// SPDX-License-Identifier: GPL-2.0-only
/*
 * Maxim MAX197 A/D Converter driver
 *
 * Copyright (c) 2012 Savoir-faire Linux Inc.
 *          Vivien Didelot <vivien.didelot@savoirfairelinux.com>
 *
 * For further information, see the Documentation/hwmon/max197.rst file.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.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 - device instance specific data
 * @pdata:              Platform data.
 * @hwmon_dev:          The hwmon device.
 * @lock:               Read/Write mutex.
 * @limit:              Max range value (10V for MAX197, 4V for MAX199).
 * @scale:              Need to scale.
 * @ctrl_bytes:         Channels control byte.
 */
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 name_show(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_RO(name);

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 max197_probe(struct platform_device *pdev)
{
        int ch, ret;
        struct max197_data *data;
        struct max197_platform_data *pdata = dev_get_platdata(&pdev->dev);
        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)
                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 void 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);
}

static const 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",
        },
        .probe = max197_probe,
        .remove = max197_remove,
        .id_table = max197_device_ids,
};
module_platform_driver(max197_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Savoir-faire Linux Inc. <kernel@savoirfairelinux.com>");
MODULE_DESCRIPTION("Maxim MAX197 A/D Converter driver");