/*
 * LM73 Sensor driver
 * Based on LM75
 *
 * Copyright (C) 2007, CenoSYS (www.cenosys.com).
 * Copyright (C) 2009, Bollore telecom (www.bolloretelecom.eu).
 *
 * Guillaume Ligneul <guillaume.ligneul@gmail.com>
 * Adrien Demarez <adrien.demarez@bolloretelecom.eu>
 * Jeremy Laine <jeremy.laine@bolloretelecom.eu>
 * Chris Verges <kg4ysn@gmail.com>
 *
 * This software program is licensed subject to the GNU General Public License
 * (GPL).Version 2,June 1991, available at
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>


/* Addresses scanned */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4c,
                                        0x4d, 0x4e, I2C_CLIENT_END };

/* LM73 registers */
#define LM73_REG_INPUT          0x00
#define LM73_REG_CONF           0x01
#define LM73_REG_MAX            0x02
#define LM73_REG_MIN            0x03
#define LM73_REG_CTRL           0x04
#define LM73_REG_ID             0x07

#define LM73_ID                 0x9001  /* 0x0190, byte-swapped */
#define DRVNAME                 "lm73"
#define LM73_TEMP_MIN           (-256000 / 250)
#define LM73_TEMP_MAX           (255750 / 250)

#define LM73_CTRL_RES_SHIFT     5
#define LM73_CTRL_RES_MASK      (BIT(5) | BIT(6))
#define LM73_CTRL_TO_MASK       BIT(7)

#define LM73_CTRL_HI_SHIFT      2
#define LM73_CTRL_LO_SHIFT      1

static const unsigned short lm73_convrates[] = {
        14,     /* 11-bits (0.25000 C/LSB): RES1 Bit = 0, RES0 Bit = 0 */
        28,     /* 12-bits (0.12500 C/LSB): RES1 Bit = 0, RES0 Bit = 1 */
        56,     /* 13-bits (0.06250 C/LSB): RES1 Bit = 1, RES0 Bit = 0 */
        112,    /* 14-bits (0.03125 C/LSB): RES1 Bit = 1, RES0 Bit = 1 */
};

struct lm73_data {
        struct i2c_client *client;
        struct mutex lock;
        u8 ctrl;                        /* control register value */
};

/*-----------------------------------------------------------------------*/

static ssize_t set_temp(struct device *dev, struct device_attribute *da,
                        const char *buf, size_t count)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct lm73_data *data = dev_get_drvdata(dev);
        long temp;
        short value;
        s32 err;

        int status = kstrtol(buf, 10, &temp);
        if (status < 0)
                return status;

        /* Write value */
        value = clamp_val(temp / 250, LM73_TEMP_MIN, LM73_TEMP_MAX) << 5;
        err = i2c_smbus_write_word_swapped(data->client, attr->index, value);
        return (err < 0) ? err : count;
}

static ssize_t show_temp(struct device *dev, struct device_attribute *da,
                         char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct lm73_data *data = dev_get_drvdata(dev);
        int temp;

        s32 err = i2c_smbus_read_word_swapped(data->client, attr->index);
        if (err < 0)
                return err;

        /* use integer division instead of equivalent right shift to
           guarantee arithmetic shift and preserve the sign */
        temp = (((s16) err) * 250) / 32;
        return scnprintf(buf, PAGE_SIZE, "%d\n", temp);
}

static ssize_t set_convrate(struct device *dev, struct device_attribute *da,
                            const char *buf, size_t count)
{
        struct lm73_data *data = dev_get_drvdata(dev);
        unsigned long convrate;
        s32 err;
        int res = 0;

        err = kstrtoul(buf, 10, &convrate);
        if (err < 0)
                return err;

        /*
         * Convert the desired conversion rate into register bits.
         * res is already initialized, and everything past the second-to-last
         * value in the array is treated as belonging to the last value
         * in the array.
         */
        while (res < (ARRAY_SIZE(lm73_convrates) - 1) &&
                        convrate > lm73_convrates[res])
                res++;

        mutex_lock(&data->lock);
        data->ctrl &= LM73_CTRL_TO_MASK;
        data->ctrl |= res << LM73_CTRL_RES_SHIFT;
        err = i2c_smbus_write_byte_data(data->client, LM73_REG_CTRL,
                                        data->ctrl);
        mutex_unlock(&data->lock);

        if (err < 0)
                return err;

        return count;
}

static ssize_t show_convrate(struct device *dev, struct device_attribute *da,
                             char *buf)
{
        struct lm73_data *data = dev_get_drvdata(dev);
        int res;

