[deliverable/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.h>
#include <linux/of_gpio.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 of_i2c_gpio_get_pins(struct device_node *np,
				unsigned int *sda_pin, unsigned int *scl_pin)
{
	if (of_gpio_count(np) < 2)
		return -ENODEV;

	*sda_pin = of_get_gpio(np, 0);
	*scl_pin = of_get_gpio(np, 1);

	if (*sda_pin == -EPROBE_DEFER || *scl_pin == -EPROBE_DEFER)
		return -EPROBE_DEFER;

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

	return 0;
}

static void of_i2c_gpio_get_props(struct device_node *np,
				  struct i2c_gpio_platform_data *pdata)
{
	u32 reg;

	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");
}

static int 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;
	unsigned int sda_pin, scl_pin;
	int ret;

	/* First get the GPIO pins; if it fails, we'll defer the probe. */
	if (pdev->dev.of_node) {
		ret = of_i2c_gpio_get_pins(pdev->dev.of_node,
					   &sda_pin, &scl_pin);
		if (ret)
			return ret;
	} else {
		if (!dev_get_platdata(&pdev->dev))
			return -ENXIO;
		pdata = dev_get_platdata(&pdev->dev);
		sda_pin = pdata->sda_pin;
		scl_pin = pdata->scl_pin;
	}

	ret = gpio_request(sda_pin, "sda");
	if (ret) {
		if (ret == -EINVAL)
			ret = -EPROBE_DEFER;	/* Try again later */
		goto err_request_sda;
	}
	ret = gpio_request(scl_pin, "scl");
	if (ret) {
		if (ret == -EINVAL)
			ret = -EPROBE_DEFER;	/* Try again later */
		goto err_request_scl;
	}

	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
	if (!priv) {
		ret = -ENOMEM;
		goto err_add_bus;
	}
	adap = &priv->adap;
	bit_data = &priv->bit_data;
	pdata = &priv->pdata;

	if (pdev->dev.of_node) {
		pdata->sda_pin = sda_pin;
		pdata->scl_pin = scl_pin;
		of_i2c_gpio_get_props(pdev->dev.of_node, pdata);
	} else {
		memcpy(pdata, dev_get_platdata(&pdev->dev), sizeof(*pdata));
	}

	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;
	if (pdev->dev.of_node)
		strlcpy(adap->name, dev_name(&pdev->dev), sizeof(adap->name));
	else
		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;

	adap->nr = pdev->id;
	ret = i2c_bit_add_numbered_bus(adap);
	if (ret)
		goto err_add_bus;

	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(scl_pin);
err_request_scl:
	gpio_free(sda_pin);
err_request_sda:
	return ret;
}

