[deliverable/linux.git] / drivers / gpio / gpio-pcf857x.c

/*
 * Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
 *
 * Copyright (C) 2007 David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/gpio.h>
#include <linux/i2c.h>
#include <linux/i2c/pcf857x.h>
#include <linux/module.h>


static const struct i2c_device_id pcf857x_id[] = {
	{ "pcf8574", 8 },
	{ "pcf8574a", 8 },
	{ "pca8574", 8 },
	{ "pca9670", 8 },
	{ "pca9672", 8 },
	{ "pca9674", 8 },
	{ "pcf8575", 16 },
	{ "pca8575", 16 },
	{ "pca9671", 16 },
	{ "pca9673", 16 },
	{ "pca9675", 16 },
	{ "max7328", 8 },
	{ "max7329", 8 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, pcf857x_id);

/*
 * The pcf857x, pca857x, and pca967x chips only expose one read and one
 * write register.  Writing a "one" bit (to match the reset state) lets
 * that pin be used as an input; it's not an open-drain model, but acts
 * a bit like one.  This is described as "quasi-bidirectional"; read the
 * chip documentation for details.
 *
 * Many other I2C GPIO expander chips (like the pca953x models) have
 * more complex register models and more conventional circuitry using
 * push/pull drivers.  They often use the same 0x20..0x27 addresses as
 * pcf857x parts, making the "legacy" I2C driver model problematic.
 */
struct pcf857x {
	struct gpio_chip	chip;
	struct i2c_client	*client;
	struct mutex		lock;		/* protect 'out' */
	unsigned		out;		/* software latch */

	int (*write)(struct i2c_client *client, unsigned data);
	int (*read)(struct i2c_client *client);
};

/*-------------------------------------------------------------------------*/

/* Talk to 8-bit I/O expander */

static int i2c_write_le8(struct i2c_client *client, unsigned data)
{
	return i2c_smbus_write_byte(client, data);
}

static int i2c_read_le8(struct i2c_client *client)
{
	return (int)i2c_smbus_read_byte(client);
}

/* Talk to 16-bit I/O expander */

static int i2c_write_le16(struct i2c_client *client, unsigned word)
{
	u8 buf[2] = { word & 0xff, word >> 8, };
	int status;

	status = i2c_master_send(client, buf, 2);
	return (status < 0) ? status : 0;
}

static int i2c_read_le16(struct i2c_client *client)
{
	u8 buf[2];
	int status;

	status = i2c_master_recv(client, buf, 2);
	if (status < 0)
		return status;
	return (buf[1] << 8) | buf[0];
}

/*-------------------------------------------------------------------------*/

static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
{
	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
	int		status;

	mutex_lock(&gpio->lock);
	gpio->out |= (1 << offset);
	status = gpio->write(gpio->client, gpio->out);
	mutex_unlock(&gpio->lock);

	return status;
}

static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
{
	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
	int		value;

	value = gpio->read(gpio->client);
	return (value < 0) ? 0 : (value & (1 << offset));
}

static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
{
	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
	unsigned	bit = 1 << offset;
	int		status;

	mutex_lock(&gpio->lock);
	if (value)
		gpio->out |= bit;
	else
		gpio->out &= ~bit;
	status = gpio->write(gpio->client, gpio->out);
	mutex_unlock(&gpio->lock);

	return status;
}

static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
{
	pcf857x_output(chip, offset, value);
}

/*-------------------------------------------------------------------------*/

static int pcf857x_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct pcf857x_platform_data	*pdata;
	struct pcf857x			*gpio;
	int				status;

	pdata = client->dev.platform_data;
	if (!pdata) {
		dev_dbg(&client->dev, "no platform data\n");
	}

	/* Allocate, initialize, and register this gpio_chip. */
	gpio = kzalloc(sizeof *gpio, GFP_KERNEL);
	if (!gpio)
		return -ENOMEM;

	mutex_init(&gpio->lock);

	gpio->chip.base			= pdata ? pdata->gpio_base : -1;
	gpio->chip.can_sleep		= 1;
	gpio->chip.dev			= &client->dev;
	gpio->chip.owner		= THIS_MODULE;
	gpio->chip.get			= pcf857x_get;
	gpio->chip.set			= pcf857x_set;
	gpio->chip.direction_input	= pcf857x_input;
	gpio->chip.direction_output	= pcf857x_output;
	gpio->chip.ngpio		= id->driver_data;