        res = (data->ctrl & LM73_CTRL_RES_MASK) >> LM73_CTRL_RES_SHIFT;
        return scnprintf(buf, PAGE_SIZE, "%hu\n", lm73_convrates[res]);
}

static ssize_t show_maxmin_alarm(struct device *dev,
                                 struct device_attribute *da, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct lm73_data *data = dev_get_drvdata(dev);
        s32 ctrl;

        mutex_lock(&data->lock);
        ctrl = i2c_smbus_read_byte_data(data->client, LM73_REG_CTRL);
        if (ctrl < 0)
                goto abort;
        data->ctrl = ctrl;
        mutex_unlock(&data->lock);

        return scnprintf(buf, PAGE_SIZE, "%d\n", (ctrl >> attr->index) & 1);

abort:
        mutex_unlock(&data->lock);
        return ctrl;
}

/*-----------------------------------------------------------------------*/

/* sysfs attributes for hwmon */

static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
                        show_temp, set_temp, LM73_REG_MAX);
static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO,
                        show_temp, set_temp, LM73_REG_MIN);
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
                        show_temp, NULL, LM73_REG_INPUT);
static SENSOR_DEVICE_ATTR(update_interval, S_IWUSR | S_IRUGO,
                        show_convrate, set_convrate, 0);
static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO,
                        show_maxmin_alarm, NULL, LM73_CTRL_HI_SHIFT);
static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO,
                        show_maxmin_alarm, NULL, LM73_CTRL_LO_SHIFT);

static struct attribute *lm73_attrs[] = {
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        &sensor_dev_attr_temp1_max.dev_attr.attr,
        &sensor_dev_attr_temp1_min.dev_attr.attr,
        &sensor_dev_attr_update_interval.dev_attr.attr,
        &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
        &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
        NULL
};
ATTRIBUTE_GROUPS(lm73);

/*-----------------------------------------------------------------------*/

/* device probe and removal */

static int
lm73_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
        struct device *dev = &client->dev;
        struct device *hwmon_dev;
        struct lm73_data *data;
        int ctrl;

        data = devm_kzalloc(dev, sizeof(struct lm73_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

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

        ctrl = i2c_smbus_read_byte_data(client, LM73_REG_CTRL);
        if (ctrl < 0)
                return ctrl;
        data->ctrl = ctrl;

        hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
                                                           data, lm73_groups);
        if (IS_ERR(hwmon_dev))
                return PTR_ERR(hwmon_dev);

        dev_info(dev, "sensor '%s'\n", client->name);

        return 0;
}

static const struct i2c_device_id lm73_ids[] = {
        { "lm73", 0 },
        { /* LIST END */ }
};
MODULE_DEVICE_TABLE(i2c, lm73_ids);

/* Return 0 if detection is successful, -ENODEV otherwise */
static int lm73_detect(struct i2c_client *new_client,
                        struct i2c_board_info *info)
{
        struct i2c_adapter *adapter = new_client->adapter;
        int id, ctrl, conf;

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
                                        I2C_FUNC_SMBUS_WORD_DATA))
                return -ENODEV;

        /*
         * Do as much detection as possible with byte reads first, as word
         * reads can confuse other devices.
         */
        ctrl = i2c_smbus_read_byte_data(new_client, LM73_REG_CTRL);
        if (ctrl < 0 || (ctrl & 0x10))
                return -ENODEV;

        conf = i2c_smbus_read_byte_data(new_client, LM73_REG_CONF);
        if (conf < 0 || (conf & 0x0c))
                return -ENODEV;

        id = i2c_smbus_read_byte_data(new_client, LM73_REG_ID);
        if (id < 0 || id != (LM73_ID & 0xff))
                return -ENODEV;

        /* Check device ID */
        id = i2c_smbus_read_word_data(new_client, LM73_REG_ID);
        if (id < 0 || id != LM73_ID)
                return -ENODEV;

        strlcpy(info->type, "lm73", I2C_NAME_SIZE);

        return 0;
}

static struct i2c_driver lm73_driver = {
        .class          = I2C_CLASS_HWMON,
        .driver = {
                .name   = "lm73",
        },
        .probe          = lm73_probe,
        .id_table       = lm73_ids,
        .detect         = lm73_detect,
        .address_list   = normal_i2c,
};

module_i2c_driver(lm73_driver);

MODULE_AUTHOR("Guillaume Ligneul <guillaume.ligneul@gmail.com>");
MODULE_DESCRIPTION("LM73 driver");
MODULE_LICENSE("GPL");