root/drivers/hwmon/tps23861.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2020 Sartura Ltd.
 *
 * Driver for the TI TPS23861 PoE PSE.
 *
 * Author: Robert Marko <robert.marko@sartura.hr>
 */

#include <linux/bitfield.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/hwmon-sysfs.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regmap.h>

#define TEMPERATURE                     0x2c
#define INPUT_VOLTAGE_LSB               0x2e
#define INPUT_VOLTAGE_MSB               0x2f
#define PORT_1_CURRENT_LSB              0x30
#define PORT_1_CURRENT_MSB              0x31
#define PORT_1_VOLTAGE_LSB              0x32
#define PORT_1_VOLTAGE_MSB              0x33
#define PORT_2_CURRENT_LSB              0x34
#define PORT_2_CURRENT_MSB              0x35
#define PORT_2_VOLTAGE_LSB              0x36
#define PORT_2_VOLTAGE_MSB              0x37
#define PORT_3_CURRENT_LSB              0x38
#define PORT_3_CURRENT_MSB              0x39
#define PORT_3_VOLTAGE_LSB              0x3a
#define PORT_3_VOLTAGE_MSB              0x3b
#define PORT_4_CURRENT_LSB              0x3c
#define PORT_4_CURRENT_MSB              0x3d
#define PORT_4_VOLTAGE_LSB              0x3e
#define PORT_4_VOLTAGE_MSB              0x3f
#define PORT_N_CURRENT_LSB_OFFSET       0x04
#define PORT_N_VOLTAGE_LSB_OFFSET       0x04
#define VOLTAGE_CURRENT_MASK            GENMASK(13, 0)
#define PORT_1_RESISTANCE_LSB           0x60
#define PORT_1_RESISTANCE_MSB           0x61
#define PORT_2_RESISTANCE_LSB           0x62
#define PORT_2_RESISTANCE_MSB           0x63
#define PORT_3_RESISTANCE_LSB           0x64
#define PORT_3_RESISTANCE_MSB           0x65
#define PORT_4_RESISTANCE_LSB           0x66
#define PORT_4_RESISTANCE_MSB           0x67
#define PORT_N_RESISTANCE_LSB_OFFSET    0x02
#define PORT_RESISTANCE_MASK            GENMASK(13, 0)
#define PORT_RESISTANCE_RSN_MASK        GENMASK(15, 14)
#define PORT_RESISTANCE_RSN_OTHER       0
#define PORT_RESISTANCE_RSN_LOW         1
#define PORT_RESISTANCE_RSN_OPEN        2
#define PORT_RESISTANCE_RSN_SHORT       3
#define PORT_1_STATUS                   0x0c
#define PORT_2_STATUS                   0x0d
#define PORT_3_STATUS                   0x0e
#define PORT_4_STATUS                   0x0f
#define PORT_STATUS_CLASS_MASK          GENMASK(7, 4)
#define PORT_STATUS_DETECT_MASK         GENMASK(3, 0)
#define PORT_CLASS_UNKNOWN              0
#define PORT_CLASS_1                    1
#define PORT_CLASS_2                    2
#define PORT_CLASS_3                    3
#define PORT_CLASS_4                    4
#define PORT_CLASS_RESERVED             5
#define PORT_CLASS_0                    6
#define PORT_CLASS_OVERCURRENT          7
#define PORT_CLASS_MISMATCH             8
#define PORT_DETECT_UNKNOWN             0
#define PORT_DETECT_SHORT               1
#define PORT_DETECT_RESERVED            2
#define PORT_DETECT_RESISTANCE_LOW      3
#define PORT_DETECT_RESISTANCE_OK       4
#define PORT_DETECT_RESISTANCE_HIGH     5
#define PORT_DETECT_OPEN_CIRCUIT        6
#define PORT_DETECT_RESERVED_2          7
#define PORT_DETECT_MOSFET_FAULT        8
#define PORT_DETECT_LEGACY              9
/* Measurment beyond clamp voltage */
#define PORT_DETECT_CAPACITANCE_INVALID_BEYOND  10
/* Insufficient voltage delta */
#define PORT_DETECT_CAPACITANCE_INVALID_DELTA   11
#define PORT_DETECT_CAPACITANCE_OUT_OF_RANGE    12
#define POE_PLUS                        0x40
#define OPERATING_MODE                  0x12
#define OPERATING_MODE_OFF              0
#define OPERATING_MODE_MANUAL           1
#define OPERATING_MODE_SEMI             2
#define OPERATING_MODE_AUTO             3
#define OPERATING_MODE_PORT_1_MASK      GENMASK(1, 0)
#define OPERATING_MODE_PORT_2_MASK      GENMASK(3, 2)
#define OPERATING_MODE_PORT_3_MASK      GENMASK(5, 4)
#define OPERATING_MODE_PORT_4_MASK      GENMASK(7, 6)

