+++ /dev/null
-Kernel driver pcf8574
-=====================
-
-Supported chips:
- * Philips PCF8574
- Prefix: 'pcf8574'
- Addresses scanned: none
- Datasheet: Publicly available at the Philips Semiconductors website
- http://www.semiconductors.philips.com/pip/PCF8574P.html
-
- * Philips PCF8574A
- Prefix: 'pcf8574a'
- Addresses scanned: none
- Datasheet: Publicly available at the Philips Semiconductors website
- http://www.semiconductors.philips.com/pip/PCF8574P.html
-
-Authors:
- Frodo Looijaard <frodol@dds.nl>,
- Philip Edelbrock <phil@netroedge.com>,
- Dan Eaton <dan.eaton@rocketlogix.com>,
- Aurelien Jarno <aurelien@aurel32.net>,
- Jean Delvare <khali@linux-fr.org>,
-
-
-Description
------------
-The PCF8574(A) 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 16
-separate devices (8 x PCF8574 and 8 x PCF8574A).
-
-This device consists of a quasi-bidirectional port. Each of the eight I/Os
-can be independently used as an input or output. To setup an I/O as an
-input, you have to write a 1 to the corresponding output.
-
-For more informations see the datasheet.
-
-
-Accessing PCF8574(A) via /sys interface
--------------------------------------
-
-The PCF8574(A) is plainly impossible to detect ! Stupid chip.
-So, you have to pass the I2C bus and address of the installed PCF857A
-and PCF8574A devices explicitly to the driver at load time via the
-force=... parameter.
-
-On detection (i.e. insmod, modprobe et al.), directories are being
-created for each detected PCF8574(A):
-
-/sys/bus/i2c/devices/<0>-<1>/
-where <0> is the bus the chip was detected on (e. g. i2c-0)
-and <1> the chip address ([20..27] or [38..3f]):
-
-(example: /sys/bus/i2c/devices/1-0020/)
-
-Inside these directories, there are two files each:
-read and write (and one file with chip name).
-
-The read file is read-only. Reading gives you the current I/O input
-if the corresponding output is set as 1, otherwise the current output
-value, that is to say 0.
-
-The write file is read/write. Writing a value outputs it on the I/O
-port. Reading returns the last written value. As it is not possible
-to read this value from the chip, you need to write at least once to
-this file before you can read back from it.
+++ /dev/null
-/*
- 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: none, device can't be detected */
-static const unsigned short normal_i2c[] = { I2C_CLIENT_END };
-
-/* Insmod parameters */
-I2C_CLIENT_INSMOD_2(pcf8574, pcf8574a);
-
-/* Each client has this additional data */
-struct pcf8574_data {
- int write; /* Remember last written value */
-};
-
-static void pcf8574_init_client(struct i2c_client *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));
-
- if (data->write < 0)
- return data->write;
-
- return sprintf(buf, "%d\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);
-
-static struct attribute *pcf8574_attributes[] = {
- &dev_attr_read.attr,
- &dev_attr_write.attr,
- NULL
-};
-
-static const struct attribute_group pcf8574_attr_group = {
- .attrs = pcf8574_attributes,
-};
-
-/*
- * Real code
- */
-
-/* Return 0 if detection is successful, -ENODEV otherwise */
-static int pcf8574_detect(struct i2c_client *client, int kind,
- struct i2c_board_info *info)
-{
- struct i2c_adapter *adapter = client->adapter;
- const char *client_name;
-
- if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
- return -ENODEV;
-
- /* 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 (client->addr >= 0x38 && client->addr <= 0x3f)
- kind = pcf8574a;
- else
- kind = pcf8574;
- }
-
- if (kind == pcf8574a)
- client_name = "pcf8574a";
- else
- client_name = "pcf8574";
- strlcpy(info->type, client_name, I2C_NAME_SIZE);
-
- return 0;
-}
-
-static int pcf8574_probe(struct i2c_client *client,
- const struct i2c_device_id *id)
-{
- struct pcf8574_data *data;
- int err;
-
- data = kzalloc(sizeof(struct pcf8574_data), GFP_KERNEL);
- if (!data) {
- err = -ENOMEM;
- goto exit;
- }
-
- i2c_set_clientdata(client, data);
-
- /* Initialize the PCF8574 chip */
- pcf8574_init_client(client);
-
- /* Register sysfs hooks */
- err = sysfs_create_group(&client->dev.kobj, &pcf8574_attr_group);
- if (err)
- goto exit_free;
- return 0;
-
- exit_free:
- kfree(data);
- exit:
- return err;
-}
-
-static int pcf8574_remove(struct i2c_client *client)
-{
- sysfs_remove_group(&client->dev.kobj, &pcf8574_attr_group);
- 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 = -EAGAIN;
-}
-
-static const struct i2c_device_id pcf8574_id[] = {
- { "pcf8574", 0 },
- { "pcf8574a", 0 },
- { }
-};
-
-static struct i2c_driver pcf8574_driver = {
- .driver = {
- .name = "pcf8574",
- },
- .probe = pcf8574_probe,
- .remove = pcf8574_remove,
- .id_table = pcf8574_id,
-
- .detect = pcf8574_detect,
- .address_data = &addr_data,
-};
-
-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);
git://ftp.safe.ca / safe / jmp / linux-2.6 / commitdiff