = kempld_i2c_probe,
	.remove = kempld_i2c_remove,
	.suspend = kempld_i2c_suspend,
	.resume = kempld_i2c_resume,
	};

	module_platform_driver(kempld_i2c_driver);

	MODULE_DESCRIPTION("KEM PLD I2C Driver");
	MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:kempld_i2c");