// SPDX-License-Identifier: GPL-2.0
/*
 * Analog Devices LTC2983 Multi-Sensor Digital Temperature Measurement System
 * driver
 *
 * Copyright 2019 Analog Devices Inc.
 */
#include <linux/bitfield.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/iio/iio.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of_gpio.h>
#include <linux/regmap.h>
#include <linux/spi/spi.h>

/* register map */
#define LTC2983_STATUS_REG                      0x0000
#define LTC2983_TEMP_RES_START_REG              0x0010
#define LTC2983_TEMP_RES_END_REG                0x005F
#define LTC2983_GLOBAL_CONFIG_REG               0x00F0
#define LTC2983_MULT_CHANNEL_START_REG          0x00F4
#define LTC2983_MULT_CHANNEL_END_REG            0x00F7
#define LTC2983_MUX_CONFIG_REG                  0x00FF
#define LTC2983_CHAN_ASSIGN_START_REG           0x0200
#define LTC2983_CHAN_ASSIGN_END_REG             0x024F
#define LTC2983_CUST_SENS_TBL_START_REG         0x0250
#define LTC2983_CUST_SENS_TBL_END_REG           0x03CF

#define LTC2983_DIFFERENTIAL_CHAN_MIN           2
#define LTC2983_MAX_CHANNELS_NR                 20
#define LTC2983_MIN_CHANNELS_NR                 1
#define LTC2983_SLEEP                           0x97
#define LTC2983_CUSTOM_STEINHART_SIZE           24
#define LTC2983_CUSTOM_SENSOR_ENTRY_SZ          6
#define LTC2983_CUSTOM_STEINHART_ENTRY_SZ       4

#define LTC2983_CHAN_START_ADDR(chan) \
                        (((chan - 1) * 4) + LTC2983_CHAN_ASSIGN_START_REG)
#define LTC2983_CHAN_RES_ADDR(chan) \
                        (((chan - 1) * 4) + LTC2983_TEMP_RES_START_REG)
#define LTC2983_THERMOCOUPLE_DIFF_MASK          BIT(3)
#define LTC2983_THERMOCOUPLE_SGL(x) \
                                FIELD_PREP(LTC2983_THERMOCOUPLE_DIFF_MASK, x)
#define LTC2983_THERMOCOUPLE_OC_CURR_MASK       GENMASK(1, 0)
#define LTC2983_THERMOCOUPLE_OC_CURR(x) \
                                FIELD_PREP(LTC2983_THERMOCOUPLE_OC_CURR_MASK, x)
#define LTC2983_THERMOCOUPLE_OC_CHECK_MASK      BIT(2)
#define LTC2983_THERMOCOUPLE_OC_CHECK(x) \
                        FIELD_PREP(LTC2983_THERMOCOUPLE_OC_CHECK_MASK, x)

#define LTC2983_THERMISTOR_DIFF_MASK            BIT(2)
#define LTC2983_THERMISTOR_SGL(x) \
                                FIELD_PREP(LTC2983_THERMISTOR_DIFF_MASK, x)
#define LTC2983_THERMISTOR_R_SHARE_MASK         BIT(1)
#define LTC2983_THERMISTOR_R_SHARE(x) \
                                FIELD_PREP(LTC2983_THERMISTOR_R_SHARE_MASK, x)
#define LTC2983_THERMISTOR_C_ROTATE_MASK        BIT(0)
#define LTC2983_THERMISTOR_C_ROTATE(x) \
                                FIELD_PREP(LTC2983_THERMISTOR_C_ROTATE_MASK, x)

#define LTC2983_DIODE_DIFF_MASK                 BIT(2)
#define LTC2983_DIODE_SGL(x) \
                        FIELD_PREP(LTC2983_DIODE_DIFF_MASK, x)
#define LTC2983_DIODE_3_CONV_CYCLE_MASK         BIT(1)
#define LTC2983_DIODE_3_CONV_CYCLE(x) \
                                FIELD_PREP(LTC2983_DIODE_3_CONV_CYCLE_MASK, x)
#define LTC2983_DIODE_AVERAGE_ON_MASK           BIT(0)
#define LTC2983_DIODE_AVERAGE_ON(x) \
                                FIELD_PREP(LTC2983_DIODE_AVERAGE_ON_MASK, x)

#define LTC2983_RTD_4_WIRE_MASK                 BIT(3)
#define LTC2983_RTD_ROTATION_MASK               BIT(1)
#define LTC2983_RTD_C_ROTATE(x) \
                        FIELD_PREP(LTC2983_RTD_ROTATION_MASK, x)
#define LTC2983_RTD_KELVIN_R_SENSE_MASK         GENMASK(3, 2)
#define LTC2983_RTD_N_WIRES_MASK                GENMASK(3, 2)
#define LTC2983_RTD_N_WIRES(x) \
                        FIELD_PREP(LTC2983_RTD_N_WIRES_MASK, x)
#define LTC2983_RTD_R_SHARE_MASK                BIT(0)
#define LTC2983_RTD_R_SHARE(x) \
                        FIELD_PREP(LTC2983_RTD_R_SHARE_MASK, 1)

#define LTC2983_COMMON_HARD_FAULT_MASK  GENMASK(31, 30)
#define LTC2983_COMMON_SOFT_FAULT_MASK  GENMASK(27, 25)

#define LTC2983_STATUS_START_MASK       BIT(7)
#define LTC2983_STATUS_START(x)         FIELD_PREP(LTC2983_STATUS_START_MASK, x)
#define LTC2983_STATUS_UP_MASK          GENMASK(7, 6)
#define LTC2983_STATUS_UP(reg)          FIELD_GET(LTC2983_STATUS_UP_MASK, reg)

#define LTC2983_STATUS_CHAN_SEL_MASK    GENMASK(4, 0)
#define LTC2983_STATUS_CHAN_SEL(x) \
                                FIELD_PREP(LTC2983_STATUS_CHAN_SEL_MASK, x)

#define LTC2983_TEMP_UNITS_MASK         BIT(2)
#define LTC2983_TEMP_UNITS(x)           FIELD_PREP(LTC2983_TEMP_UNITS_MASK, x)

#define LTC2983_NOTCH_FREQ_MASK         GENMASK(1, 0)
#define LTC2983_NOTCH_FREQ(x)           FIELD_PREP(LTC2983_NOTCH_FREQ_MASK, x)

#define LTC2983_RES_VALID_MASK          BIT(24)
#define LTC2983_DATA_MASK               GENMASK(23, 0)
#define LTC2983_DATA_SIGN_BIT           23

#define LTC2983_CHAN_TYPE_MASK          GENMASK(31, 27)
#define LTC2983_CHAN_TYPE(x)            FIELD_PREP(LTC2983_CHAN_TYPE_MASK, x)

/* cold junction for thermocouples and rsense for rtd's and thermistor's */
#define LTC2983_CHAN_ASSIGN_MASK        GENMASK(26, 22)
#define LTC2983_CHAN_ASSIGN(x)          FIELD_PREP(LTC2983_CHAN_ASSIGN_MASK, x)

#define LTC2983_CUSTOM_LEN_MASK         GENMASK(5, 0)
#define LTC2983_CUSTOM_LEN(x)           FIELD_PREP(LTC2983_CUSTOM_LEN_MASK, x)

