// SPDX-License-Identifier: GPL-2.0+
/*
 * Hardware monitoring driver for EMC2305 fan controller
 *
 * Copyright (C) 2022 Nvidia Technologies Ltd.
 */

#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/platform_data/emc2305.h>
#include <linux/thermal.h>
#include <linux/pwm.h>
#include <linux/of_device.h>
#include <linux/util_macros.h>

#define EMC2305_REG_DRIVE_FAIL_STATUS   0x27
#define EMC2305_REG_VENDOR              0xfe
#define EMC2305_FAN_MAX                 0xff
#define EMC2305_FAN_MIN                 0x00
#define EMC2305_FAN_MAX_STATE           10
#define EMC2305_DEVICE                  0x34
#define EMC2305_VENDOR                  0x5d
#define EMC2305_REG_PRODUCT_ID          0xfd
#define EMC2305_TACH_REGS_UNUSE_BITS    3
#define EMC2305_TACH_CNT_MULTIPLIER     0x02
#define EMC2305_TACH_RANGE_MIN          480
#define EMC2305_DEFAULT_OUTPUT          0x0
#define EMC2305_DEFAULT_POLARITY        0x0
#define EMC2305_REG_POLARITY            0x2a
#define EMC2305_REG_DRIVE_PWM_OUT       0x2b
#define EMC2305_OPEN_DRAIN              0x0
#define EMC2305_PUSH_PULL               0x1

#define EMC2305_PWM_DUTY2STATE(duty, max_state, pwm_max) \
        DIV_ROUND_CLOSEST((duty) * (max_state), (pwm_max))
#define EMC2305_PWM_STATE2DUTY(state, max_state, pwm_max) \
        DIV_ROUND_CLOSEST((state) * (pwm_max), (max_state))

/*
 * Factor by equations [2] and [3] from data sheet; valid for fans where the number of edges
 * equal (poles * 2 + 1).
 */
#define EMC2305_RPM_FACTOR              3932160

#define EMC2305_REG_FAN_DRIVE(n)        (0x30 + 0x10 * (n))
#define EMC2305_REG_FAN_MIN_DRIVE(n)    (0x38 + 0x10 * (n))
#define EMC2305_REG_FAN_TACH(n)         (0x3e + 0x10 * (n))

/* Supported base PWM frequencies */
static const unsigned int base_freq_table[] = { 2441, 4882, 19530, 26000 };

enum emc230x_product_id {
        EMC2305 = 0x34,
        EMC2303 = 0x35,
        EMC2302 = 0x36,
        EMC2301 = 0x37,
};

static const struct i2c_device_id emc2305_ids[] = {
        { "emc2305" },
        { "emc2303" },
        { "emc2302" },
        { "emc2301" },
        { }
};
MODULE_DEVICE_TABLE(i2c, emc2305_ids);

/**
 * struct emc2305_cdev_data - device-specific cooling device state
 * @cdev: cooling device
 * @cur_state: cooling current state
 * @last_hwmon_state: last cooling state updated by hwmon subsystem
 * @last_thermal_state: last cooling state updated by thermal subsystem
 *
 * The 'last_hwmon_state' and 'last_thermal_state' fields are provided to support fan low limit
 * speed feature. The purpose of this feature is to provides ability to limit fan speed
 * according to some system wise considerations, like absence of some replaceable units (PSU or
 * line cards), high system ambient temperature, unreliable transceivers temperature sensing or
 * some other factors which indirectly impacts system's airflow
 * Fan low limit feature is supported through 'hwmon' interface: 'hwmon' 'pwm' attribute is
 * used for setting low limit for fan speed in case 'thermal' subsystem is configured in
 * kernel. In this case setting fan speed through 'hwmon' will never let the 'thermal'
 * subsystem to select a lower duty cycle than the duty cycle selected with the 'pwm'
 * attribute.
 * From other side, fan speed is to be updated in hardware through 'pwm' only in case the
 * requested fan speed is above last speed set by 'thermal' subsystem, otherwise requested fan
 * speed will be just stored with no PWM update.
 */
struct emc2305_cdev_data {
        struct thermal_cooling_device *cdev;
        unsigned int cur_state;
        unsigned long last_hwmon_state;
        unsigned long last_thermal_state;
};

