drivers/i2c/chips/pcf8574.c - maze/linux - Git at Google

 /*
     pcf8574.c - Part of lm_sensors, Linux kernel modules for hardware
              monitoring
     Copyright (c) 2000  Frodo Looijaard <frodol@dds.nl>,
                         Philip Edelbrock <phil@netroedge.com>,
                         Dan Eaton <dan.eaton@rocketlogix.com>
     Ported to Linux 2.6 by Aurelien Jarno <aurel32@debian.org> with
     the help of Jean Delvare <khali@linux-fr.org>

     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.
 */

 /* A few notes about the PCF8574:

 * The PCF8574 is an 8-bit I/O expander for the I2C bus produced by
   Philips Semiconductors.  It is designed to provide a byte I2C
   interface to up to 8 separate devices.

 * The PCF8574 appears as a very simple SMBus device which can be
   read from or written to with SMBUS byte read/write accesses.

   --Dan

 */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>

 /* Addresses to scan */
 static unsigned short normal_i2c[] = { 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
 					0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
 					I2C_CLIENT_END };

 /* Insmod parameters */
 I2C_CLIENT_INSMOD_2(pcf8574, pcf8574a);

 /* Initial values */
 #define PCF8574_INIT 255	/* All outputs on (input mode) */

 /* Each client has this additional data */
 struct pcf8574_data {
 	struct i2c_client client;

 	u8 write;			/* Remember last written value */
 };

 static int pcf8574_attach_adapter(struct i2c_adapter *adapter);
 static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind);
 static int pcf8574_detach_client(struct i2c_client *client);
 static void pcf8574_init_client(struct i2c_client *client);

 /* This is the driver that will be inserted */
 static struct i2c_driver pcf8574_driver = {
 	.driver = {
 		.name	= "pcf8574",
 	},
 	.id		= I2C_DRIVERID_PCF8574,
 	.attach_adapter	= pcf8574_attach_adapter,
 	.detach_client	= pcf8574_detach_client,
 };

 /* following are the sysfs callback functions */
 static ssize_t show_read(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	return sprintf(buf, "%u\n", i2c_smbus_read_byte(client));
 }

 static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);

 static ssize_t show_write(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct pcf8574_data *data = i2c_get_clientdata(to_i2c_client(dev));
 	return sprintf(buf, "%u\n", data->write);
 }

 static ssize_t set_write(struct device *dev, struct device_attribute *attr, const char *buf,
 			 size_t count)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct pcf8574_data *data = i2c_get_clientdata(client);
 	unsigned long val = simple_strtoul(buf, NULL, 10);

 	if (val > 0xff)
 		return -EINVAL;

 	data->write = val;
 	i2c_smbus_write_byte(client, data->write);
 	return count;
 }

 static DEVICE_ATTR(write, S_IWUSR | S_IRUGO, show_write, set_write);

 /*
  * Real code
  */

 static int pcf8574_attach_adapter(struct i2c_adapter *adapter)
 {
 	return i2c_probe(adapter, &addr_data, pcf8574_detect);
 }

 /* This function is called by i2c_probe */
 static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind)
 {
 	struct i2c_client *new_client;
 	struct pcf8574_data *data;
 	int err = 0;
 	const char *client_name = "";

 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
 		goto exit;

 	/* OK. For now, we presume we have a valid client. We now create the
 	   client structure, even though we cannot fill it completely yet. */
 	if (!(data = kzalloc(sizeof(struct pcf8574_data), GFP_KERNEL))) {
 		err = -ENOMEM;
 		goto exit;
 	}

 	new_client = &data->client;
 	i2c_set_clientdata(new_client, data);
 	new_client->addr = address;
 	new_client->adapter = adapter;
 	new_client->driver = &pcf8574_driver;
 	new_client->flags = 0;

 	/* Now, we would do the remaining detection. But the PCF8574 is plainly
 	   impossible to detect! Stupid chip. */

 	/* Determine the chip type */
 	if (kind <= 0) {
 		if (address >= 0x38 && address <= 0x3f)
 			kind = pcf8574a;
 		else
 			kind = pcf8574;
 	}

 	if (kind == pcf8574a)
 		client_name = "pcf8574a";
 	else
 		client_name = "pcf8574";