#define LTC2983_CUSTOM_ADDR_MASK        GENMASK(11, 6)
#define LTC2983_CUSTOM_ADDR(x)          FIELD_PREP(LTC2983_CUSTOM_ADDR_MASK, x)

#define LTC2983_THERMOCOUPLE_CFG_MASK   GENMASK(21, 18)
#define LTC2983_THERMOCOUPLE_CFG(x) \
                                FIELD_PREP(LTC2983_THERMOCOUPLE_CFG_MASK, x)
#define LTC2983_THERMOCOUPLE_HARD_FAULT_MASK    GENMASK(31, 29)
#define LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK    GENMASK(28, 25)

#define LTC2983_RTD_CFG_MASK            GENMASK(21, 18)
#define LTC2983_RTD_CFG(x)              FIELD_PREP(LTC2983_RTD_CFG_MASK, x)
#define LTC2983_RTD_EXC_CURRENT_MASK    GENMASK(17, 14)
#define LTC2983_RTD_EXC_CURRENT(x) \
                                FIELD_PREP(LTC2983_RTD_EXC_CURRENT_MASK, x)
#define LTC2983_RTD_CURVE_MASK          GENMASK(13, 12)
#define LTC2983_RTD_CURVE(x)            FIELD_PREP(LTC2983_RTD_CURVE_MASK, x)

#define LTC2983_THERMISTOR_CFG_MASK     GENMASK(21, 19)
#define LTC2983_THERMISTOR_CFG(x) \
                                FIELD_PREP(LTC2983_THERMISTOR_CFG_MASK, x)
#define LTC2983_THERMISTOR_EXC_CURRENT_MASK     GENMASK(18, 15)
#define LTC2983_THERMISTOR_EXC_CURRENT(x) \
                        FIELD_PREP(LTC2983_THERMISTOR_EXC_CURRENT_MASK, x)

#define LTC2983_DIODE_CFG_MASK          GENMASK(26, 24)
#define LTC2983_DIODE_CFG(x)            FIELD_PREP(LTC2983_DIODE_CFG_MASK, x)
#define LTC2983_DIODE_EXC_CURRENT_MASK  GENMASK(23, 22)
#define LTC2983_DIODE_EXC_CURRENT(x) \
                                FIELD_PREP(LTC2983_DIODE_EXC_CURRENT_MASK, x)
#define LTC2983_DIODE_IDEAL_FACTOR_MASK GENMASK(21, 0)
#define LTC2983_DIODE_IDEAL_FACTOR(x) \
                                FIELD_PREP(LTC2983_DIODE_IDEAL_FACTOR_MASK, x)

#define LTC2983_R_SENSE_VAL_MASK        GENMASK(26, 0)
#define LTC2983_R_SENSE_VAL(x)          FIELD_PREP(LTC2983_R_SENSE_VAL_MASK, x)

#define LTC2983_ADC_SINGLE_ENDED_MASK   BIT(26)
#define LTC2983_ADC_SINGLE_ENDED(x) \
                                FIELD_PREP(LTC2983_ADC_SINGLE_ENDED_MASK, x)

enum {
        LTC2983_SENSOR_THERMOCOUPLE = 1,
        LTC2983_SENSOR_THERMOCOUPLE_CUSTOM = 9,
        LTC2983_SENSOR_RTD = 10,
        LTC2983_SENSOR_RTD_CUSTOM = 18,
        LTC2983_SENSOR_THERMISTOR = 19,
        LTC2983_SENSOR_THERMISTOR_STEINHART = 26,
        LTC2983_SENSOR_THERMISTOR_CUSTOM = 27,
        LTC2983_SENSOR_DIODE = 28,
        LTC2983_SENSOR_SENSE_RESISTOR = 29,
        LTC2983_SENSOR_DIRECT_ADC = 30,
};

#define to_thermocouple(_sensor) \
                container_of(_sensor, struct ltc2983_thermocouple, sensor)

#define to_rtd(_sensor) \
                container_of(_sensor, struct ltc2983_rtd, sensor)

#define to_thermistor(_sensor) \
                container_of(_sensor, struct ltc2983_thermistor, sensor)

#define to_diode(_sensor) \
                container_of(_sensor, struct ltc2983_diode, sensor)

#define to_rsense(_sensor) \
                container_of(_sensor, struct ltc2983_rsense, sensor)

#define to_adc(_sensor) \
                container_of(_sensor, struct ltc2983_adc, sensor)

struct ltc2983_data {
        struct regmap *regmap;
        struct spi_device *spi;
        struct mutex lock;
        struct completion completion;
        struct iio_chan_spec *iio_chan;
        struct ltc2983_sensor **sensors;
        u32 mux_delay_config;
        u32 filter_notch_freq;
        u16 custom_table_size;
        u8 num_channels;
        u8 iio_channels;
        /*
         * DMA (thus cache coherency maintenance) requires the
         * transfer buffers to live in their own cache lines.
         * Holds the converted temperature
         */
        __be32 temp ____cacheline_aligned;
};

struct ltc2983_sensor {
        int (*fault_handler)(const struct ltc2983_data *st, const u32 result);
        int (*assign_chan)(struct ltc2983_data *st,
                           const struct ltc2983_sensor *sensor);
        /* specifies the sensor channel */
        u32 chan;
        /* sensor type */
        u32 type;
};

struct ltc2983_custom_sensor {
        /* raw table sensor data */
        u8 *table;
        size_t size;
        /* address offset */
        s8 offset;
        bool is_steinhart;
};

struct ltc2983_thermocouple {
        struct ltc2983_sensor sensor;
        struct ltc2983_custom_sensor *custom;
        u32 sensor_config;
        u32 cold_junction_chan;
};

struct ltc2983_rtd {
        struct ltc2983_sensor sensor;
        struct ltc2983_custom_sensor *custom;
        u32 sensor_config;
        u32 r_sense_chan;
        u32 excitation_current;
        u32 rtd_curve;
};

struct ltc2983_thermistor {
        struct ltc2983_sensor sensor;
        struct ltc2983_custom_sensor *custom;
        u32 sensor_config;
        u32 r_sense_chan;
        u32 excitation_current;
};

struct ltc2983_diode {
        struct ltc2983_sensor sensor;
        u32 sensor_config;
        u32 excitation_current;
        u32 ideal_factor_value;
};

struct ltc2983_rsense {
        struct ltc2983_sensor sensor;
        u32 r_sense_val;
};

struct ltc2983_adc {
        struct ltc2983_sensor sensor;
        bool single_ended;
};

/*
 * Convert to Q format numbers. These number's are integers where
 * the number of integer and fractional bits are specified. The resolution
 * is given by 1/@resolution and tell us the number of fractional bits. For
 * instance a resolution of 2^-10 means we have 10 fractional bits.
 */
static u32 __convert_to_raw(const u64 val, const u32 resolution)
{
        u64 __res = val * resolution;

        /* all values are multiplied by 1000000 to remove the fraction */
        do_div(__res, 1000000);

        return __res;
}

static u32 __convert_to_raw_sign(const u64 val, const u32 resolution)
{
        s64 __res = -(s32)val;

