max197.c

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/*
 * Maxim MAX197 A/D Converter driver
 *
 * Copyright (c) 2012 Savoir-faire Linux Inc.
 *          Vivien Didelot <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * For further information, see the Documentation/hwmon/max197 file.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/sysfs.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/platform_device.h>
#include <linux/platform_data/max197.h>

#define MAX199_LIMIT    4000        /* 4V */
#define MAX197_LIMIT    10000       /* 10V */

#define MAX197_NUM_CH   8       /* 8 Analog Input Channels */

/* Control byte format */
#define MAX197_BIP  (1 << 3)    /* Bipolarity */
#define MAX197_RNG  (1 << 4)    /* Full range */

#define MAX197_SCALE    12207       /* Scale coefficient for raw data */

/* List of supported chips */
enum max197_chips { max197, max199 };

struct max197_data {
    struct max197_platform_data *pdata;
    struct device *hwmon_dev;
    struct mutex lock;
    int limit;
    bool scale;
    u8 ctrl_bytes[MAX197_NUM_CH];
};

static inline void max197_set_unipolarity(struct max197_data *data, int channel)
{
    data->ctrl_bytes[channel] &= ~MAX197_BIP;
}

static inline void max197_set_bipolarity(struct max197_data *data, int channel)
{
    data->ctrl_bytes[channel] |= MAX197_BIP;
}

static inline void max197_set_half_range(struct max197_data *data, int channel)
{
    data->ctrl_bytes[channel] &= ~MAX197_RNG;
}

static inline void max197_set_full_range(struct max197_data *data, int channel)
{
    data->ctrl_bytes[channel] |= MAX197_RNG;
}

static inline bool max197_is_bipolar(struct max197_data *data, int channel)
{
    return data->ctrl_bytes[channel] & MAX197_BIP;
}

static inline bool max197_is_full_range(struct max197_data *data, int channel)
{
    return data->ctrl_bytes[channel] & MAX197_RNG;
}

/* Function called on read access on in{0,1,2,3,4,5,6,7}_{min,max} */
static ssize_t max197_show_range(struct device *dev,
                 struct device_attribute *devattr, char *buf)
{
    struct max197_data *data = dev_get_drvdata(dev);
    struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
    int channel = attr->index;
    bool is_min = attr->nr;
    int range;

    if (mutex_lock_interruptible(&data->lock))
        return -ERESTARTSYS;

    range = max197_is_full_range(data, channel) ?
        data->limit : data->limit / 2;
    if (is_min) {
        if (max197_is_bipolar(data, channel))
            range = -range;
        else
            range = 0;
    }

    mutex_unlock(&data->lock);

    return sprintf(buf, "%d\n", range);
}

/* Function called on write access on in{0,1,2,3,4,5,6,7}_{min,max} */
static ssize_t max197_store_range(struct device *dev,
                  struct device_attribute *devattr,
                  const char *buf, size_t count)
{
    struct max197_data *data = dev_get_drvdata(dev);
    struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
    int channel = attr->index;
    bool is_min = attr->nr;
    long value;
    int half = data->limit / 2;
    int full = data->limit;

    if (kstrtol(buf, 10, &value))
        return -EINVAL;

    if (is_min) {
        if (value <= -full)
            value = -full;
        else if (value < 0)
            value = -half;
        else
            value = 0;
    } else {
        if (value >= full)
            value = full;
        else
            value = half;
    }

    if (mutex_lock_interruptible(&data->lock))
        return -ERESTARTSYS;

    if (value == 0) {
        /* We can deduce only the polarity */
        max197_set_unipolarity(data, channel);
    } else if (value == -half) {
        max197_set_bipolarity(data, channel);
        max197_set_half_range(data, channel);
    } else if (value == -full) {
        max197_set_bipolarity(data, channel);
        max197_set_full_range(data, channel);
    } else if (value == half) {
        /* We can deduce only the range */
        max197_set_half_range(data, channel);
    } else if (value == full) {
        /* We can deduce only the range */
        max197_set_full_range(data, channel);
    }

    mutex_unlock(&data->lock);

    return count;
}

/* Function called on read access on in{0,1,2,3,4,5,6,7}_input */
static ssize_t max197_show_input(struct device *dev,
                 struct device_attribute *devattr,
                 char *buf)
{
    struct max197_data *data = dev_get_drvdata(dev);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
    int channel = attr->index;
    s32 value;
    int ret;

    if (mutex_lock_interruptible(&data->lock))
        return -ERESTARTSYS;

    ret = data->pdata->convert(data->ctrl_bytes[channel]);
    if (ret < 0) {
        dev_err(dev, "conversion failed\n");
        goto unlock;
    }
    value = ret;

    /*
     * Coefficient to apply on raw value.
     * See Table 1. Full Scale and Zero Scale in the MAX197 datasheet.
     */
    if (data->scale) {
        value *= MAX197_SCALE;
        if (max197_is_full_range(data, channel))
            value *= 2;
        value /= 10000;
    }

    ret = sprintf(buf, "%d\n", value);

unlock:
    mutex_unlock(&data->lock);
    return ret;
}

static ssize_t max197_show_name(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    struct platform_device *pdev = to_platform_device(dev);
    return sprintf(buf, "%s\n", pdev->name);
}