	/* NOTE:  the OnSemi jlc1562b is also largely compatible with
	 * these parts, notably for output.  It has a low-resolution
	 * DAC instead of pin change IRQs; and its inputs can be the
	 * result of comparators.
	 */

	/* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
	 * 9670, 9672, 9764, and 9764a use quite a variety.
	 *
	 * NOTE: we don't distinguish here between *4 and *4a parts.
	 */
	if (gpio->chip.ngpio == 8) {
		gpio->write	= i2c_write_le8;
		gpio->read	= i2c_read_le8;

		if (!i2c_check_functionality(client->adapter,
				I2C_FUNC_SMBUS_BYTE))
			status = -EIO;

		/* fail if there's no chip present */
		else
			status = i2c_smbus_read_byte(client);

	/* '75/'75c addresses are 0x20..0x27, just like the '74;
	 * the '75c doesn't have a current source pulling high.
	 * 9671, 9673, and 9765 use quite a variety of addresses.
	 *
	 * NOTE: we don't distinguish here between '75 and '75c parts.
	 */
	} else if (gpio->chip.ngpio == 16) {
		gpio->write	= i2c_write_le16;
		gpio->read	= i2c_read_le16;

		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
			status = -EIO;

		/* fail if there's no chip present */
		else
			status = i2c_read_le16(client);

	} else {
		dev_dbg(&client->dev, "unsupported number of gpios\n");
		status = -EINVAL;
	}

	if (status < 0)
		goto fail;

	gpio->chip.label = client->name;

	gpio->client = client;
	i2c_set_clientdata(client, gpio);

	/* NOTE:  these chips have strange "quasi-bidirectional" I/O pins.
	 * We can't actually know whether a pin is configured (a) as output
	 * and driving the signal low, or (b) as input and reporting a low
	 * value ... without knowing the last value written since the chip
	 * came out of reset (if any).  We can't read the latched output.
	 *
	 * In short, the only reliable solution for setting up pin direction
	 * is to do it explicitly.  The setup() method can do that, but it
	 * may cause transient glitching since it can't know the last value
	 * written (some pins may need to be driven low).
	 *
	 * Using pdata->n_latch avoids that trouble.  When left initialized
	 * to zero, our software copy of the "latch" then matches the chip's
	 * all-ones reset state.  Otherwise it flags pins to be driven low.
	 */
	gpio->out = pdata ? ~pdata->n_latch : ~0;

	status = gpiochip_add(&gpio->chip);
	if (status < 0)
		goto fail;

	/* NOTE: these chips can issue "some pin-changed" IRQs, which we
	 * don't yet even try to use.  Among other issues, the relevant
	 * genirq state isn't available to modular drivers; and most irq
	 * methods can't be called from sleeping contexts.
	 */

	dev_info(&client->dev, "%s\n",
			client->irq ? " (irq ignored)" : "");

	/* Let platform code set up the GPIOs and their users.
	 * Now is the first time anyone could use them.
	 */
	if (pdata && pdata->setup) {
		status = pdata->setup(client,
				gpio->chip.base, gpio->chip.ngpio,
				pdata->context);
		if (status < 0)
			dev_warn(&client->dev, "setup --> %d\n", status);
	}

	return 0;

fail:
	dev_dbg(&client->dev, "probe error %d for '%s'\n",
			status, client->name);
	kfree(gpio);
	return status;
}

static int pcf857x_remove(struct i2c_client *client)
{
	struct pcf857x_platform_data	*pdata = client->dev.platform_data;
	struct pcf857x			*gpio = i2c_get_clientdata(client);
	int				status = 0;

	if (pdata && pdata->teardown) {
		status = pdata->teardown(client,
				gpio->chip.base, gpio->chip.ngpio,
				pdata->context);
		if (status < 0) {
			dev_err(&client->dev, "%s --> %d\n",
					"teardown", status);
			return status;
		}
	}

	status = gpiochip_remove(&gpio->chip);
	if (status == 0)
		kfree(gpio);
	else
		dev_err(&client->dev, "%s --> %d\n", "remove", status);
	return status;
}

static struct i2c_driver pcf857x_driver = {
	.driver = {
		.name	= "pcf857x",
		.owner	= THIS_MODULE,
	},
	.probe	= pcf857x_probe,
	.remove	= pcf857x_remove,
	.id_table = pcf857x_id,
};

