// SPDX-License-Identifier: GPL-2.0-only
/*
 * ADC12130/ADC12132/ADC12138 12-bit plus sign ADC driver
 *
 * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
 *
 * Datasheet: http://www.ti.com/lit/ds/symlink/adc12138.pdf
 */

#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <linux/clk.h>
#include <linux/property.h>
#include <linux/spi/spi.h>
#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/regulator/consumer.h>

#define ADC12138_MODE_AUTO_CAL                  0x08
#define ADC12138_MODE_READ_STATUS               0x0c
#define ADC12138_MODE_ACQUISITION_TIME_6        0x0e
#define ADC12138_MODE_ACQUISITION_TIME_10       0x4e
#define ADC12138_MODE_ACQUISITION_TIME_18       0x8e
#define ADC12138_MODE_ACQUISITION_TIME_34       0xce

#define ADC12138_STATUS_CAL                     BIT(6)

enum {
        adc12130,
        adc12132,
        adc12138,
};

struct adc12138 {
        struct spi_device *spi;
        unsigned int id;
        /* positive analog voltage reference */
        struct regulator *vref_p;
        /* negative analog voltage reference */
        struct regulator *vref_n;
        struct mutex lock;
        struct completion complete;
        /* The number of conversion clock periods for the S/H's acquisition time */
        unsigned int acquisition_time;
        /*
         * Maximum size needed: 16x 2 bytes ADC data + 8 bytes timestamp.
         * Less may be need if not all channels are enabled, as long as
         * the 8 byte alignment of the timestamp is maintained.
         */
        __be16 data[20] __aligned(8);

        u8 tx_buf[2] __aligned(IIO_DMA_MINALIGN);
        u8 rx_buf[2];
};

#define ADC12138_VOLTAGE_CHANNEL(chan)                                  \
        {                                                               \
                .type = IIO_VOLTAGE,                                    \
                .indexed = 1,                                           \
                .channel = chan,                                        \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)    \
                                        | BIT(IIO_CHAN_INFO_OFFSET),    \
                .scan_index = chan,                                     \
                .scan_type = {                                          \
                        .sign = 's',                                    \
                        .realbits = 13,                                 \
                        .storagebits = 16,                              \
                        .shift = 3,                                     \
                        .endianness = IIO_BE,                           \
                },                                                      \
        }

#define ADC12138_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si)                 \
        {                                                               \
                .type = IIO_VOLTAGE,                                    \
                .indexed = 1,                                           \
                .channel = (chan1),                                     \
                .channel2 = (chan2),                                    \
                .differential = 1,                                      \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)    \
                                        | BIT(IIO_CHAN_INFO_OFFSET),    \
                .scan_index = si,                                       \
                .scan_type = {                                          \
                        .sign = 's',                                    \
                        .realbits = 13,                                 \
                        .storagebits = 16,                              \
                        .shift = 3,                                     \
                        .endianness = IIO_BE,                           \
                },                                                      \
        }

static const struct iio_chan_spec adc12132_channels[] = {
        ADC12138_VOLTAGE_CHANNEL(0),
        ADC12138_VOLTAGE_CHANNEL(1),
        ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
        ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
        IIO_CHAN_SOFT_TIMESTAMP(4),
};

static const struct iio_chan_spec adc12138_channels[] = {
        ADC12138_VOLTAGE_CHANNEL(0),
        ADC12138_VOLTAGE_CHANNEL(1),
        ADC12138_VOLTAGE_CHANNEL(2),
        ADC12138_VOLTAGE_CHANNEL(3),
        ADC12138_VOLTAGE_CHANNEL(4),
        ADC12138_VOLTAGE_CHANNEL(5),
        ADC12138_VOLTAGE_CHANNEL(6),
        ADC12138_VOLTAGE_CHANNEL(7),
        ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
        ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
        ADC12138_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
        ADC12138_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
        ADC12138_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
        ADC12138_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
        ADC12138_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
        ADC12138_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
        IIO_CHAN_SOFT_TIMESTAMP(16),
};

static int adc12138_mode_programming(struct adc12138 *adc, u8 mode,
                                     void *rx_buf, int len)
{
        struct spi_transfer xfer = {
                .tx_buf = adc->tx_buf,
                .rx_buf = adc->rx_buf,
                .len = len,
        };
        int ret;

