[linux-2.6-block.git] / drivers / i2c / busses / i2c-gpio.c

/*
 * Bitbanging I2C bus driver using the GPIO API
 *
 * Copyright (C) 2007 Atmel Corporation
 *
 * 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/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <linux/i2c-gpio.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/platform_device.h>

#include <asm/gpio.h>

/* Toggle SDA by changing the direction of the pin */
static void i2c_gpio_setsda_dir(void *data, int state)
{
	struct i2c_gpio_platform_data *pdata = data;

	if (state)
		gpio_direction_input(pdata->sda_pin);
	else
		gpio_direction_output(pdata->sda_pin, 0);
}

/*
 * Toggle SDA by changing the output value of the pin. This is only
 * valid for pins configured as open drain (i.e. setting the value
 * high effectively turns off the output driver.)
 */
static void i2c_gpio_setsda_val(void *data, int state)
{
	struct i2c_gpio_platform_data *pdata = data;

	gpio_set_value(pdata->sda_pin, state);
}

/* Toggle SCL by changing the direction of the pin. */
static void i2c_gpio_setscl_dir(void *data, int state)
{
	struct i2c_gpio_platform_data *pdata = data;

	if (state)
		gpio_direction_input(pdata->scl_pin);
	else
		gpio_direction_output(pdata->scl_pin, 0);
}

/*
 * Toggle SCL by changing the output value of the pin. This is used
 * for pins that are configured as open drain and for output-only
 * pins. The latter case will break the i2c protocol, but it will
 * often work in practice.
 */
static void i2c_gpio_setscl_val(void *data, int state)
{
	struct i2c_gpio_platform_data *pdata = data;

	gpio_set_value(pdata->scl_pin, state);
}

static int i2c_gpio_getsda(void *data)
{
	struct i2c_gpio_platform_data *pdata = data;

	return gpio_get_value(pdata->sda_pin);
}

static int i2c_gpio_getscl(void *data)
{
	struct i2c_gpio_platform_data *pdata = data;

	return gpio_get_value(pdata->scl_pin);
}

static int __devinit i2c_gpio_probe(struct platform_device *pdev)
{
	struct i2c_gpio_platform_data *pdata;
	struct i2c_algo_bit_data *bit_data;
	struct i2c_adapter *adap;
	int ret;

	pdata = pdev->dev.platform_data;
	if (!pdata)
		return -ENXIO;

	ret = -ENOMEM;
	adap = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
	if (!adap)
		goto err_alloc_adap;
	bit_data = kzalloc(sizeof(struct i2c_algo_bit_data), GFP_KERNEL);
	if (!bit_data)
		goto err_alloc_bit_data;

	ret = gpio_request(pdata->sda_pin, "sda");
	if (ret)
		goto err_request_sda;
	ret = gpio_request(pdata->scl_pin, "scl");
	if (ret)
		goto err_request_scl;

	if (pdata->sda_is_open_drain) {
		gpio_direction_output(pdata->sda_pin, 1);
		bit_data->setsda = i2c_gpio_setsda_val;
	} else {
		gpio_direction_input(pdata->sda_pin);
		bit_data->setsda = i2c_gpio_setsda_dir;
	}

	if (pdata->scl_is_open_drain || pdata->scl_is_output_only) {
		gpio_direction_output(pdata->scl_pin, 1);
		bit_data->setscl = i2c_gpio_setscl_val;
	} else {
		gpio_direction_input(pdata->scl_pin);
		bit_data->setscl = i2c_gpio_setscl_dir;
	}

	if (!pdata->scl_is_output_only)
		bit_data->getscl = i2c_gpio_getscl;
	bit_data->getsda = i2c_gpio_getsda;

	if (pdata->udelay)
		bit_data->udelay = pdata->udelay;
	else if (pdata->scl_is_output_only)
		bit_data->udelay = 50;			/* 10 kHz */
	else
		bit_data->udelay = 5;			/* 100 kHz */

	if (pdata->timeout)
		bit_data->timeout = pdata->timeout;
	else
		bit_data->timeout = HZ / 10;		/* 100 ms */

	bit_data->data = pdata;

	adap->owner = THIS_MODULE;
	snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
	adap->algo_data = bit_data;
	adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
	adap->dev.parent = &pdev->dev;

