// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * lm92 - Hardware monitoring driver
 * Copyright (C) 2005-2008  Jean Delvare <jdelvare@suse.de>
 *
 * Based on the lm90 driver, with some ideas taken from the lm_sensors
 * lm92 driver as well.
 *
 * The LM92 is a sensor chip made by National Semiconductor. It reports
 * its own temperature with a 0.0625 deg resolution and a 0.33 deg
 * accuracy. Complete datasheet can be obtained from National's website
 * at:
 *   http://www.national.com/pf/LM/LM92.html
 *
 * This driver also supports the MAX6635 sensor chip made by Maxim.
 * This chip is compatible with the LM92, but has a lesser accuracy
 * (1.0 deg). Complete datasheet can be obtained from Maxim's website
 * at:
 *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3074
 *
 * Since the LM92 was the first chipset supported by this driver, most
 * comments will refer to this chipset, but are actually general and
 * concern all supported chipsets, unless mentioned otherwise.
 *
 * Support could easily be added for the National Semiconductor LM76
 * and Maxim MAX6633 and MAX6634 chips, which are mostly compatible
 * with the LM92.
 */

#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/slab.h>

/*
 * The LM92 and MAX6635 have 2 two-state pins for address selection,
 * resulting in 4 possible addresses.
 */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
                                                I2C_CLIENT_END };
/* The LM92 registers */
#define LM92_REG_CONFIG                 0x01 /* 8-bit, RW */
#define LM92_REG_TEMP                   0x00 /* 16-bit, RO */
#define LM92_REG_TEMP_HYST              0x02 /* 16-bit, RW */
#define LM92_REG_TEMP_CRIT              0x03 /* 16-bit, RW */
#define LM92_REG_TEMP_LOW               0x04 /* 16-bit, RW */
#define LM92_REG_TEMP_HIGH              0x05 /* 16-bit, RW */
#define LM92_REG_MAN_ID                 0x07 /* 16-bit, RO, LM92 only */

/*
 * The LM92 uses signed 13-bit values with LSB = 0.0625 degree Celsius,
 * left-justified in 16-bit registers. No rounding is done, with such
 * a resolution it's just not worth it. Note that the MAX6635 doesn't
 * make use of the 4 lower bits for limits (i.e. effective resolution
 * for limits is 1 degree Celsius).
 */
static inline int TEMP_FROM_REG(s16 reg)
{
        return reg / 8 * 625 / 10;
}

static inline s16 TEMP_TO_REG(long val, int resolution)
{
        val = clamp_val(val, -60000, 160000);
        return DIV_ROUND_CLOSEST(val << (resolution - 9), 1000) << (16 - resolution);
}

/* Alarm flags are stored in the 3 LSB of the temperature register */
static inline u8 ALARMS_FROM_REG(s16 reg)
{
        return reg & 0x0007;
}

/* Client data (each client gets its own) */
struct lm92_data {
        struct regmap *regmap;
        int resolution;
};

static int lm92_temp_read(struct lm92_data *data, u32 attr, int channel, long *val)
{
        int reg = -1, hyst_reg = -1, alarm_bit = 0;
        struct regmap *regmap = data->regmap;
        u32 temp;
        int ret;

        switch (attr) {
        case hwmon_temp_input:
                reg = LM92_REG_TEMP;
                break;
        case hwmon_temp_min:
                reg = LM92_REG_TEMP_LOW;
                break;
        case hwmon_temp_max:
                reg = LM92_REG_TEMP_HIGH;
                break;
        case hwmon_temp_crit:
                reg = LM92_REG_TEMP_CRIT;
                break;
        case hwmon_temp_min_hyst:
                hyst_reg = LM92_REG_TEMP_LOW;
                break;
        case hwmon_temp_max_hyst:
                hyst_reg = LM92_REG_TEMP_HIGH;
                break;
        case hwmon_temp_crit_hyst:
                hyst_reg = LM92_REG_TEMP_CRIT;
                break;
        case hwmon_temp_min_alarm:
                alarm_bit = 0;
                break;
        case hwmon_temp_max_alarm:
                alarm_bit = 1;
                break;
        case hwmon_temp_crit_alarm:
                alarm_bit = 2;
                break;
        default:
                return -EOPNOTSUPP;
        }
        if (reg >= 0) {
                ret = regmap_read(regmap, reg, &temp);
                if (ret < 0)
                        return ret;
                *val = TEMP_FROM_REG(temp);
        } else if (hyst_reg >= 0) {
                u32 regs[2] = { hyst_reg, LM92_REG_TEMP_HYST };
                u16 regvals[2];

