drivers/i2c/busses/i2c-cbus-gpio.c - kernel/bruno - Git at Google

 /*
  * CBUS I2C driver for Nokia Internet Tablets.
  *
  * Copyright (C) 2004-2010 Nokia Corporation
  *
  * Based on code written by Juha Yrjölä, David Weinehall, Mikko Ylinen and
  * Felipe Balbi. Converted to I2C driver by Aaro Koskinen.
  *
  * This file is subject to the terms and conditions of the GNU General
  * Public License. See the file "COPYING" in the main directory of this
  * archive for more details.
  *
  * 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/io.h>
 #include <linux/i2c.h>
 #include <linux/gpio.h>
 #include <linux/slab.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of_gpio.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/platform_data/i2c-cbus-gpio.h>

 /*
  * Bit counts are derived from Nokia implementation. These should be checked
  * if other CBUS implementations appear.
  */
 #define CBUS_ADDR_BITS	3
 #define CBUS_REG_BITS	5

 struct cbus_host {
 	spinlock_t	lock;		/* host lock */
 	struct device	*dev;
 	int		clk_gpio;
 	int		dat_gpio;
 	int		sel_gpio;
 };

 /**
  * cbus_send_bit - sends one bit over the bus
  * @host: the host we're using
  * @bit: one bit of information to send
  */
 static void cbus_send_bit(struct cbus_host *host, unsigned bit)
 {
 	gpio_set_value(host->dat_gpio, bit ? 1 : 0);
 	gpio_set_value(host->clk_gpio, 1);
 	gpio_set_value(host->clk_gpio, 0);
 }

 /**
  * cbus_send_data - sends @len amount of data over the bus
  * @host: the host we're using
  * @data: the data to send
  * @len: size of the transfer
  */
 static void cbus_send_data(struct cbus_host *host, unsigned data, unsigned len)
 {
 	int i;

 	for (i = len; i > 0; i--)
 		cbus_send_bit(host, data & (1 << (i - 1)));
 }

 /**
  * cbus_receive_bit - receives one bit from the bus
  * @host: the host we're using
  */
 static int cbus_receive_bit(struct cbus_host *host)
 {
 	int ret;

 	gpio_set_value(host->clk_gpio, 1);
 	ret = gpio_get_value(host->dat_gpio);
 	gpio_set_value(host->clk_gpio, 0);
 	return ret;
 }

 /**
  * cbus_receive_word - receives 16-bit word from the bus
  * @host: the host we're using
  */
 static int cbus_receive_word(struct cbus_host *host)
 {
 	int ret = 0;
 	int i;

 	for (i = 16; i > 0; i--) {
 		int bit = cbus_receive_bit(host);

 		if (bit < 0)
 			return bit;

 		if (bit)
 			ret |= 1 << (i - 1);
 	}
 	return ret;
 }

 /**
  * cbus_transfer - transfers data over the bus
  * @host: the host we're using
  * @rw: read/write flag
  * @dev: device address
  * @reg: register address
  * @data: if @rw == I2C_SBUS_WRITE data to send otherwise 0
  */
 static int cbus_transfer(struct cbus_host *host, char rw, unsigned dev,
 			 unsigned reg, unsigned data)
 {
 	unsigned long flags;
 	int ret;

 	/* We don't want interrupts disturbing our transfer */
 	spin_lock_irqsave(&host->lock, flags);

 	/* Reset state and start of transfer, SEL stays down during transfer */
 	gpio_set_value(host->sel_gpio, 0);

 	/* Set the DAT pin to output */
 	gpio_direction_output(host->dat_gpio, 1);

 	/* Send the device address */
 	cbus_send_data(host, dev, CBUS_ADDR_BITS);

 	/* Send the rw flag */
 	cbus_send_bit(host, rw == I2C_SMBUS_READ);

 	/* Send the register address */
 	cbus_send_data(host, reg, CBUS_REG_BITS);

 	if (rw == I2C_SMBUS_WRITE) {
 		cbus_send_data(host, data, 16);
 		ret = 0;
 	} else {
 		ret = gpio_direction_input(host->dat_gpio);
 		if (ret) {
 			dev_dbg(host->dev, "failed setting direction\n");
 			goto out;
 		}
 		gpio_set_value(host->clk_gpio, 1);

 		ret = cbus_receive_word(host);
 		if (ret < 0) {
 			dev_dbg(host->dev, "failed receiving data\n");
 			goto out;
 		}
 	}