/**
 * struct emc2305_data - device-specific data
 * @client: i2c client
 * @hwmon_dev: hwmon device
 * @max_state: maximum cooling state of the cooling device
 * @pwm_num: number of PWM channels
 * @pwm_output_mask: PWM output mask
 * @pwm_polarity_mask: PWM polarity mask
 * @pwm_separate: separate PWM settings for every channel
 * @pwm_min: array of minimum PWM per channel
 * @pwm_freq: array of PWM frequency per channel
 * @cdev_data: array of cooling devices data
 */
struct emc2305_data {
        struct i2c_client *client;
        struct device *hwmon_dev;
        u8 max_state;
        u8 pwm_num;
        u8 pwm_output_mask;
        u8 pwm_polarity_mask;
        bool pwm_separate;
        u8 pwm_min[EMC2305_PWM_MAX];
        u16 pwm_freq[EMC2305_PWM_MAX];
        struct emc2305_cdev_data cdev_data[EMC2305_PWM_MAX];
};

static char *emc2305_fan_name[] = {
        "emc2305_fan",
        "emc2305_fan1",
        "emc2305_fan2",
        "emc2305_fan3",
        "emc2305_fan4",
        "emc2305_fan5",
};

static int emc2305_get_max_channel(const struct emc2305_data *data)
{
        return data->pwm_num;
}

static int emc2305_get_cdev_idx(struct thermal_cooling_device *cdev)
{
        struct emc2305_data *data = cdev->devdata;
        size_t len = strlen(cdev->type);
        int ret;

        if (len <= 0)
                return -EINVAL;

        /*
         * Returns index of cooling device 0..4 in case of separate PWM setting.
         * Zero index is used in case of one common PWM setting.
         * If the mode is not set as pwm_separate, all PWMs are to be bound
         * to the common thermal zone and should work at the same speed
         * to perform cooling for the same thermal junction.
         * Otherwise, return specific channel that will be used in bound
         * related PWM to the thermal zone.
         */
        if (!data->pwm_separate)
                return 0;

        ret = cdev->type[len - 1];
        switch (ret) {
        case '1' ... '5':
                return ret - '1';
        default:
                break;
        }
        return -EINVAL;
}

static int emc2305_get_cur_state(struct thermal_cooling_device *cdev, unsigned long *state)
{
        int cdev_idx;
        struct emc2305_data *data = cdev->devdata;

        cdev_idx = emc2305_get_cdev_idx(cdev);
        if (cdev_idx < 0)
                return cdev_idx;

        *state = data->cdev_data[cdev_idx].cur_state;
        return 0;
}

static int emc2305_get_max_state(struct thermal_cooling_device *cdev, unsigned long *state)
{
        struct emc2305_data *data = cdev->devdata;
        *state = data->max_state;
        return 0;
}

static int __emc2305_set_cur_state(struct emc2305_data *data, int cdev_idx, unsigned long state)
{
        int ret;
        struct i2c_client *client = data->client;
        u8 val, i;

        state = max_t(unsigned long, state, data->cdev_data[cdev_idx].last_hwmon_state);

        val = EMC2305_PWM_STATE2DUTY(state, data->max_state, EMC2305_FAN_MAX);

        data->cdev_data[cdev_idx].cur_state = state;
        if (data->pwm_separate) {
                ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_DRIVE(cdev_idx), val);
                if (ret < 0)
                        return ret;
        } else {
                /*
                 * Set the same PWM value in all channels
                 * if common PWM channel is used.
                 */
                for (i = 0; i < data->pwm_num; i++) {
                        ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_DRIVE(i), val);
                        if (ret < 0)
                                return ret;
                }
        }

        return 0;
}

static int emc2305_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
{
        int cdev_idx, ret;
        struct emc2305_data *data = cdev->devdata;

        if (state > data->max_state)
                return -EINVAL;

        cdev_idx =  emc2305_get_cdev_idx(cdev);
        if (cdev_idx < 0)
                return cdev_idx;

        /* Save thermal state. */
        data->cdev_data[cdev_idx].last_thermal_state = state;
        ret = __emc2305_set_cur_state(data, cdev_idx, state);
        if (ret < 0)
                return ret;

        return 0;
}

static const struct thermal_cooling_device_ops emc2305_cooling_ops = {
        .get_max_state = emc2305_get_max_state,
        .get_cur_state = emc2305_get_cur_state,
        .set_cur_state = emc2305_set_cur_state,
};

static int emc2305_show_fault(struct device *dev, int channel)
{
        struct emc2305_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        int status_reg;

        status_reg = i2c_smbus_read_byte_data(client, EMC2305_REG_DRIVE_FAIL_STATUS);
        if (status_reg < 0)
                return status_reg;

