drivers/hwmon/ads1015.c

   1 /*
   2  * ads1015.c - lm_sensors driver for ads1015 12-bit 4-input ADC
   3  * (C) Copyright 2010
   4  * Dirk Eibach, Guntermann & Drunck GmbH <eibach@gdsys.de>
   5  *
   6  * Based on the ads7828 driver by Steve Hardy.
   7  *
   8  * Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads1015.pdf
   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 #include <linux/module.h>
  26 #include <linux/init.h>
  27 #include <linux/slab.h>
  28 #include <linux/delay.h>
  29 #include <linux/i2c.h>
  30 #include <linux/hwmon.h>
  31 #include <linux/hwmon-sysfs.h>
  32 #include <linux/err.h>
  33 #include <linux/mutex.h>
  34 #include <linux/of.h>
  35
  36 #include <linux/i2c/ads1015.h>
  37
  38 /* ADS1015 registers */
  39 enum {
  40         ADS1015_CONVERSION = 0,
  41         ADS1015_CONFIG = 1,
  42 };
  43
  44 /* PGA fullscale voltages in mV */
  45 static const unsigned int fullscale_table[8] = {
  46         6144, 4096, 2048, 1024, 512, 256, 256, 256 };
  47
  48 /* Data rates in samples per second */
  49 static const unsigned int data_rate_table[8] = {
  50         128, 250, 490, 920, 1600, 2400, 3300, 3300 };
  51
  52 #define ADS1015_DEFAULT_CHANNELS 0xff
  53 #define ADS1015_DEFAULT_PGA 2
  54 #define ADS1015_DEFAULT_DATA_RATE 4
  55
  56 struct ads1015_data {
  57         struct device *hwmon_dev;
  58         struct mutex update_lock; /* mutex protect updates */
  59         struct ads1015_channel_data channel_data[ADS1015_CHANNELS];
  60 };
  61
  62 static s32 ads1015_read_reg(struct i2c_client *client, unsigned int reg)
  63 {
  64         s32 data = i2c_smbus_read_word_data(client, reg);
  65
  66         return (data < 0) ? data : swab16(data);
  67 }
  68
  69 static s32 ads1015_write_reg(struct i2c_client *client, unsigned int reg,
  70                              u16 val)
  71 {
  72         return i2c_smbus_write_word_data(client, reg, swab16(val));
  73 }
  74
  75 static int ads1015_read_value(struct i2c_client *client, unsigned int channel,
  76                               int *value)
  77 {
  78         u16 config;
  79         s16 conversion;
  80         struct ads1015_data *data = i2c_get_clientdata(client);
  81         unsigned int pga = data->channel_data[channel].pga;
  82         int fullscale;
  83         unsigned int data_rate = data->channel_data[channel].data_rate;
  84         unsigned int conversion_time_ms;
  85         int res;
  86
  87         mutex_lock(&data->update_lock);
  88
  89         /* get channel parameters */
  90         res = ads1015_read_reg(client, ADS1015_CONFIG);
  91         if (res < 0)
  92                 goto err_unlock;
  93         config = res;
  94         fullscale = fullscale_table[pga];
  95         conversion_time_ms = DIV_ROUND_UP(1000, data_rate_table[data_rate]);
  96
  97         /* setup and start single conversion */
  98         config &= 0x001f;
  99         config |= (1 << 15) | (1 << 8);
 100         config |= (channel & 0x0007) << 12;
 101         config |= (pga & 0x0007) << 9;
 102         config |= (data_rate & 0x0007) << 5;
 103
 104         res = ads1015_write_reg(client, ADS1015_CONFIG, config);
 105         if (res < 0)
 106                 goto err_unlock;
 107
 108         /* wait until conversion finished */
 109         msleep(conversion_time_ms);
 110         res = ads1015_read_reg(client, ADS1015_CONFIG);
 111         if (res < 0)
 112                 goto err_unlock;
 113         config = res;
 114         if (!(config & (1 << 15))) {
 115                 /* conversion not finished in time */
 116                 res = -EIO;
 117                 goto err_unlock;
 118         }
 119
 120         res = ads1015_read_reg(client, ADS1015_CONVERSION);
 121         if (res < 0)
 122                 goto err_unlock;
 123         conversion = res;
