drivers/i2c/chips/pcf8591.c

   1 /*
   2     pcf8591.c - Part of lm_sensors, Linux kernel modules for hardware
   3                 monitoring
   4     Copyright (C) 2001-2004 Aurelien Jarno <aurelien@aurel32.net>
   5     Ported to Linux 2.6 by Aurelien Jarno <aurelien@aurel32.net> 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 #include <linux/module.h>
  24 #include <linux/init.h>
  25 #include <linux/slab.h>
  26 #include <linux/i2c.h>
  27 #include <linux/mutex.h>
  28
  29 /* Addresses to scan */
  30 static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
  31                                         0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
  32
  33 /* Insmod parameters */
  34 I2C_CLIENT_INSMOD_1(pcf8591);
  35
  36 static int input_mode;
  37 module_param(input_mode, int, 0);
  38 MODULE_PARM_DESC(input_mode,
  39         "Analog input mode:\n"
  40         " 0 = four single ended inputs\n"
  41         " 1 = three differential inputs\n"
  42         " 2 = single ended and differential mixed\n"
  43         " 3 = two differential inputs\n");
  44
  45 /* The PCF8591 control byte
  46       7    6    5    4    3    2    1    0
  47    |  0 |AOEF|   AIP   |  0 |AINC|  AICH   | */
  48
  49 /* Analog Output Enable Flag (analog output active if 1) */
  50 #define PCF8591_CONTROL_AOEF            0x40
  51
  52 /* Analog Input Programming
  53    0x00 = four single ended inputs
  54    0x10 = three differential inputs
  55    0x20 = single ended and differential mixed
  56    0x30 = two differential inputs */
  57 #define PCF8591_CONTROL_AIP_MASK        0x30
  58
  59 /* Autoincrement Flag (switch on if 1) */
  60 #define PCF8591_CONTROL_AINC            0x04
  61
  62 /* Channel selection
  63    0x00 = channel 0
  64    0x01 = channel 1
  65    0x02 = channel 2
  66    0x03 = channel 3 */
  67 #define PCF8591_CONTROL_AICH_MASK       0x03
  68
  69 /* Initial values */
  70 #define PCF8591_INIT_CONTROL    ((input_mode << 4) | PCF8591_CONTROL_AOEF)
  71 #define PCF8591_INIT_AOUT       0       /* DAC out = 0 */
  72
  73 /* Conversions */
  74 #define REG_TO_SIGNED(reg)      (((reg) & 0x80)?((reg) - 256):(reg))
  75
  76 struct pcf8591_data {
  77         struct i2c_client client;
  78         struct mutex update_lock;
  79
  80         u8 control;
  81         u8 aout;
  82 };
  83
  84 static int pcf8591_attach_adapter(struct i2c_adapter *adapter);
  85 static int pcf8591_detect(struct i2c_adapter *adapter, int address, int kind);
  86 static int pcf8591_detach_client(struct i2c_client *client);
  87 static void pcf8591_init_client(struct i2c_client *client);
  88 static int pcf8591_read_channel(struct device *dev, int channel);
  89
  90 /* This is the driver that will be inserted */
  91 static struct i2c_driver pcf8591_driver = {
  92         .driver = {
  93                 .name   = "pcf8591",
  94         },
  95         .id             = I2C_DRIVERID_PCF8591,
  96         .attach_adapter = pcf8591_attach_adapter,
  97         .detach_client  = pcf8591_detach_client,
  98 };
  99
 100 /* following are the sysfs callback functions */
 101 #define show_in_channel(channel)                                        \
 102 static ssize_t show_in##channel##_input(struct device *dev, struct device_attribute *attr, char *buf)   \
 103 {                                                                       \
 104         return sprintf(buf, "%d\n", pcf8591_read_channel(dev, channel));\
 105 }                                                                       \
 106 static DEVICE_ATTR(in##channel##_input, S_IRUGO,                        \
 107                    show_in##channel##_input, NULL);
 108
 109 show_in_channel(0);
 110 show_in_channel(1);
 111 show_in_channel(2);
 112 show_in_channel(3);
 113