 	/* Fill in the remaining client fields and put it into the global list */
 	strlcpy(new_client->name, client_name, I2C_NAME_SIZE);

 	/* Tell the I2C layer a new client has arrived */
 	if ((err = i2c_attach_client(new_client)))
 		goto exit_free;

 	/* Initialize the PCF8574 chip */
 	pcf8574_init_client(new_client);

 	/* Register sysfs hooks */
 	device_create_file(&new_client->dev, &dev_attr_read);
 	device_create_file(&new_client->dev, &dev_attr_write);
 	return 0;

 /* OK, this is not exactly good programming practice, usually. But it is
    very code-efficient in this case. */

       exit_free:
 	kfree(data);
       exit:
 	return err;
 }

 static int pcf8574_detach_client(struct i2c_client *client)
 {
 	int err;

 	if ((err = i2c_detach_client(client)))
 		return err;

 	kfree(i2c_get_clientdata(client));
 	return 0;
 }

 /* Called when we have found a new PCF8574. */
 static void pcf8574_init_client(struct i2c_client *client)
 {
 	struct pcf8574_data *data = i2c_get_clientdata(client);
 	data->write = PCF8574_INIT;
 	i2c_smbus_write_byte(client, data->write);
 }

 static int __init pcf8574_init(void)
 {
 	return i2c_add_driver(&pcf8574_driver);
 }

 static void __exit pcf8574_exit(void)
 {
 	i2c_del_driver(&pcf8574_driver);
 }


 MODULE_AUTHOR
     ("Frodo Looijaard <frodol@dds.nl>, "
      "Philip Edelbrock <phil@netroedge.com>, "
      "Dan Eaton <dan.eaton@rocketlogix.com> "
      "and Aurelien Jarno <aurelien@aurel32.net>");
 MODULE_DESCRIPTION("PCF8574 driver");
 MODULE_LICENSE("GPL");

 module_init(pcf8574_init);
 module_exit(pcf8574_exit);
	/*
	pcf8574.c - Part of lm_sensors, Linux kernel modules for hardware
	monitoring
	Copyright (c) 2000 Frodo Looijaard <frodol@dds.nl>,
	Philip Edelbrock <phil@netroedge.com>,
	Dan Eaton <dan.eaton@rocketlogix.com>
	Ported to Linux 2.6 by Aurelien Jarno <aurel32@debian.org> with
	the help of Jean Delvare <khali@linux-fr.org>

	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.
	*/

	/* A few notes about the PCF8574:

	* The PCF8574 is an 8-bit I/O expander for the I2C bus produced by
	Philips Semiconductors. It is designed to provide a byte I2C
	interface to up to 8 separate devices.

	* The PCF8574 appears as a very simple SMBus device which can be
	read from or written to with SMBUS byte read/write accesses.

	--Dan

	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/i2c.h>

	/* Addresses to scan */
	static unsigned short normal_i2c[] = { 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
	I2C_CLIENT_END };

	/* Insmod parameters */
	I2C_CLIENT_INSMOD_2(pcf8574, pcf8574a);

	/* Initial values */
	#define PCF8574_INIT 255 /* All outputs on (input mode) */

	/* Each client has this additional data */
	struct pcf8574_data {
	struct i2c_client client;

	u8 write; /* Remember last written value */
	};

	static int pcf8574_attach_adapter(struct i2c_adapter *adapter);
	static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind);
	static int pcf8574_detach_client(struct i2c_client *client);
	static void pcf8574_init_client(struct i2c_client *client);

	/* This is the driver that will be inserted */
	static struct i2c_driver pcf8574_driver = {
	.driver = {
	.name = "pcf8574",
	},
	.id = I2C_DRIVERID_PCF8574,
	.attach_adapter = pcf8574_attach_adapter,
	.detach_client = pcf8574_detach_client,
	};

