ChangeSet 1.1643.36.2, 2004/03/19 13:24:39-08:00, aurelien@aurel32.net [PATCH] I2C: add new chip driver: pcf8574 Please find below a patch against kernel 2.6.5-rc1 to add the pcf8574 driver (an I/O expander for the I2C bus). I have ported it from the 2.4 version, and it includes some fixes and simplifications. It has been reviewed by Jean Delvare on IRC. drivers/i2c/chips/Kconfig | 11 + drivers/i2c/chips/Makefile | 1 drivers/i2c/chips/pcf8574.c | 245 ++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 257 insertions(+) diff -Nru a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig --- a/drivers/i2c/chips/Kconfig Wed Apr 14 15:14:55 2004 +++ b/drivers/i2c/chips/Kconfig Wed Apr 14 15:14:55 2004 @@ -209,4 +209,15 @@ This driver can also be built as a module. If so, the module will be called eeprom. +config SENSORS_PCF8574 + tristate "Philips PCF8574 and PCF8574A" + depends on I2C && EXPERIMENTAL + select I2C_SENSOR + help + If you say yes here you get support for Philips PCF8574 and + PCF8574A chips. + + This driver can also be built as a module. If so, the module + will be called pcf8574. + endmenu diff -Nru a/drivers/i2c/chips/Makefile b/drivers/i2c/chips/Makefile --- a/drivers/i2c/chips/Makefile Wed Apr 14 15:14:55 2004 +++ b/drivers/i2c/chips/Makefile Wed Apr 14 15:14:55 2004 @@ -19,6 +19,7 @@ obj-$(CONFIG_SENSORS_LM83) += lm83.o obj-$(CONFIG_SENSORS_LM85) += lm85.o obj-$(CONFIG_SENSORS_LM90) += lm90.o +obj-$(CONFIG_SENSORS_PCF8574) += pcf8574.o obj-$(CONFIG_SENSORS_VIA686A) += via686a.o obj-$(CONFIG_SENSORS_W83L785TS) += w83l785ts.o diff -Nru a/drivers/i2c/chips/pcf8574.c b/drivers/i2c/chips/pcf8574.c --- /dev/null Wed Dec 31 16:00:00 1969 +++ b/drivers/i2c/chips/pcf8574.c Wed Apr 14 15:14:55 2004 @@ -0,0 +1,245 @@ +/* + pcf8574.c - Part of lm_sensors, Linux kernel modules for hardware + monitoring + Copyright (c) 2000 Frodo Looijaard , + Philip Edelbrock , + Dan Eaton + Ported to Linux 2.6 by Aurelien Jarno with + the help of Jean Delvare + + 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 +#include +#include +#include +#include + +/* Addresses to scan */ +static unsigned short normal_i2c[] = { I2C_CLIENT_END }; +static unsigned short normal_i2c_range[] = { 0x20, 0x27, 0x38, 0x3f, I2C_CLIENT_END }; +static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END }; +static unsigned int normal_isa_range[] = { 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 semaphore update_lock; + + 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); +static struct pcf8574_data *pcf8574_update_client(struct device *dev); + +/* 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, +}; + +static int pcf8574_id = 0; + +/* following are the sysfs callback functions */ +static ssize_t show_read(struct device *dev, char *buf) +{ + struct pcf8574_data *data = pcf8574_update_client(dev); + 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); + data->write = simple_strtoul(buf, NULL, 10); + 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 (!(new_client = kmalloc(sizeof(struct i2c_client) + + sizeof(struct pcf8574_data), + GFP_KERNEL))) { + err = -ENOMEM; + goto exit; + } + + memset(new_client, 0, sizeof(struct i2c_client) + + sizeof(struct pcf8574_data)); + + data = (struct pcf8574_data *) (new_client + 1); + 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); + + new_client->id = pcf8574_id++; + init_MUTEX(&data->update_lock); + + /* 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(new_client); + 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(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 struct pcf8574_data *pcf8574_update_client(struct device *dev) +{ + struct i2c_client *client = to_i2c_client(dev); + struct pcf8574_data *data = i2c_get_clientdata(client); + + down(&data->update_lock); + dev_dbg(&client->dev, "Starting pcf8574 update\n"); + data->read = i2c_smbus_read_byte(client); + up(&data->update_lock); + + return 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 , " + "Philip Edelbrock , " + "Dan Eaton " + "and Aurelien Jarno "); +MODULE_DESCRIPTION("PCF8574 driver"); +MODULE_LICENSE("GPL"); + +module_init(pcf8574_init); +module_exit(pcf8574_exit);