diff options
Diffstat (limited to 'drivers/i2c/chips/pcf8574.c')
-rw-r--r-- | drivers/i2c/chips/pcf8574.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/drivers/i2c/chips/pcf8574.c b/drivers/i2c/chips/pcf8574.c new file mode 100644 index 0000000..6ec3098 --- /dev/null +++ b/drivers/i2c/chips/pcf8574.c @@ -0,0 +1,215 @@ +/* + 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); |