static int 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		= 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	17	#include <linux/gpio.h>
4edd65e6	18	#include <linux/of.h>
8ffaa0f4	19	#include <linux/of_gpio.h>
8ffaa0f4 JCPV	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
1b295c83 JD	88	static int of_i2c_gpio_get_pins(struct device_node *np,
1b295c83 JD	89	unsigned int sda_pin, unsigned int scl_pin)
8ffaa0f4	90	{
8ffaa0f4 JCPV	91	if (of_gpio_count(np) < 2)
	92	return -ENODEV;
	93
1b295c83 JD	94	*sda_pin = of_get_gpio(np, 0);
1b295c83 JD	95	*scl_pin = of_get_gpio(np, 1);
8ffaa0f4	96
40e7b115 BD	97	if (sda_pin == -EPROBE_DEFER \|\| scl_pin == -EPROBE_DEFER)
	98	return -EPROBE_DEFER;
	99
1b295c83	100	if (!gpio_is_valid(sda_pin) \|\| !gpio_is_valid(scl_pin)) {
8ffaa0f4	101	pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
1b295c83	102	np->full_name, sda_pin, scl_pin);
8ffaa0f4 JCPV	103	return -ENODEV;
	104	}
	105
1b295c83 JD	106	return 0;
	107	}
	108
	109	static void of_i2c_gpio_get_props(struct device_node *np,
	110	struct i2c_gpio_platform_data *pdata)
	111	{
	112	u32 reg;
	113
8ffaa0f4 JCPV	114	of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
	115
	116	if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", &reg))
	117	pdata->timeout = msecs_to_jiffies(reg);
	118
	119	pdata->sda_is_open_drain =
	120	of_property_read_bool(np, "i2c-gpio,sda-open-drain");
	121	pdata->scl_is_open_drain =
	122	of_property_read_bool(np, "i2c-gpio,scl-open-drain");
	123	pdata->scl_is_output_only =
	124	of_property_read_bool(np, "i2c-gpio,scl-output-only");
8ffaa0f4 JCPV	125	}
8ffaa0f4 JCPV	126
0b255e92	127	static int i2c_gpio_probe(struct platform_device *pdev)
1c23af90	128	{
8ffaa0f4	129	struct i2c_gpio_private_data *priv;
1c23af90 HS	130	struct i2c_gpio_platform_data *pdata;
	131	struct i2c_algo_bit_data *bit_data;
	132	struct i2c_adapter *adap;
1b295c83	133	unsigned int sda_pin, scl_pin;
1c23af90 HS	134	int ret;
1c23af90 HS	135
1b295c83	136	/* First get the GPIO pins; if it fails, we'll defer the probe. */
8ffaa0f4	137	if (pdev->dev.of_node) {
1b295c83 JD	138	ret = of_i2c_gpio_get_pins(pdev->dev.of_node,
1b295c83 JD	139	&sda_pin, &scl_pin);
8ffaa0f4 JCPV	140	if (ret)
	141	return ret;
	142	} else {
6d4028c6	143	if (!dev_get_platdata(&pdev->dev))
8ffaa0f4	144	return -ENXIO;
6d4028c6	145	pdata = dev_get_platdata(&pdev->dev);
1b295c83 JD	146	sda_pin = pdata->sda_pin;
1b295c83 JD	147	scl_pin = pdata->scl_pin;
8ffaa0f4	148	}
1c23af90	149
1b295c83 JD	150	ret = gpio_request(sda_pin, "sda");
	151	if (ret) {
	152	if (ret == -EINVAL)
	153	ret = -EPROBE_DEFER; /* Try again later */
1c23af90	154	goto err_request_sda;
1b295c83 JD	155	}
	156	ret = gpio_request(scl_pin, "scl");
	157	if (ret) {
	158	if (ret == -EINVAL)
	159	ret = -EPROBE_DEFER; /* Try again later */
1c23af90	160	goto err_request_scl;
1b295c83 JD	161	}
	162
	163	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
	164	if (!priv) {
	165	ret = -ENOMEM;
	166	goto err_add_bus;
	167	}
	168	adap = &priv->adap;
	169	bit_data = &priv->bit_data;
	170	pdata = &priv->pdata;
	171
	172	if (pdev->dev.of_node) {
	173	pdata->sda_pin = sda_pin;
	174	pdata->scl_pin = scl_pin;
	175	of_i2c_gpio_get_props(pdev->dev.of_node, pdata);
	176	} else {
6d4028c6	177	memcpy(pdata, dev_get_platdata(&pdev->dev), sizeof(*pdata));
1b295c83	178	}
1c23af90 HS	179
	180	if (pdata->sda_is_open_drain) {
	181	gpio_direction_output(pdata->sda_pin, 1);
	182	bit_data->setsda = i2c_gpio_setsda_val;
	183	} else {
	184	gpio_direction_input(pdata->sda_pin);
