linux/drivers/hwmon/ads1015.c
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   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 */
  39enum {
  40        ADS1015_CONVERSION = 0,
  41        ADS1015_CONFIG = 1,
  42};
  43
  44/* PGA fullscale voltages in mV */
  45static const unsigned int fullscale_table[8] = {
  46        6144, 4096, 2048, 1024, 512, 256, 256, 256 };
  47
  48/* Data rates in samples per second */
  49static const unsigned int data_rate_table_1015[8] = {
  50        128, 250, 490, 920, 1600, 2400, 3300, 3300
  51};
  52
  53static const unsigned int data_rate_table_1115[8] = {
  54        8, 16, 32, 64, 128, 250, 475, 860
  55};
  56
  57#define ADS1015_DEFAULT_CHANNELS 0xff
  58#define ADS1015_DEFAULT_PGA 2
  59#define ADS1015_DEFAULT_DATA_RATE 4
  60
  61enum ads1015_chips {
  62        ads1015,
  63        ads1115,
  64};
  65
  66struct ads1015_data {
  67        struct device *hwmon_dev;
  68        struct mutex update_lock; /* mutex protect updates */
  69        struct ads1015_channel_data channel_data[ADS1015_CHANNELS];
  70        enum ads1015_chips id;
  71};
  72
  73static int ads1015_read_adc(struct i2c_client *client, unsigned int channel)
  74{
  75        u16 config;
  76        struct ads1015_data *data = i2c_get_clientdata(client);
  77        unsigned int pga = data->channel_data[channel].pga;
  78        unsigned int data_rate = data->channel_data[channel].data_rate;
  79        unsigned int conversion_time_ms;
  80        const unsigned int * const rate_table = data->id == ads1115 ?
  81                data_rate_table_1115 : data_rate_table_1015;
  82        int res;
  83
  84        mutex_lock(&data->update_lock);
  85
  86        /* get channel parameters */
  87        res = i2c_smbus_read_word_swapped(client, ADS1015_CONFIG);
  88        if (res < 0)
  89                goto err_unlock;
  90        config = res;
  91        conversion_time_ms = DIV_ROUND_UP(1000, rate_table[data_rate]);
  92
  93        /* setup and start single conversion */
  94        config &= 0x001f;
  95        config |= (1 << 15) | (1 << 8);
  96        config |= (channel & 0x0007) << 12;
  97        config |= (pga & 0x0007) << 9;
  98        config |= (data_rate & 0x0007) << 5;
  99
 100        res = i2c_smbus_write_word_swapped(client, ADS1015_CONFIG, config);
 101        if (res < 0)
 102                goto err_unlock;
 103
 104        /* wait until conversion finished */
 105        msleep(conversion_time_ms);
 106        res = i2c_smbus_read_word_swapped(client, ADS1015_CONFIG);
 107        if (res < 0)
 108                goto err_unlock;
 109        config = res;
 110        if (!(config & (1 << 15))) {
 111                /* conversion not finished in time */
 112                res = -EIO;
 113                goto err_unlock;
 114        }
 115
 116        res = i2c_smbus_read_word_swapped(client, ADS1015_CONVERSION);
 117
 118err_unlock:
 119        mutex_unlock(&data->update_lock);
 120        return res;
 121}
 122
 123static int ads1015_reg_to_mv(struct i2c_client *client, unsigned int channel,
 124                             s16 reg)
 125{
 126        struct ads1015_data *data = i2c_get_clientdata(client);
 127        unsigned int pga = data->channel_data[channel].pga;
 128        int fullscale = fullscale_table[pga];
 129        const unsigned mask = data->id == ads1115 ? 0x7fff : 0x7ff0;
 130
 131        return DIV_ROUND_CLOSEST(reg * fullscale, mask);
 132}
 133
 134/* sysfs callback function */
 135static ssize_t show_in(struct device *dev, struct device_attribute *da,
 136        char *buf)
 137{
 138        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 139        struct i2c_client *client = to_i2c_client(dev);
 140        int res;
 141        int index = attr->index;
 142
 143        res = ads1015_read_adc(client, index);
 144        if (res < 0)
 145                return res;
 146
 147        return sprintf(buf, "%d\n", ads1015_reg_to_mv(client, index, res));
 148}
 149
 150static 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
 165static 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        return 0;
 174}
 175
 176#ifdef CONFIG_OF
 177static int ads1015_get_channels_config_of(struct i2c_client *client)
 178{
 179        struct ads1015_data *data = i2c_get_clientdata(client);
 180        struct device_node *node;
 181
 182        if (!client->dev.of_node
 183            || !of_get_next_child(client->dev.of_node, NULL))
 184                return -EINVAL;
 185
 186        for_each_child_of_node(client->dev.of_node, node) {
 187                const __be32 *property;
 188                int len;
 189                unsigned int channel;
 190                unsigned int pga = ADS1015_DEFAULT_PGA;
 191                unsigned int data_rate = ADS1015_DEFAULT_DATA_RATE;
 192
