[linux.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 <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/of_i2c.h>

struct i2c_gpio_private_data {
	struct i2c_adapter adap;
	struct i2c_algo_bit_data bit_data;
	struct i2c_gpio_platform_data pdata;
};

/* 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 of_i2c_gpio_probe(struct device_node *np,
			     struct i2c_gpio_platform_data *pdata)
{
	u32 reg;

	if (of_gpio_count(np) < 2)
		return -ENODEV;

	pdata->sda_pin = of_get_gpio(np, 0);
	pdata->scl_pin = of_get_gpio(np, 1);

	if (!gpio_is_valid(pdata->sda_pin) || !gpio_is_valid(pdata->scl_pin)) {
		pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
		       np->full_name, pdata->sda_pin, pdata->scl_pin);
		return -ENODEV;
	}

	of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);

	if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", &reg))
		pdata->timeout = msecs_to_jiffies(reg);

	pdata->sda_is_open_drain =
		of_property_read_bool(np, "i2c-gpio,sda-open-drain");
	pdata->scl_is_open_drain =
		of_property_read_bool(np, "i2c-gpio,scl-open-drain");
	pdata->scl_is_output_only =
		of_property_read_bool(np, "i2c-gpio,scl-output-only");

	return 0;
}

static int __devinit i2c_gpio_probe(struct platform_device *pdev)
{
	struct i2c_gpio_private_data *priv;
	struct i2c_gpio_platform_data *pdata;
	struct i2c_algo_bit_data *bit_data;
	struct i2c_adapter *adap;
	int ret;

	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;
	adap = &priv->adap;
	bit_data = &priv->bit_data;
	pdata = &priv->pdata;

	if (pdev->dev.of_node) {
		ret = of_i2c_gpio_probe(pdev->dev.of_node, pdata);
		if (ret)
			return ret;
	} else {
		if (!pdev->dev.platform_data)
			return -ENXIO;
		memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata));
	}

	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;
	adap->dev.of_node = pdev->dev.of_node;

	/*
	 * 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;

	of_i2c_register_devices(adap);

	platform_set_drvdata(pdev, priv);

	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:
	return ret;
}

static int __devexit i2c_gpio_remove(struct platform_device *pdev)
{
	struct i2c_gpio_private_data *priv;
	struct i2c_gpio_platform_data *pdata;
	struct i2c_adapter *adap;

	priv = platform_get_drvdata(pdev);
	adap = &priv->adap;
	pdata = &priv->pdata;

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

	return 0;
}

#if defined(CONFIG_OF)
static const struct of_device_id i2c_gpio_dt_ids[] = {
	{ .compatible = "i2c-gpio", },
	{ /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
#endif