static int __init pcf857x_init(void)
{
	return i2c_add_driver(&pcf857x_driver);
}
/* register after i2c postcore initcall and before
 * subsys initcalls that may rely on these GPIOs
 */
subsys_initcall(pcf857x_init);

static void __exit pcf857x_exit(void)
{
	i2c_del_driver(&pcf857x_driver);
}
module_exit(pcf857x_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Brownell");
Commit	Line	Data
15fae37d	1	/*
c103de24	2	* Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
15fae37d DB	3	*
	4	* Copyright (C) 2007 David Brownell
	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 as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	19	*/
	20
	21	#include <linux/kernel.h>
	22	#include <linux/slab.h>
d120c17f	23	#include <linux/gpio.h>
15fae37d DB	24	#include <linux/i2c.h>
15fae37d DB	25	#include <linux/i2c/pcf857x.h>
bb207ef1	26	#include <linux/module.h>
15fae37d	27
15fae37d	28
3760f736 JD	29	static const struct i2c_device_id pcf857x_id[] = {
3760f736 JD	30	{ "pcf8574", 8 },
4ba2ccb8	31	{ "pcf8574a", 8 },
3760f736 JD	32	{ "pca8574", 8 },
	33	{ "pca9670", 8 },
	34	{ "pca9672", 8 },
	35	{ "pca9674", 8 },
	36	{ "pcf8575", 16 },
	37	{ "pca8575", 16 },
	38	{ "pca9671", 16 },
	39	{ "pca9673", 16 },
	40	{ "pca9675", 16 },
1673ad52 DB	41	{ "max7328", 8 },
1673ad52 DB	42	{ "max7329", 8 },
3760f736 JD	43	{ }
	44	};
	45	MODULE_DEVICE_TABLE(i2c, pcf857x_id);
	46
15fae37d DB	47	/*
	48	* The pcf857x, pca857x, and pca967x chips only expose one read and one
	49	* write register. Writing a "one" bit (to match the reset state) lets
	50	* that pin be used as an input; it's not an open-drain model, but acts
	51	* a bit like one. This is described as "quasi-bidirectional"; read the
	52	* chip documentation for details.
	53	*
	54	* Many other I2C GPIO expander chips (like the pca953x models) have
	55	* more complex register models and more conventional circuitry using
	56	* push/pull drivers. They often use the same 0x20..0x27 addresses as
	57	* pcf857x parts, making the "legacy" I2C driver model problematic.
	58	*/
	59	struct pcf857x {
	60	struct gpio_chip chip;
	61	struct i2c_client *client;
1673ad52	62	struct mutex lock; /* protect 'out' */
15fae37d	63	unsigned out; /* software latch */
0c65ddd4 KM	64
	65	int (write)(struct i2c_client client, unsigned data);
	66	int (read)(struct i2c_client client);
15fae37d DB	67	};
	68
	69	/-------------------------------------------------------------------------/
	70
	71	/* Talk to 8-bit I/O expander */
	72
0c65ddd4	73	static int i2c_write_le8(struct i2c_client *client, unsigned data)
15fae37d	74	{
0c65ddd4	75	return i2c_smbus_write_byte(client, data);
15fae37d DB	76	}
15fae37d DB	77
0c65ddd4	78	static int i2c_read_le8(struct i2c_client *client)
15fae37d	79	{
0c65ddd4	80	return (int)i2c_smbus_read_byte(client);
15fae37d DB	81	}
15fae37d DB	82
15fae37d DB	83	/* Talk to 16-bit I/O expander */
15fae37d DB	84
0c65ddd4	85	static int i2c_write_le16(struct i2c_client *client, unsigned word)
15fae37d DB	86	{
	87	u8 buf[2] = { word & 0xff, word >> 8, };
	88	int status;
	89
	90	status = i2c_master_send(client, buf, 2);
	91	return (status < 0) ? status : 0;
	92	}
	93
	94	static int i2c_read_le16(struct i2c_client *client)
	95	{
	96	u8 buf[2];
	97	int status;
	98
	99	status = i2c_master_recv(client, buf, 2);
	100	if (status < 0)
	101	return status;
	102	return (buf[1] << 8) \| buf[0];
	103	}
	104
0c65ddd4 KM	105	/-------------------------------------------------------------------------/
	106
	107	static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
15fae37d DB	108	{
15fae37d DB	109	struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
1673ad52	110	int status;