#define MAX197_SENSOR_DEVICE_ATTR_CH(chan)              \
    static SENSOR_DEVICE_ATTR(in##chan##_input, S_IRUGO,        \
                  max197_show_input, NULL, chan);   \
    static SENSOR_DEVICE_ATTR_2(in##chan##_min, S_IRUGO | S_IWUSR,  \
                    max197_show_range,          \
                    max197_store_range,         \
                    true, chan);            \
    static SENSOR_DEVICE_ATTR_2(in##chan##_max, S_IRUGO | S_IWUSR,  \
                    max197_show_range,          \
                    max197_store_range,         \
                    false, chan)

#define MAX197_SENSOR_DEV_ATTR_IN(chan)                 \
    &sensor_dev_attr_in##chan##_input.dev_attr.attr,        \
    &sensor_dev_attr_in##chan##_max.dev_attr.attr,          \
    &sensor_dev_attr_in##chan##_min.dev_attr.attr

static DEVICE_ATTR(name, S_IRUGO, max197_show_name, NULL);

MAX197_SENSOR_DEVICE_ATTR_CH(0);
MAX197_SENSOR_DEVICE_ATTR_CH(1);
MAX197_SENSOR_DEVICE_ATTR_CH(2);
MAX197_SENSOR_DEVICE_ATTR_CH(3);
MAX197_SENSOR_DEVICE_ATTR_CH(4);
MAX197_SENSOR_DEVICE_ATTR_CH(5);
MAX197_SENSOR_DEVICE_ATTR_CH(6);
MAX197_SENSOR_DEVICE_ATTR_CH(7);

static const struct attribute_group max197_sysfs_group = {
    .attrs = (struct attribute *[]) {
        &dev_attr_name.attr,
        MAX197_SENSOR_DEV_ATTR_IN(0),
        MAX197_SENSOR_DEV_ATTR_IN(1),
        MAX197_SENSOR_DEV_ATTR_IN(2),
        MAX197_SENSOR_DEV_ATTR_IN(3),
        MAX197_SENSOR_DEV_ATTR_IN(4),
        MAX197_SENSOR_DEV_ATTR_IN(5),
        MAX197_SENSOR_DEV_ATTR_IN(6),
        MAX197_SENSOR_DEV_ATTR_IN(7),
        NULL
    },
};

static int __devinit max197_probe(struct platform_device *pdev)
{
    int ch, ret;
    struct max197_data *data;
    struct max197_platform_data *pdata = pdev->dev.platform_data;
    enum max197_chips chip = platform_get_device_id(pdev)->driver_data;

    if (pdata == NULL) {
        dev_err(&pdev->dev, "no platform data supplied\n");
        return -EINVAL;
    }

    if (pdata->convert == NULL) {
        dev_err(&pdev->dev, "no convert function supplied\n");
        return -EINVAL;
    }

    data = devm_kzalloc(&pdev->dev, sizeof(struct max197_data), GFP_KERNEL);
    if (!data) {
        dev_err(&pdev->dev, "devm_kzalloc failed\n");
        return -ENOMEM;
    }

    data->pdata = pdata;
    mutex_init(&data->lock);

    if (chip == max197) {
        data->limit = MAX197_LIMIT;
        data->scale = true;
    } else {
        data->limit = MAX199_LIMIT;
        data->scale = false;
    }

    for (ch = 0; ch < MAX197_NUM_CH; ch++)
        data->ctrl_bytes[ch] = (u8) ch;

    platform_set_drvdata(pdev, data);

    ret = sysfs_create_group(&pdev->dev.kobj, &max197_sysfs_group);
    if (ret) {
        dev_err(&pdev->dev, "sysfs create group failed\n");
        return ret;
    }

    data->hwmon_dev = hwmon_device_register(&pdev->dev);
    if (IS_ERR(data->hwmon_dev)) {
        ret = PTR_ERR(data->hwmon_dev);
        dev_err(&pdev->dev, "hwmon device register failed\n");
        goto error;
    }

    return 0;

error:
    sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
    return ret;
}

static int __devexit max197_remove(struct platform_device *pdev)
{
    struct max197_data *data = platform_get_drvdata(pdev);

    hwmon_device_unregister(data->hwmon_dev);
    sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);

    return 0;
}

static struct platform_device_id max197_device_ids[] = {
    { "max197", max197 },
    { "max199", max199 },
    { }
};
MODULE_DEVICE_TABLE(platform, max197_device_ids);

static struct platform_driver max197_driver = {
    .driver = {
        .name = "max197",
        .owner = THIS_MODULE,
    },
    .probe = max197_probe,
    .remove = __devexit_p(max197_remove),
    .id_table = max197_device_ids,
};
module_platform_driver(max197_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Savoir-faire Linux Inc. <[email protected]>");
MODULE_DESCRIPTION("Maxim MAX197 A/D Converter driver");