        return status_reg & (1 << channel) ? 1 : 0;
}

static int emc2305_show_fan(struct device *dev, int channel)
{
        struct emc2305_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        int ret;

        ret = i2c_smbus_read_word_swapped(client, EMC2305_REG_FAN_TACH(channel));
        if (ret <= 0)
                return ret;

        ret = ret >> EMC2305_TACH_REGS_UNUSE_BITS;
        ret = EMC2305_RPM_FACTOR / ret;
        if (ret <= EMC2305_TACH_RANGE_MIN)
                return 0;

        return ret * EMC2305_TACH_CNT_MULTIPLIER;
}

static int emc2305_show_pwm(struct device *dev, int channel)
{
        struct emc2305_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;

        return i2c_smbus_read_byte_data(client, EMC2305_REG_FAN_DRIVE(channel));
}

static int emc2305_set_pwm(struct device *dev, long val, int channel)
{
        struct emc2305_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        int ret;

        if (val < data->pwm_min[channel] || val > EMC2305_FAN_MAX)
                return -EINVAL;

        ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_DRIVE(channel), val);
        if (ret < 0)
                return ret;
        data->cdev_data[channel].cur_state = EMC2305_PWM_DUTY2STATE(val, data->max_state,
                                                                    EMC2305_FAN_MAX);
        return 0;
}

static int emc2305_set_single_tz(struct device *dev, struct device_node *fan_node, int idx)
{
        struct emc2305_data *data = dev_get_drvdata(dev);
        long pwm;
        int i, cdev_idx, ret;

        cdev_idx = (idx) ? idx - 1 : 0;
        pwm = data->pwm_min[cdev_idx];

        data->cdev_data[cdev_idx].cdev =
                devm_thermal_of_cooling_device_register(dev, fan_node,
                                                        emc2305_fan_name[idx], data,
                                                        &emc2305_cooling_ops);

        if (IS_ERR(data->cdev_data[cdev_idx].cdev)) {
                dev_err(dev, "Failed to register cooling device %s\n", emc2305_fan_name[idx]);
                return PTR_ERR(data->cdev_data[cdev_idx].cdev);
        }

        if (data->cdev_data[cdev_idx].cur_state > 0)
                /* Update pwm when temperature is above trips */
                pwm = EMC2305_PWM_STATE2DUTY(data->cdev_data[cdev_idx].cur_state,
                                             data->max_state, EMC2305_FAN_MAX);

        /* Set minimal PWM speed. */
        if (data->pwm_separate) {
                ret = emc2305_set_pwm(dev, pwm, cdev_idx);
                if (ret < 0)
                        return ret;
        } else {
                for (i = 0; i < data->pwm_num; i++) {
                        ret = emc2305_set_pwm(dev, pwm, i);
                        if (ret < 0)
                                return ret;
                }
        }
        data->cdev_data[cdev_idx].cur_state =
                EMC2305_PWM_DUTY2STATE(pwm, data->max_state,
                                       EMC2305_FAN_MAX);
        data->cdev_data[cdev_idx].last_hwmon_state =
                EMC2305_PWM_DUTY2STATE(pwm, data->max_state,
                                       EMC2305_FAN_MAX);
        return 0;
}

static int emc2305_set_tz(struct device *dev)
{
        struct emc2305_data *data = dev_get_drvdata(dev);
        int i, ret;

        if (!data->pwm_separate)
                return emc2305_set_single_tz(dev, dev->of_node, 0);

        for (i = 0; i < data->pwm_num; i++) {
                ret = emc2305_set_single_tz(dev, dev->of_node, i + 1);
                if (ret)
                        return ret;
        }
        return 0;
}

static umode_t
emc2305_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr, int channel)
{
        int max_channel = emc2305_get_max_channel(data);

        /* Don't show channels which are not physically connected. */
        if (channel >= max_channel)
                return 0;
        switch (type) {
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_input:
                        return 0444;
                case hwmon_fan_fault:
                        return 0444;
                default:
                        break;
                }
                break;
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        return 0644;
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return 0;
};

static int
emc2305_write(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long val)
{
        struct emc2305_data *data = dev_get_drvdata(dev);
        int cdev_idx;