	/*
	 * If "dev->id" is negative we consider it as zero.
	 * The reason to do so is to avoid sysfs names that only make
	 * sense when there are multiple adapters.
	 */
	adap->nr = (pdev->id != -1) ? pdev->id : 0;
	ret = i2c_bit_add_numbered_bus(adap);
	if (ret)
		goto err_add_bus;

	platform_set_drvdata(pdev, adap);

	dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n",
		 pdata->sda_pin, pdata->scl_pin,
		 pdata->scl_is_output_only
		 ? ", no clock stretching" : "");

	return 0;

err_add_bus:
	gpio_free(pdata->scl_pin);
err_request_scl:
	gpio_free(pdata->sda_pin);
err_request_sda:
	kfree(bit_data);
err_alloc_bit_data:
	kfree(adap);
err_alloc_adap:
	return ret;
}

static int __devexit i2c_gpio_remove(struct platform_device *pdev)
{
	struct i2c_gpio_platform_data *pdata;
	struct i2c_adapter *adap;

	adap = platform_get_drvdata(pdev);
	pdata = pdev->dev.platform_data;

	i2c_del_adapter(adap);
	gpio_free(pdata->scl_pin);
	gpio_free(pdata->sda_pin);
	kfree(adap->algo_data);
	kfree(adap);

	return 0;
}

static struct platform_driver i2c_gpio_driver = {
	.driver		= {
		.name	= "i2c-gpio",
		.owner	= THIS_MODULE,
	},
	.probe		= i2c_gpio_probe,
	.remove		= __devexit_p(i2c_gpio_remove),
};

static int __init i2c_gpio_init(void)
{
	int ret;

	ret = platform_driver_register(&i2c_gpio_driver);
	if (ret)
		printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);

	return ret;
}
module_init(i2c_gpio_init);

static void __exit i2c_gpio_exit(void)
{
	platform_driver_unregister(&i2c_gpio_driver);
}
module_exit(i2c_gpio_exit);

MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:i2c-gpio");
Commit	Line	Data
1c23af90 HS	1	/*
	2	* Bitbanging I2C bus driver using the GPIO API
	3	*
	4	* Copyright (C) 2007 Atmel Corporation
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*/
	10	#include <linux/i2c.h>
	11	#include <linux/i2c-algo-bit.h>
	12	#include <linux/i2c-gpio.h>
	13	#include <linux/init.h>
	14	#include <linux/module.h>
5a0e3ad6	15	#include <linux/slab.h>
1c23af90 HS	16	#include <linux/platform_device.h>
	17
	18	#include <asm/gpio.h>
	19
	20	/* Toggle SDA by changing the direction of the pin */
	21	static void i2c_gpio_setsda_dir(void *data, int state)
	22	{
	23	struct i2c_gpio_platform_data *pdata = data;
	24
	25	if (state)
	26	gpio_direction_input(pdata->sda_pin);
	27	else
	28	gpio_direction_output(pdata->sda_pin, 0);
	29	}
	30
	31	/*
	32	* Toggle SDA by changing the output value of the pin. This is only
	33	* valid for pins configured as open drain (i.e. setting the value
	34	* high effectively turns off the output driver.)
	35	*/
	36	static void i2c_gpio_setsda_val(void *data, int state)
	37	{
	38	struct i2c_gpio_platform_data *pdata = data;
	39
	40	gpio_set_value(pdata->sda_pin, state);
	41	}
	42
	43	/* Toggle SCL by changing the direction of the pin. */
	44	static void i2c_gpio_setscl_dir(void *data, int state)
	45	{
	46	struct i2c_gpio_platform_data *pdata = data;
	47
	48	if (state)
	49	gpio_direction_input(pdata->scl_pin);
	50	else
	51	gpio_direction_output(pdata->scl_pin, 0);
	52	}
	53
	54	/*
	55	* Toggle SCL by changing the output value of the pin. This is used
	56	* for pins that are configured as open drain and for output-only
	57	* pins. The latter case will break the i2c protocol, but it will
	58	* often work in practice.
	59	*/
	60	static void i2c_gpio_setscl_val(void *data, int state)
	61	{
	62	struct i2c_gpio_platform_data *pdata = data;
	63
	64	gpio_set_value(pdata->scl_pin, state);
	65	}
	66
4d6ceed4	67	static int i2c_gpio_getsda(void *data)
1c23af90 HS	68	{
	69	struct i2c_gpio_platform_data *pdata = data;
	70
	71	return gpio_get_value(pdata->sda_pin);
	72	}
	73
4d6ceed4	74	static int i2c_gpio_getscl(void *data)
1c23af90 HS	75	{
	76	struct i2c_gpio_platform_data *pdata = data;
	77
	78	return gpio_get_value(pdata->scl_pin);
	79	}
	80
1efe7c55	81	static int __devinit i2c_gpio_probe(struct platform_device *pdev)
1c23af90 HS	82	{
	83	struct i2c_gpio_platform_data *pdata;
	84	struct i2c_algo_bit_data *bit_data;
	85	struct i2c_adapter *adap;
	86	int ret;
	87
	88	pdata = pdev->dev.platform_data;
	89	if (!pdata)
	90	return -ENXIO;
	91
	92	ret = -ENOMEM;
	93	adap = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
	94	if (!adap)
	95	goto err_alloc_adap;
	96	bit_data = kzalloc(sizeof(struct i2c_algo_bit_data), GFP_KERNEL);
	97	if (!bit_data)
	98	goto err_alloc_bit_data;
	99
	100	ret = gpio_request(pdata->sda_pin, "sda");
	101	if (ret)
	102	goto err_request_sda;
	103	ret = gpio_request(pdata->scl_pin, "scl");
	104	if (ret)
	105	goto err_request_scl;
	106
	107	if (pdata->sda_is_open_drain) {
	108	gpio_direction_output(pdata->sda_pin, 1);
	109	bit_data->setsda = i2c_gpio_setsda_val;
	110	} else {
	111	gpio_direction_input(pdata->sda_pin);
	112	bit_data->setsda = i2c_gpio_setsda_dir;
	113	}
	114
	115	if (pdata->scl_is_open_drain \|\| pdata->scl_is_output_only) {
	116	gpio_direction_output(pdata->scl_pin, 1);
	117	bit_data->setscl = i2c_gpio_setscl_val;
	118	} else {
	119	gpio_direction_input(pdata->scl_pin);
	120	bit_data->setscl = i2c_gpio_setscl_dir;
	121	}
	122
	123	if (!pdata->scl_is_output_only)
	124	bit_data->getscl = i2c_gpio_getscl;
	125	bit_data->getsda = i2c_gpio_getsda;
	126
	127	if (pdata->udelay)
	128	bit_data->udelay = pdata->udelay;
	129	else if (pdata->scl_is_output_only)
	130	bit_data->udelay = 50; /* 10 kHz */
	131	else
	132	bit_data->udelay = 5; /* 100 kHz */
	133
	134	if (pdata->timeout)
	135	bit_data->timeout = pdata->timeout;
	136	else
	137	bit_data->timeout = HZ / 10; /* 100 ms */
	138
	139	bit_data->data = pdata;
	140
	141	adap->owner = THIS_MODULE;
	142	snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
	143	adap->algo_data = bit_data;
3401b2ff	144	adap->class = I2C_CLASS_HWMON \| I2C_CLASS_SPD;
1c23af90 HS	145	adap->dev.parent = &pdev->dev;
1c23af90 HS	146
7e69c3ac AN	147	/*
	148	* If "dev->id" is negative we consider it as zero.
	149	* The reason to do so is to avoid sysfs names that only make
	150	* sense when there are multiple adapters.
	151	*/
9a3180e7	152	adap->nr = (pdev->id != -1) ? pdev->id : 0;
7e69c3ac	153	ret = i2c_bit_add_numbered_bus(adap);
1c23af90 HS	154	if (ret)
	155	goto err_add_bus;
	156
	157	platform_set_drvdata(pdev, adap);
	158
	159	dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n",
	160	pdata->sda_pin, pdata->scl_pin,
	161	pdata->scl_is_output_only
	162	? ", no clock stretching" : "");
	163
	164	return 0;
	165
	166	err_add_bus:
	167	gpio_free(pdata->scl_pin);
	168	err_request_scl:
	169	gpio_free(pdata->sda_pin);
	170	err_request_sda:
	171	kfree(bit_data);
	172	err_alloc_bit_data:
	173	kfree(adap);
	174	err_alloc_adap:
	175	return ret;
	176	}
	177
1efe7c55	178	static int __devexit i2c_gpio_remove(struct platform_device *pdev)
1c23af90 HS	179	{
	180	struct i2c_gpio_platform_data *pdata;
	181	struct i2c_adapter *adap;
	182
	183	adap = platform_get_drvdata(pdev);
	184	pdata = pdev->dev.platform_data;
	185
	186	i2c_del_adapter(adap);
	187	gpio_free(pdata->scl_pin);
	188	gpio_free(pdata->sda_pin);
	189	kfree(adap->algo_data);
	190	kfree(adap);
	191
	192	return 0;
	193	}
	194
	195	static struct platform_driver i2c_gpio_driver = {
	196	.driver = {
	197	.name = "i2c-gpio",
	198	.owner = THIS_MODULE,
	199	},
1efe7c55 BD	200	.probe = i2c_gpio_probe,
1efe7c55 BD	201	.remove = __devexit_p(i2c_gpio_remove),
1c23af90 HS	202	};
	203
	204	static int __init i2c_gpio_init(void)
	205	{
	206	int ret;
	207
1efe7c55	208	ret = platform_driver_register(&i2c_gpio_driver);
1c23af90 HS	209	if (ret)
	210	printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
	211
	212	return ret;
	213	}
	214	module_init(i2c_gpio_init);
	215
	216	static void __exit i2c_gpio_exit(void)
	217	{
	218	platform_driver_unregister(&i2c_gpio_driver);
	219	}
	220	module_exit(i2c_gpio_exit);
	221
	222	MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
	223	MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
	224	MODULE_LICENSE("GPL");
add8eda7	225	MODULE_ALIAS("platform:i2c-gpio");