#define DETECT_CLASS_RESTART            0x18
#define POWER_ENABLE                    0x19
#define TPS23861_NUM_PORTS              4

#define TPS23861_GENERAL_MASK_1         0x17
#define TPS23861_CURRENT_SHUNT_MASK     BIT(0)

#define TEMPERATURE_LSB                 652 /* 0.652 degrees Celsius */
#define VOLTAGE_LSB                     3662 /* 3.662 mV */
#define SHUNT_RESISTOR_DEFAULT          255000 /* 255 mOhm */
#define CURRENT_LSB_250                 62260 /* 62.260 uA */
#define CURRENT_LSB_255                 61039 /* 61.039 uA */
#define RESISTANCE_LSB                  110966 /* 11.0966 Ohm*/
#define RESISTANCE_LSB_LOW              157216 /* 15.7216 Ohm*/

struct tps23861_data {
        struct regmap *regmap;
        u32 shunt_resistor;
        struct i2c_client *client;
};

static const struct regmap_config tps23861_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = 0x6f,
};

static int tps23861_read_temp(struct tps23861_data *data, long *val)
{
        unsigned int regval;
        int err;

        err = regmap_read(data->regmap, TEMPERATURE, &regval);
        if (err < 0)
                return err;

        *val = ((long)regval * TEMPERATURE_LSB) - 20000;

        return 0;
}

static int tps23861_read_voltage(struct tps23861_data *data, int channel,
                                 long *val)
{
        __le16 regval;
        long raw_val;
        int err;

        if (channel < TPS23861_NUM_PORTS) {
                err = regmap_bulk_read(data->regmap,
                                       PORT_1_VOLTAGE_LSB + channel * PORT_N_VOLTAGE_LSB_OFFSET,
                                       &regval, 2);
        } else {
                err = regmap_bulk_read(data->regmap,
                                       INPUT_VOLTAGE_LSB,
                                       &regval, 2);
        }
        if (err < 0)
                return err;

        raw_val = le16_to_cpu(regval);
        *val = (FIELD_GET(VOLTAGE_CURRENT_MASK, raw_val) * VOLTAGE_LSB) / 1000;

        return 0;
}

static int tps23861_read_current(struct tps23861_data *data, int channel,
                                 long *val)
{
        long raw_val, current_lsb;
        __le16 regval;

        int err;

        if (data->shunt_resistor == SHUNT_RESISTOR_DEFAULT)
                current_lsb = CURRENT_LSB_255;
        else
                current_lsb = CURRENT_LSB_250;

        err = regmap_bulk_read(data->regmap,
                               PORT_1_CURRENT_LSB + channel * PORT_N_CURRENT_LSB_OFFSET,
                               &regval, 2);
        if (err < 0)
                return err;

        raw_val = le16_to_cpu(regval);
        *val = (FIELD_GET(VOLTAGE_CURRENT_MASK, raw_val) * current_lsb) / 1000000;

        return 0;
}

static int tps23861_port_disable(struct tps23861_data *data, int channel)
{
        unsigned int regval = 0;
        int err;

        regval |= BIT(channel + 4);
        err = regmap_write(data->regmap, POWER_ENABLE, regval);

        return err;
}

static int tps23861_port_enable(struct tps23861_data *data, int channel)
{
        unsigned int regval = 0;
        int err;

        regval |= BIT(channel);
        regval |= BIT(channel + 4);
        err = regmap_write(data->regmap, DETECT_CLASS_RESTART, regval);

        return err;
}

static umode_t tps23861_is_visible(const void *data, enum hwmon_sensor_types type,
                                   u32 attr, int channel)
{
        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_input:
                case hwmon_temp_label:
                        return 0444;
                default:
                        return 0;
                }
        case hwmon_in:
                switch (attr) {
                case hwmon_in_input:
                case hwmon_in_label:
                        return 0444;
                case hwmon_in_enable:
                        return 0200;
                default:
                        return 0;
                }
        case hwmon_curr:
                switch (attr) {
                case hwmon_curr_input:
                case hwmon_curr_label:
                        return 0444;
                default:
                        return 0;
                }
        default:
                return 0;
        }
}

static int tps23861_write(struct device *dev, enum hwmon_sensor_types type,
                          u32 attr, int channel, long val)
{
        struct tps23861_data *data = dev_get_drvdata(dev);
        int err;

        switch (type) {
        case hwmon_in:
                switch (attr) {
                case hwmon_in_enable:
                        if (val == 0)
                                err = tps23861_port_disable(data, channel);
                        else if (val == 1)
                                err = tps23861_port_enable(data, channel);
                        else
                                err = -EINVAL;
                        break;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        default:
                return -EOPNOTSUPP;
        }

        return err;
}

static int tps23861_read(struct device *dev, enum hwmon_sensor_types type,
                         u32 attr, int channel, long *val)
{
        struct tps23861_data *data = dev_get_drvdata(dev);
        int err;