        __res = __convert_to_raw(__res, resolution);

        return (u32)-__res;
}

static int __ltc2983_fault_handler(const struct ltc2983_data *st,
                                   const u32 result, const u32 hard_mask,
                                   const u32 soft_mask)
{
        const struct device *dev = &st->spi->dev;

        if (result & hard_mask) {
                dev_err(dev, "Invalid conversion: Sensor HARD fault\n");
                return -EIO;
        } else if (result & soft_mask) {
                /* just print a warning */
                dev_warn(dev, "Suspicious conversion: Sensor SOFT fault\n");
        }

        return 0;
}

static int __ltc2983_chan_assign_common(const struct ltc2983_data *st,
                                        const struct ltc2983_sensor *sensor,
                                        u32 chan_val)
{
        u32 reg = LTC2983_CHAN_START_ADDR(sensor->chan);
        __be32 __chan_val;

        chan_val |= LTC2983_CHAN_TYPE(sensor->type);
        dev_dbg(&st->spi->dev, "Assign reg:0x%04X, val:0x%08X\n", reg,
                chan_val);
        __chan_val = cpu_to_be32(chan_val);
        return regmap_bulk_write(st->regmap, reg, &__chan_val,
                                 sizeof(__chan_val));
}

static int __ltc2983_chan_custom_sensor_assign(struct ltc2983_data *st,
                                          struct ltc2983_custom_sensor *custom,
                                          u32 *chan_val)
{
        u32 reg;
        u8 mult = custom->is_steinhart ? LTC2983_CUSTOM_STEINHART_ENTRY_SZ :
                LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
        const struct device *dev = &st->spi->dev;
        /*
         * custom->size holds the raw size of the table. However, when
         * configuring the sensor channel, we must write the number of
         * entries of the table minus 1. For steinhart sensors 0 is written
         * since the size is constant!
         */
        const u8 len = custom->is_steinhart ? 0 :
                (custom->size / LTC2983_CUSTOM_SENSOR_ENTRY_SZ) - 1;
        /*
         * Check if the offset was assigned already. It should be for steinhart
         * sensors. When coming from sleep, it should be assigned for all.
         */
        if (custom->offset < 0) {
                /*
                 * This needs to be done again here because, from the moment
                 * when this test was done (successfully) for this custom
                 * sensor, a steinhart sensor might have been added changing
                 * custom_table_size...
                 */
                if (st->custom_table_size + custom->size >
                    (LTC2983_CUST_SENS_TBL_END_REG -
                     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
                        dev_err(dev,
                                "Not space left(%d) for new custom sensor(%zu)",
                                st->custom_table_size,
                                custom->size);
                        return -EINVAL;
                }

                custom->offset = st->custom_table_size /
                                        LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
                st->custom_table_size += custom->size;
        }

        reg = (custom->offset * mult) + LTC2983_CUST_SENS_TBL_START_REG;

        *chan_val |= LTC2983_CUSTOM_LEN(len);
        *chan_val |= LTC2983_CUSTOM_ADDR(custom->offset);
        dev_dbg(dev, "Assign custom sensor, reg:0x%04X, off:%d, sz:%zu",
                reg, custom->offset,
                custom->size);
        /* write custom sensor table */
        return regmap_bulk_write(st->regmap, reg, custom->table, custom->size);
}

static struct ltc2983_custom_sensor *__ltc2983_custom_sensor_new(
                                                struct ltc2983_data *st,
                                                const struct device_node *np,
                                                const char *propname,
                                                const bool is_steinhart,
                                                const u32 resolution,
                                                const bool has_signed)
{
        struct ltc2983_custom_sensor *new_custom;
        u8 index, n_entries, tbl = 0;
        struct device *dev = &st->spi->dev;
        /*
         * For custom steinhart, the full u32 is taken. For all the others
         * the MSB is discarded.
         */
        const u8 n_size = is_steinhart ? 4 : 3;
        const u8 e_size = is_steinhart ? sizeof(u32) : sizeof(u64);

        n_entries = of_property_count_elems_of_size(np, propname, e_size);
        /* n_entries must be an even number */
        if (!n_entries || (n_entries % 2) != 0) {
                dev_err(dev, "Number of entries either 0 or not even\n");
                return ERR_PTR(-EINVAL);
        }

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

        new_custom->size = n_entries * n_size;
        /* check Steinhart size */
        if (is_steinhart && new_custom->size != LTC2983_CUSTOM_STEINHART_SIZE) {
                dev_err(dev, "Steinhart sensors size(%zu) must be 24",
                                                        new_custom->size);
                return ERR_PTR(-EINVAL);
        }
        /* Check space on the table. */
        if (st->custom_table_size + new_custom->size >
            (LTC2983_CUST_SENS_TBL_END_REG -
             LTC2983_CUST_SENS_TBL_START_REG) + 1) {
                dev_err(dev, "No space left(%d) for new custom sensor(%zu)",
                                st->custom_table_size, new_custom->size);
                return ERR_PTR(-EINVAL);
        }

        /* allocate the table */
        new_custom->table = devm_kzalloc(dev, new_custom->size, GFP_KERNEL);
        if (!new_custom->table)
                return ERR_PTR(-ENOMEM);

        for (index = 0; index < n_entries; index++) {
                u64 temp = 0, j;
                /*
                 * Steinhart sensors are configured with raw values in the
                 * devicetree. For the other sensors we must convert the
                 * value to raw. The odd index's correspond to temperarures
                 * and always have 1/1024 of resolution. Temperatures also
                 * come in kelvin, so signed values is not possible
                 */
                if (!is_steinhart) {
                        of_property_read_u64_index(np, propname, index, &temp);

                        if ((index % 2) != 0)
                                temp = __convert_to_raw(temp, 1024);
                        else if (has_signed && (s64)temp < 0)
                                temp = __convert_to_raw_sign(temp, resolution);
                        else
                                temp = __convert_to_raw(temp, resolution);
                } else {
                        u32 t32;

                        of_property_read_u32_index(np, propname, index, &t32);
                        temp = t32;
                }

                for (j = 0; j < n_size; j++)
                        new_custom->table[tbl++] =
                                temp >> (8 * (n_size - j - 1));
        }

        new_custom->is_steinhart = is_steinhart;
        /*
         * This is done to first add all the steinhart sensors to the table,
         * in order to maximize the table usage. If we mix adding steinhart
         * with the other sensors, we might have to do some roundup to make
         * sure that sensor_addr - 0x250(start address) is a multiple of 4
         * (for steinhart), and a multiple of 6 for all the other sensors.
         * Since we have const 24 bytes for steinhart sensors and 24 is
         * also a multiple of 6, we guarantee that the first non-steinhart
         * sensor will sit in a correct address without the need of filling
         * addresses.
         */
        if (is_steinhart) {
                new_custom->offset = st->custom_table_size /
                                        LTC2983_CUSTOM_STEINHART_ENTRY_SZ;
                st->custom_table_size += new_custom->size;
        } else {
                /* mark as unset. This is checked later on the assign phase */
                new_custom->offset = -1;
        }

