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 int ads1015_read_adc(struct i2c_client *client, unsigned int channel)
  63 {
  64         u16 config;
  65         struct ads1015_data *data = i2c_get_clientdata(client);
  66         unsigned int pga = data->channel_data[channel].pga;
  67         unsigned int data_rate = data->channel_data[channel].data_rate;
  68         unsigned int conversion_time_ms;
  69         int res;
  70
  71         mutex_lock(&data->update_lock);
  72
  73         /* get channel parameters */
  74         res = i2c_smbus_read_word_swapped(client, ADS1015_CONFIG);
  75         if (res < 0)
  76                 goto err_unlock;
  77         config = res;
  78         conversion_time_ms = DIV_ROUND_UP(1000, data_rate_table[data_rate]);
  79
  80         /* setup and start single conversion */
  81         config &= 0x001f;
  82         config |= (1 << 15) | (1 << 8);
  83         config |= (channel & 0x0007) << 12;
  84         config |= (pga & 0x0007) << 9;
  85         config |= (data_rate & 0x0007) << 5;
  86
  87         res = i2c_smbus_write_word_swapped(client, ADS1015_CONFIG, config);
  88         if (res < 0)
  89                 goto err_unlock;
  90
  91         /* wait until conversion finished */
  92         msleep(conversion_time_ms);
  93         res = i2c_smbus_read_word_swapped(client, ADS1015_CONFIG);
  94         if (res < 0)
  95                 goto err_unlock;
  96         config = res;
  97         if (!(config & (1 << 15))) {
  98                 /* conversion not finished in time */
  99                 res = -EIO;
 100                 goto err_unlock;
 101         }
 102
 103         res = i2c_smbus_read_word_swapped(client, ADS1015_CONVERSION);
 104
 105 err_unlock:
 106         mutex_unlock(&data->update_lock);
 107         return res;
 108 }
 109
 110 static int ads1015_reg_to_mv(struct i2c_client *client, unsigned int channel,
 111                              s16 reg)
 112 {
 113         struct ads1015_data *data = i2c_get_clientdata(client);
 114         unsigned int pga = data->channel_data[channel].pga;
 115         int fullscale = fullscale_table[pga];
 116
 117         return DIV_ROUND_CLOSEST(reg * fullscale, 0x7ff0);
 118 }
 119
 120 /* sysfs callback function */
 121 static ssize_t show_in(struct device *dev, struct device_attribute *da,
 122         char *buf)
 123 {
 124         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 125         struct i2c_client *client = to_i2c_client(dev);
 126         int res;
 127         int index = attr->index;
 128
 129         res = ads1015_read_adc(client, index);
 130         if (res < 0)
 131                 return res;
 132
 133         return sprintf(buf, "%d\n", ads1015_reg_to_mv(client, index, res));
 134 }
 135
 136 static const struct sensor_device_attribute ads1015_in[] = {
 137         SENSOR_ATTR(in0_input, S_IRUGO, show_in, NULL, 0),
 138         SENSOR_ATTR(in1_input, S_IRUGO, show_in, NULL, 1),
 139         SENSOR_ATTR(in2_input, S_IRUGO, show_in, NULL, 2),
 140         SENSOR_ATTR(in3_input, S_IRUGO, show_in, NULL, 3),
 141         SENSOR_ATTR(in4_input, S_IRUGO, show_in, NULL, 4),
 142         SENSOR_ATTR(in5_input, S_IRUGO, show_in, NULL, 5),
 143         SENSOR_ATTR(in6_input, S_IRUGO, show_in, NULL, 6),
 144         SENSOR_ATTR(in7_input, S_IRUGO, show_in, NULL, 7),
 145 };
 146
 147 /*
 148  * Driver interface
 149  */
 150
 151 static int ads1015_remove(struct i2c_client *client)
 152 {
 153         struct ads1015_data *data = i2c_get_clientdata(client);
 154         int k;
 155
 156         hwmon_device_unregister(data->hwmon_dev);
 157         for (k = 0; k < ADS1015_CHANNELS; ++k)
 158                 device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
 159         kfree(data);
 160         return 0;
 161 }
 162
 163 #ifdef CONFIG_OF
 164 static int ads1015_get_channels_config_of(struct i2c_client *client)
 165 {
 166         struct ads1015_data *data = i2c_get_clientdata(client);
 167         struct device_node *node;
 168
 169         if (!client->dev.of_node
 170             || !of_get_next_child(client->dev.of_node, NULL))
 171                 return -EINVAL;
 172
 173         for_each_child_of_node(client->dev.of_node, node) {
 174                 const __be32 *property;
 175                 int len;
 176                 unsigned int channel;
 177                 unsigned int pga = ADS1015_DEFAULT_PGA;
 178                 unsigned int data_rate = ADS1015_DEFAULT_DATA_RATE;
 179
 180                 property = of_get_property(node, "reg", &len);
 181                 if (!property || len != sizeof(int)) {
 182                         dev_err(&client->dev, "invalid reg on %s\n",