                ret = regmap_multi_reg_read(regmap, regs, regvals, 2);
                if (ret)
                        return ret;
                if (attr == hwmon_temp_min_hyst)
                        *val = TEMP_FROM_REG(regvals[0]) + TEMP_FROM_REG(regvals[1]);
                else
                        *val = TEMP_FROM_REG(regvals[0]) - TEMP_FROM_REG(regvals[1]);
        } else {
                ret = regmap_read(regmap, LM92_REG_TEMP, &temp);
                if (ret)
                        return ret;
                *val = !!(temp & BIT(alarm_bit));
        }
        return 0;
}

static int lm92_chip_read(struct lm92_data *data, u32 attr, long *val)
{
        u32 temp;
        int ret;

        switch (attr) {
        case hwmon_chip_alarms:
                ret = regmap_read(data->regmap, LM92_REG_TEMP, &temp);
                if (ret)
                        return ret;
                *val = ALARMS_FROM_REG(temp);
                break;
        default:
                return -EOPNOTSUPP;
        }
        return 0;
}

static int lm92_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
                     int channel, long *val)
{
        struct lm92_data *data = dev_get_drvdata(dev);

        switch (type) {
        case hwmon_chip:
                return lm92_chip_read(data, attr, val);
        case hwmon_temp:
                return lm92_temp_read(data, attr, channel, val);
        default:
                return -EOPNOTSUPP;
        }
}

static int lm92_temp_write(struct lm92_data *data, u32 attr, long val)
{
        struct regmap *regmap = data->regmap;
        int reg, err;
        u32 temp;

        switch (attr) {
        case hwmon_temp_min:
                reg = LM92_REG_TEMP_LOW;
                break;
        case hwmon_temp_max:
                reg = LM92_REG_TEMP_HIGH;
                break;
        case hwmon_temp_crit:
                reg = LM92_REG_TEMP_CRIT;
                break;
        case hwmon_temp_crit_hyst:
                val = clamp_val(val, -120000, 220000);
                err = regmap_read(regmap, LM92_REG_TEMP_CRIT, &temp);
                if (err)
                        return err;
                val = TEMP_TO_REG(TEMP_FROM_REG(temp) - val, data->resolution);
                return regmap_write(regmap, LM92_REG_TEMP_HYST, val);
        default:
                return -EOPNOTSUPP;
        }
        return regmap_write(regmap, reg, TEMP_TO_REG(val, data->resolution));
}

static int lm92_write(struct device *dev, enum hwmon_sensor_types type,
                      u32 attr, int channel, long val)
{
        struct lm92_data *data = dev_get_drvdata(dev);

        switch (type) {
        case hwmon_temp:
                return lm92_temp_write(data, attr, val);
        default:
                return -EOPNOTSUPP;
        }
}

static umode_t lm92_is_visible(const void *_data, enum hwmon_sensor_types type,
                               u32 attr, int channel)
{
        switch (type) {
        case hwmon_chip:
                switch (attr) {
                case hwmon_chip_alarms:
                        return 0444;
                default:
                        break;
                }
                break;
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_min:
                case hwmon_temp_max:
                case hwmon_temp_crit:
                case hwmon_temp_crit_hyst:
                        return 0644;
                case hwmon_temp_input:
                case hwmon_temp_min_hyst:
                case hwmon_temp_max_hyst:
                case hwmon_temp_min_alarm:
                case hwmon_temp_max_alarm:
                case hwmon_temp_crit_alarm:
                        return 0444;
                default:
                        break;
                }
                break;
        default:
                break;
        }
        return 0;
}

static const struct hwmon_channel_info * const lm92_info[] = {
        HWMON_CHANNEL_INFO(chip, HWMON_C_ALARMS),
        HWMON_CHANNEL_INFO(temp,
                           HWMON_T_INPUT |
                           HWMON_T_MIN | HWMON_T_MIN_HYST |
                           HWMON_T_MAX | HWMON_T_MAX_HYST |
                           HWMON_T_CRIT | HWMON_T_CRIT_HYST |
                           HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
                           HWMON_T_CRIT_ALARM),
        NULL
};

static const struct hwmon_ops lm92_hwmon_ops = {
        .is_visible = lm92_is_visible,
        .read = lm92_read,
        .write = lm92_write,
};

static const struct hwmon_chip_info lm92_chip_info = {
        .ops = &lm92_hwmon_ops,
        .info = lm92_info,
};

