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[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
  56struct 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
  62static 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
 105err_unlock:
 106        mutex_unlock(&data->update_lock);
 107        return res;
 108}
 109
 110static 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 */
 121static 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
 136static 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
 151static 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
 164static 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
 224static 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
 250static 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
 284exit_remove:
 285        for (k = 0; k < ADS1015_CHANNELS; ++k)
 286                device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
 287        kfree(data);
 288exit:
 289        return err;
 290}
 291
 292static const struct i2c_device_id ads1015_id[] = {
 293        { "ads1015", 0 },
 294        { }
 295};
 296MODULE_DEVICE_TABLE(i2c, ads1015_id);
 297
 298static 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
 307module_i2c_driver(ads1015_driver);
 308
 309MODULE_AUTHOR("Dirk Eibach <eibach@gdsys.de>");
 310MODULE_DESCRIPTION("ADS1015 driver");
 311MODULE_LICENSE("GPL");
 312
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