drivers/i2c/chips/pcf8575.c

   1 /*
   2   pcf8575.c
   3
   4   About the PCF8575 chip: the PCF8575 is a 16-bit I/O expander for the I2C bus
   5   produced by a.o. Philips Semiconductors.
   6
   7   Copyright (C) 2006 Michael Hennerich, Analog Devices Inc.
   8   <hennerich@blackfin.uclinux.org>
   9   Based on pcf8574.c.
  10
  11   Copyright (c) 2007 Bart Van Assche <bart.vanassche@gmail.com>.
  12   Ported this driver from ucLinux to the mainstream Linux kernel.
  13
  14   This program is free software; you can redistribute it and/or modify
  15   it under the terms of the GNU General Public License as published by
  16   the Free Software Foundation; either version 2 of the License, or
  17   (at your option) any later version.
  18
  19   This program is distributed in the hope that it will be useful,
  20   but WITHOUT ANY WARRANTY; without even the implied warranty of
  21   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22   GNU General Public License for more details.
  23
  24   You should have received a copy of the GNU General Public License
  25   along with this program; if not, write to the Free Software
  26   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  27 */
  28
  29 #include <linux/module.h>
  30 #include <linux/init.h>
  31 #include <linux/i2c.h>
  32 #include <linux/slab.h>  /* kzalloc() */
  33 #include <linux/sysfs.h> /* sysfs_create_group() */
  34
  35 /* Addresses to scan */
  36 static const unsigned short normal_i2c[] = {
  37         0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
  38         I2C_CLIENT_END
  39 };
  40
  41 /* Insmod parameters */
  42 I2C_CLIENT_INSMOD;
  43
  44
  45 /* Each client has this additional data */
  46 struct pcf8575_data {
  47         struct i2c_client client;
  48         int write;              /* last written value, or error code */
  49 };
  50
  51 static int pcf8575_attach_adapter(struct i2c_adapter *adapter);
  52 static int pcf8575_detect(struct i2c_adapter *adapter, int address, int kind);
  53 static int pcf8575_detach_client(struct i2c_client *client);
  54
  55 /* This is the driver that will be inserted */
  56 static struct i2c_driver pcf8575_driver = {
  57         .driver = {
  58                 .owner  = THIS_MODULE,
  59                 .name   = "pcf8575",
  60         },
  61         .attach_adapter = pcf8575_attach_adapter,
  62         .detach_client  = pcf8575_detach_client,
  63 };
  64
  65 /* following are the sysfs callback functions */
  66 static ssize_t show_read(struct device *dev, struct device_attribute *attr,
  67                          char *buf)
  68 {
  69         struct i2c_client *client = to_i2c_client(dev);
  70         u16 val;
  71         u8 iopin_state[2];
  72
  73         i2c_master_recv(client, iopin_state, 2);
  74
  75         val = iopin_state[0];
  76         val |= iopin_state[1] << 8;
  77
  78         return sprintf(buf, "%u\n", val);
  79 }
  80
  81 static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);
  82
  83 static ssize_t show_write(struct device *dev, struct device_attribute *attr,
  84                           char *buf)
  85 {
  86         struct pcf8575_data *data = dev_get_drvdata(dev);
  87         if (data->write < 0)
  88                 return data->write;
  89         return sprintf(buf, "%d\n", data->write);
  90 }
  91
  92 static ssize_t set_write(struct device *dev, struct device_attribute *attr,
  93                          const char *buf, size_t count)
  94 {
  95         struct i2c_client *client = to_i2c_client(dev);
  96         struct pcf8575_data *data = i2c_get_clientdata(client);
  97         unsigned long val = simple_strtoul(buf, NULL, 10);
  98         u8 iopin_state[2];
  99
 100         if (val > 0xffff)
 101                 return -EINVAL;
 102
 103         data->write = val;
 104
 105         iopin_state[0] = val & 0xFF;
 106         iopin_state[1] = val >> 8;
 107
 108         i2c_master_send(client, iopin_state, 2);
 109
 110         return count;
 111 }
 112
 113 static DEVICE_ATTR(write, S_IWUSR | S_IRUGO, show_write, set_write);
 114
 115 static struct attribute *pcf8575_attributes[] = {
 116         &dev_attr_read.attr,
 117         &dev_attr_write.attr,
 118         NULL
 119 };
 120
 121 static const struct attribute_group pcf8575_attr_group = {
 122         .attrs = pcf8575_attributes,
 123 };
 124
 125 /*
 126  * Real code
 127  */
 128
 129 static int pcf8575_attach_adapter(struct i2c_adapter *adapter)
 130 {
 131         return i2c_probe(adapter, &addr_data, pcf8575_detect);
 132 }
 133
 134 /* This function is called by i2c_probe */
 135 static int pcf8575_detect(struct i2c_adapter *adapter, int address, int kind)
 136 {
 137         struct i2c_client *client;
 138         struct pcf8575_data *data;
 139         int err = 0;
 140
 141         if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
 142                 goto exit;
 143
 144         /* OK. For now, we presume we have a valid client. We now create the
 145            client structure, even though we cannot fill it completely yet. */
 146         data = kzalloc(sizeof(struct pcf8575_data), GFP_KERNEL);
 147         if (!data) {
 148                 err = -ENOMEM;
 149                 goto exit;
 150         }
 151
 152         client = &data->client;
 153         i2c_set_clientdata(client, data);
 154         client->addr = address;
 155         client->adapter = adapter;
 156         client->driver = &pcf8575_driver;
 157         strlcpy(client->name, "pcf8575", I2C_NAME_SIZE);
 158         data->write = -EAGAIN;
 159
 160         /* This is the place to detect whether the chip at the specified
 161            address really is a PCF8575 chip. However, there is no method known
 162            to detect whether an I2C chip is a PCF8575 or any other I2C chip. */
 163
 164         /* Tell the I2C layer a new client has arrived */
 165         err = i2c_attach_client(client);
 166         if (err)
 167                 goto exit_free;
 168
 169         /* Register sysfs hooks */
 170         err = sysfs_create_group(&client->dev.kobj, &pcf8575_attr_group);
 171         if (err)
 172                 goto exit_detach;
 173
 174         return 0;
 175
 176 exit_detach:
 177         i2c_detach_client(client);
 178 exit_free:
 179         kfree(data);
 180 exit:
 181         return err;
 182 }
 183
 184 static int pcf8575_detach_client(struct i2c_client *client)
 185 {
 186         int err;
 187
 188         sysfs_remove_group(&client->dev.kobj, &pcf8575_attr_group);
 189
 190         err = i2c_detach_client(client);
 191         if (err)
 192                 return err;
 193
 194         kfree(i2c_get_clientdata(client));
 195         return 0;
 196 }
 197
 198 static int __init pcf8575_init(void)
 199 {
 200         return i2c_add_driver(&pcf8575_driver);
 201 }
 202
 203 static void __exit pcf8575_exit(void)
 204 {
 205         i2c_del_driver(&pcf8575_driver);
 206 }
 207
 208 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>, "
 209               "Bart Van Assche <bart.vanassche@gmail.com>");
 210 MODULE_DESCRIPTION("pcf8575 driver");
 211 MODULE_LICENSE("GPL");
 212
 213 module_init(pcf8575_init);
 214 module_exit(pcf8575_exit);