 	/* Indicate end of transfer, SEL goes up until next transfer */
 	gpio_set_value(host->sel_gpio, 1);
 	gpio_set_value(host->clk_gpio, 1);
 	gpio_set_value(host->clk_gpio, 0);

 out:
 	spin_unlock_irqrestore(&host->lock, flags);

 	return ret;
 }

 static int cbus_i2c_smbus_xfer(struct i2c_adapter	*adapter,
 			       u16			addr,
 			       unsigned short		flags,
 			       char			read_write,
 			       u8			command,
 			       int			size,
 			       union i2c_smbus_data	*data)
 {
 	struct cbus_host *chost = i2c_get_adapdata(adapter);
 	int ret;

 	if (size != I2C_SMBUS_WORD_DATA)
 		return -EINVAL;

 	ret = cbus_transfer(chost, read_write == I2C_SMBUS_READ, addr,
 			    command, data->word);
 	if (ret < 0)
 		return ret;

 	if (read_write == I2C_SMBUS_READ)
 		data->word = ret;

 	return 0;
 }

 static u32 cbus_i2c_func(struct i2c_adapter *adapter)
 {
 	return I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA;
 }

 static const struct i2c_algorithm cbus_i2c_algo = {
 	.smbus_xfer	= cbus_i2c_smbus_xfer,
 	.functionality	= cbus_i2c_func,
 };

 static int cbus_i2c_remove(struct platform_device *pdev)
 {
 	struct i2c_adapter *adapter = platform_get_drvdata(pdev);

 	i2c_del_adapter(adapter);

 	return 0;
 }

 static int cbus_i2c_probe(struct platform_device *pdev)
 {
 	struct i2c_adapter *adapter;
 	struct cbus_host *chost;
 	int ret;

 	adapter = devm_kzalloc(&pdev->dev, sizeof(struct i2c_adapter),
 			       GFP_KERNEL);
 	if (!adapter)
 		return -ENOMEM;

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

 	if (pdev->dev.of_node) {
 		struct device_node *dnode = pdev->dev.of_node;
 		if (of_gpio_count(dnode) != 3)
 			return -ENODEV;
 		chost->clk_gpio = of_get_gpio(dnode, 0);
 		chost->dat_gpio = of_get_gpio(dnode, 1);
 		chost->sel_gpio = of_get_gpio(dnode, 2);
 	} else if (dev_get_platdata(&pdev->dev)) {
 		struct i2c_cbus_platform_data *pdata =
 			dev_get_platdata(&pdev->dev);
 		chost->clk_gpio = pdata->clk_gpio;
 		chost->dat_gpio = pdata->dat_gpio;
 		chost->sel_gpio = pdata->sel_gpio;
 	} else {
 		return -ENODEV;
 	}

 	adapter->owner		= THIS_MODULE;
 	adapter->class		= I2C_CLASS_HWMON;
 	adapter->dev.parent	= &pdev->dev;
 	adapter->dev.of_node	= pdev->dev.of_node;
 	adapter->nr		= pdev->id;
 	adapter->timeout	= HZ;
 	adapter->algo		= &cbus_i2c_algo;
 	strlcpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name));

 	spin_lock_init(&chost->lock);
 	chost->dev = &pdev->dev;

 	ret = devm_gpio_request_one(&pdev->dev, chost->clk_gpio,
 				    GPIOF_OUT_INIT_LOW, "CBUS clk");
 	if (ret)
 		return ret;

 	ret = devm_gpio_request_one(&pdev->dev, chost->dat_gpio, GPIOF_IN,
 				    "CBUS data");
 	if (ret)
 		return ret;

 	ret = devm_gpio_request_one(&pdev->dev, chost->sel_gpio,
 				    GPIOF_OUT_INIT_HIGH, "CBUS sel");
 	if (ret)
 		return ret;

 	i2c_set_adapdata(adapter, chost);
 	platform_set_drvdata(pdev, adapter);

 	return i2c_add_numbered_adapter(adapter);
 }

 #if defined(CONFIG_OF)
 static const struct of_device_id i2c_cbus_dt_ids[] = {
 	{ .compatible = "i2c-cbus-gpio", },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, i2c_cbus_dt_ids);
 #endif

 static struct platform_driver cbus_i2c_driver = {
 	.probe	= cbus_i2c_probe,
 	.remove	= cbus_i2c_remove,
 	.driver	= {
 		.name	= "i2c-cbus-gpio",
 		.of_match_table = of_match_ptr(i2c_cbus_dt_ids),
 	},
 };
 module_platform_driver(cbus_i2c_driver);