static struct platform_driver i2c_gpio_driver = {
	.driver		= {
		.name	= "i2c-gpio",
		.owner	= THIS_MODULE,
		.of_match_table	= of_match_ptr(i2c_gpio_dt_ids),
	},
	.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;
}
subsys_initcall(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 (Atmel)");
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	16	#include <linux/platform_device.h>
8ffaa0f4 JCPV	17	#include <linux/gpio.h>
	18	#include <linux/of_gpio.h>
	19	#include <linux/of_i2c.h>
	20
	21	struct i2c_gpio_private_data {
	22	struct i2c_adapter adap;
	23	struct i2c_algo_bit_data bit_data;
	24	struct i2c_gpio_platform_data pdata;
	25	};
1c23af90 HS	26
	27	/* Toggle SDA by changing the direction of the pin */
	28	static void i2c_gpio_setsda_dir(void *data, int state)
	29	{
	30	struct i2c_gpio_platform_data *pdata = data;
	31
	32	if (state)
	33	gpio_direction_input(pdata->sda_pin);
	34	else
	35	gpio_direction_output(pdata->sda_pin, 0);
	36	}
	37
	38	/*
	39	* Toggle SDA by changing the output value of the pin. This is only
	40	* valid for pins configured as open drain (i.e. setting the value
	41	* high effectively turns off the output driver.)
	42	*/
	43	static void i2c_gpio_setsda_val(void *data, int state)
	44	{
	45	struct i2c_gpio_platform_data *pdata = data;
	46
	47	gpio_set_value(pdata->sda_pin, state);
	48	}
	49
	50	/* Toggle SCL by changing the direction of the pin. */
	51	static void i2c_gpio_setscl_dir(void *data, int state)
	52	{
	53	struct i2c_gpio_platform_data *pdata = data;
	54
	55	if (state)
	56	gpio_direction_input(pdata->scl_pin);
	57	else
	58	gpio_direction_output(pdata->scl_pin, 0);
	59	}
	60
	61	/*
	62	* Toggle SCL by changing the output value of the pin. This is used
	63	* for pins that are configured as open drain and for output-only
	64	* pins. The latter case will break the i2c protocol, but it will
	65	* often work in practice.
	66	*/
	67	static void i2c_gpio_setscl_val(void *data, int state)
	68	{
	69	struct i2c_gpio_platform_data *pdata = data;
	70
	71	gpio_set_value(pdata->scl_pin, state);
	72	}
	73
4d6ceed4	74	static int i2c_gpio_getsda(void *data)
1c23af90 HS	75	{
	76	struct i2c_gpio_platform_data *pdata = data;
	77
	78	return gpio_get_value(pdata->sda_pin);
	79	}
	80
4d6ceed4	81	static int i2c_gpio_getscl(void *data)
1c23af90 HS	82	{
	83	struct i2c_gpio_platform_data *pdata = data;
	84
	85	return gpio_get_value(pdata->scl_pin);
	86	}
	87
8ffaa0f4 JCPV	88	static int __devinit of_i2c_gpio_probe(struct device_node *np,
	89	struct i2c_gpio_platform_data *pdata)
	90	{
	91	u32 reg;
	92
	93	if (of_gpio_count(np) < 2)
	94	return -ENODEV;
	95
	96	pdata->sda_pin = of_get_gpio(np, 0);
	97	pdata->scl_pin = of_get_gpio(np, 1);
	98
	99	if (!gpio_is_valid(pdata->sda_pin) \|\| !gpio_is_valid(pdata->scl_pin)) {
	100	pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
	101	np->full_name, pdata->sda_pin, pdata->scl_pin);
	102	return -ENODEV;
	103	}
	104
	105	of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
	106
	107	if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", &reg))
	108	pdata->timeout = msecs_to_jiffies(reg);
	109
	110	pdata->sda_is_open_drain =
	111	of_property_read_bool(np, "i2c-gpio,sda-open-drain");
	112	pdata->scl_is_open_drain =
	113	of_property_read_bool(np, "i2c-gpio,scl-open-drain");
	114	pdata->scl_is_output_only =
	115	of_property_read_bool(np, "i2c-gpio,scl-output-only");
	116
	117	return 0;
	118	}
	119
1efe7c55	120	static int __devinit i2c_gpio_probe(struct platform_device *pdev)
1c23af90	121	{
8ffaa0f4	122	struct i2c_gpio_private_data *priv;
1c23af90 HS	123	struct i2c_gpio_platform_data *pdata;
	124	struct i2c_algo_bit_data *bit_data;
	125	struct i2c_adapter *adap;
	126	int ret;
	127
8ffaa0f4 JCPV	128	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
	129	if (!priv)
	130	return -ENOMEM;
	131	adap = &priv->adap;
	132	bit_data = &priv->bit_data;
	133	pdata = &priv->pdata;
	134
	135	if (pdev->dev.of_node) {
	136	ret = of_i2c_gpio_probe(pdev->dev.of_node, pdata);
	137	if (ret)
	138	return ret;
	139	} else {
	140	if (!pdev->dev.platform_data)
	141	return -ENXIO;
