1 /*
2 Copyright (c) 2000 Frodo Looijaard <frodol@dds.nl>,
3 Philip Edelbrock <phil@netroedge.com>,
4 Dan Eaton <dan.eaton@rocketlogix.com>
5 Ported to Linux 2.6 by Aurelien Jarno <aurel32@debian.org> with
6 the help of Jean Delvare <khali@linux-fr.org>
7
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
12
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23 /* A few notes about the PCF8574:
24
25 * The PCF8574 is an 8-bit I/O expander for the I2C bus produced by
26 Philips Semiconductors. It is designed to provide a byte I2C
27 interface to up to 8 separate devices.
28
29 * The PCF8574 appears as a very simple SMBus device which can be
30 read from or written to with SMBUS byte read/write accesses.
31
32 --Dan
33
34 */
35
36 #include <linux/module.h>
37 #include <linux/init.h>
38 #include <linux/slab.h>
39 #include <linux/i2c.h>
40
41 /* Addresses to scan: none, device can't be detected */
42 static const unsigned short normal_i2c[] = { I2C_CLIENT_END };
43
44 /* Insmod parameters */
45 I2C_CLIENT_INSMOD_2(pcf8574, pcf8574a);
46
47 /* Each client has this additional data */
48 struct pcf8574_data {
49 int write; /* Remember last written value */
50 };
51
52 static void pcf8574_init_client(struct i2c_client *client);
53
54 /* following are the sysfs callback functions */
show_read(struct device * dev,struct device_attribute * attr,char * buf)55 static ssize_t show_read(struct device *dev, struct device_attribute *attr, char *buf)
56 {
57 struct i2c_client *client = to_i2c_client(dev);
58 return sprintf(buf, "%u\n", i2c_smbus_read_byte(client));
59 }
60
61 static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);
62
show_write(struct device * dev,struct device_attribute * attr,char * buf)63 static ssize_t show_write(struct device *dev, struct device_attribute *attr, char *buf)
64 {
65 struct pcf8574_data *data = i2c_get_clientdata(to_i2c_client(dev));
66
67 if (data->write < 0)
68 return data->write;
69
70 return sprintf(buf, "%d\n", data->write);
71 }
72
set_write(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)73 static ssize_t set_write(struct device *dev, struct device_attribute *attr, const char *buf,
74 size_t count)
75 {
76 struct i2c_client *client = to_i2c_client(dev);
77 struct pcf8574_data *data = i2c_get_clientdata(client);
78 unsigned long val = simple_strtoul(buf, NULL, 10);
79
80 if (val > 0xff)
81 return -EINVAL;
82
83 data->write = val;
84 i2c_smbus_write_byte(client, data->write);
85 return count;
86 }
87
88 static DEVICE_ATTR(write, S_IWUSR | S_IRUGO, show_write, set_write);
89
90 static struct attribute *pcf8574_attributes[] = {
91 &dev_attr_read.attr,
92 &dev_attr_write.attr,
93 NULL
94 };
95
96 static const struct attribute_group pcf8574_attr_group = {
97 .attrs = pcf8574_attributes,
98 };
99
100 /*
101 * Real code
102 */
103
104 /* Return 0 if detection is successful, -ENODEV otherwise */
pcf8574_detect(struct i2c_client * client,int kind,struct i2c_board_info * info)105 static int pcf8574_detect(struct i2c_client *client, int kind,
106 struct i2c_board_info *info)
107 {
108 struct i2c_adapter *adapter = client->adapter;
109 const char *client_name;
110
111 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
112 return -ENODEV;
113
114 /* Now, we would do the remaining detection. But the PCF8574 is plainly
115 impossible to detect! Stupid chip. */
116
117 /* Determine the chip type */
118 if (kind <= 0) {
119 if (client->addr >= 0x38 && client->addr <= 0x3f)
120 kind = pcf8574a;
121 else
122 kind = pcf8574;
123 }
124
125 if (kind == pcf8574a)
126 client_name = "pcf8574a";
127 else
128 client_name = "pcf8574";
129 strlcpy(info->type, client_name, I2C_NAME_SIZE);
130
131 return 0;
132 }
133
pcf8574_probe(struct i2c_client * client,const struct i2c_device_id * id)134 static int pcf8574_probe(struct i2c_client *client,
135 const struct i2c_device_id *id)
136 {
137 struct pcf8574_data *data;
138 int err;
139
140 data = kzalloc(sizeof(struct pcf8574_data), GFP_KERNEL);
141 if (!data) {
142 err = -ENOMEM;
143 goto exit;
144 }
145
146 i2c_set_clientdata(client, data);
147
148 /* Initialize the PCF8574 chip */
149 pcf8574_init_client(client);
150
151 /* Register sysfs hooks */
152 err = sysfs_create_group(&client->dev.kobj, &pcf8574_attr_group);
153 if (err)
154 goto exit_free;
155 return 0;
156
157 exit_free:
158 kfree(data);
159 exit:
160 return err;
161 }
162
pcf8574_remove(struct i2c_client * client)163 static int pcf8574_remove(struct i2c_client *client)
164 {
165 sysfs_remove_group(&client->dev.kobj, &pcf8574_attr_group);
166 kfree(i2c_get_clientdata(client));
167 return 0;
168 }
169
170 /* Called when we have found a new PCF8574. */
pcf8574_init_client(struct i2c_client * client)171 static void pcf8574_init_client(struct i2c_client *client)
172 {
173 struct pcf8574_data *data = i2c_get_clientdata(client);
174 data->write = -EAGAIN;
175 }
176
177 static const struct i2c_device_id pcf8574_id[] = {
178 { "pcf8574", 0 },
179 { "pcf8574a", 0 },
180 { }
181 };
182
183 static struct i2c_driver pcf8574_driver = {
184 .driver = {
185 .name = "pcf8574",
186 },
187 .probe = pcf8574_probe,
188 .remove = pcf8574_remove,
189 .id_table = pcf8574_id,
190
191 .detect = pcf8574_detect,
192 .address_data = &addr_data,
193 };
194
pcf8574_init(void)195 static int __init pcf8574_init(void)
196 {
197 return i2c_add_driver(&pcf8574_driver);
198 }
199
pcf8574_exit(void)200 static void __exit pcf8574_exit(void)
201 {
202 i2c_del_driver(&pcf8574_driver);
203 }
204
205
206 MODULE_AUTHOR
207 ("Frodo Looijaard <frodol@dds.nl>, "
208 "Philip Edelbrock <phil@netroedge.com>, "
209 "Dan Eaton <dan.eaton@rocketlogix.com> "
210 "and Aurelien Jarno <aurelien@aurel32.net>");
211 MODULE_DESCRIPTION("PCF8574 driver");
212 MODULE_LICENSE("GPL");
213
214 module_init(pcf8574_init);
215 module_exit(pcf8574_exit);
216