1/*
2    pcf8574.c - Part of lm_sensors, Linux kernel modules for hardware
3             monitoring
4    Copyright (c) 2000  Frodo Looijaard <frodol@dds.nl>,
5                        Philip Edelbrock <phil@netroedge.com>,
6                        Dan Eaton <dan.eaton@rocketlogix.com>
7    Ported to Linux 2.6 by Aurelien Jarno <aurel32@debian.org> with
8    the help of Jean Delvare <khali@linux-fr.org>
9
10    This program is free software; you can redistribute it and/or modify
11    it under the terms of the GNU General Public License as published by
12    the Free Software Foundation; either version 2 of the License, or
13    (at your option) any later version.
14
15    This program is distributed in the hope that it will be useful,
16    but WITHOUT ANY WARRANTY; without even the implied warranty of
17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18    GNU General Public License for more details.
19
20    You should have received a copy of the GNU General Public License
21    along with this program; if not, write to the Free Software
22    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23*/
24
25/* A few notes about the PCF8574:
26
27* The PCF8574 is an 8-bit I/O expander for the I2C bus produced by
28  Philips Semiconductors.  It is designed to provide a byte I2C
29  interface to up to 8 separate devices.
30
31* The PCF8574 appears as a very simple SMBus device which can be
32  read from or written to with SMBUS byte read/write accesses.
33
34  --Dan
35
36*/
37
38#include <linux/module.h>
39#include <linux/init.h>
40#include <linux/slab.h>
41#include <linux/i2c.h>
42
43/* Addresses to scan */
44static unsigned short normal_i2c[] = { 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
45					0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
46					I2C_CLIENT_END };
47
48/* Insmod parameters */
49I2C_CLIENT_INSMOD_2(pcf8574, pcf8574a);
50
51/* Initial values */
52#define PCF8574_INIT 255	/* All outputs on (input mode) */
53
54/* Each client has this additional data */
55struct pcf8574_data {
56	struct i2c_client client;
57
58	u8 write;			/* Remember last written value */
59};
60
61static int pcf8574_attach_adapter(struct i2c_adapter *adapter);
62static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind);
63static int pcf8574_detach_client(struct i2c_client *client);
64static void pcf8574_init_client(struct i2c_client *client);
65
66/* This is the driver that will be inserted */
67static struct i2c_driver pcf8574_driver = {
68	.driver = {
69		.name	= "pcf8574",
70	},
71	.id		= I2C_DRIVERID_PCF8574,
72	.attach_adapter	= pcf8574_attach_adapter,
73	.detach_client	= pcf8574_detach_client,
74};
75
76/* following are the sysfs callback functions */
77static ssize_t show_read(struct device *dev, struct device_attribute *attr, char *buf)
78{
79	struct i2c_client *client = to_i2c_client(dev);
80	return sprintf(buf, "%u\n", i2c_smbus_read_byte(client));
81}
82
83static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);
84
85static ssize_t show_write(struct device *dev, struct device_attribute *attr, char *buf)
86{
87	struct pcf8574_data *data = i2c_get_clientdata(to_i2c_client(dev));
88	return sprintf(buf, "%u\n", data->write);
89}
90
91static ssize_t set_write(struct device *dev, struct device_attribute *attr, const char *buf,
92			 size_t count)
93{
94	struct i2c_client *client = to_i2c_client(dev);
95	struct pcf8574_data *data = i2c_get_clientdata(client);
96	unsigned long val = simple_strtoul(buf, NULL, 10);
97
98	if (val > 0xff)
99		return -EINVAL;
100
101	data->write = val;
102	i2c_smbus_write_byte(client, data->write);
103	return count;
104}
105
106static DEVICE_ATTR(write, S_IWUSR | S_IRUGO, show_write, set_write);
107
108static struct attribute *pcf8574_attributes[] = {
109	&dev_attr_read.attr,
110	&dev_attr_write.attr,
111	NULL
112};
113
114static const struct attribute_group pcf8574_attr_group = {
115	.attrs = pcf8574_attributes,
116};
117
118/*
119 * Real code
120 */
121
122static int pcf8574_attach_adapter(struct i2c_adapter *adapter)
123{
124	return i2c_probe(adapter, &addr_data, pcf8574_detect);
125}
126
127/* This function is called by i2c_probe */
128static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind)
129{
130	struct i2c_client *new_client;
131	struct pcf8574_data *data;
132	int err = 0;
133	const char *client_name = "";
134
135	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
136		goto exit;
137
138	/* OK. For now, we presume we have a valid client. We now create the
139	   client structure, even though we cannot fill it completely yet. */
140	if (!(data = kzalloc(sizeof(struct pcf8574_data), GFP_KERNEL))) {
141		err = -ENOMEM;
142		goto exit;
143	}
144
145	new_client = &data->client;
146	i2c_set_clientdata(new_client, data);
147	new_client->addr = address;
148	new_client->adapter = adapter;
149	new_client->driver = &pcf8574_driver;
150	new_client->flags = 0;
151
152	/* Now, we would do the remaining detection. But the PCF8574 is plainly
153	   impossible to detect! Stupid chip. */
154
155	/* Determine the chip type */
156	if (kind <= 0) {
157		if (address >= 0x38 && address <= 0x3f)
158			kind = pcf8574a;
159		else
160			kind = pcf8574;
161	}
162
163	if (kind == pcf8574a)
164		client_name = "pcf8574a";
165	else
166		client_name = "pcf8574";
167
168	/* Fill in the remaining client fields and put it into the global list */
169	strlcpy(new_client->name, client_name, I2C_NAME_SIZE);
170
171	/* Tell the I2C layer a new client has arrived */
172	if ((err = i2c_attach_client(new_client)))
173		goto exit_free;
174
175	/* Initialize the PCF8574 chip */
176	pcf8574_init_client(new_client);
177
178	/* Register sysfs hooks */
179	err = sysfs_create_group(&new_client->dev.kobj, &pcf8574_attr_group);
180	if (err)
181		goto exit_detach;
182	return 0;
183
184      exit_detach:
185	i2c_detach_client(new_client);
186      exit_free:
187	kfree(data);
188      exit:
189	return err;
190}
191
192static int pcf8574_detach_client(struct i2c_client *client)
193{
194	int err;
195
196	sysfs_remove_group(&client->dev.kobj, &pcf8574_attr_group);
197
198	if ((err = i2c_detach_client(client)))
199		return err;
200
201	kfree(i2c_get_clientdata(client));
202	return 0;
203}
204
205/* Called when we have found a new PCF8574. */
206static void pcf8574_init_client(struct i2c_client *client)
207{
208	struct pcf8574_data *data = i2c_get_clientdata(client);
209	data->write = PCF8574_INIT;
210	i2c_smbus_write_byte(client, data->write);
211}
212
213static int __init pcf8574_init(void)
214{
215	return i2c_add_driver(&pcf8574_driver);
216}
217
218static void __exit pcf8574_exit(void)
219{
220	i2c_del_driver(&pcf8574_driver);
221}
222
223
224MODULE_AUTHOR
225    ("Frodo Looijaard <frodol@dds.nl>, "
226     "Philip Edelbrock <phil@netroedge.com>, "
227     "Dan Eaton <dan.eaton@rocketlogix.com> "
228     "and Aurelien Jarno <aurelien@aurel32.net>");
229MODULE_DESCRIPTION("PCF8574 driver");
230MODULE_LICENSE("GPL");
231
232module_init(pcf8574_init);
233module_exit(pcf8574_exit);
234