 114 static ssize_t show_out0_ouput(struct device *dev, struct device_attribute *attr, char *buf)
 115 {
 116         struct pcf8591_data *data = i2c_get_clientdata(to_i2c_client(dev));
 117         return sprintf(buf, "%d\n", data->aout * 10);
 118 }
 119
 120 static ssize_t set_out0_output(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 121 {
 122         unsigned int value;
 123         struct i2c_client *client = to_i2c_client(dev);
 124         struct pcf8591_data *data = i2c_get_clientdata(client);
 125         if ((value = (simple_strtoul(buf, NULL, 10) + 5) / 10) <= 255) {
 126                 data->aout = value;
 127                 i2c_smbus_write_byte_data(client, data->control, data->aout);
 128                 return count;
 129         }
 130         return -EINVAL;
 131 }
 132
 133 static DEVICE_ATTR(out0_output, S_IWUSR | S_IRUGO,
 134                    show_out0_ouput, set_out0_output);
 135
 136 static ssize_t show_out0_enable(struct device *dev, struct device_attribute *attr, char *buf)
 137 {
 138         struct pcf8591_data *data = i2c_get_clientdata(to_i2c_client(dev));
 139         return sprintf(buf, "%u\n", !(!(data->control & PCF8591_CONTROL_AOEF)));
 140 }
 141
 142 static ssize_t set_out0_enable(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 143 {
 144         struct i2c_client *client = to_i2c_client(dev);
 145         struct pcf8591_data *data = i2c_get_clientdata(client);
 146         unsigned long val = simple_strtoul(buf, NULL, 10);
 147
 148         mutex_lock(&data->update_lock);
 149         if (val)
 150                 data->control |= PCF8591_CONTROL_AOEF;
 151         else
 152                 data->control &= ~PCF8591_CONTROL_AOEF;
 153         i2c_smbus_write_byte(client, data->control);
 154         mutex_unlock(&data->update_lock);
 155         return count;
 156 }
 157
 158 static DEVICE_ATTR(out0_enable, S_IWUSR | S_IRUGO,
 159                    show_out0_enable, set_out0_enable);
 160
 161 /*
 162  * Real code
 163  */
 164 static int pcf8591_attach_adapter(struct i2c_adapter *adapter)
 165 {
 166         return i2c_probe(adapter, &addr_data, pcf8591_detect);
 167 }
 168
 169 /* This function is called by i2c_probe */
 170 static int pcf8591_detect(struct i2c_adapter *adapter, int address, int kind)
 171 {
 172         struct i2c_client *new_client;
 173         struct pcf8591_data *data;
 174         int err = 0;
 175
 176         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE
 177                                      | I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
 178                 goto exit;
 179
 180         /* OK. For now, we presume we have a valid client. We now create the
 181            client structure, even though we cannot fill it completely yet. */
 182         if (!(data = kzalloc(sizeof(struct pcf8591_data), GFP_KERNEL))) {
 183                 err = -ENOMEM;
 184                 goto exit;
 185         }
 186
 187         new_client = &data->client;
 188         i2c_set_clientdata(new_client, data);
 189         new_client->addr = address;
 190         new_client->adapter = adapter;
 191         new_client->driver = &pcf8591_driver;
 192         new_client->flags = 0;
 193
 194         /* Now, we would do the remaining detection. But the PCF8591 is plainly
 195            impossible to detect! Stupid chip. */
 196
 197         /* Determine the chip type - only one kind supported! */
 198         if (kind <= 0)
 199                 kind = pcf8591;
 200
 201         /* Fill in the remaining client fields and put it into the global
 202            list */
 203         strlcpy(new_client->name, "pcf8591", I2C_NAME_SIZE);
 204         mutex_init(&data->update_lock);
 205
 206         /* Tell the I2C layer a new client has arrived */