 MODULE_ALIAS("platform:i2c-cbus-gpio");
 MODULE_DESCRIPTION("CBUS I2C driver");
 MODULE_AUTHOR("Juha Yrjölä");
 MODULE_AUTHOR("David Weinehall");
 MODULE_AUTHOR("Mikko Ylinen");
 MODULE_AUTHOR("Felipe Balbi");
 MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
 MODULE_LICENSE("GPL");
	/*
	* CBUS I2C driver for Nokia Internet Tablets.
	*
	* Copyright (C) 2004-2010 Nokia Corporation
	*
	* Based on code written by Juha Yrjölä, David Weinehall, Mikko Ylinen and
	* Felipe Balbi. Converted to I2C driver by Aaro Koskinen.
	*
	* This file is subject to the terms and conditions of the GNU General
	* Public License. See the file "COPYING" in the main directory of this
	* archive for more details.
	*
	* 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/io.h>
	#include <linux/i2c.h>
	#include <linux/gpio.h>
	#include <linux/slab.h>
	#include <linux/delay.h>
	#include <linux/errno.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/of_gpio.h>
	#include <linux/interrupt.h>
	#include <linux/platform_device.h>
	#include <linux/platform_data/i2c-cbus-gpio.h>

	/*
	* Bit counts are derived from Nokia implementation. These should be checked
	* if other CBUS implementations appear.
	*/
	#define CBUS_ADDR_BITS 3
	#define CBUS_REG_BITS 5

	struct cbus_host {
	spinlock_t lock; /* host lock */
	struct device *dev;
	int clk_gpio;
	int dat_gpio;
	int sel_gpio;
	};

	/**
	* cbus_send_bit - sends one bit over the bus
	* @host: the host we're using
	* @bit: one bit of information to send
	*/
	static void cbus_send_bit(struct cbus_host *host, unsigned bit)
	{
	gpio_set_value(host->dat_gpio, bit ? 1 : 0);
	gpio_set_value(host->clk_gpio, 1);
	gpio_set_value(host->clk_gpio, 0);
	}

	/**
	* cbus_send_data - sends @len amount of data over the bus
	* @host: the host we're using
	* @data: the data to send
	* @len: size of the transfer
	*/
	static void cbus_send_data(struct cbus_host *host, unsigned data, unsigned len)
	{
	int i;

	for (i = len; i > 0; i--)
	cbus_send_bit(host, data & (1 << (i - 1)));
	}

	/**
	* cbus_receive_bit - receives one bit from the bus
	* @host: the host we're using
	*/
	static int cbus_receive_bit(struct cbus_host *host)
	{
	int ret;

	gpio_set_value(host->clk_gpio, 1);
	ret = gpio_get_value(host->dat_gpio);
	gpio_set_value(host->clk_gpio, 0);
	return ret;
	}

	/**
	* cbus_receive_word - receives 16-bit word from the bus
	* @host: the host we're using
	*/
	static int cbus_receive_word(struct cbus_host *host)
	{
	int ret = 0;
	int i;

	for (i = 16; i > 0; i--) {
	int bit = cbus_receive_bit(host);

	if (bit < 0)
	return bit;

	if (bit)
	ret \|= 1 << (i - 1);
	}
	return ret;
	}

	/**
	* cbus_transfer - transfers data over the bus
	* @host: the host we're using
	* @rw: read/write flag
	* @dev: device address
	* @reg: register address
	* @data: if @rw == I2C_SBUS_WRITE data to send otherwise 0
	*/
	static int cbus_transfer(struct cbus_host *host, char rw, unsigned dev,
	unsigned reg, unsigned data)
	{
	unsigned long flags;
	int ret;

	/* We don't want interrupts disturbing our transfer */
	spin_lock_irqsave(&host->lock, flags);

	/* Reset state and start of transfer, SEL stays down during transfer */
	gpio_set_value(host->sel_gpio, 0);

	/* Set the DAT pin to output */
	gpio_direction_output(host->dat_gpio, 1);

	/* Send the device address */
	cbus_send_data(host, dev, CBUS_ADDR_BITS);

	/* Send the rw flag */
	cbus_send_bit(host, rw == I2C_SMBUS_READ);

	/* Send the register address */
	cbus_send_data(host, reg, CBUS_REG_BITS);

	if (rw == I2C_SMBUS_WRITE) {
	cbus_send_data(host, data, 16);
	ret = 0;
	} else {
	ret = gpio_direction_input(host->dat_gpio);
	if (ret) {
	dev_dbg(host->dev, "failed setting direction\n");
	goto out;
	}
	gpio_set_value(host->clk_gpio, 1);

	ret = cbus_receive_word(host);
	if (ret < 0) {
	dev_dbg(host->dev, "failed receiving data\n");
	goto out;
	}
	}