        /* Skip unused bits for ADC12130 and ADC12132 */
        if (adc->id != adc12138)
                mode = (mode & 0xc0) | ((mode & 0x0f) << 2);

        adc->tx_buf[0] = mode;

        ret = spi_sync_transfer(adc->spi, &xfer, 1);
        if (ret)
                return ret;

        memcpy(rx_buf, adc->rx_buf, len);

        return 0;
}

static int adc12138_read_status(struct adc12138 *adc)
{
        u8 rx_buf[2];
        int ret;

        ret = adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
                                        rx_buf, 2);
        if (ret)
                return ret;

        return (rx_buf[0] << 1) | (rx_buf[1] >> 7);
}

static int __adc12138_start_conv(struct adc12138 *adc,
                                 struct iio_chan_spec const *channel,
                                 void *data, int len)

{
        static const u8 ch_to_mux[] = { 0, 4, 1, 5, 2, 6, 3, 7 };
        u8 mode = (ch_to_mux[channel->channel] << 4) |
                  (channel->differential ? 0 : 0x80);

        return adc12138_mode_programming(adc, mode, data, len);
}

static int adc12138_start_conv(struct adc12138 *adc,
                               struct iio_chan_spec const *channel)
{
        u8 trash;

        return __adc12138_start_conv(adc, channel, &trash, 1);
}

static int adc12138_start_and_read_conv(struct adc12138 *adc,
                                        struct iio_chan_spec const *channel,
                                        __be16 *data)
{
        return __adc12138_start_conv(adc, channel, data, 2);
}

static int adc12138_read_conv_data(struct adc12138 *adc, __be16 *value)
{
        /* Issue a read status instruction and read previous conversion data */
        return adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
                                         value, sizeof(*value));
}

static int adc12138_wait_eoc(struct adc12138 *adc, unsigned long timeout)
{
        if (!wait_for_completion_timeout(&adc->complete, timeout))
                return -ETIMEDOUT;

        return 0;
}

static int adc12138_adc_conversion(struct adc12138 *adc,
                                   struct iio_chan_spec const *channel,
                                   __be16 *value)
{
        int ret;

        reinit_completion(&adc->complete);

        ret = adc12138_start_conv(adc, channel);
        if (ret)
                return ret;

        ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
        if (ret)
                return ret;

        return adc12138_read_conv_data(adc, value);
}

static int adc12138_read_raw(struct iio_dev *iio,
                             struct iio_chan_spec const *channel, int *value,
                             int *shift, long mask)
{
        struct adc12138 *adc = iio_priv(iio);
        int ret;
        __be16 data;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&adc->lock);
                ret = adc12138_adc_conversion(adc, channel, &data);
                mutex_unlock(&adc->lock);
                if (ret)
                        return ret;

                *value = sign_extend32(be16_to_cpu(data) >> channel->scan_type.shift,
                                       channel->scan_type.realbits - 1);

                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                ret = regulator_get_voltage(adc->vref_p);
                if (ret < 0)
                        return ret;
                *value = ret;

                if (!IS_ERR(adc->vref_n)) {
                        ret = regulator_get_voltage(adc->vref_n);
                        if (ret < 0)
                                return ret;
                        *value -= ret;
                }

                /* convert regulator output voltage to mV */
                *value /= 1000;
                *shift = channel->scan_type.realbits - 1;

                return IIO_VAL_FRACTIONAL_LOG2;
        case IIO_CHAN_INFO_OFFSET:
                if (!IS_ERR(adc->vref_n)) {
                        *value = regulator_get_voltage(adc->vref_n);
                        if (*value < 0)
                                return *value;
                } else {
                        *value = 0;
                }