 124
 125         mutex_unlock(&data->update_lock);
 126
 127         *value = DIV_ROUND_CLOSEST(conversion * fullscale, 0x7ff0);
 128
 129         return 0;
 130
 131 err_unlock:
 132         mutex_unlock(&data->update_lock);
 133         return res;
 134 }
 135
 136 /* sysfs callback function */
 137 static ssize_t show_in(struct device *dev, struct device_attribute *da,
 138         char *buf)
 139 {
 140         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 141         struct i2c_client *client = to_i2c_client(dev);
 142         int in;
 143         int res;
 144
 145         res = ads1015_read_value(client, attr->index, &in);
 146
 147         return (res < 0) ? res : sprintf(buf, "%d\n", in);
 148 }
 149
 150 static const struct sensor_device_attribute ads1015_in[] = {
 151         SENSOR_ATTR(in0_input, S_IRUGO, show_in, NULL, 0),
 152         SENSOR_ATTR(in1_input, S_IRUGO, show_in, NULL, 1),
 153         SENSOR_ATTR(in2_input, S_IRUGO, show_in, NULL, 2),
 154         SENSOR_ATTR(in3_input, S_IRUGO, show_in, NULL, 3),
 155         SENSOR_ATTR(in4_input, S_IRUGO, show_in, NULL, 4),
 156         SENSOR_ATTR(in5_input, S_IRUGO, show_in, NULL, 5),
 157         SENSOR_ATTR(in6_input, S_IRUGO, show_in, NULL, 6),
 158         SENSOR_ATTR(in7_input, S_IRUGO, show_in, NULL, 7),
 159 };
 160
 161 /*
 162  * Driver interface
 163  */
 164
 165 static int ads1015_remove(struct i2c_client *client)
 166 {
 167         struct ads1015_data *data = i2c_get_clientdata(client);
 168         int k;
 169
 170         hwmon_device_unregister(data->hwmon_dev);
 171         for (k = 0; k < ADS1015_CHANNELS; ++k)
 172                 device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
 173         kfree(data);
 174         return 0;
 175 }
 176
 177 #ifdef CONFIG_OF
 178 static int ads1015_get_channels_config_of(struct i2c_client *client)
 179 {
 180         struct ads1015_data *data = i2c_get_clientdata(client);
 181         struct device_node *node;
 182
 183         if (!client->dev.of_node
 184             || !of_get_next_child(client->dev.of_node, NULL))
 185                 return -EINVAL;
 186
 187         for_each_child_of_node(client->dev.of_node, node) {
 188                 const __be32 *property;
 189                 int len;
 190                 unsigned int channel;
 191                 unsigned int pga = ADS1015_DEFAULT_PGA;
 192                 unsigned int data_rate = ADS1015_DEFAULT_DATA_RATE;
 193
 194                 property = of_get_property(node, "reg", &len);
 195                 if (!property || len != sizeof(int)) {
 196                         dev_err(&client->dev, "invalid reg on %s\n",
 197                                 node->full_name);
 198                         continue;
 199                 }
 200
 201                 channel = be32_to_cpup(property);
 202                 if (channel > ADS1015_CHANNELS) {
 203                         dev_err(&client->dev,
 204                                 "invalid channel index %d on %s\n",
 205                                 channel, node->full_name);
 206                         continue;
 207                 }
 208
 209                 property = of_get_property(node, "ti,gain", &len);
 210                 if (property && len == sizeof(int)) {
 211                         pga = be32_to_cpup(property);
 212                         if (pga > 6) {
 213                                 dev_err(&client->dev,
 214                                         "invalid gain on %s\n",
 215                                         node->full_name);
 216                         }
 217                 }
 218
 219                 property = of_get_property(node, "ti,datarate", &len);
 220                 if (property && len == sizeof(int)) {
 221                         data_rate = be32_to_cpup(property);
