// SPDX-License-Identifier: GPL-2.0-only
/*
 * TI ADC081C/ADC101C/ADC121C 8/10/12-bit ADC driver
 *
 * Copyright (C) 2012 Avionic Design GmbH
 * Copyright (C) 2016 Intel
 *
 * Datasheets:
 *      https://www.ti.com/lit/ds/symlink/adc081c021.pdf
 *      https://www.ti.com/lit/ds/symlink/adc101c021.pdf
 *      https://www.ti.com/lit/ds/symlink/adc121c021.pdf
 *
 * The devices have a very similar interface and differ mostly in the number of
 * bits handled. For the 8-bit and 10-bit models the least-significant 4 or 2
 * bits of value registers are reserved.
 */

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>

#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/regulator/consumer.h>

struct adc081c {
        struct i2c_client *i2c;
        struct regulator *ref;

        /* 8, 10 or 12 */
        int bits;

        /* Ensure natural alignment of buffer elements */
        struct {
                u16 channel;
                aligned_s64 ts;
        } scan;
};

#define REG_CONV_RES 0x00

static int adc081c_read_raw(struct iio_dev *iio,
                            struct iio_chan_spec const *channel, int *value,
                            int *shift, long mask)
{
        struct adc081c *adc = iio_priv(iio);
        int err;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                err = i2c_smbus_read_word_swapped(adc->i2c, REG_CONV_RES);
                if (err < 0)
                        return err;

                *value = (err & 0xFFF) >> (12 - adc->bits);
                return IIO_VAL_INT;

        case IIO_CHAN_INFO_SCALE:
                err = regulator_get_voltage(adc->ref);
                if (err < 0)
                        return err;

                *value = err / 1000;
                *shift = adc->bits;

                return IIO_VAL_FRACTIONAL_LOG2;

        default:
                break;
        }

        return -EINVAL;
}

#define ADCxx1C_CHAN(_bits) {                                   \
        .type = IIO_VOLTAGE,                                    \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
        .scan_type = {                                          \
                .sign = 'u',                                    \
                .realbits = (_bits),                            \
                .storagebits = 16,                              \
                .shift = 12 - (_bits),                          \
                .endianness = IIO_CPU,                          \
        },                                                      \
}

#define DEFINE_ADCxx1C_CHANNELS(_name, _bits)                           \
        static const struct iio_chan_spec _name ## _channels[] = {      \
                ADCxx1C_CHAN((_bits)),                                  \
                IIO_CHAN_SOFT_TIMESTAMP(1),                             \
        };                                                              \

#define ADC081C_NUM_CHANNELS 2

struct adcxx1c_model {
        const struct iio_chan_spec* channels;
        int bits;
};

DEFINE_ADCxx1C_CHANNELS(adc081c,  8);
DEFINE_ADCxx1C_CHANNELS(adc101c, 10);
DEFINE_ADCxx1C_CHANNELS(adc121c, 12);

static const struct adcxx1c_model adc081c_model = {
        .channels = adc081c_channels,
        .bits = 8,
};

static const struct adcxx1c_model adc101c_model = {
        .channels = adc101c_channels,
        .bits = 10,
};

static const struct adcxx1c_model adc121c_model = {
        .channels = adc121c_channels,
        .bits = 12,
};

static const struct iio_info adc081c_info = {
        .read_raw = adc081c_read_raw,
};

static irqreturn_t adc081c_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct adc081c *data = iio_priv(indio_dev);
        int ret;

        ret = i2c_smbus_read_word_swapped(data->i2c, REG_CONV_RES);
        if (ret < 0)
                goto out;
        data->scan.channel = ret;
        iio_push_to_buffers_with_ts(indio_dev, &data->scan, sizeof(data->scan),
                                    iio_get_time_ns(indio_dev));
out:
        iio_trigger_notify_done(indio_dev->trig);
        return IRQ_HANDLED;
}

static void adc081c_reg_disable(void *reg)
{
        regulator_disable(reg);
}

static int adc081c_probe(struct i2c_client *client)
{
        struct iio_dev *iio;
        struct adc081c *adc;
        const struct adcxx1c_model *model;
        int err;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
                return -EOPNOTSUPP;

        model = i2c_get_match_data(client);

        iio = devm_iio_device_alloc(&client->dev, sizeof(*adc));
        if (!iio)
                return -ENOMEM;

        adc = iio_priv(iio);
        adc->i2c = client;
        adc->bits = model->bits;

        adc->ref = devm_regulator_get(&client->dev, "vref");
        if (IS_ERR(adc->ref))
                return PTR_ERR(adc->ref);

        err = regulator_enable(adc->ref);
        if (err < 0)
                return err;

        err = devm_add_action_or_reset(&client->dev, adc081c_reg_disable,
                                       adc->ref);
        if (err)
                return err;

        iio->name = dev_name(&client->dev);
        iio->modes = INDIO_DIRECT_MODE;
        iio->info = &adc081c_info;

        iio->channels = model->channels;
        iio->num_channels = ADC081C_NUM_CHANNELS;

        err = devm_iio_triggered_buffer_setup(&client->dev, iio, NULL,
                                              adc081c_trigger_handler, NULL);
        if (err < 0) {
                dev_err(&client->dev, "iio triggered buffer setup failed\n");
                return err;
        }

        return devm_iio_device_register(&client->dev, iio);
}

static const struct i2c_device_id adc081c_id[] = {
        { "adc081c", (kernel_ulong_t)&adc081c_model },
        { "adc101c", (kernel_ulong_t)&adc101c_model },
        { "adc121c", (kernel_ulong_t)&adc121c_model },
        { }
};
MODULE_DEVICE_TABLE(i2c, adc081c_id);

static const struct acpi_device_id adc081c_acpi_match[] = {
        /* Used on some AAEON boards */
        { "ADC081C", (kernel_ulong_t)&adc081c_model },
        { }
};
MODULE_DEVICE_TABLE(acpi, adc081c_acpi_match);

static const struct of_device_id adc081c_of_match[] = {
        { .compatible = "ti,adc081c", .data = &adc081c_model },
        { .compatible = "ti,adc101c", .data = &adc101c_model },
        { .compatible = "ti,adc121c", .data = &adc121c_model },
        { }
};
MODULE_DEVICE_TABLE(of, adc081c_of_match);

static struct i2c_driver adc081c_driver = {
        .driver = {
                .name = "adc081c",
                .of_match_table = adc081c_of_match,
                .acpi_match_table = adc081c_acpi_match,
        },
        .probe = adc081c_probe,
        .id_table = adc081c_id,
};
module_i2c_driver(adc081c_driver);

MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
MODULE_DESCRIPTION("Texas Instruments ADC081C/ADC101C/ADC121C driver");
MODULE_LICENSE("GPL v2");