diff options
Diffstat (limited to 'drivers/i2c/chips/pcf8574.c')
| -rw-r--r-- | drivers/i2c/chips/pcf8574.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/drivers/i2c/chips/pcf8574.c b/drivers/i2c/chips/pcf8574.c new file mode 100644 index 000000000000..48b4e22eaffe --- /dev/null +++ b/drivers/i2c/chips/pcf8574.c @@ -0,0 +1,229 @@ +/* + 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> +#include <linux/i2c-sensor.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 }; +static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END }; + +/* Insmod parameters */ +SENSORS_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 read, write; /* Register values */ +}; + +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 = { + .owner = THIS_MODULE, + .name = "pcf8574", + .id = I2C_DRIVERID_PCF8574, + .flags = I2C_DF_NOTIFY, + .attach_adapter = pcf8574_attach_adapter, + .detach_client = pcf8574_detach_client, +}; + +/* following are the sysfs callback functions */ +static ssize_t show_read(struct device *dev, char *buf) +{ + struct i2c_client *client = to_i2c_client(dev); + struct pcf8574_data *data = i2c_get_clientdata(client); + data->read = i2c_smbus_read_byte(client); + return sprintf(buf, "%u\n", data->read); +} + +static DEVICE_ATTR(read, S_IRUGO, show_read, NULL); + +static ssize_t show_write(struct device *dev, 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, 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_detect(adapter, &addr_data, pcf8574_detect); +} + +/* This function is called by i2c_detect */ +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 = kmalloc(sizeof(struct pcf8574_data), GFP_KERNEL))) { + err = -ENOMEM; + goto exit; + } + memset(data, 0, sizeof(struct pcf8574_data)); + + 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))) { + dev_err(&client->dev, + "Client deregistration failed, client not detached.\n"); + 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); |