	/* following are the sysfs callback functions */
	static ssize_t show_read(struct device dev, struct device_attribute attr, char *buf)
	{
	struct i2c_client *client = to_i2c_client(dev);
	return sprintf(buf, "%u\n", i2c_smbus_read_byte(client));
	}

	static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);

	static ssize_t show_write(struct device dev, struct device_attribute attr, char *buf)
	{
	struct pcf8574_data *data = i2c_get_clientdata(to_i2c_client(dev));
	return sprintf(buf, "%u\n", data->write);
	}

	static ssize_t set_write(struct device dev, struct device_attribute attr, const char *buf,
	size_t count)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct pcf8574_data *data = i2c_get_clientdata(client);
	unsigned long val = simple_strtoul(buf, NULL, 10);

	if (val > 0xff)
	return -EINVAL;

	data->write = val;
	i2c_smbus_write_byte(client, data->write);
	return count;
	}

	static DEVICE_ATTR(write, S_IWUSR \| S_IRUGO, show_write, set_write);

	/*
	* Real code
	*/

	static int pcf8574_attach_adapter(struct i2c_adapter *adapter)
	{
	return i2c_probe(adapter, &addr_data, pcf8574_detect);
	}

	/* This function is called by i2c_probe */
	static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind)
	{
	struct i2c_client *new_client;
	struct pcf8574_data *data;
	int err = 0;
	const char *client_name = "";

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
	goto exit;

	/* OK. For now, we presume we have a valid client. We now create the
	client structure, even though we cannot fill it completely yet. */
	if (!(data = kzalloc(sizeof(struct pcf8574_data), GFP_KERNEL))) {
	err = -ENOMEM;
	goto exit;
	}

	new_client = &data->client;
	i2c_set_clientdata(new_client, data);
	new_client->addr = address;
	new_client->adapter = adapter;
	new_client->driver = &pcf8574_driver;
	new_client->flags = 0;

	/* Now, we would do the remaining detection. But the PCF8574 is plainly
	impossible to detect! Stupid chip. */

	/* Determine the chip type */
	if (kind <= 0) {
	if (address >= 0x38 && address <= 0x3f)
	kind = pcf8574a;
	else
	kind = pcf8574;
	}

	if (kind == pcf8574a)
	client_name = "pcf8574a";
	else
	client_name = "pcf8574";

	/* Fill in the remaining client fields and put it into the global list */
	strlcpy(new_client->name, client_name, I2C_NAME_SIZE);

	/* Tell the I2C layer a new client has arrived */
	if ((err = i2c_attach_client(new_client)))
	goto exit_free;

	/* Initialize the PCF8574 chip */
	pcf8574_init_client(new_client);

	/* Register sysfs hooks */
	device_create_file(&new_client->dev, &dev_attr_read);
	device_create_file(&new_client->dev, &dev_attr_write);
	return 0;

	/* OK, this is not exactly good programming practice, usually. But it is
	very code-efficient in this case. */

	exit_free:
	kfree(data);
	exit:
	return err;
	}

	static int pcf8574_detach_client(struct i2c_client *client)
	{
	int err;

	if ((err = i2c_detach_client(client)))
	return err;

	kfree(i2c_get_clientdata(client));
	return 0;
	}

	/* Called when we have found a new PCF8574. */
	static void pcf8574_init_client(struct i2c_client *client)
	{
	struct pcf8574_data *data = i2c_get_clientdata(client);
	data->write = PCF8574_INIT;
	i2c_smbus_write_byte(client, data->write);
	}

	static int __init pcf8574_init(void)
	{
	return i2c_add_driver(&pcf8574_driver);
	}

	static void __exit pcf8574_exit(void)
	{
	i2c_del_driver(&pcf8574_driver);
	}


	MODULE_AUTHOR
	("Frodo Looijaard <frodol@dds.nl>, "
	"Philip Edelbrock <phil@netroedge.com>, "
	"Dan Eaton <dan.eaton@rocketlogix.com> "
	"and Aurelien Jarno <aurelien@aurel32.net>");
	MODULE_DESCRIPTION("PCF8574 driver");
	MODULE_LICENSE("GPL");

	module_init(pcf8574_init);
	module_exit(pcf8574_exit);