        return new_custom;
}

static int ltc2983_thermocouple_fault_handler(const struct ltc2983_data *st,
                                              const u32 result)
{
        return __ltc2983_fault_handler(st, result,
                                       LTC2983_THERMOCOUPLE_HARD_FAULT_MASK,
                                       LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK);
}

static int ltc2983_common_fault_handler(const struct ltc2983_data *st,
                                        const u32 result)
{
        return __ltc2983_fault_handler(st, result,
                                       LTC2983_COMMON_HARD_FAULT_MASK,
                                       LTC2983_COMMON_SOFT_FAULT_MASK);
}

static int ltc2983_thermocouple_assign_chan(struct ltc2983_data *st,
                                const struct ltc2983_sensor *sensor)
{
        struct ltc2983_thermocouple *thermo = to_thermocouple(sensor);
        u32 chan_val;

        chan_val = LTC2983_CHAN_ASSIGN(thermo->cold_junction_chan);
        chan_val |= LTC2983_THERMOCOUPLE_CFG(thermo->sensor_config);

        if (thermo->custom) {
                int ret;

                ret = __ltc2983_chan_custom_sensor_assign(st, thermo->custom,
                                                          &chan_val);
                if (ret)
                        return ret;
        }
        return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static int ltc2983_rtd_assign_chan(struct ltc2983_data *st,
                                   const struct ltc2983_sensor *sensor)
{
        struct ltc2983_rtd *rtd = to_rtd(sensor);
        u32 chan_val;

        chan_val = LTC2983_CHAN_ASSIGN(rtd->r_sense_chan);
        chan_val |= LTC2983_RTD_CFG(rtd->sensor_config);
        chan_val |= LTC2983_RTD_EXC_CURRENT(rtd->excitation_current);
        chan_val |= LTC2983_RTD_CURVE(rtd->rtd_curve);

        if (rtd->custom) {
                int ret;

                ret = __ltc2983_chan_custom_sensor_assign(st, rtd->custom,
                                                          &chan_val);
                if (ret)
                        return ret;
        }
        return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static int ltc2983_thermistor_assign_chan(struct ltc2983_data *st,
                                          const struct ltc2983_sensor *sensor)
{
        struct ltc2983_thermistor *thermistor = to_thermistor(sensor);
        u32 chan_val;

        chan_val = LTC2983_CHAN_ASSIGN(thermistor->r_sense_chan);
        chan_val |= LTC2983_THERMISTOR_CFG(thermistor->sensor_config);
        chan_val |=
                LTC2983_THERMISTOR_EXC_CURRENT(thermistor->excitation_current);

        if (thermistor->custom) {
                int ret;

                ret = __ltc2983_chan_custom_sensor_assign(st,
                                                          thermistor->custom,
                                                          &chan_val);
                if (ret)
                        return ret;
        }
        return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static int ltc2983_diode_assign_chan(struct ltc2983_data *st,
                                     const struct ltc2983_sensor *sensor)
{
        struct ltc2983_diode *diode = to_diode(sensor);
        u32 chan_val;

        chan_val = LTC2983_DIODE_CFG(diode->sensor_config);
        chan_val |= LTC2983_DIODE_EXC_CURRENT(diode->excitation_current);
        chan_val |= LTC2983_DIODE_IDEAL_FACTOR(diode->ideal_factor_value);

        return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static int ltc2983_r_sense_assign_chan(struct ltc2983_data *st,
                                       const struct ltc2983_sensor *sensor)
{
        struct ltc2983_rsense *rsense = to_rsense(sensor);
        u32 chan_val;

        chan_val = LTC2983_R_SENSE_VAL(rsense->r_sense_val);

        return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static int ltc2983_adc_assign_chan(struct ltc2983_data *st,
                                   const struct ltc2983_sensor *sensor)
{
        struct ltc2983_adc *adc = to_adc(sensor);
        u32 chan_val;

        chan_val = LTC2983_ADC_SINGLE_ENDED(adc->single_ended);

        return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static struct ltc2983_sensor *ltc2983_thermocouple_new(
                                        const struct device_node *child,
                                        struct ltc2983_data *st,
                                        const struct ltc2983_sensor *sensor)
{
        struct ltc2983_thermocouple *thermo;
        struct device_node *phandle;
        u32 oc_current;
        int ret;

        thermo = devm_kzalloc(&st->spi->dev, sizeof(*thermo), GFP_KERNEL);
        if (!thermo)
                return ERR_PTR(-ENOMEM);

        if (of_property_read_bool(child, "adi,single-ended"))
                thermo->sensor_config = LTC2983_THERMOCOUPLE_SGL(1);

        ret = of_property_read_u32(child, "adi,sensor-oc-current-microamp",
                                   &oc_current);
        if (!ret) {
                switch (oc_current) {
                case 10:
                        thermo->sensor_config |=
                                        LTC2983_THERMOCOUPLE_OC_CURR(0);
                        break;
                case 100:
                        thermo->sensor_config |=
                                        LTC2983_THERMOCOUPLE_OC_CURR(1);
                        break;
                case 500:
                        thermo->sensor_config |=
                                        LTC2983_THERMOCOUPLE_OC_CURR(2);
                        break;
                case 1000:
                        thermo->sensor_config |=
                                        LTC2983_THERMOCOUPLE_OC_CURR(3);
                        break;
                default:
                        dev_err(&st->spi->dev,
                                "Invalid open circuit current:%u", oc_current);
                        return ERR_PTR(-EINVAL);
                }

                thermo->sensor_config |= LTC2983_THERMOCOUPLE_OC_CHECK(1);
        }
        /* validate channel index */
        if (!(thermo->sensor_config & LTC2983_THERMOCOUPLE_DIFF_MASK) &&
            sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
                dev_err(&st->spi->dev,
                        "Invalid chann:%d for differential thermocouple",
                        sensor->chan);
                return ERR_PTR(-EINVAL);
        }

        phandle = of_parse_phandle(child, "adi,cold-junction-handle", 0);
        if (phandle) {
                int ret;

                ret = of_property_read_u32(phandle, "reg",
                                           &thermo->cold_junction_chan);
                if (ret) {
                        /*
                         * This would be catched later but we can just return
                         * the error right away.
                         */
                        dev_err(&st->spi->dev, "Property reg must be given\n");
                        of_node_put(phandle);
                        return ERR_PTR(-EINVAL);
                }
        }

        /* check custom sensor */
        if (sensor->type == LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
                const char *propname = "adi,custom-thermocouple";

                thermo->custom = __ltc2983_custom_sensor_new(st, child,
                                                             propname, false,
                                                             16384, true);
                if (IS_ERR(thermo->custom)) {
                        of_node_put(phandle);
                        return ERR_CAST(thermo->custom);
                }
        }

        /* set common parameters */
        thermo->sensor.fault_handler = ltc2983_thermocouple_fault_handler;
        thermo->sensor.assign_chan = ltc2983_thermocouple_assign_chan;

        of_node_put(phandle);
        return &thermo->sensor;
}

static struct ltc2983_sensor *ltc2983_rtd_new(const struct device_node *child,
                                          struct ltc2983_data *st,
                                          const struct ltc2983_sensor *sensor)
{
        struct ltc2983_rtd *rtd;
        int ret = 0;
        struct device *dev = &st->spi->dev;
        struct device_node *phandle;
        u32 excitation_current = 0, n_wires = 0;

