kernel-ark/drivers/i2c/chips/pcf8574.c
Jean Delvare 7d9db67feb i2c: __must_check fixes (chip drivers)
i2c: __must_check fixes (chip drivers)

Check for error on sysfs file creation.
Delete sysfs files on device removal.

The approach taken for the most complex case (pcf8591) is similar to
what Mark M. Hoffman proposed for hardware monitoring chip drivers.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Ben Gardner <bgardner@wabtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-09-26 15:38:51 -07:00

234 lines
6.3 KiB
C

/*
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);
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
*/
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 */
err = sysfs_create_group(&new_client->dev.kobj, &pcf8574_attr_group);
if (err)
goto exit_detach;
return 0;
exit_detach:
i2c_detach_client(new_client);
exit_free:
kfree(data);
exit:
return err;
}
static int pcf8574_detach_client(struct i2c_client *client)
{
int err;
sysfs_remove_group(&client->dev.kobj, &pcf8574_attr_group);
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);