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-rw-r--r--drivers/i2c/chips/pcf8574.c215
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);
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