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

        phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
        if (!phandle) {
                dev_err(dev, "Property adi,rsense-handle missing or invalid");
                return ERR_PTR(-EINVAL);
        }

        ret = of_property_read_u32(phandle, "reg", &rtd->r_sense_chan);
        if (ret) {
                dev_err(dev, "Property reg must be given\n");
                goto fail;
        }

        ret = of_property_read_u32(child, "adi,number-of-wires", &n_wires);
        if (!ret) {
                switch (n_wires) {
                case 2:
                        rtd->sensor_config = LTC2983_RTD_N_WIRES(0);
                        break;
                case 3:
                        rtd->sensor_config = LTC2983_RTD_N_WIRES(1);
                        break;
                case 4:
                        rtd->sensor_config = LTC2983_RTD_N_WIRES(2);
                        break;
                case 5:
                        /* 4 wires, Kelvin Rsense */
                        rtd->sensor_config = LTC2983_RTD_N_WIRES(3);
                        break;
                default:
                        dev_err(dev, "Invalid number of wires:%u\n", n_wires);
                        ret = -EINVAL;
                        goto fail;
                }
        }

        if (of_property_read_bool(child, "adi,rsense-share")) {
                /* Current rotation is only available with rsense sharing */
                if (of_property_read_bool(child, "adi,current-rotate")) {
                        if (n_wires == 2 || n_wires == 3) {
                                dev_err(dev,
                                        "Rotation not allowed for 2/3 Wire RTDs");
                                ret = -EINVAL;
                                goto fail;
                        }
                        rtd->sensor_config |= LTC2983_RTD_C_ROTATE(1);
                } else {
                        rtd->sensor_config |= LTC2983_RTD_R_SHARE(1);
                }
        }
        /*
         * rtd channel indexes are a bit more complicated to validate.
         * For 4wire RTD with rotation, the channel selection cannot be
         * >=19 since the chann + 1 is used in this configuration.
         * For 4wire RTDs with kelvin rsense, the rsense channel cannot be
         * <=1 since chanel - 1 and channel - 2 are used.
         */
        if (rtd->sensor_config & LTC2983_RTD_4_WIRE_MASK) {
                /* 4-wire */
                u8 min = LTC2983_DIFFERENTIAL_CHAN_MIN,
                        max = LTC2983_MAX_CHANNELS_NR;

                if (rtd->sensor_config & LTC2983_RTD_ROTATION_MASK)
                        max = LTC2983_MAX_CHANNELS_NR - 1;

                if (((rtd->sensor_config & LTC2983_RTD_KELVIN_R_SENSE_MASK)
                     == LTC2983_RTD_KELVIN_R_SENSE_MASK) &&
                    (rtd->r_sense_chan <=  min)) {
                        /* kelvin rsense*/
                        dev_err(dev,
                                "Invalid rsense chann:%d to use in kelvin rsense",
                                rtd->r_sense_chan);

                        ret = -EINVAL;
                        goto fail;
                }

                if (sensor->chan < min || sensor->chan > max) {
                        dev_err(dev, "Invalid chann:%d for the rtd config",
                                sensor->chan);

                        ret = -EINVAL;
                        goto fail;
                }
        } else {
                /* same as differential case */
                if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
                        dev_err(&st->spi->dev,
                                "Invalid chann:%d for RTD", sensor->chan);

                        ret = -EINVAL;
                        goto fail;
                }
        }

        /* check custom sensor */
        if (sensor->type == LTC2983_SENSOR_RTD_CUSTOM) {
                rtd->custom = __ltc2983_custom_sensor_new(st, child,
                                                          "adi,custom-rtd",
                                                          false, 2048, false);
                if (IS_ERR(rtd->custom)) {
                        of_node_put(phandle);
                        return ERR_CAST(rtd->custom);
                }
        }

        /* set common parameters */
        rtd->sensor.fault_handler = ltc2983_common_fault_handler;
        rtd->sensor.assign_chan = ltc2983_rtd_assign_chan;

        ret = of_property_read_u32(child, "adi,excitation-current-microamp",
                                   &excitation_current);
        if (ret) {
                /* default to 5uA */
                rtd->excitation_current = 1;
        } else {
                switch (excitation_current) {
                case 5:
                        rtd->excitation_current = 0x01;
                        break;
                case 10:
                        rtd->excitation_current = 0x02;
                        break;
                case 25:
                        rtd->excitation_current = 0x03;
                        break;
                case 50:
                        rtd->excitation_current = 0x04;
                        break;
                case 100:
                        rtd->excitation_current = 0x05;
                        break;
                case 250:
                        rtd->excitation_current = 0x06;
                        break;
                case 500:
                        rtd->excitation_current = 0x07;
                        break;
                case 1000:
                        rtd->excitation_current = 0x08;
                        break;
                default:
                        dev_err(&st->spi->dev,
                                "Invalid value for excitation current(%u)",
                                excitation_current);
                        ret = -EINVAL;
                        goto fail;
                }
        }

        of_property_read_u32(child, "adi,rtd-curve", &rtd->rtd_curve);

        of_node_put(phandle);
        return &rtd->sensor;
fail:
        of_node_put(phandle);
        return ERR_PTR(ret);
}

static struct ltc2983_sensor *ltc2983_thermistor_new(
                                        const struct device_node *child,
                                        struct ltc2983_data *st,
                                        const struct ltc2983_sensor *sensor)
{
        struct ltc2983_thermistor *thermistor;
        struct device *dev = &st->spi->dev;
        struct device_node *phandle;
        u32 excitation_current = 0;
        int ret = 0;

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

        phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
        if (!phandle) {
                dev_err(dev, "Property adi,rsense-handle missing or invalid");
                return ERR_PTR(-EINVAL);
        }

        ret = of_property_read_u32(phandle, "reg", &thermistor->r_sense_chan);
        if (ret) {
                dev_err(dev, "rsense channel must be configured...\n");
                goto fail;
        }

        if (of_property_read_bool(child, "adi,single-ended")) {
                thermistor->sensor_config = LTC2983_THERMISTOR_SGL(1);
        } else if (of_property_read_bool(child, "adi,rsense-share")) {
                /* rotation is only possible if sharing rsense */
                if (of_property_read_bool(child, "adi,current-rotate"))
                        thermistor->sensor_config =
                                                LTC2983_THERMISTOR_C_ROTATE(1);
                else
                        thermistor->sensor_config =
                                                LTC2983_THERMISTOR_R_SHARE(1);
        }
        /* validate channel index */
        if (!(thermistor->sensor_config & LTC2983_THERMISTOR_DIFF_MASK) &&
            sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
                dev_err(&st->spi->dev,
                        "Invalid chann:%d for differential thermistor",
                        sensor->chan);
                ret = -EINVAL;
                goto fail;
        }