        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_input:
                        err = tps23861_read_temp(data, val);
                        break;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        case hwmon_in:
                switch (attr) {
                case hwmon_in_input:
                        err = tps23861_read_voltage(data, channel, val);
                        break;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        case hwmon_curr:
                switch (attr) {
                case hwmon_curr_input:
                        err = tps23861_read_current(data, channel, val);
                        break;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        default:
                return -EOPNOTSUPP;
        }

        return err;
}

static const char * const tps23861_port_label[] = {
        "Port1",
        "Port2",
        "Port3",
        "Port4",
        "Input",
};

static int tps23861_read_string(struct device *dev,
                                enum hwmon_sensor_types type,
                                u32 attr, int channel, const char **str)
{
        switch (type) {
        case hwmon_in:
        case hwmon_curr:
                *str = tps23861_port_label[channel];
                break;
        case hwmon_temp:
                *str = "Die";
                break;
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static const struct hwmon_channel_info * const tps23861_info[] = {
        HWMON_CHANNEL_INFO(chip,
                           HWMON_C_REGISTER_TZ),
        HWMON_CHANNEL_INFO(temp,
                           HWMON_T_INPUT | HWMON_T_LABEL),
        HWMON_CHANNEL_INFO(in,
                           HWMON_I_INPUT | HWMON_I_ENABLE | HWMON_I_LABEL,
                           HWMON_I_INPUT | HWMON_I_ENABLE | HWMON_I_LABEL,
                           HWMON_I_INPUT | HWMON_I_ENABLE | HWMON_I_LABEL,
                           HWMON_I_INPUT | HWMON_I_ENABLE | HWMON_I_LABEL,
                           HWMON_I_INPUT | HWMON_I_LABEL),
        HWMON_CHANNEL_INFO(curr,
                           HWMON_C_INPUT | HWMON_C_LABEL,
                           HWMON_C_INPUT | HWMON_C_LABEL,
                           HWMON_C_INPUT | HWMON_C_LABEL,
                           HWMON_C_INPUT | HWMON_C_LABEL),
        NULL
};

static const struct hwmon_ops tps23861_hwmon_ops = {
        .is_visible = tps23861_is_visible,
        .write = tps23861_write,
        .read = tps23861_read,
        .read_string = tps23861_read_string,
};

static const struct hwmon_chip_info tps23861_chip_info = {
        .ops = &tps23861_hwmon_ops,
        .info = tps23861_info,
};

static char *port_operating_mode_string(uint8_t mode_reg, unsigned int port)
{
        unsigned int mode = ~0;

        if (port < TPS23861_NUM_PORTS)
                mode = (mode_reg >> (2 * port)) & OPERATING_MODE_PORT_1_MASK;

        switch (mode) {
        case OPERATING_MODE_OFF:
                return "Off";
        case OPERATING_MODE_MANUAL:
                return "Manual";
        case OPERATING_MODE_SEMI:
                return "Semi-Auto";
        case OPERATING_MODE_AUTO:
                return "Auto";
        default:
                return "Invalid";
        }
}

static char *port_detect_status_string(uint8_t status_reg)
{
        switch (FIELD_GET(PORT_STATUS_DETECT_MASK, status_reg)) {
        case PORT_DETECT_UNKNOWN:
                return "Unknown device";
        case PORT_DETECT_SHORT:
                return "Short circuit";
        case PORT_DETECT_RESISTANCE_LOW:
                return "Too low resistance";
        case PORT_DETECT_RESISTANCE_OK:
                return "Valid resistance";
        case PORT_DETECT_RESISTANCE_HIGH:
                return "Too high resistance";
        case PORT_DETECT_OPEN_CIRCUIT:
                return "Open circuit";
        case PORT_DETECT_MOSFET_FAULT:
                return "MOSFET fault";
        case PORT_DETECT_LEGACY:
                return "Legacy device";
        case PORT_DETECT_CAPACITANCE_INVALID_BEYOND:
                return "Invalid capacitance, beyond clamp voltage";
        case PORT_DETECT_CAPACITANCE_INVALID_DELTA:
                return "Invalid capacitance, insufficient voltage delta";
        case PORT_DETECT_CAPACITANCE_OUT_OF_RANGE:
                return "Valid capacitance, outside of legacy range";
        case PORT_DETECT_RESERVED:
        case PORT_DETECT_RESERVED_2:
        default:
                return "Invalid";
        }
}