 183                                 node->full_name);
 184                         continue;
 185                 }
 186
 187                 channel = be32_to_cpup(property);
 188                 if (channel > ADS1015_CHANNELS) {
 189                         dev_err(&client->dev,
 190                                 "invalid channel index %d on %s\n",
 191                                 channel, node->full_name);
 192                         continue;
 193                 }
 194
 195                 property = of_get_property(node, "ti,gain", &len);
 196                 if (property && len == sizeof(int)) {
 197                         pga = be32_to_cpup(property);
 198                         if (pga > 6) {
 199                                 dev_err(&client->dev,
 200                                         "invalid gain on %s\n",
 201                                         node->full_name);
 202                         }
 203                 }
 204
 205                 property = of_get_property(node, "ti,datarate", &len);
 206                 if (property && len == sizeof(int)) {
 207                         data_rate = be32_to_cpup(property);
 208                         if (data_rate > 7) {
 209                                 dev_err(&client->dev,
 210                                         "invalid data_rate on %s\n",
 211                                         node->full_name);
 212                         }
 213                 }
 214
 215                 data->channel_data[channel].enabled = true;
 216                 data->channel_data[channel].pga = pga;
 217                 data->channel_data[channel].data_rate = data_rate;
 218         }
 219
 220         return 0;
 221 }
 222 #endif
 223
 224 static void ads1015_get_channels_config(struct i2c_client *client)
 225 {
 226         unsigned int k;
 227         struct ads1015_data *data = i2c_get_clientdata(client);
 228         struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);
 229
 230         /* prefer platform data */
 231         if (pdata) {
 232                 memcpy(data->channel_data, pdata->channel_data,
 233                        sizeof(data->channel_data));
 234                 return;
 235         }
 236
 237 #ifdef CONFIG_OF
 238         if (!ads1015_get_channels_config_of(client))
 239                 return;
 240 #endif
 241
 242         /* fallback on default configuration */
 243         for (k = 0; k < ADS1015_CHANNELS; ++k) {
 244                 data->channel_data[k].enabled = true;
 245                 data->channel_data[k].pga = ADS1015_DEFAULT_PGA;
 246                 data->channel_data[k].data_rate = ADS1015_DEFAULT_DATA_RATE;
 247         }
 248 }
 249
 250 static int ads1015_probe(struct i2c_client *client,
 251                          const struct i2c_device_id *id)
 252 {
 253         struct ads1015_data *data;
 254         int err;
 255         unsigned int k;
 256
 257         data = kzalloc(sizeof(struct ads1015_data), GFP_KERNEL);
 258         if (!data) {
 259                 err = -ENOMEM;
 260                 goto exit;
 261         }
 262
 263         i2c_set_clientdata(client, data);
 264         mutex_init(&data->update_lock);
 265
 266         /* build sysfs attribute group */
 267         ads1015_get_channels_config(client);
 268         for (k = 0; k < ADS1015_CHANNELS; ++k) {
 269                 if (!data->channel_data[k].enabled)
 270                         continue;
 271                 err = device_create_file(&client->dev, &ads1015_in[k].dev_attr);
 272                 if (err)
 273                         goto exit_remove;
 274         }
 275
 276         data->hwmon_dev = hwmon_device_register(&client->dev);
 277         if (IS_ERR(data->hwmon_dev)) {
 278                 err = PTR_ERR(data->hwmon_dev);
 279                 goto exit_remove;
 280         }
 281
 282         return 0;
 283
 284 exit_remove:
 285         for (k = 0; k < ADS1015_CHANNELS; ++k)
 286                 device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
 287         kfree(data);
 288 exit:
 289         return err;
 290 }
 291
 292 static const struct i2c_device_id ads1015_id[] = {
 293         { "ads1015", 0 },
 294         { }
 295 };
 296 MODULE_DEVICE_TABLE(i2c, ads1015_id);
 297
 298 static struct i2c_driver ads1015_driver = {
 299         .driver = {
 300                 .name = "ads1015",
 301         },
 302         .probe = ads1015_probe,
 303         .remove = ads1015_remove,
 304         .id_table = ads1015_id,
 305 };
 306
 307 module_i2c_driver(ads1015_driver);
 308
 309 MODULE_AUTHOR("Dirk Eibach <eibach@gdsys.de>");
 310 MODULE_DESCRIPTION("ADS1015 driver");
 311 MODULE_LICENSE("GPL");