 222                         if (data_rate > 7) {
 223                                 dev_err(&client->dev,
 224                                         "invalid data_rate on %s\n",
 225                                         node->full_name);
 226                         }
 227                 }
 228
 229                 data->channel_data[channel].enabled = true;
 230                 data->channel_data[channel].pga = pga;
 231                 data->channel_data[channel].data_rate = data_rate;
 232         }
 233
 234         return 0;
 235 }
 236 #endif
 237
 238 static void ads1015_get_channels_config(struct i2c_client *client)
 239 {
 240         unsigned int k;
 241         struct ads1015_data *data = i2c_get_clientdata(client);
 242         struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);
 243
 244         /* prefer platform data */
 245         if (pdata) {
 246                 memcpy(data->channel_data, pdata->channel_data,
 247                        sizeof(data->channel_data));
 248                 return;
 249         }
 250
 251 #ifdef CONFIG_OF
 252         if (!ads1015_get_channels_config_of(client))
 253                 return;
 254 #endif
 255
 256         /* fallback on default configuration */
 257         for (k = 0; k < ADS1015_CHANNELS; ++k) {
 258                 data->channel_data[k].enabled = true;
 259                 data->channel_data[k].pga = ADS1015_DEFAULT_PGA;
 260                 data->channel_data[k].data_rate = ADS1015_DEFAULT_DATA_RATE;
 261         }
 262 }
 263
 264 static int ads1015_probe(struct i2c_client *client,
 265                          const struct i2c_device_id *id)
 266 {
 267         struct ads1015_data *data;
 268         int err;
 269         unsigned int k;
 270
 271         data = kzalloc(sizeof(struct ads1015_data), GFP_KERNEL);
 272         if (!data) {
 273                 err = -ENOMEM;
 274                 goto exit;
 275         }
 276
 277         i2c_set_clientdata(client, data);
 278         mutex_init(&data->update_lock);
 279
 280         /* build sysfs attribute group */
 281         ads1015_get_channels_config(client);
 282         for (k = 0; k < ADS1015_CHANNELS; ++k) {
 283                 if (!data->channel_data[k].enabled)
 284                         continue;
 285                 err = device_create_file(&client->dev, &ads1015_in[k].dev_attr);
 286                 if (err)
 287                         goto exit_free;
 288         }
 289
 290         data->hwmon_dev = hwmon_device_register(&client->dev);
 291         if (IS_ERR(data->hwmon_dev)) {
 292                 err = PTR_ERR(data->hwmon_dev);
 293                 goto exit_remove;
 294         }
 295
 296         return 0;
 297
 298 exit_remove:
 299         for (k = 0; k < ADS1015_CHANNELS; ++k)
 300                 device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
 301 exit_free:
 302         kfree(data);
 303 exit:
 304         return err;
 305 }
 306
 307 static const struct i2c_device_id ads1015_id[] = {
 308         { "ads1015", 0 },
 309         { }
 310 };
 311 MODULE_DEVICE_TABLE(i2c, ads1015_id);
 312
 313 static struct i2c_driver ads1015_driver = {
 314         .driver = {
 315                 .name = "ads1015",
 316         },
 317         .probe = ads1015_probe,
 318         .remove = ads1015_remove,
 319         .id_table = ads1015_id,
 320 };
 321
 322 static int __init sensors_ads1015_init(void)
 323 {
 324         return i2c_add_driver(&ads1015_driver);
 325 }
 326
 327 static void __exit sensors_ads1015_exit(void)
 328 {
 329         i2c_del_driver(&ads1015_driver);
 330 }
 331
 332 MODULE_AUTHOR("Dirk Eibach <eibach@gdsys.de>");
 333 MODULE_DESCRIPTION("ADS1015 driver");
 334 MODULE_LICENSE("GPL");
 335
 336 module_init(sensors_ads1015_init);
 337 module_exit(sensors_ads1015_exit);