	185	bit_data->setsda = i2c_gpio_setsda_dir;
	186	}
	187
	188	if (pdata->scl_is_open_drain \|\| pdata->scl_is_output_only) {
	189	gpio_direction_output(pdata->scl_pin, 1);
	190	bit_data->setscl = i2c_gpio_setscl_val;
	191	} else {
	192	gpio_direction_input(pdata->scl_pin);
	193	bit_data->setscl = i2c_gpio_setscl_dir;
	194	}
	195
	196	if (!pdata->scl_is_output_only)
	197	bit_data->getscl = i2c_gpio_getscl;
	198	bit_data->getsda = i2c_gpio_getsda;
	199
	200	if (pdata->udelay)
	201	bit_data->udelay = pdata->udelay;
	202	else if (pdata->scl_is_output_only)
	203	bit_data->udelay = 50; /* 10 kHz */
	204	else
	205	bit_data->udelay = 5; /* 100 kHz */
	206
	207	if (pdata->timeout)
	208	bit_data->timeout = pdata->timeout;
	209	else
	210	bit_data->timeout = HZ / 10; /* 100 ms */
	211
	212	bit_data->data = pdata;
	213
	214	adap->owner = THIS_MODULE;
58a7371a BS	215	if (pdev->dev.of_node)
	216	strlcpy(adap->name, dev_name(&pdev->dev), sizeof(adap->name));
	217	else
	218	snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
	219
1c23af90	220	adap->algo_data = bit_data;
3401b2ff	221	adap->class = I2C_CLASS_HWMON \| I2C_CLASS_SPD;
1c23af90	222	adap->dev.parent = &pdev->dev;
8ffaa0f4	223	adap->dev.of_node = pdev->dev.of_node;
1c23af90	224
44454baa	225	adap->nr = pdev->id;
7e69c3ac	226	ret = i2c_bit_add_numbered_bus(adap);
1c23af90 HS	227	if (ret)
	228	goto err_add_bus;
	229
8ffaa0f4	230	platform_set_drvdata(pdev, priv);
1c23af90 HS	231
	232	dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n",
	233	pdata->sda_pin, pdata->scl_pin,
	234	pdata->scl_is_output_only
	235	? ", no clock stretching" : "");
	236
	237	return 0;
	238
	239	err_add_bus:
1b295c83	240	gpio_free(scl_pin);
1c23af90	241	err_request_scl:
1b295c83	242	gpio_free(sda_pin);
1c23af90	243	err_request_sda:
1c23af90 HS	244	return ret;
	245	}
	246
0b255e92	247	static int i2c_gpio_remove(struct platform_device *pdev)
1c23af90	248	{
8ffaa0f4	249	struct i2c_gpio_private_data *priv;
1c23af90 HS	250	struct i2c_gpio_platform_data *pdata;
	251	struct i2c_adapter *adap;
	252
8ffaa0f4 JCPV	253	priv = platform_get_drvdata(pdev);
	254	adap = &priv->adap;
	255	pdata = &priv->pdata;
1c23af90 HS	256
	257	i2c_del_adapter(adap);
	258	gpio_free(pdata->scl_pin);
	259	gpio_free(pdata->sda_pin);
1c23af90 HS	260
	261	return 0;
	262	}
	263
8ffaa0f4 JCPV	264	#if defined(CONFIG_OF)
	265	static const struct of_device_id i2c_gpio_dt_ids[] = {
	266	{ .compatible = "i2c-gpio", },
	267	{ /* sentinel */ }
	268	};
	269
	270	MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
	271	#endif
	272
1c23af90 HS	273	static struct platform_driver i2c_gpio_driver = {
	274	.driver = {
	275	.name = "i2c-gpio",
	276	.owner = THIS_MODULE,
8ffaa0f4	277	.of_match_table = of_match_ptr(i2c_gpio_dt_ids),
1c23af90	278	},
1efe7c55	279	.probe = i2c_gpio_probe,
0b255e92	280	.remove = i2c_gpio_remove,
1c23af90 HS	281	};
	282
	283	static int __init i2c_gpio_init(void)
	284	{
	285	int ret;
	286
1efe7c55	287	ret = platform_driver_register(&i2c_gpio_driver);
1c23af90 HS	288	if (ret)
	289	printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
	290
	291	return ret;
	292	}
b8680784	293	subsys_initcall(i2c_gpio_init);
1c23af90 HS	294
	295	static void __exit i2c_gpio_exit(void)
	296	{
	297	platform_driver_unregister(&i2c_gpio_driver);
	298	}
	299	module_exit(i2c_gpio_exit);
	300
e05503ef	301	MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
1c23af90 HS	302	MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
1c23af90 HS	303	MODULE_LICENSE("GPL");
add8eda7	304	MODULE_ALIAS("platform:i2c-gpio");