 193                property = of_get_property(node, "reg", &len);
 194                if (!property || len != sizeof(int)) {
 195                        dev_err(&client->dev, "invalid reg on %s\n",
 196                                node->full_name);
 197                        continue;
 198                }
 199
 200                channel = be32_to_cpup(property);
 201                if (channel > ADS1015_CHANNELS) {
 202                        dev_err(&client->dev,
 203                                "invalid channel index %d on %s\n",
 204                                channel, node->full_name);
 205                        continue;
 206                }
 207
 208                property = of_get_property(node, "ti,gain", &len);
 209                if (property && len == sizeof(int)) {
 210                        pga = be32_to_cpup(property);
 211                        if (pga > 6) {
 212                                dev_err(&client->dev,
 213                                        "invalid gain on %s\n",
 214                                        node->full_name);
 215                        }
 216                }
 217
 218                property = of_get_property(node, "ti,datarate", &len);
 219                if (property && len == sizeof(int)) {
 220                        data_rate = be32_to_cpup(property);
 221                        if (data_rate > 7) {
 222                                dev_err(&client->dev,
 223                                        "invalid data_rate on %s\n",
 224                                        node->full_name);
 225                        }
 226                }
 227
 228                data->channel_data[channel].enabled = true;
 229                data->channel_data[channel].pga = pga;
 230                data->channel_data[channel].data_rate = data_rate;
 231        }
 232
 233        return 0;
 234}
 235#endif
 236
 237static void ads1015_get_channels_config(struct i2c_client *client)
 238{
 239        unsigned int k;
 240        struct ads1015_data *data = i2c_get_clientdata(client);
 241        struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);
 242
 243        /* prefer platform data */
 244        if (pdata) {
 245                memcpy(data->channel_data, pdata->channel_data,
 246                       sizeof(data->channel_data));
 247                return;
 248        }
 249
 250#ifdef CONFIG_OF
 251        if (!ads1015_get_channels_config_of(client))
 252                return;
 253#endif
 254
 255        /* fallback on default configuration */
 256        for (k = 0; k < ADS1015_CHANNELS; ++k) {
 257                data->channel_data[k].enabled = true;
 258                data->channel_data[k].pga = ADS1015_DEFAULT_PGA;
 259                data->channel_data[k].data_rate = ADS1015_DEFAULT_DATA_RATE;
 260        }
 261}
 262
 263static int ads1015_probe(struct i2c_client *client,
 264                         const struct i2c_device_id *id)
 265{
 266        struct ads1015_data *data;
 267        int err;
 268        unsigned int k;
 269
 270        data = devm_kzalloc(&client->dev, sizeof(struct ads1015_data),
 271                            GFP_KERNEL);
 272        if (!data)
 273                return -ENOMEM;
 274        data->id = id->driver_data;
 275        i2c_set_clientdata(client, data);
 276        mutex_init(&data->update_lock);
 277
 278        /* build sysfs attribute group */
 279        ads1015_get_channels_config(client);
 280        for (k = 0; k < ADS1015_CHANNELS; ++k) {
 281                if (!data->channel_data[k].enabled)
 282                        continue;
 283                err = device_create_file(&client->dev, &ads1015_in[k].dev_attr);
 284                if (err)
 285                        goto exit_remove;
 286        }
 287
 288        data->hwmon_dev = hwmon_device_register(&client->dev);
 289        if (IS_ERR(data->hwmon_dev)) {
 290                err = PTR_ERR(data->hwmon_dev);
 291                goto exit_remove;
 292        }
 293
 294        return 0;
 295
 296exit_remove:
 297        for (k = 0; k < ADS1015_CHANNELS; ++k)
 298                device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
 299        return err;
 300}
 301
 302static const struct i2c_device_id ads1015_id[] = {
 303        { "ads1015",  ads1015},
 304        { "ads1115",  ads1115},
 305        { }
 306};
 307MODULE_DEVICE_TABLE(i2c, ads1015_id);
 308
 309static struct i2c_driver ads1015_driver = {
 310        .driver = {
 311                .name = "ads1015",
 312        },
 313        .probe = ads1015_probe,
 314        .remove = ads1015_remove,
 315        .id_table = ads1015_id,
 316};
 317
 318module_i2c_driver(ads1015_driver);
 319
 320MODULE_AUTHOR("Dirk Eibach <eibach@gdsys.de>");
 321MODULE_DESCRIPTION("ADS1015 driver");
 322MODULE_LICENSE("GPL");
 323
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