15fae37d	111
1673ad52	112	mutex_lock(&gpio->lock);
15fae37d	113	gpio->out \|= (1 << offset);
0c65ddd4	114	status = gpio->write(gpio->client, gpio->out);
1673ad52 DB	115	mutex_unlock(&gpio->lock);
	116
	117	return status;
15fae37d DB	118	}
15fae37d DB	119
0c65ddd4	120	static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
15fae37d DB	121	{
	122	struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
	123	int value;
	124
0c65ddd4	125	value = gpio->read(gpio->client);
15fae37d DB	126	return (value < 0) ? 0 : (value & (1 << offset));
	127	}
	128
0c65ddd4	129	static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
15fae37d DB	130	{
	131	struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
	132	unsigned bit = 1 << offset;
1673ad52	133	int status;
15fae37d	134
1673ad52	135	mutex_lock(&gpio->lock);
15fae37d DB	136	if (value)
	137	gpio->out \|= bit;
	138	else
	139	gpio->out &= ~bit;
0c65ddd4	140	status = gpio->write(gpio->client, gpio->out);
1673ad52 DB	141	mutex_unlock(&gpio->lock);
	142
	143	return status;
15fae37d DB	144	}
15fae37d DB	145
0c65ddd4	146	static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
15fae37d	147	{
0c65ddd4	148	pcf857x_output(chip, offset, value);
15fae37d DB	149	}
	150
	151	/-------------------------------------------------------------------------/
	152
d2653e92 JD	153	static int pcf857x_probe(struct i2c_client *client,
d2653e92 JD	154	const struct i2c_device_id *id)
15fae37d DB	155	{
	156	struct pcf857x_platform_data *pdata;
	157	struct pcf857x *gpio;
	158	int status;
	159
	160	pdata = client->dev.platform_data;
a342d215 BD	161	if (!pdata) {
a342d215 BD	162	dev_dbg(&client->dev, "no platform data\n");
a342d215	163	}
15fae37d DB	164
	165	/* Allocate, initialize, and register this gpio_chip. */
	166	gpio = kzalloc(sizeof *gpio, GFP_KERNEL);
	167	if (!gpio)
	168	return -ENOMEM;
	169
1673ad52 DB	170	mutex_init(&gpio->lock);
1673ad52 DB	171
0c65ddd4 KM	172	gpio->chip.base = pdata ? pdata->gpio_base : -1;
	173	gpio->chip.can_sleep = 1;
	174	gpio->chip.dev = &client->dev;
	175	gpio->chip.owner = THIS_MODULE;
	176	gpio->chip.get = pcf857x_get;
	177	gpio->chip.set = pcf857x_set;
	178	gpio->chip.direction_input = pcf857x_input;
	179	gpio->chip.direction_output = pcf857x_output;
	180	gpio->chip.ngpio = id->driver_data;
15fae37d DB	181
	182	/* NOTE: the OnSemi jlc1562b is also largely compatible with
	183	* these parts, notably for output. It has a low-resolution
	184	* DAC instead of pin change IRQs; and its inputs can be the
	185	* result of comparators.
	186	*/
	187
	188	/* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
	189	* 9670, 9672, 9764, and 9764a use quite a variety.
	190	*
	191	* NOTE: we don't distinguish here between 4 and 4a parts.
	192	*/
3760f736	193	if (gpio->chip.ngpio == 8) {
0c65ddd4 KM	194	gpio->write = i2c_write_le8;
0c65ddd4 KM	195	gpio->read = i2c_read_le8;
15fae37d DB	196
	197	if (!i2c_check_functionality(client->adapter,
	198	I2C_FUNC_SMBUS_BYTE))
	199	status = -EIO;
	200
	201	/* fail if there's no chip present */
	202	else
	203	status = i2c_smbus_read_byte(client);
	204
	205	/* '75/'75c addresses are 0x20..0x27, just like the '74;
	206	* the '75c doesn't have a current source pulling high.
	207	* 9671, 9673, and 9765 use quite a variety of addresses.
	208	*
	209	* NOTE: we don't distinguish here between '75 and '75c parts.
	210	*/
3760f736	211	} else if (gpio->chip.ngpio == 16) {
0c65ddd4 KM	212	gpio->write = i2c_write_le16;
0c65ddd4 KM	213	gpio->read = i2c_read_le16;
15fae37d DB	214
	215	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	216	status = -EIO;
	217
	218	/* fail if there's no chip present */
	219	else
