ads1015.c

Go to the documentation of this file.

/*
 * ads1015.c - lm_sensors driver for ads1015 12-bit 4-input ADC
 * (C) Copyright 2010
 * Dirk Eibach, Guntermann & Drunck GmbH <[email protected]>
 *
 * Based on the ads7828 driver by Steve Hardy.
 *
 * Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads1015.pdf
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/of.h>

#include <linux/i2c/ads1015.h>

/* ADS1015 registers */
enum {
    ADS1015_CONVERSION = 0,
    ADS1015_CONFIG = 1,
};

/* PGA fullscale voltages in mV */
static const unsigned int fullscale_table[8] = {
    6144, 4096, 2048, 1024, 512, 256, 256, 256 };

/* Data rates in samples per second */
static const unsigned int data_rate_table[8] = {
    128, 250, 490, 920, 1600, 2400, 3300, 3300 };

#define ADS1015_DEFAULT_CHANNELS 0xff
#define ADS1015_DEFAULT_PGA 2
#define ADS1015_DEFAULT_DATA_RATE 4

struct ads1015_data {
    struct device *hwmon_dev;
    struct mutex update_lock; /* mutex protect updates */
    struct ads1015_channel_data channel_data[ADS1015_CHANNELS];
};

static int ads1015_read_adc(struct i2c_client *client, unsigned int channel)
{
    u16 config;
    struct ads1015_data *data = i2c_get_clientdata(client);
    unsigned int pga = data->channel_data[channel].pga;
    unsigned int data_rate = data->channel_data[channel].data_rate;
    unsigned int conversion_time_ms;
    int res;

    mutex_lock(&data->update_lock);

    /* get channel parameters */
    res = i2c_smbus_read_word_swapped(client, ADS1015_CONFIG);
    if (res < 0)
        goto err_unlock;
    config = res;
    conversion_time_ms = DIV_ROUND_UP(1000, data_rate_table[data_rate]);

    /* setup and start single conversion */
    config &= 0x001f;
    config |= (1 << 15) | (1 << 8);
    config |= (channel & 0x0007) << 12;
    config |= (pga & 0x0007) << 9;
    config |= (data_rate & 0x0007) << 5;

    res = i2c_smbus_write_word_swapped(client, ADS1015_CONFIG, config);
    if (res < 0)
        goto err_unlock;

    /* wait until conversion finished */
    msleep(conversion_time_ms);
    res = i2c_smbus_read_word_swapped(client, ADS1015_CONFIG);
    if (res < 0)
        goto err_unlock;
    config = res;
    if (!(config & (1 << 15))) {
        /* conversion not finished in time */
        res = -EIO;
        goto err_unlock;
    }

    res = i2c_smbus_read_word_swapped(client, ADS1015_CONVERSION);

err_unlock:
    mutex_unlock(&data->update_lock);
    return res;
}

static int ads1015_reg_to_mv(struct i2c_client *client, unsigned int channel,
                 s16 reg)
{
    struct ads1015_data *data = i2c_get_clientdata(client);
    unsigned int pga = data->channel_data[channel].pga;
    int fullscale = fullscale_table[pga];

    return DIV_ROUND_CLOSEST(reg * fullscale, 0x7ff0);
}

/* sysfs callback function */
static ssize_t show_in(struct device *dev, struct device_attribute *da,
    char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
    struct i2c_client *client = to_i2c_client(dev);
    int res;
    int index = attr->index;

    res = ads1015_read_adc(client, index);
    if (res < 0)
        return res;

    return sprintf(buf, "%d\n", ads1015_reg_to_mv(client, index, res));
}

static const struct sensor_device_attribute ads1015_in[] = {
    SENSOR_ATTR(in0_input, S_IRUGO, show_in, NULL, 0),
    SENSOR_ATTR(in1_input, S_IRUGO, show_in, NULL, 1),
    SENSOR_ATTR(in2_input, S_IRUGO, show_in, NULL, 2),
    SENSOR_ATTR(in3_input, S_IRUGO, show_in, NULL, 3),
    SENSOR_ATTR(in4_input, S_IRUGO, show_in, NULL, 4),
    SENSOR_ATTR(in5_input, S_IRUGO, show_in, NULL, 5),
    SENSOR_ATTR(in6_input, S_IRUGO, show_in, NULL, 6),
    SENSOR_ATTR(in7_input, S_IRUGO, show_in, NULL, 7),
};

