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