        switch (type) {
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        /* If thermal is configured - handle PWM limit setting. */
                        if (IS_REACHABLE(CONFIG_THERMAL)) {
                                if (data->pwm_separate)
                                        cdev_idx = channel;
                                else
                                        cdev_idx = 0;
                                data->cdev_data[cdev_idx].last_hwmon_state =
                                        EMC2305_PWM_DUTY2STATE(val, data->max_state,
                                                               EMC2305_FAN_MAX);
                                /*
                                 * Update PWM only in case requested state is not less than the
                                 * last thermal state.
                                 */
                                if (data->cdev_data[cdev_idx].last_hwmon_state >=
                                    data->cdev_data[cdev_idx].last_thermal_state)
                                        return __emc2305_set_cur_state(data, cdev_idx,
                                                        data->cdev_data[cdev_idx].last_hwmon_state);
                                return 0;
                        }
                        return emc2305_set_pwm(dev, val, channel);
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return -EOPNOTSUPP;
};

static int
emc2305_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long *val)
{
        int ret;

        switch (type) {
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_input:
                        ret = emc2305_show_fan(dev, channel);
                        if (ret < 0)
                                return ret;
                        *val = ret;
                        return 0;
                case hwmon_fan_fault:
                        ret = emc2305_show_fault(dev, channel);
                        if (ret < 0)
                                return ret;
                        *val = ret;
                        return 0;
                default:
                        break;
                }
                break;
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        ret = emc2305_show_pwm(dev, channel);
                        if (ret < 0)
                                return ret;
                        *val = ret;
                        return 0;
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return -EOPNOTSUPP;
};

static const struct hwmon_ops emc2305_ops = {
        .is_visible = emc2305_is_visible,
        .read = emc2305_read,
        .write = emc2305_write,
};

static const struct hwmon_channel_info * const emc2305_info[] = {
        HWMON_CHANNEL_INFO(fan,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT),
        HWMON_CHANNEL_INFO(pwm,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT),
        NULL
};

static const struct hwmon_chip_info emc2305_chip_info = {
        .ops = &emc2305_ops,
        .info = emc2305_info,
};

static int emc2305_identify(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct emc2305_data *data = i2c_get_clientdata(client);
        int ret;

        ret = i2c_smbus_read_byte_data(client, EMC2305_REG_PRODUCT_ID);
        if (ret < 0)
                return ret;

        switch (ret) {
        case EMC2305:
                data->pwm_num = 5;
                break;
        case EMC2303:
                data->pwm_num = 3;
                break;
        case EMC2302:
                data->pwm_num = 2;
                break;
        case EMC2301:
                data->pwm_num = 1;
                break;
        default:
                return -ENODEV;
        }

        return 0;
}

static int emc2305_of_parse_pwm_child(struct device *dev,
                                      struct device_node *child,
                                      struct emc2305_data *data)
{       u32 ch;
        int ret;
        struct of_phandle_args args;

        ret = of_property_read_u32(child, "reg", &ch);
        if (ret) {
                dev_err(dev, "missing reg property of %pOFn\n", child);
                return ret;
        }

        ret = of_parse_phandle_with_args(child, "pwms", "#pwm-cells", 0, &args);

        if (ret)
                return ret;

        if (args.args_count > 0) {
                data->pwm_freq[ch] = find_closest(args.args[0], base_freq_table,
                                                  ARRAY_SIZE(base_freq_table));
        } else {
                data->pwm_freq[ch] = base_freq_table[3];
        }

        if (args.args_count > 1) {
                if (args.args[1] == PWM_POLARITY_NORMAL || args.args[1] == PWM_POLARITY_INVERSED)
                        data->pwm_polarity_mask |= args.args[1] << ch;
                else
                        dev_err(dev, "Wrong PWM polarity config provided: %d\n", args.args[0]);
        } else {
                data->pwm_polarity_mask |= PWM_POLARITY_NORMAL << ch;
        }

        if (args.args_count > 2) {
                if (args.args[2] == EMC2305_PUSH_PULL || args.args[2] <= EMC2305_OPEN_DRAIN)
                        data->pwm_output_mask |= args.args[2] << ch;
                else
                        dev_err(dev, "Wrong PWM output config provided: %d\n", args.args[1]);
        } else {
                data->pwm_output_mask |= EMC2305_OPEN_DRAIN << ch;
        }

        of_node_put(args.np);
        return 0;
}

static int emc2305_probe_childs_from_dt(struct device *dev)
{
        struct emc2305_data *data = dev_get_drvdata(dev);
        struct device_node *child;
        int ret, count = 0;

        data->pwm_output_mask = 0x0;
        data->pwm_polarity_mask = 0x0;

        for_each_child_of_node(dev->of_node, child) {
                if (of_property_present(child, "reg")) {
                        ret = emc2305_of_parse_pwm_child(dev, child, data);
                        if (ret)
                                continue;
                        count++;
                }
        }
        return count;
}

static int emc2305_probe(struct i2c_client *client)
{
        struct i2c_adapter *adapter = client->adapter;
        struct device *dev = &client->dev;
        struct emc2305_data *data;
        struct emc2305_platform_data *pdata;
        int vendor;
        int ret;
        int i;
        int pwm_childs;