/*
 * Driver interface
 */

static int ads1015_remove(struct i2c_client *client)
{
    struct ads1015_data *data = i2c_get_clientdata(client);
    int k;

    hwmon_device_unregister(data->hwmon_dev);
    for (k = 0; k < ADS1015_CHANNELS; ++k)
        device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
    return 0;
}

#ifdef CONFIG_OF
static int ads1015_get_channels_config_of(struct i2c_client *client)
{
    struct ads1015_data *data = i2c_get_clientdata(client);
    struct device_node *node;

    if (!client->dev.of_node
        || !of_get_next_child(client->dev.of_node, NULL))
        return -EINVAL;

    for_each_child_of_node(client->dev.of_node, node) {
        const __be32 *property;
        int len;
        unsigned int channel;
        unsigned int pga = ADS1015_DEFAULT_PGA;
        unsigned int data_rate = ADS1015_DEFAULT_DATA_RATE;

        property = of_get_property(node, "reg", &len);
        if (!property || len != sizeof(int)) {
            dev_err(&client->dev, "invalid reg on %s\n",
                node->full_name);
            continue;
        }

        channel = be32_to_cpup(property);
        if (channel > ADS1015_CHANNELS) {
            dev_err(&client->dev,
                "invalid channel index %d on %s\n",
                channel, node->full_name);
            continue;
        }

        property = of_get_property(node, "ti,gain", &len);
        if (property && len == sizeof(int)) {
            pga = be32_to_cpup(property);
            if (pga > 6) {
                dev_err(&client->dev,
                    "invalid gain on %s\n",
                    node->full_name);
            }
        }

        property = of_get_property(node, "ti,datarate", &len);
        if (property && len == sizeof(int)) {
            data_rate = be32_to_cpup(property);
            if (data_rate > 7) {
                dev_err(&client->dev,
                    "invalid data_rate on %s\n",
                    node->full_name);
            }
        }

        data->channel_data[channel].enabled = true;
        data->channel_data[channel].pga = pga;
        data->channel_data[channel].data_rate = data_rate;
    }

    return 0;
}
#endif

static void ads1015_get_channels_config(struct i2c_client *client)
{
    unsigned int k;
    struct ads1015_data *data = i2c_get_clientdata(client);
    struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);

    /* prefer platform data */
    if (pdata) {
        memcpy(data->channel_data, pdata->channel_data,
               sizeof(data->channel_data));
        return;
    }

#ifdef CONFIG_OF
    if (!ads1015_get_channels_config_of(client))
        return;
#endif

    /* fallback on default configuration */
    for (k = 0; k < ADS1015_CHANNELS; ++k) {
        data->channel_data[k].enabled = true;
        data->channel_data[k].pga = ADS1015_DEFAULT_PGA;
        data->channel_data[k].data_rate = ADS1015_DEFAULT_DATA_RATE;
    }
}

static int ads1015_probe(struct i2c_client *client,
             const struct i2c_device_id *id)
{
    struct ads1015_data *data;
    int err;
    unsigned int k;

    data = devm_kzalloc(&client->dev, sizeof(struct ads1015_data),
                GFP_KERNEL);
    if (!data)
        return -ENOMEM;

    i2c_set_clientdata(client, data);
    mutex_init(&data->update_lock);

    /* build sysfs attribute group */
    ads1015_get_channels_config(client);
    for (k = 0; k < ADS1015_CHANNELS; ++k) {
        if (!data->channel_data[k].enabled)
            continue;
        err = device_create_file(&client->dev, &ads1015_in[k].dev_attr);
        if (err)
            goto exit_remove;
    }

    data->hwmon_dev = hwmon_device_register(&client->dev);
    if (IS_ERR(data->hwmon_dev)) {
        err = PTR_ERR(data->hwmon_dev);
        goto exit_remove;
    }

    return 0;

exit_remove:
    for (k = 0; k < ADS1015_CHANNELS; ++k)
        device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
    return err;
}

static const struct i2c_device_id ads1015_id[] = {
    { "ads1015", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, ads1015_id);

static struct i2c_driver ads1015_driver = {
    .driver = {
        .name = "ads1015",
    },
    .probe = ads1015_probe,
    .remove = ads1015_remove,
    .id_table = ads1015_id,
};

module_i2c_driver(ads1015_driver);

MODULE_AUTHOR("Dirk Eibach <[email protected]>");
MODULE_DESCRIPTION("ADS1015 driver");
MODULE_LICENSE("GPL");