	/* Indicate end of transfer, SEL goes up until next transfer */
	gpio_set_value(host->sel_gpio, 1);
	gpio_set_value(host->clk_gpio, 1);
	gpio_set_value(host->clk_gpio, 0);

	out:
	spin_unlock_irqrestore(&host->lock, flags);

	return ret;
	}

	static int cbus_i2c_smbus_xfer(struct i2c_adapter *adapter,
	u16 addr,
	unsigned short flags,
	char read_write,
	u8 command,
	int size,
	union i2c_smbus_data *data)
	{
	struct cbus_host *chost = i2c_get_adapdata(adapter);
	int ret;

	if (size != I2C_SMBUS_WORD_DATA)
	return -EINVAL;

	ret = cbus_transfer(chost, read_write == I2C_SMBUS_READ, addr,
	command, data->word);
	if (ret < 0)
	return ret;

	if (read_write == I2C_SMBUS_READ)
	data->word = ret;

	return 0;
	}

	static u32 cbus_i2c_func(struct i2c_adapter *adapter)
	{
	return I2C_FUNC_SMBUS_READ_WORD_DATA \| I2C_FUNC_SMBUS_WRITE_WORD_DATA;
	}

	static const struct i2c_algorithm cbus_i2c_algo = {
	.smbus_xfer = cbus_i2c_smbus_xfer,
	.functionality = cbus_i2c_func,
	};

	static int cbus_i2c_remove(struct platform_device *pdev)
	{
	struct i2c_adapter *adapter = platform_get_drvdata(pdev);

	i2c_del_adapter(adapter);

	return 0;
	}

	static int cbus_i2c_probe(struct platform_device *pdev)
	{
	struct i2c_adapter *adapter;
	struct cbus_host *chost;
	int ret;

	adapter = devm_kzalloc(&pdev->dev, sizeof(struct i2c_adapter),
	GFP_KERNEL);
	if (!adapter)
	return -ENOMEM;

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

	if (pdev->dev.of_node) {
	struct device_node *dnode = pdev->dev.of_node;
	if (of_gpio_count(dnode) != 3)
	return -ENODEV;
	chost->clk_gpio = of_get_gpio(dnode, 0);
	chost->dat_gpio = of_get_gpio(dnode, 1);
	chost->sel_gpio = of_get_gpio(dnode, 2);
	} else if (dev_get_platdata(&pdev->dev)) {
	struct i2c_cbus_platform_data *pdata =
	dev_get_platdata(&pdev->dev);
	chost->clk_gpio = pdata->clk_gpio;
	chost->dat_gpio = pdata->dat_gpio;
	chost->sel_gpio = pdata->sel_gpio;
	} else {
	return -ENODEV;
	}

	adapter->owner = THIS_MODULE;
	adapter->class = I2C_CLASS_HWMON;
	adapter->dev.parent = &pdev->dev;
	adapter->dev.of_node = pdev->dev.of_node;
	adapter->nr = pdev->id;
	adapter->timeout = HZ;
	adapter->algo = &cbus_i2c_algo;
	strlcpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name));

	spin_lock_init(&chost->lock);
	chost->dev = &pdev->dev;

	ret = devm_gpio_request_one(&pdev->dev, chost->clk_gpio,
	GPIOF_OUT_INIT_LOW, "CBUS clk");
	if (ret)
	return ret;

	ret = devm_gpio_request_one(&pdev->dev, chost->dat_gpio, GPIOF_IN,
	"CBUS data");
	if (ret)
	return ret;

	ret = devm_gpio_request_one(&pdev->dev, chost->sel_gpio,
	GPIOF_OUT_INIT_HIGH, "CBUS sel");
	if (ret)
	return ret;

	i2c_set_adapdata(adapter, chost);
	platform_set_drvdata(pdev, adapter);

	return i2c_add_numbered_adapter(adapter);
	}

	#if defined(CONFIG_OF)
	static const struct of_device_id i2c_cbus_dt_ids[] = {
	{ .compatible = "i2c-cbus-gpio", },
	{ }
	};
	MODULE_DEVICE_TABLE(of, i2c_cbus_dt_ids);
	#endif

	static struct platform_driver cbus_i2c_driver = {
	.probe = cbus_i2c_probe,
	.remove = cbus_i2c_remove,
	.driver = {
	.name = "i2c-cbus-gpio",
	.of_match_table = of_match_ptr(i2c_cbus_dt_ids),
	},
	};
	module_platform_driver(cbus_i2c_driver);

	MODULE_ALIAS("platform:i2c-cbus-gpio");
	MODULE_DESCRIPTION("CBUS I2C driver");
	MODULE_AUTHOR("Juha Yrjölä");
	MODULE_AUTHOR("David Weinehall");
	MODULE_AUTHOR("Mikko Ylinen");
	MODULE_AUTHOR("Felipe Balbi");
	MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
	MODULE_LICENSE("GPL");