	220	status = i2c_read_le16(client);
	221
a342d215 BD	222	} else {
	223	dev_dbg(&client->dev, "unsupported number of gpios\n");
	224	status = -EINVAL;
	225	}
15fae37d DB	226
	227	if (status < 0)
	228	goto fail;
	229
	230	gpio->chip.label = client->name;
	231
	232	gpio->client = client;
	233	i2c_set_clientdata(client, gpio);
	234
	235	/* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
	236	* We can't actually know whether a pin is configured (a) as output
	237	* and driving the signal low, or (b) as input and reporting a low
	238	* value ... without knowing the last value written since the chip
	239	* came out of reset (if any). We can't read the latched output.
	240	*
	241	* In short, the only reliable solution for setting up pin direction
	242	* is to do it explicitly. The setup() method can do that, but it
	243	* may cause transient glitching since it can't know the last value
	244	* written (some pins may need to be driven low).
	245	*
	246	* Using pdata->n_latch avoids that trouble. When left initialized
	247	* to zero, our software copy of the "latch" then matches the chip's
	248	* all-ones reset state. Otherwise it flags pins to be driven low.
	249	*/
49946f68	250	gpio->out = pdata ? ~pdata->n_latch : ~0;
15fae37d DB	251
	252	status = gpiochip_add(&gpio->chip);
	253	if (status < 0)
	254	goto fail;
	255
	256	/* NOTE: these chips can issue "some pin-changed" IRQs, which we
	257	* don't yet even try to use. Among other issues, the relevant
	258	* genirq state isn't available to modular drivers; and most irq
	259	* methods can't be called from sleeping contexts.
	260	*/
	261
64842aad	262	dev_info(&client->dev, "%s\n",
15fae37d DB	263	client->irq ? " (irq ignored)" : "");
	264
	265	/* Let platform code set up the GPIOs and their users.
	266	* Now is the first time anyone could use them.
	267	*/
49946f68	268	if (pdata && pdata->setup) {
15fae37d DB	269	status = pdata->setup(client,
	270	gpio->chip.base, gpio->chip.ngpio,
	271	pdata->context);
	272	if (status < 0)
	273	dev_warn(&client->dev, "setup --> %d\n", status);
	274	}
	275
	276	return 0;
	277
	278	fail:
	279	dev_dbg(&client->dev, "probe error %d for '%s'\n",
	280	status, client->name);
	281	kfree(gpio);
	282	return status;
	283	}
	284
	285	static int pcf857x_remove(struct i2c_client *client)
	286	{
	287	struct pcf857x_platform_data *pdata = client->dev.platform_data;
	288	struct pcf857x *gpio = i2c_get_clientdata(client);
	289	int status = 0;
	290
49946f68	291	if (pdata && pdata->teardown) {
15fae37d DB	292	status = pdata->teardown(client,
	293	gpio->chip.base, gpio->chip.ngpio,
	294	pdata->context);
	295	if (status < 0) {
	296	dev_err(&client->dev, "%s --> %d\n",
	297	"teardown", status);
	298	return status;
	299	}
	300	}
	301
	302	status = gpiochip_remove(&gpio->chip);
	303	if (status == 0)
	304	kfree(gpio);
	305	else
	306	dev_err(&client->dev, "%s --> %d\n", "remove", status);
	307	return status;
	308	}
	309
	310	static struct i2c_driver pcf857x_driver = {
	311	.driver = {
	312	.name = "pcf857x",
	313	.owner = THIS_MODULE,
	314	},
	315	.probe = pcf857x_probe,
	316	.remove = pcf857x_remove,
3760f736	317	.id_table = pcf857x_id,
15fae37d DB	318	};
	319
	320	static int __init pcf857x_init(void)
	321	{
	322	return i2c_add_driver(&pcf857x_driver);
	323	}
2f8d1197 DB	324	/* register after i2c postcore initcall and before
	325	* subsys initcalls that may rely on these GPIOs
	326	*/
	327	subsys_initcall(pcf857x_init);
15fae37d DB	328
	329	static void __exit pcf857x_exit(void)
	330	{
	331	i2c_del_driver(&pcf857x_driver);
	332	}
	333	module_exit(pcf857x_exit);
	334
	335	MODULE_LICENSE("GPL");
	336	MODULE_AUTHOR("David Brownell");