source: src/linux/universal/linux-3.2/drivers/hwmon/ads1015.c @ 18171

/*
 * ads1015.c - lm_sensors driver for ads1015 12-bit 4-input ADC
 * (C) Copyright 2010
 * Dirk Eibach, Guntermann & Drunck GmbH <eibach@gdsys.de>
 *
 * 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_value(struct i2c_client *client, unsigned int channel,
                              int *value)
{
        u16 config;
        s16 conversion;
        struct ads1015_data *data = i2c_get_clientdata(client);
        unsigned int pga = data->channel_data[channel].pga;
        int fullscale;
        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;
        fullscale = fullscale_table[pga];
        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);
        if (res < 0)
                goto err_unlock;
        conversion = res;

        mutex_unlock(&data->update_lock);

        *value = DIV_ROUND_CLOSEST(conversion * fullscale, 0x7ff0);

        return 0;

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

/* 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 in;
        int res;

        res = ads1015_read_value(client, attr->index, &in);

        return (res < 0) ? res : sprintf(buf, "%d\n", in);
}

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);
        kfree(data);
        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 = kzalloc(sizeof(struct ads1015_data), GFP_KERNEL);
        if (!data) {
                err = -ENOMEM;
                goto exit;
        }

        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_free;
        }

        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);
exit_free:
        kfree(data);
exit:
        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,
};

static int __init sensors_ads1015_init(void)
{
        return i2c_add_driver(&ads1015_driver);
}

static void __exit sensors_ads1015_exit(void)
{
        i2c_del_driver(&ads1015_driver);
}

MODULE_AUTHOR("Dirk Eibach <eibach@gdsys.de>");
MODULE_DESCRIPTION("ADS1015 driver");
MODULE_LICENSE("GPL");

module_init(sensors_ads1015_init);
module_exit(sensors_ads1015_exit);