        /* check custom sensor */
        if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART) {
                bool steinhart = false;
                const char *propname;

                if (sensor->type == LTC2983_SENSOR_THERMISTOR_STEINHART) {
                        steinhart = true;
                        propname = "adi,custom-steinhart";
                } else {
                        propname = "adi,custom-thermistor";
                }

                thermistor->custom = __ltc2983_custom_sensor_new(st, child,
                                                                 propname,
                                                                 steinhart,
                                                                 64, false);
                if (IS_ERR(thermistor->custom)) {
                        of_node_put(phandle);
                        return ERR_CAST(thermistor->custom);
                }
        }
        /* set common parameters */
        thermistor->sensor.fault_handler = ltc2983_common_fault_handler;
        thermistor->sensor.assign_chan = ltc2983_thermistor_assign_chan;

        ret = of_property_read_u32(child, "adi,excitation-current-nanoamp",
                                   &excitation_current);
        if (ret) {
                /* Auto range is not allowed for custom sensors */
                if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART)
                        /* default to 1uA */
                        thermistor->excitation_current = 0x03;
                else
                        /* default to auto-range */
                        thermistor->excitation_current = 0x0c;
        } else {
                switch (excitation_current) {
                case 0:
                        /* auto range */
                        if (sensor->type >=
                            LTC2983_SENSOR_THERMISTOR_STEINHART) {
                                dev_err(&st->spi->dev,
                                        "Auto Range not allowed for custom sensors\n");
                                ret = -EINVAL;
                                goto fail;
                        }
                        thermistor->excitation_current = 0x0c;
                        break;
                case 250:
                        thermistor->excitation_current = 0x01;
                        break;
                case 500:
                        thermistor->excitation_current = 0x02;
                        break;
                case 1000:
                        thermistor->excitation_current = 0x03;
                        break;
                case 5000:
                        thermistor->excitation_current = 0x04;
                        break;
                case 10000:
                        thermistor->excitation_current = 0x05;
                        break;
                case 25000:
                        thermistor->excitation_current = 0x06;
                        break;
                case 50000:
                        thermistor->excitation_current = 0x07;
                        break;
                case 100000:
                        thermistor->excitation_current = 0x08;
                        break;
                case 250000:
                        thermistor->excitation_current = 0x09;
                        break;
                case 500000:
                        thermistor->excitation_current = 0x0a;
                        break;
                case 1000000:
                        thermistor->excitation_current = 0x0b;
                        break;
                default:
                        dev_err(&st->spi->dev,
                                "Invalid value for excitation current(%u)",
                                excitation_current);
                        ret = -EINVAL;
                        goto fail;
                }
        }

        of_node_put(phandle);
        return &thermistor->sensor;
fail:
        of_node_put(phandle);
        return ERR_PTR(ret);
}

static struct ltc2983_sensor *ltc2983_diode_new(
                                        const struct device_node *child,
                                        const struct ltc2983_data *st,
                                        const struct ltc2983_sensor *sensor)
{
        struct ltc2983_diode *diode;
        u32 temp = 0, excitation_current = 0;
        int ret;

        diode = devm_kzalloc(&st->spi->dev, sizeof(*diode), GFP_KERNEL);
        if (!diode)
                return ERR_PTR(-ENOMEM);

        if (of_property_read_bool(child, "adi,single-ended"))
                diode->sensor_config = LTC2983_DIODE_SGL(1);

        if (of_property_read_bool(child, "adi,three-conversion-cycles"))
                diode->sensor_config |= LTC2983_DIODE_3_CONV_CYCLE(1);

        if (of_property_read_bool(child, "adi,average-on"))
                diode->sensor_config |= LTC2983_DIODE_AVERAGE_ON(1);

        /* validate channel index */
        if (!(diode->sensor_config & LTC2983_DIODE_DIFF_MASK) &&
            sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
                dev_err(&st->spi->dev,
                        "Invalid chann:%d for differential thermistor",
                        sensor->chan);
                return ERR_PTR(-EINVAL);
        }
        /* set common parameters */
        diode->sensor.fault_handler = ltc2983_common_fault_handler;
        diode->sensor.assign_chan = ltc2983_diode_assign_chan;

        ret = of_property_read_u32(child, "adi,excitation-current-microamp",
                                   &excitation_current);
        if (!ret) {
                switch (excitation_current) {
                case 10:
                        diode->excitation_current = 0x00;
                        break;
                case 20:
                        diode->excitation_current = 0x01;
                        break;
                case 40:
                        diode->excitation_current = 0x02;
                        break;
                case 80:
                        diode->excitation_current = 0x03;
                        break;
                default:
                        dev_err(&st->spi->dev,
                                "Invalid value for excitation current(%u)",
                                excitation_current);
                        return ERR_PTR(-EINVAL);
                }
        }

        of_property_read_u32(child, "adi,ideal-factor-value", &temp);

        /* 2^20 resolution */
        diode->ideal_factor_value = __convert_to_raw(temp, 1048576);

        return &diode->sensor;
}

static struct ltc2983_sensor *ltc2983_r_sense_new(struct device_node *child,
                                        struct ltc2983_data *st,
                                        const struct ltc2983_sensor *sensor)
{
        struct ltc2983_rsense *rsense;
        int ret;
        u32 temp;

        rsense = devm_kzalloc(&st->spi->dev, sizeof(*rsense), GFP_KERNEL);
        if (!rsense)
                return ERR_PTR(-ENOMEM);

        /* validate channel index */
        if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
                dev_err(&st->spi->dev, "Invalid chann:%d for r_sense",
                        sensor->chan);
                return ERR_PTR(-EINVAL);
        }

        ret = of_property_read_u32(child, "adi,rsense-val-milli-ohms", &temp);
        if (ret) {
                dev_err(&st->spi->dev, "Property adi,rsense-val-milli-ohms missing\n");
                return ERR_PTR(-EINVAL);
        }
        /*
         * Times 1000 because we have milli-ohms and __convert_to_raw
         * expects scales of 1000000 which are used for all other
         * properties.
         * 2^10 resolution
         */
        rsense->r_sense_val = __convert_to_raw((u64)temp * 1000, 1024);

        /* set common parameters */
        rsense->sensor.assign_chan = ltc2983_r_sense_assign_chan;

        return &rsense->sensor;
}

static struct ltc2983_sensor *ltc2983_adc_new(struct device_node *child,
                                         struct ltc2983_data *st,
                                         const struct ltc2983_sensor *sensor)
{
        struct ltc2983_adc *adc;

        adc = devm_kzalloc(&st->spi->dev, sizeof(*adc), GFP_KERNEL);
        if (!adc)
                return ERR_PTR(-ENOMEM);

        if (of_property_read_bool(child, "adi,single-ended"))
                adc->single_ended = true;

        if (!adc->single_ended &&
            sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
                dev_err(&st->spi->dev, "Invalid chan:%d for differential adc\n",
                        sensor->chan);
                return ERR_PTR(-EINVAL);
        }
        /* set common parameters */
        adc->sensor.assign_chan = ltc2983_adc_assign_chan;
        adc->sensor.fault_handler = ltc2983_common_fault_handler;

        return &adc->sensor;
}

static int ltc2983_chan_read(struct ltc2983_data *st,
                        const struct ltc2983_sensor *sensor, int *val)
{
        u32 start_conversion = 0;
        int ret;
        unsigned long time;

        start_conversion = LTC2983_STATUS_START(true);
        start_conversion |= LTC2983_STATUS_CHAN_SEL(sensor->chan);
        dev_dbg(&st->spi->dev, "Start conversion on chan:%d, status:%02X\n",
                sensor->chan, start_conversion);
        /* start conversion */
        ret = regmap_write(st->regmap, LTC2983_STATUS_REG, start_conversion);
        if (ret)
                return ret;

        reinit_completion(&st->completion);
        /*
         * wait for conversion to complete.
         * 300 ms should be more than enough to complete the conversion.
         * Depending on the sensor configuration, there are 2/3 conversions
         * cycles of 82ms.
         */
        time = wait_for_completion_timeout(&st->completion,
                                           msecs_to_jiffies(300));
        if (!time) {
                dev_warn(&st->spi->dev, "Conversion timed out\n");
                return -ETIMEDOUT;
        }

