![Jean Delvare](/assets/img/avatar_default.png)
The new-style pcf8575 driver implements the optional detect() callback to cover the use cases of the legacy driver. Warning: users will now have to use the force module parameter to get the driver to attach to their device. That's not a bad thing as these devices can't be detected anyway. Note that this doesn't change the fact that this driver is deprecated in favor of gpio/pcf857x. Signed-off-by: Jean Delvare <khali@linux-fr.org>
199 lines
4.7 KiB
C
199 lines
4.7 KiB
C
/*
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pcf8575.c
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About the PCF8575 chip: the PCF8575 is a 16-bit I/O expander for the I2C bus
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produced by a.o. Philips Semiconductors.
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Copyright (C) 2006 Michael Hennerich, Analog Devices Inc.
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<hennerich@blackfin.uclinux.org>
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Based on pcf8574.c.
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Copyright (c) 2007 Bart Van Assche <bart.vanassche@gmail.com>.
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Ported this driver from ucLinux to the mainstream Linux kernel.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/i2c.h>
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#include <linux/slab.h> /* kzalloc() */
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#include <linux/sysfs.h> /* sysfs_create_group() */
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/* Addresses to scan: none, device can't be detected */
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static const unsigned short normal_i2c[] = { I2C_CLIENT_END };
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/* Insmod parameters */
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I2C_CLIENT_INSMOD;
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/* Each client has this additional data */
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struct pcf8575_data {
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int write; /* last written value, or error code */
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};
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/* following are the sysfs callback functions */
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static ssize_t show_read(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct i2c_client *client = to_i2c_client(dev);
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u16 val;
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u8 iopin_state[2];
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i2c_master_recv(client, iopin_state, 2);
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val = iopin_state[0];
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val |= iopin_state[1] << 8;
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return sprintf(buf, "%u\n", val);
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}
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static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);
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static ssize_t show_write(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct pcf8575_data *data = dev_get_drvdata(dev);
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if (data->write < 0)
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return data->write;
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return sprintf(buf, "%d\n", data->write);
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}
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static ssize_t set_write(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct pcf8575_data *data = i2c_get_clientdata(client);
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unsigned long val = simple_strtoul(buf, NULL, 10);
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u8 iopin_state[2];
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if (val > 0xffff)
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return -EINVAL;
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data->write = val;
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iopin_state[0] = val & 0xFF;
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iopin_state[1] = val >> 8;
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i2c_master_send(client, iopin_state, 2);
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return count;
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}
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static DEVICE_ATTR(write, S_IWUSR | S_IRUGO, show_write, set_write);
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static struct attribute *pcf8575_attributes[] = {
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&dev_attr_read.attr,
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&dev_attr_write.attr,
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NULL
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};
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static const struct attribute_group pcf8575_attr_group = {
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.attrs = pcf8575_attributes,
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};
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/*
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* Real code
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*/
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/* Return 0 if detection is successful, -ENODEV otherwise */
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static int pcf8575_detect(struct i2c_client *client, int kind,
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struct i2c_board_info *info)
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{
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struct i2c_adapter *adapter = client->adapter;
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if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
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return -ENODEV;
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/* This is the place to detect whether the chip at the specified
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address really is a PCF8575 chip. However, there is no method known
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to detect whether an I2C chip is a PCF8575 or any other I2C chip. */
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strlcpy(info->type, "pcf8575", I2C_NAME_SIZE);
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return 0;
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}
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static int pcf8575_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct pcf8575_data *data;
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int err;
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data = kzalloc(sizeof(struct pcf8575_data), GFP_KERNEL);
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if (!data) {
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err = -ENOMEM;
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goto exit;
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}
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i2c_set_clientdata(client, data);
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data->write = -EAGAIN;
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/* Register sysfs hooks */
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err = sysfs_create_group(&client->dev.kobj, &pcf8575_attr_group);
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if (err)
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goto exit_free;
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return 0;
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exit_free:
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kfree(data);
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exit:
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return err;
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}
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static int pcf8575_remove(struct i2c_client *client)
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{
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sysfs_remove_group(&client->dev.kobj, &pcf8575_attr_group);
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kfree(i2c_get_clientdata(client));
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return 0;
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}
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static const struct i2c_device_id pcf8575_id[] = {
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{ "pcf8575", 0 },
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{ }
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};
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static struct i2c_driver pcf8575_driver = {
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.driver = {
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.owner = THIS_MODULE,
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.name = "pcf8575",
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},
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.probe = pcf8575_probe,
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.remove = pcf8575_remove,
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.id_table = pcf8575_id,
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.detect = pcf8575_detect,
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.address_data = &addr_data,
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};
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static int __init pcf8575_init(void)
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{
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return i2c_add_driver(&pcf8575_driver);
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}
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static void __exit pcf8575_exit(void)
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{
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i2c_del_driver(&pcf8575_driver);
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}
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MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>, "
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"Bart Van Assche <bart.vanassche@gmail.com>");
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MODULE_DESCRIPTION("pcf8575 driver");
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MODULE_LICENSE("GPL");
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module_init(pcf8575_init);
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module_exit(pcf8575_exit);
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