 207         if ((err = i2c_attach_client(new_client)))
 208                 goto exit_kfree;
 209
 210         /* Initialize the PCF8591 chip */
 211         pcf8591_init_client(new_client);
 212
 213         /* Register sysfs hooks */
 214         device_create_file(&new_client->dev, &dev_attr_out0_enable);
 215         device_create_file(&new_client->dev, &dev_attr_out0_output);
 216         device_create_file(&new_client->dev, &dev_attr_in0_input);
 217         device_create_file(&new_client->dev, &dev_attr_in1_input);
 218
 219         /* Register input2 if not in "two differential inputs" mode */
 220         if (input_mode != 3 )
 221                 device_create_file(&new_client->dev, &dev_attr_in2_input);
 222
 223         /* Register input3 only in "four single ended inputs" mode */
 224         if (input_mode == 0)
 225                 device_create_file(&new_client->dev, &dev_attr_in3_input);
 226
 227         return 0;
 228
 229         /* OK, this is not exactly good programming practice, usually. But it is
 230            very code-efficient in this case. */
 231
 232 exit_kfree:
 233         kfree(data);
 234 exit:
 235         return err;
 236 }
 237
 238 static int pcf8591_detach_client(struct i2c_client *client)
 239 {
 240         int err;
 241
 242         if ((err = i2c_detach_client(client)))
 243                 return err;
 244
 245         kfree(i2c_get_clientdata(client));
 246         return 0;
 247 }
 248
 249 /* Called when we have found a new PCF8591. */
 250 static void pcf8591_init_client(struct i2c_client *client)
 251 {
 252         struct pcf8591_data *data = i2c_get_clientdata(client);
 253         data->control = PCF8591_INIT_CONTROL;
 254         data->aout = PCF8591_INIT_AOUT;
 255
 256         i2c_smbus_write_byte_data(client, data->control, data->aout);
 257
 258         /* The first byte transmitted contains the conversion code of the
 259            previous read cycle. FLUSH IT! */
 260         i2c_smbus_read_byte(client);
 261 }
 262
 263 static int pcf8591_read_channel(struct device *dev, int channel)
 264 {
 265         u8 value;
 266         struct i2c_client *client = to_i2c_client(dev);
 267         struct pcf8591_data *data = i2c_get_clientdata(client);
 268
 269         mutex_lock(&data->update_lock);
 270
 271         if ((data->control & PCF8591_CONTROL_AICH_MASK) != channel) {
 272                 data->control = (data->control & ~PCF8591_CONTROL_AICH_MASK)
 273                               | channel;
 274                 i2c_smbus_write_byte(client, data->control);
 275
 276                 /* The first byte transmitted contains the conversion code of
 277                    the previous read cycle. FLUSH IT! */
 278                 i2c_smbus_read_byte(client);
 279         }
 280         value = i2c_smbus_read_byte(client);
 281
 282         mutex_unlock(&data->update_lock);
 283
 284         if ((channel == 2 && input_mode == 2) ||
 285             (channel != 3 && (input_mode == 1 || input_mode == 3)))
 286                 return (10 * REG_TO_SIGNED(value));
 287         else
 288                 return (10 * value);
 289 }
 290
 291 static int __init pcf8591_init(void)
 292 {
 293         if (input_mode < 0 || input_mode > 3) {
 294                 printk(KERN_WARNING "pcf8591: invalid input_mode (%d)\n",
 295                        input_mode);
 296                 input_mode = 0;
 297         }
 298         return i2c_add_driver(&pcf8591_driver);
 299 }
 300
 301 static void __exit pcf8591_exit(void)
 302 {
 303         i2c_del_driver(&pcf8591_driver);
 304 }
 305
 306 MODULE_AUTHOR("Aurelien Jarno <aurelien@aurel32.net>");
 307 MODULE_DESCRIPTION("PCF8591 driver");
 308 MODULE_LICENSE("GPL");
 309
 310 module_init(pcf8591_init);
 311 module_exit(pcf8591_exit);