        /* read the converted data */
        ret = regmap_bulk_read(st->regmap, LTC2983_CHAN_RES_ADDR(sensor->chan),
                               &st->temp, sizeof(st->temp));
        if (ret)
                return ret;

        *val = __be32_to_cpu(st->temp);

        if (!(LTC2983_RES_VALID_MASK & *val)) {
                dev_err(&st->spi->dev, "Invalid conversion detected\n");
                return -EIO;
        }

        ret = sensor->fault_handler(st, *val);
        if (ret)
                return ret;

        *val = sign_extend32((*val) & LTC2983_DATA_MASK, LTC2983_DATA_SIGN_BIT);
        return 0;
}

static int ltc2983_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int *val, int *val2, long mask)
{
        struct ltc2983_data *st = iio_priv(indio_dev);
        int ret;

        /* sanity check */
        if (chan->address >= st->num_channels) {
                dev_err(&st->spi->dev, "Invalid chan address:%ld",
                        chan->address);
                return -EINVAL;
        }

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&st->lock);
                ret = ltc2983_chan_read(st, st->sensors[chan->address], val);
                mutex_unlock(&st->lock);
                return ret ?: IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_TEMP:
                        /* value in milli degrees */
                        *val = 1000;
                        /* 2^10 */
                        *val2 = 1024;
                        return IIO_VAL_FRACTIONAL;
                case IIO_VOLTAGE:
                        /* value in millivolt */
                        *val = 1000;
                        /* 2^21 */
                        *val2 = 2097152;
                        return IIO_VAL_FRACTIONAL;
                default:
                        return -EINVAL;
                }
        }

        return -EINVAL;
}

static int ltc2983_reg_access(struct iio_dev *indio_dev,
                              unsigned int reg,
                              unsigned int writeval,
                              unsigned int *readval)
{
        struct ltc2983_data *st = iio_priv(indio_dev);

        if (readval)
                return regmap_read(st->regmap, reg, readval);
        else
                return regmap_write(st->regmap, reg, writeval);
}

static irqreturn_t ltc2983_irq_handler(int irq, void *data)
{
        struct ltc2983_data *st = data;

        complete(&st->completion);
        return IRQ_HANDLED;
}

#define LTC2983_CHAN(__type, index, __address) ({ \
        struct iio_chan_spec __chan = { \
                .type = __type, \
                .indexed = 1, \
                .channel = index, \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
                .address = __address, \
        }; \
        __chan; \
})

static int ltc2983_parse_dt(struct ltc2983_data *st)
{
        struct device_node *child;
        struct device *dev = &st->spi->dev;
        int ret = 0, chan = 0, channel_avail_mask = 0;

        of_property_read_u32(dev->of_node, "adi,mux-delay-config-us",
                             &st->mux_delay_config);

        of_property_read_u32(dev->of_node, "adi,filter-notch-freq",
                             &st->filter_notch_freq);

        st->num_channels = of_get_available_child_count(dev->of_node);
        st->sensors = devm_kcalloc(dev, st->num_channels, sizeof(*st->sensors),
                                   GFP_KERNEL);
        if (!st->sensors)
                return -ENOMEM;

        st->iio_channels = st->num_channels;
        for_each_available_child_of_node(dev->of_node, child) {
                struct ltc2983_sensor sensor;

                ret = of_property_read_u32(child, "reg", &sensor.chan);
                if (ret) {
                        dev_err(dev, "reg property must given for child nodes\n");
                        goto put_child;
                }

                /* check if we have a valid channel */
                if (sensor.chan < LTC2983_MIN_CHANNELS_NR ||
                    sensor.chan > LTC2983_MAX_CHANNELS_NR) {
                        ret = -EINVAL;
                        dev_err(dev,
                                "chan:%d must be from 1 to 20\n", sensor.chan);
                        goto put_child;
                } else if (channel_avail_mask & BIT(sensor.chan)) {
                        ret = -EINVAL;
                        dev_err(dev, "chan:%d already in use\n", sensor.chan);
                        goto put_child;
                }

                ret = of_property_read_u32(child, "adi,sensor-type",
                                               &sensor.type);
                if (ret) {
                        dev_err(dev,
                                "adi,sensor-type property must given for child nodes\n");
                        goto put_child;
                }

                dev_dbg(dev, "Create new sensor, type %u, chann %u",
                                                                sensor.type,
                                                                sensor.chan);

                if (sensor.type >= LTC2983_SENSOR_THERMOCOUPLE &&
                    sensor.type <= LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
                        st->sensors[chan] = ltc2983_thermocouple_new(child, st,
                                                                     &sensor);
                } else if (sensor.type >= LTC2983_SENSOR_RTD &&
                           sensor.type <= LTC2983_SENSOR_RTD_CUSTOM) {
                        st->sensors[chan] = ltc2983_rtd_new(child, st, &sensor);
                } else if (sensor.type >= LTC2983_SENSOR_THERMISTOR &&
                           sensor.type <= LTC2983_SENSOR_THERMISTOR_CUSTOM) {
                        st->sensors[chan] = ltc2983_thermistor_new(child, st,
                                                                   &sensor);
                } else if (sensor.type == LTC2983_SENSOR_DIODE) {
                        st->sensors[chan] = ltc2983_diode_new(child, st,
                                                              &sensor);
                } else if (sensor.type == LTC2983_SENSOR_SENSE_RESISTOR) {
                        st->sensors[chan] = ltc2983_r_sense_new(child, st,
                                                                &sensor);
                        /* don't add rsense to iio */
                        st->iio_channels--;
                } else if (sensor.type == LTC2983_SENSOR_DIRECT_ADC) {
                        st->sensors[chan] = ltc2983_adc_new(child, st, &sensor);
                } else {
                        dev_err(dev, "Unknown sensor type %d\n", sensor.type);
                        ret = -EINVAL;
                        goto put_child;
                }

                if (IS_ERR(st->sensors[chan])) {
                        dev_err(dev, "Failed to create sensor %ld",
                                PTR_ERR(st->sensors[chan]));
                        ret = PTR_ERR(st->sensors[chan]);
                        goto put_child;
                }
                /* set generic sensor parameters */
                st->sensors[chan]->chan = sensor.chan;
                st->sensors[chan]->type = sensor.type;

                channel_avail_mask |= BIT(sensor.chan);
                chan++;
        }

        return 0;
put_child:
        of_node_put(child);
        return ret;
}

static int ltc2983_setup(struct ltc2983_data *st, bool assign_iio)
{
        u32 iio_chan_t = 0, iio_chan_v = 0, chan, iio_idx = 0, status;
        int ret;