                /* convert regulator output voltage to mV */
                *value /= 1000;

                return IIO_VAL_INT;
        }

        return -EINVAL;
}

static const struct iio_info adc12138_info = {
        .read_raw = adc12138_read_raw,
};

static int adc12138_init(struct adc12138 *adc)
{
        int ret;
        int status;
        u8 mode;
        u8 trash;

        reinit_completion(&adc->complete);

        ret = adc12138_mode_programming(adc, ADC12138_MODE_AUTO_CAL, &trash, 1);
        if (ret)
                return ret;

        /* data output at this time has no significance */
        status = adc12138_read_status(adc);
        if (status < 0)
                return status;

        adc12138_wait_eoc(adc, msecs_to_jiffies(100));

        status = adc12138_read_status(adc);
        if (status & ADC12138_STATUS_CAL) {
                dev_warn(&adc->spi->dev,
                        "Auto Cal sequence is still in progress: %#x\n",
                        status);
                return -EIO;
        }

        switch (adc->acquisition_time) {
        case 6:
                mode = ADC12138_MODE_ACQUISITION_TIME_6;
                break;
        case 10:
                mode = ADC12138_MODE_ACQUISITION_TIME_10;
                break;
        case 18:
                mode = ADC12138_MODE_ACQUISITION_TIME_18;
                break;
        case 34:
                mode = ADC12138_MODE_ACQUISITION_TIME_34;
                break;
        default:
                return -EINVAL;
        }

        return adc12138_mode_programming(adc, mode, &trash, 1);
}

static irqreturn_t adc12138_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct adc12138 *adc = iio_priv(indio_dev);
        __be16 trash;
        int ret;
        int scan_index;
        int i = 0;

        mutex_lock(&adc->lock);

        iio_for_each_active_channel(indio_dev, scan_index) {
                const struct iio_chan_spec *scan_chan =
                                &indio_dev->channels[scan_index];

                reinit_completion(&adc->complete);

                ret = adc12138_start_and_read_conv(adc, scan_chan,
                                        i ? &adc->data[i - 1] : &trash);
                if (ret) {
                        dev_warn(&adc->spi->dev,
                                 "failed to start conversion\n");
                        goto out;
                }

                ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
                if (ret) {
                        dev_warn(&adc->spi->dev, "wait eoc timeout\n");
                        goto out;
                }

                i++;
        }

        if (i) {
                ret = adc12138_read_conv_data(adc, &adc->data[i - 1]);
                if (ret) {
                        dev_warn(&adc->spi->dev,
                                 "failed to get conversion data\n");
                        goto out;
                }
        }

        iio_push_to_buffers_with_ts(indio_dev, adc->data, sizeof(adc->data),
                                    iio_get_time_ns(indio_dev));
out:
        mutex_unlock(&adc->lock);

        iio_trigger_notify_done(indio_dev->trig);

        return IRQ_HANDLED;
}

static irqreturn_t adc12138_eoc_handler(int irq, void *p)
{
        struct iio_dev *indio_dev = p;
        struct adc12138 *adc = iio_priv(indio_dev);

        complete(&adc->complete);

        return IRQ_HANDLED;
}

static int adc12138_probe(struct spi_device *spi)
{
        struct iio_dev *indio_dev;
        struct adc12138 *adc;
        struct clk *cclk;
        int ret;