	142	memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata));
	143	}
1c23af90 HS	144
	145	ret = gpio_request(pdata->sda_pin, "sda");
	146	if (ret)
	147	goto err_request_sda;
	148	ret = gpio_request(pdata->scl_pin, "scl");
	149	if (ret)
	150	goto err_request_scl;
	151
	152	if (pdata->sda_is_open_drain) {
	153	gpio_direction_output(pdata->sda_pin, 1);
	154	bit_data->setsda = i2c_gpio_setsda_val;
	155	} else {
	156	gpio_direction_input(pdata->sda_pin);
	157	bit_data->setsda = i2c_gpio_setsda_dir;
	158	}
	159
	160	if (pdata->scl_is_open_drain \|\| pdata->scl_is_output_only) {
	161	gpio_direction_output(pdata->scl_pin, 1);
	162	bit_data->setscl = i2c_gpio_setscl_val;
	163	} else {
	164	gpio_direction_input(pdata->scl_pin);
	165	bit_data->setscl = i2c_gpio_setscl_dir;
	166	}
	167
	168	if (!pdata->scl_is_output_only)
	169	bit_data->getscl = i2c_gpio_getscl;
	170	bit_data->getsda = i2c_gpio_getsda;
	171
	172	if (pdata->udelay)
	173	bit_data->udelay = pdata->udelay;
	174	else if (pdata->scl_is_output_only)
	175	bit_data->udelay = 50; /* 10 kHz */
	176	else
	177	bit_data->udelay = 5; /* 100 kHz */
	178
	179	if (pdata->timeout)
	180	bit_data->timeout = pdata->timeout;
	181	else
	182	bit_data->timeout = HZ / 10; /* 100 ms */
	183
	184	bit_data->data = pdata;
	185
	186	adap->owner = THIS_MODULE;
	187	snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
	188	adap->algo_data = bit_data;
3401b2ff	189	adap->class = I2C_CLASS_HWMON \| I2C_CLASS_SPD;
1c23af90	190	adap->dev.parent = &pdev->dev;
8ffaa0f4	191	adap->dev.of_node = pdev->dev.of_node;
1c23af90	192
7e69c3ac AN	193	/*
	194	* If "dev->id" is negative we consider it as zero.
	195	* The reason to do so is to avoid sysfs names that only make
	196	* sense when there are multiple adapters.
	197	*/
9a3180e7	198	adap->nr = (pdev->id != -1) ? pdev->id : 0;
7e69c3ac	199	ret = i2c_bit_add_numbered_bus(adap);
1c23af90 HS	200	if (ret)
	201	goto err_add_bus;
	202
8ffaa0f4 JCPV	203	of_i2c_register_devices(adap);
	204
	205	platform_set_drvdata(pdev, priv);
1c23af90 HS	206
	207	dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n",
	208	pdata->sda_pin, pdata->scl_pin,
	209	pdata->scl_is_output_only
	210	? ", no clock stretching" : "");
	211
	212	return 0;
	213
	214	err_add_bus:
	215	gpio_free(pdata->scl_pin);
	216	err_request_scl:
	217	gpio_free(pdata->sda_pin);
	218	err_request_sda:
1c23af90 HS	219	return ret;
	220	}
	221
1efe7c55	222	static int __devexit i2c_gpio_remove(struct platform_device *pdev)
1c23af90	223	{
8ffaa0f4	224	struct i2c_gpio_private_data *priv;
1c23af90 HS	225	struct i2c_gpio_platform_data *pdata;
	226	struct i2c_adapter *adap;
	227
8ffaa0f4 JCPV	228	priv = platform_get_drvdata(pdev);
	229	adap = &priv->adap;
	230	pdata = &priv->pdata;
1c23af90 HS	231
	232	i2c_del_adapter(adap);
	233	gpio_free(pdata->scl_pin);
	234	gpio_free(pdata->sda_pin);
1c23af90 HS	235
	236	return 0;
	237	}
	238
8ffaa0f4 JCPV	239	#if defined(CONFIG_OF)
	240	static const struct of_device_id i2c_gpio_dt_ids[] = {
	241	{ .compatible = "i2c-gpio", },
	242	{ /* sentinel */ }
	243	};
	244
	245	MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
	246	#endif
	247
1c23af90 HS	248	static struct platform_driver i2c_gpio_driver = {
	249	.driver = {
	250	.name = "i2c-gpio",
	251	.owner = THIS_MODULE,
8ffaa0f4	252	.of_match_table = of_match_ptr(i2c_gpio_dt_ids),
1c23af90	253	},
1efe7c55 BD	254	.probe = i2c_gpio_probe,
1efe7c55 BD	255	.remove = __devexit_p(i2c_gpio_remove),
1c23af90 HS	256	};
	257
	258	static int __init i2c_gpio_init(void)
	259	{
	260	int ret;
	261
1efe7c55	262	ret = platform_driver_register(&i2c_gpio_driver);
1c23af90 HS	263	if (ret)
	264	printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
	265
	266	return ret;
	267	}
b8680784	268	subsys_initcall(i2c_gpio_init);
1c23af90 HS	269
	270	static void __exit i2c_gpio_exit(void)
	271	{
	272	platform_driver_unregister(&i2c_gpio_driver);
	273	}
	274	module_exit(i2c_gpio_exit);
	275
e05503ef	276	MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
1c23af90 HS	277	MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
1c23af90 HS	278	MODULE_LICENSE("GPL");
add8eda7	279	MODULE_ALIAS("platform:i2c-gpio");