        /* make sure the device is up: start bit (7) is 0 and done bit (6) is 1 */
        ret = regmap_read_poll_timeout(st->regmap, LTC2983_STATUS_REG, status,
                                       LTC2983_STATUS_UP(status) == 1, 25000,
                                       25000 * 10);
        if (ret) {
                dev_err(&st->spi->dev, "Device startup timed out\n");
                return ret;
        }

        st->iio_chan = devm_kzalloc(&st->spi->dev,
                                    st->iio_channels * sizeof(*st->iio_chan),
                                    GFP_KERNEL);

        if (!st->iio_chan)
                return -ENOMEM;

        ret = regmap_update_bits(st->regmap, LTC2983_GLOBAL_CONFIG_REG,
                                 LTC2983_NOTCH_FREQ_MASK,
                                 LTC2983_NOTCH_FREQ(st->filter_notch_freq));
        if (ret)
                return ret;

        ret = regmap_write(st->regmap, LTC2983_MUX_CONFIG_REG,
                           st->mux_delay_config);
        if (ret)
                return ret;

        for (chan = 0; chan < st->num_channels; chan++) {
                u32 chan_type = 0, *iio_chan;

                ret = st->sensors[chan]->assign_chan(st, st->sensors[chan]);
                if (ret)
                        return ret;
                /*
                 * The assign_iio flag is necessary for when the device is
                 * coming out of sleep. In that case, we just need to
                 * re-configure the device channels.
                 * We also don't assign iio channels for rsense.
                 */
                if (st->sensors[chan]->type == LTC2983_SENSOR_SENSE_RESISTOR ||
                    !assign_iio)
                        continue;

                /* assign iio channel */
                if (st->sensors[chan]->type != LTC2983_SENSOR_DIRECT_ADC) {
                        chan_type = IIO_TEMP;
                        iio_chan = &iio_chan_t;
                } else {
                        chan_type = IIO_VOLTAGE;
                        iio_chan = &iio_chan_v;
                }

                /*
                 * add chan as the iio .address so that, we can directly
                 * reference the sensor given the iio_chan_spec
                 */
                st->iio_chan[iio_idx++] = LTC2983_CHAN(chan_type, (*iio_chan)++,
                                                       chan);
        }

        return 0;
}

static const struct regmap_range ltc2983_reg_ranges[] = {
        regmap_reg_range(LTC2983_STATUS_REG, LTC2983_STATUS_REG),
        regmap_reg_range(LTC2983_TEMP_RES_START_REG, LTC2983_TEMP_RES_END_REG),
        regmap_reg_range(LTC2983_GLOBAL_CONFIG_REG, LTC2983_GLOBAL_CONFIG_REG),
        regmap_reg_range(LTC2983_MULT_CHANNEL_START_REG,
                         LTC2983_MULT_CHANNEL_END_REG),
        regmap_reg_range(LTC2983_MUX_CONFIG_REG, LTC2983_MUX_CONFIG_REG),
        regmap_reg_range(LTC2983_CHAN_ASSIGN_START_REG,
                         LTC2983_CHAN_ASSIGN_END_REG),
        regmap_reg_range(LTC2983_CUST_SENS_TBL_START_REG,
                         LTC2983_CUST_SENS_TBL_END_REG),
};

static const struct regmap_access_table ltc2983_reg_table = {
        .yes_ranges = ltc2983_reg_ranges,
        .n_yes_ranges = ARRAY_SIZE(ltc2983_reg_ranges),
};

/*
 *  The reg_bits are actually 12 but the device needs the first *complete*
 *  byte for the command (R/W).
 */
static const struct regmap_config ltc2983_regmap_config = {
        .reg_bits = 24,
        .val_bits = 8,
        .wr_table = &ltc2983_reg_table,
        .rd_table = &ltc2983_reg_table,
        .read_flag_mask = GENMASK(1, 0),
        .write_flag_mask = BIT(1),
};

static const struct  iio_info ltc2983_iio_info = {
        .read_raw = ltc2983_read_raw,
        .debugfs_reg_access = ltc2983_reg_access,
};

static int ltc2983_probe(struct spi_device *spi)
{
        struct ltc2983_data *st;
        struct iio_dev *indio_dev;
        const char *name = spi_get_device_id(spi)->name;
        int ret;

        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
        if (!indio_dev)
                return -ENOMEM;

        st = iio_priv(indio_dev);

        st->regmap = devm_regmap_init_spi(spi, &ltc2983_regmap_config);
        if (IS_ERR(st->regmap)) {
                dev_err(&spi->dev, "Failed to initialize regmap\n");
                return PTR_ERR(st->regmap);
        }

        mutex_init(&st->lock);
        init_completion(&st->completion);
        st->spi = spi;
        spi_set_drvdata(spi, st);

        ret = ltc2983_parse_dt(st);
        if (ret)
                return ret;

        ret = ltc2983_setup(st, true);
        if (ret)
                return ret;

        ret = devm_request_irq(&spi->dev, spi->irq, ltc2983_irq_handler,
                               IRQF_TRIGGER_RISING, name, st);
        if (ret) {
                dev_err(&spi->dev, "failed to request an irq, %d", ret);
                return ret;
        }

        indio_dev->name = name;
        indio_dev->num_channels = st->iio_channels;
        indio_dev->channels = st->iio_chan;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->info = &ltc2983_iio_info;

        return devm_iio_device_register(&spi->dev, indio_dev);
}

static int __maybe_unused ltc2983_resume(struct device *dev)
{
        struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));
        int dummy;

        /* dummy read to bring the device out of sleep */
        regmap_read(st->regmap, LTC2983_STATUS_REG, &dummy);
        /* we need to re-assign the channels */
        return ltc2983_setup(st, false);
}

static int __maybe_unused ltc2983_suspend(struct device *dev)
{
        struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));

        return regmap_write(st->regmap, LTC2983_STATUS_REG, LTC2983_SLEEP);
}

static SIMPLE_DEV_PM_OPS(ltc2983_pm_ops, ltc2983_suspend, ltc2983_resume);

static const struct spi_device_id ltc2983_id_table[] = {
        { "ltc2983" },
        {},
};
MODULE_DEVICE_TABLE(spi, ltc2983_id_table);

static const struct of_device_id ltc2983_of_match[] = {
        { .compatible = "adi,ltc2983" },
        {},
};
MODULE_DEVICE_TABLE(of, ltc2983_of_match);

static struct spi_driver ltc2983_driver = {
        .driver = {
                .name = "ltc2983",
                .of_match_table = ltc2983_of_match,
                .pm = &ltc2983_pm_ops,
        },
        .probe = ltc2983_probe,
        .id_table = ltc2983_id_table,
};

module_spi_driver(ltc2983_driver);

MODULE_AUTHOR("Nuno Sa <nuno.sa@analog.com>");
MODULE_DESCRIPTION("Analog Devices LTC2983 SPI Temperature sensors");
MODULE_LICENSE("GPL");