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

        adc = iio_priv(indio_dev);
        adc->spi = spi;
        adc->id = spi_get_device_id(spi)->driver_data;
        mutex_init(&adc->lock);
        init_completion(&adc->complete);

        indio_dev->name = spi_get_device_id(spi)->name;
        indio_dev->info = &adc12138_info;
        indio_dev->modes = INDIO_DIRECT_MODE;

        switch (adc->id) {
        case adc12130:
        case adc12132:
                indio_dev->channels = adc12132_channels;
                indio_dev->num_channels = ARRAY_SIZE(adc12132_channels);
                break;
        case adc12138:
                indio_dev->channels = adc12138_channels;
                indio_dev->num_channels = ARRAY_SIZE(adc12138_channels);
                break;
        default:
                return -EINVAL;
        }

        ret = device_property_read_u32(&spi->dev, "ti,acquisition-time",
                                       &adc->acquisition_time);
        if (ret)
                adc->acquisition_time = 10;

        ret = devm_request_irq(&spi->dev, spi->irq, adc12138_eoc_handler,
                               IRQF_TRIGGER_RISING, indio_dev->name, indio_dev);
        if (ret)
                return ret;

        cclk = devm_clk_get_enabled(&spi->dev, NULL);
        if (IS_ERR(cclk))
                return PTR_ERR(cclk);

        adc->vref_p = devm_regulator_get(&spi->dev, "vref-p");
        if (IS_ERR(adc->vref_p))
                return PTR_ERR(adc->vref_p);

        adc->vref_n = devm_regulator_get_optional(&spi->dev, "vref-n");
        if (IS_ERR(adc->vref_n)) {
                /*
                 * Assume vref_n is 0V if an optional regulator is not
                 * specified, otherwise return the error code.
                 */
                ret = PTR_ERR(adc->vref_n);
                if (ret != -ENODEV)
                        return ret;
        }

        ret = regulator_enable(adc->vref_p);
        if (ret)
                return ret;

        if (!IS_ERR(adc->vref_n)) {
                ret = regulator_enable(adc->vref_n);
                if (ret)
                        goto err_vref_p_disable;
        }

        ret = adc12138_init(adc);
        if (ret)
                goto err_vref_n_disable;

        spi_set_drvdata(spi, indio_dev);

        ret = iio_triggered_buffer_setup(indio_dev, NULL,
                                         adc12138_trigger_handler, NULL);
        if (ret)
                goto err_vref_n_disable;

        ret = iio_device_register(indio_dev);
        if (ret)
                goto err_buffer_cleanup;

        return 0;
err_buffer_cleanup:
        iio_triggered_buffer_cleanup(indio_dev);
err_vref_n_disable:
        if (!IS_ERR(adc->vref_n))
                regulator_disable(adc->vref_n);
err_vref_p_disable:
        regulator_disable(adc->vref_p);

        return ret;
}

static void adc12138_remove(struct spi_device *spi)
{
        struct iio_dev *indio_dev = spi_get_drvdata(spi);
        struct adc12138 *adc = iio_priv(indio_dev);

        iio_device_unregister(indio_dev);
        iio_triggered_buffer_cleanup(indio_dev);
        if (!IS_ERR(adc->vref_n))
                regulator_disable(adc->vref_n);
        regulator_disable(adc->vref_p);
}

static const struct of_device_id adc12138_dt_ids[] = {
        { .compatible = "ti,adc12130", },
        { .compatible = "ti,adc12132", },
        { .compatible = "ti,adc12138", },
        { }
};
MODULE_DEVICE_TABLE(of, adc12138_dt_ids);

static const struct spi_device_id adc12138_id[] = {
        { "adc12130", adc12130 },
        { "adc12132", adc12132 },
        { "adc12138", adc12138 },
        { }
};
MODULE_DEVICE_TABLE(spi, adc12138_id);

static struct spi_driver adc12138_driver = {
        .driver = {
                .name = "adc12138",
                .of_match_table = adc12138_dt_ids,
        },
        .probe = adc12138_probe,
        .remove = adc12138_remove,
        .id_table = adc12138_id,
};
module_spi_driver(adc12138_driver);

MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
MODULE_DESCRIPTION("ADC12130/ADC12132/ADC12138 driver");
MODULE_LICENSE("GPL v2");