static char *port_class_status_string(uint8_t status_reg)
{
        switch (FIELD_GET(PORT_STATUS_CLASS_MASK, status_reg)) {
        case PORT_CLASS_UNKNOWN:
                return "Unknown";
        case PORT_CLASS_RESERVED:
        case PORT_CLASS_0:
                return "0";
        case PORT_CLASS_1:
                return "1";
        case PORT_CLASS_2:
                return "2";
        case PORT_CLASS_3:
                return "3";
        case PORT_CLASS_4:
                return "4";
        case PORT_CLASS_OVERCURRENT:
                return "Overcurrent";
        case PORT_CLASS_MISMATCH:
                return "Mismatch";
        default:
                return "Invalid";
        }
}

static char *port_poe_plus_status_string(uint8_t poe_plus, unsigned int port)
{
        return (BIT(port + 4) & poe_plus) ? "Yes" : "No";
}

static int tps23861_port_resistance(struct tps23861_data *data, int port)
{
        unsigned int raw_val;
        __le16 regval;

        regmap_bulk_read(data->regmap,
                         PORT_1_RESISTANCE_LSB + PORT_N_RESISTANCE_LSB_OFFSET * port,
                         &regval,
                         2);

        raw_val = le16_to_cpu(regval);
        switch (FIELD_GET(PORT_RESISTANCE_RSN_MASK, raw_val)) {
        case PORT_RESISTANCE_RSN_OTHER:
                return (FIELD_GET(PORT_RESISTANCE_MASK, raw_val) * RESISTANCE_LSB) / 10000;
        case PORT_RESISTANCE_RSN_LOW:
                return (FIELD_GET(PORT_RESISTANCE_MASK, raw_val) * RESISTANCE_LSB_LOW) / 10000;
        case PORT_RESISTANCE_RSN_SHORT:
        case PORT_RESISTANCE_RSN_OPEN:
        default:
                return 0;
        }
}

static int tps23861_port_status_show(struct seq_file *s, void *data)
{
        struct tps23861_data *priv = s->private;
        unsigned int i, mode, poe_plus, status;

        regmap_read(priv->regmap, OPERATING_MODE, &mode);
        regmap_read(priv->regmap, POE_PLUS, &poe_plus);

        for (i = 0; i < TPS23861_NUM_PORTS; i++) {
                regmap_read(priv->regmap, PORT_1_STATUS + i, &status);

                seq_printf(s, "Port: \t\t%d\n", i + 1);
                seq_printf(s, "Operating mode: %s\n", port_operating_mode_string(mode, i));
                seq_printf(s, "Detected: \t%s\n", port_detect_status_string(status));
                seq_printf(s, "Class: \t\t%s\n", port_class_status_string(status));
                seq_printf(s, "PoE Plus: \t%s\n", port_poe_plus_status_string(poe_plus, i));
                seq_printf(s, "Resistance: \t%d\n", tps23861_port_resistance(priv, i));
                seq_putc(s, '\n');
        }

        return 0;
}

DEFINE_SHOW_ATTRIBUTE(tps23861_port_status);

static int tps23861_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct tps23861_data *data;
        struct device *hwmon_dev;
        u32 shunt_resistor;

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

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

        data->regmap = devm_regmap_init_i2c(client, &tps23861_regmap_config);
        if (IS_ERR(data->regmap)) {
                dev_err(dev, "failed to allocate register map\n");
                return PTR_ERR(data->regmap);
        }

        if (!of_property_read_u32(dev->of_node, "shunt-resistor-micro-ohms", &shunt_resistor))
                data->shunt_resistor = shunt_resistor;
        else
                data->shunt_resistor = SHUNT_RESISTOR_DEFAULT;

        if (data->shunt_resistor == SHUNT_RESISTOR_DEFAULT)
                regmap_clear_bits(data->regmap,
                                  TPS23861_GENERAL_MASK_1,
                                  TPS23861_CURRENT_SHUNT_MASK);
        else
                regmap_set_bits(data->regmap,
                                TPS23861_GENERAL_MASK_1,
                                TPS23861_CURRENT_SHUNT_MASK);

        hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
                                                         data, &tps23861_chip_info,
                                                         NULL);
        if (IS_ERR(hwmon_dev))
                return PTR_ERR(hwmon_dev);

        debugfs_create_file("port_status", 0400, client->debugfs, data,
                            &tps23861_port_status_fops);

        return 0;
}

static const struct of_device_id __maybe_unused tps23861_of_match[] = {
        { .compatible = "ti,tps23861", },
        { },
};
MODULE_DEVICE_TABLE(of, tps23861_of_match);

static struct i2c_driver tps23861_driver = {
        .probe                  = tps23861_probe,
        .driver = {
                .name           = "tps23861",
                .of_match_table = of_match_ptr(tps23861_of_match),
        },
};
module_i2c_driver(tps23861_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Robert Marko <robert.marko@sartura.hr>");
MODULE_DESCRIPTION("TI TPS23861 PoE PSE");