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

        vendor = i2c_smbus_read_byte_data(client, EMC2305_REG_VENDOR);
        if (vendor != EMC2305_VENDOR)
                return -ENODEV;

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

        i2c_set_clientdata(client, data);
        data->client = client;

        ret = emc2305_identify(dev);
        if (ret)
                return ret;

        pwm_childs = emc2305_probe_childs_from_dt(dev);

        pdata = dev_get_platdata(&client->dev);

        if (!pwm_childs) {
                if (pdata) {
                        if (!pdata->max_state || pdata->max_state > EMC2305_FAN_MAX_STATE)
                                return -EINVAL;
                        data->max_state = pdata->max_state;
                        /*
                         * Validate a number of active PWM channels. Note that
                         * configured number can be less than the actual maximum
                         * supported by the device.
                         */
                        if (!pdata->pwm_num || pdata->pwm_num > EMC2305_PWM_MAX)
                                return -EINVAL;
                        data->pwm_num = pdata->pwm_num;
                        data->pwm_output_mask = pdata->pwm_output_mask;
                        data->pwm_polarity_mask = pdata->pwm_polarity_mask;
                        data->pwm_separate = pdata->pwm_separate;
                        for (i = 0; i < EMC2305_PWM_MAX; i++) {
                                data->pwm_min[i] = pdata->pwm_min[i];
                                data->pwm_freq[i] = pdata->pwm_freq[i];
                        }
                } else {
                        data->max_state = EMC2305_FAN_MAX_STATE;
                        data->pwm_separate = false;
                        data->pwm_output_mask = EMC2305_DEFAULT_OUTPUT;
                        data->pwm_polarity_mask = EMC2305_DEFAULT_POLARITY;
                        for (i = 0; i < EMC2305_PWM_MAX; i++) {
                                data->pwm_min[i] = EMC2305_FAN_MIN;
                                data->pwm_freq[i] = base_freq_table[3];
                        }
                }
        } else {
                data->max_state = EMC2305_FAN_MAX_STATE;
                data->pwm_separate = false;
                for (i = 0; i < EMC2305_PWM_MAX; i++)
                        data->pwm_min[i] = EMC2305_FAN_MIN;
        }

        data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "emc2305", data,
                                                               &emc2305_chip_info, NULL);
        if (IS_ERR(data->hwmon_dev))
                return PTR_ERR(data->hwmon_dev);

        if (IS_REACHABLE(CONFIG_THERMAL)) {
                /* Parse and check for the available PWM child nodes */
                if (pwm_childs > 0) {
                        i = 0;
                        for_each_child_of_node_scoped(dev->of_node, child) {
                                ret = emc2305_set_single_tz(dev, child, i);
                                if (ret != 0)
                                        return ret;
                                i++;
                        }
                } else {
                        ret = emc2305_set_tz(dev);
                        if (ret != 0)
                                return ret;
                }
        }

        ret = i2c_smbus_write_byte_data(client, EMC2305_REG_DRIVE_PWM_OUT,
                                        data->pwm_output_mask);
        if (ret < 0)
                dev_err(dev, "Failed to configure pwm output, using default\n");

        ret = i2c_smbus_write_byte_data(client, EMC2305_REG_POLARITY,
                                        data->pwm_polarity_mask);
        if (ret < 0)
                dev_err(dev, "Failed to configure pwm polarity, using default\n");

        for (i = 0; i < data->pwm_num; i++) {
                ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_MIN_DRIVE(i),
                                                data->pwm_min[i]);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

static const struct of_device_id of_emc2305_match_table[] = {
        { .compatible = "microchip,emc2305", },
        {},
};
MODULE_DEVICE_TABLE(of, of_emc2305_match_table);

static struct i2c_driver emc2305_driver = {
        .driver = {
                .name = "emc2305",
                .of_match_table = of_emc2305_match_table,
        },
        .probe = emc2305_probe,
        .id_table = emc2305_ids,
};

module_i2c_driver(emc2305_driver);

MODULE_AUTHOR("Nvidia");
MODULE_DESCRIPTION("Microchip EMC2305 fan controller driver");
MODULE_LICENSE("GPL");