/*
 * Detection and registration
 */

static int lm92_init_client(struct regmap *regmap)
{
        return regmap_clear_bits(regmap, LM92_REG_CONFIG, 0x01);
}

/* Return 0 if detection is successful, -ENODEV otherwise */
static int lm92_detect(struct i2c_client *new_client,
                       struct i2c_board_info *info)
{
        struct i2c_adapter *adapter = new_client->adapter;
        u8 config_addr = LM92_REG_CONFIG;
        u8 man_id_addr = LM92_REG_MAN_ID;
        int i, regval;

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

        /*
         * Register values repeat with multiples of 8.
         * Read twice to improve detection accuracy.
         */
        for (i = 0; i < 2; i++) {
                regval = i2c_smbus_read_word_data(new_client, man_id_addr);
                if (regval != 0x0180)
                        return -ENODEV;
                regval = i2c_smbus_read_byte_data(new_client, config_addr);
                if (regval < 0 || (regval & 0xe0))
                        return -ENODEV;
                config_addr += 8;
                man_id_addr += 8;
        }

        strscpy(info->type, "lm92", I2C_NAME_SIZE);

        return 0;
}

/* regmap */

static int lm92_reg_read(void *context, unsigned int reg, unsigned int *val)
{
        int ret;

        if (reg == LM92_REG_CONFIG)
                ret = i2c_smbus_read_byte_data(context, reg);
        else
                ret = i2c_smbus_read_word_swapped(context, reg);
        if (ret < 0)
                return ret;

        *val = ret;
        return 0;
}

static int lm92_reg_write(void *context, unsigned int reg, unsigned int val)
{
        if (reg == LM92_REG_CONFIG)
                return i2c_smbus_write_byte_data(context, LM92_REG_CONFIG, val);

        return i2c_smbus_write_word_swapped(context, reg, val);
}

static bool lm92_regmap_is_volatile(struct device *dev, unsigned int reg)
{
        return reg == LM92_REG_TEMP;
}

static bool lm92_regmap_is_writeable(struct device *dev, unsigned int reg)
{
        return reg >= LM92_REG_CONFIG;
}

static const struct regmap_config lm92_regmap_config = {
        .reg_bits = 8,
        .val_bits = 16,
        .max_register = LM92_REG_TEMP_HIGH,
        .cache_type = REGCACHE_MAPLE,
        .volatile_reg = lm92_regmap_is_volatile,
        .writeable_reg = lm92_regmap_is_writeable,
};

static const struct regmap_bus lm92_regmap_bus = {
        .reg_write = lm92_reg_write,
        .reg_read = lm92_reg_read,
};

static int lm92_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct device *hwmon_dev;
        struct lm92_data *data;
        struct regmap *regmap;
        int err;

        regmap = devm_regmap_init(dev, &lm92_regmap_bus, client,
                                  &lm92_regmap_config);
        if (IS_ERR(regmap))
                return PTR_ERR(regmap);

        data = devm_kzalloc(dev, sizeof(struct lm92_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->regmap = regmap;
        data->resolution = (unsigned long)i2c_get_match_data(client);

        /* Initialize the chipset */
        err = lm92_init_client(regmap);
        if (err)
                return err;

        hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data,
                                                         &lm92_chip_info, NULL);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

/*
 * Module and driver stuff
 */

/* .driver_data is limit register resolution */ 
static const struct i2c_device_id lm92_id[] = {
        { "lm92", 13 },
        { "max6635", 9 },
        { }
};
MODULE_DEVICE_TABLE(i2c, lm92_id);

static struct i2c_driver lm92_driver = {
        .class          = I2C_CLASS_HWMON,
        .driver = {
                .name   = "lm92",
        },
        .probe          = lm92_probe,
        .id_table       = lm92_id,
        .detect         = lm92_detect,
        .address_list   = normal_i2c,
};

module_i2c_driver(lm92_driver);

MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
MODULE_DESCRIPTION("LM92/MAX6635 driver");
MODULE_LICENSE("GPL");