drivers/gpio/pcf857x.c - kernel/prism - Git at Google

 /*
  * pcf857x - 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>


 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 */
 };

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

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

 static int pcf857x_input8(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 = i2c_smbus_write_byte(gpio->client, gpio->out);
 	mutex_unlock(&gpio->lock);

 	return status;
 }

 static int pcf857x_get8(struct gpio_chip *chip, unsigned offset)
 {
 	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
 	s32		value;

 	value = i2c_smbus_read_byte(gpio->client);
 	return (value < 0) ? 0 : (value & (1 << offset));
 }

 static int pcf857x_output8(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 = i2c_smbus_write_byte(gpio->client, gpio->out);
 	mutex_unlock(&gpio->lock);

 	return status;
 }

 static void pcf857x_set8(struct gpio_chip *chip, unsigned offset, int value)
 {
 	pcf857x_output8(chip, offset, value);
 }

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

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

 static int i2c_write_le16(struct i2c_client *client, u16 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_input16(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 = i2c_write_le16(gpio->client, gpio->out);
 	mutex_unlock(&gpio->lock);

 	return status;
 }

 static int pcf857x_get16(struct gpio_chip *chip, unsigned offset)
 {
 	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
 	int		value;

 	value = i2c_read_le16(gpio->client);
 	return (value < 0) ? 0 : (value & (1 << offset));
 }

 static int pcf857x_output16(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 = i2c_write_le16(gpio->client, gpio->out);
 	mutex_unlock(&gpio->lock);

 	return status;
 }

 static void pcf857x_set16(struct gpio_chip *chip, unsigned offset, int value)
 {
 	pcf857x_output16(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");
 		return -EINVAL;
 	}

 	/* 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->gpio_base;
 	gpio->chip.can_sleep = 1;
 	gpio->chip.dev = &client->dev;
 	gpio->chip.owner = THIS_MODULE;

 	/* 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.
 	 */
 	gpio->chip.ngpio = id->driver_data;
 	if (gpio->chip.ngpio == 8) {
 		gpio->chip.direction_input = pcf857x_input8;
 		gpio->chip.get = pcf857x_get8;
 		gpio->chip.direction_output = pcf857x_output8;
 		gpio->chip.set = pcf857x_set8;

 		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->chip.direction_input = pcf857x_input16;
 		gpio->chip.get = pcf857x_get16;
 		gpio->chip.direction_output = pcf857x_output16;
 		gpio->chip.set = pcf857x_set16;

 		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->n_latch;

 	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, "gpios %d..%d on a %s%s\n",
 			gpio->chip.base,
 			gpio->chip.base + gpio->chip.ngpio - 1,
 			client->name,
 			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->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->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");
	/*
	* pcf857x - 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>


	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 */
	};

	/-------------------------------------------------------------------------/

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

	static int pcf857x_input8(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 = i2c_smbus_write_byte(gpio->client, gpio->out);
	mutex_unlock(&gpio->lock);

	return status;
	}

	static int pcf857x_get8(struct gpio_chip *chip, unsigned offset)
	{
	struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
	s32 value;

	value = i2c_smbus_read_byte(gpio->client);
	return (value < 0) ? 0 : (value & (1 << offset));
	}

	static int pcf857x_output8(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 = i2c_smbus_write_byte(gpio->client, gpio->out);
	mutex_unlock(&gpio->lock);

	return status;
	}

	static void pcf857x_set8(struct gpio_chip *chip, unsigned offset, int value)
	{
	pcf857x_output8(chip, offset, value);
	}

	/-------------------------------------------------------------------------/

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

	static int i2c_write_le16(struct i2c_client *client, u16 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_input16(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 = i2c_write_le16(gpio->client, gpio->out);
	mutex_unlock(&gpio->lock);

	return status;
	}

	static int pcf857x_get16(struct gpio_chip *chip, unsigned offset)
	{
	struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
	int value;

	value = i2c_read_le16(gpio->client);
	return (value < 0) ? 0 : (value & (1 << offset));
	}

	static int pcf857x_output16(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 = i2c_write_le16(gpio->client, gpio->out);
	mutex_unlock(&gpio->lock);

	return status;
	}

	static void pcf857x_set16(struct gpio_chip *chip, unsigned offset, int value)
	{
	pcf857x_output16(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");
	return -EINVAL;
	}

	/* 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->gpio_base;
	gpio->chip.can_sleep = 1;
	gpio->chip.dev = &client->dev;
	gpio->chip.owner = THIS_MODULE;

	/* 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.
	*/
	gpio->chip.ngpio = id->driver_data;
	if (gpio->chip.ngpio == 8) {
	gpio->chip.direction_input = pcf857x_input8;
	gpio->chip.get = pcf857x_get8;
	gpio->chip.direction_output = pcf857x_output8;
	gpio->chip.set = pcf857x_set8;

	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->chip.direction_input = pcf857x_input16;
	gpio->chip.get = pcf857x_get16;
	gpio->chip.direction_output = pcf857x_output16;
	gpio->chip.set = pcf857x_set16;

	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->n_latch;

	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, "gpios %d..%d on a %s%s\n",
	gpio->chip.base,
	gpio->chip.base + gpio->chip.ngpio - 1,
	client->name,
	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->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->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");