// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2013 Oskar Andero <oskar.andero@gmail.com>
 * Copyright (C) 2014 Rose Technology
 *         Allan Bendorff Jensen <abj@rosetechnology.dk>
 *         Soren Andersen <san@rosetechnology.dk>
 *
 * Driver for following ADC chips from Microchip Technology's:
 * 10 Bit converter
 * MCP3001
 * MCP3002
 * MCP3004
 * MCP3008
 * ------------
 * 12 bit converter
 * MCP3201
 * MCP3202
 * MCP3204
 * MCP3208
 * ------------
 * 13 bit converter
 * MCP3301
 * ------------
 * 22 bit converter
 * MCP3550
 * MCP3551
 * MCP3553
 *
 * Datasheet can be found here:
 * https://ww1.microchip.com/downloads/en/DeviceDoc/21293C.pdf  mcp3001
 * https://ww1.microchip.com/downloads/en/DeviceDoc/21294E.pdf  mcp3002
 * https://ww1.microchip.com/downloads/en/DeviceDoc/21295d.pdf  mcp3004/08
 * http://ww1.microchip.com/downloads/en/DeviceDoc/21290D.pdf  mcp3201
 * http://ww1.microchip.com/downloads/en/DeviceDoc/21034D.pdf  mcp3202
 * http://ww1.microchip.com/downloads/en/DeviceDoc/21298c.pdf  mcp3204/08
 * https://ww1.microchip.com/downloads/en/DeviceDoc/21700E.pdf  mcp3301
 * http://ww1.microchip.com/downloads/en/DeviceDoc/21950D.pdf  mcp3550/1/3
 */

#include <linux/err.h>
#include <linux/delay.h>
#include <linux/spi/spi.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/iio/iio.h>
#include <linux/regulator/consumer.h>

enum {
        mcp3001,
        mcp3002,
        mcp3004,
        mcp3008,
        mcp3201,
        mcp3202,
        mcp3204,
        mcp3208,
        mcp3301,
        mcp3550_50,
        mcp3550_60,
        mcp3551,
        mcp3553,
};

struct mcp320x_chip_info {
        const struct iio_chan_spec *channels;
        unsigned int num_channels;
        unsigned int resolution;
        unsigned int conv_time; /* usec */
};

/**
 * struct mcp320x - Microchip SPI ADC instance
 * @spi: SPI slave (parent of the IIO device)
 * @msg: SPI message to select a channel and receive a value from the ADC
 * @transfer: SPI transfers used by @msg
 * @start_conv_msg: SPI message to start a conversion by briefly asserting CS
 * @start_conv_transfer: SPI transfer used by @start_conv_msg
 * @reg: regulator generating Vref
 * @lock: protects read sequences
 * @chip_info: ADC properties
 * @tx_buf: buffer for @transfer[0] (not used on single-channel converters)
 * @rx_buf: buffer for @transfer[1]
 */
struct mcp320x {
        struct spi_device *spi;
        struct spi_message msg;
        struct spi_transfer transfer[2];
        struct spi_message start_conv_msg;
        struct spi_transfer start_conv_transfer;

        struct regulator *reg;
        struct mutex lock;
        const struct mcp320x_chip_info *chip_info;

        u8 tx_buf __aligned(IIO_DMA_MINALIGN);
        u8 rx_buf[4];
};

static int mcp320x_channel_to_tx_data(int device_index,
                        const unsigned int channel, bool differential)
{
        int start_bit = 1;

        switch (device_index) {
        case mcp3002:
        case mcp3202:
                return ((start_bit << 4) | (!differential << 3) |
                                                        (channel << 2));
        case mcp3004:
        case mcp3204:
        case mcp3008:
        case mcp3208:
                return ((start_bit << 6) | (!differential << 5) |
                                                        (channel << 2));
        default:
                return -EINVAL;
        }
}

static int mcp320x_adc_conversion(struct mcp320x *adc, u8 channel,
                                  bool differential, int device_index, int *val)
{
        int ret;

        if (adc->chip_info->conv_time) {
                ret = spi_sync(adc->spi, &adc->start_conv_msg);
                if (ret < 0)
                        return ret;

                usleep_range(adc->chip_info->conv_time,
                             adc->chip_info->conv_time + 100);
        }

        memset(&adc->rx_buf, 0, sizeof(adc->rx_buf));
        if (adc->chip_info->num_channels > 1)
                adc->tx_buf = mcp320x_channel_to_tx_data(device_index, channel,
                                                         differential);

        ret = spi_sync(adc->spi, &adc->msg);
        if (ret < 0)
                return ret;

        switch (device_index) {
        case mcp3001:
                *val = (adc->rx_buf[0] << 5 | adc->rx_buf[1] >> 3);
                return 0;
        case mcp3002:
        case mcp3004:
        case mcp3008:
                *val = (adc->rx_buf[0] << 2 | adc->rx_buf[1] >> 6);
                return 0;
        case mcp3201:
                *val = (adc->rx_buf[0] << 7 | adc->rx_buf[1] >> 1);
                return 0;
        case mcp3202:
        case mcp3204:
        case mcp3208:
                *val = (adc->rx_buf[0] << 4 | adc->rx_buf[1] >> 4);
                return 0;
        case mcp3301:
                *val = sign_extend32((adc->rx_buf[0] & 0x1f) << 8
                                    | adc->rx_buf[1], 12);
                return 0;
        case mcp3550_50:
        case mcp3550_60:
        case mcp3551:
        case mcp3553: {
                u32 raw = be32_to_cpup((__be32 *)adc->rx_buf);

                if (!(adc->spi->mode & SPI_CPOL))
                        raw <<= 1; /* strip Data Ready bit in SPI mode 0,0 */

                /*
                 * If the input is within -vref and vref, bit 21 is the sign.
                 * Up to 12% overrange or underrange are allowed, in which case
                 * bit 23 is the sign and bit 0 to 21 is the value.
                 */
                raw >>= 8;
                if (raw & BIT(22) && raw & BIT(23))
                        return -EIO; /* cannot have overrange AND underrange */
                else if (raw & BIT(22))
                        raw &= ~BIT(22); /* overrange */
                else if (raw & BIT(23) || raw & BIT(21))
                        raw |= GENMASK(31, 22); /* underrange or negative */

                *val = (s32)raw;
                return 0;
                }
        default:
                return -EINVAL;
        }
}

static int mcp320x_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *channel, int *val,
                            int *val2, long mask)
{
        struct mcp320x *adc = iio_priv(indio_dev);
        int ret = -EINVAL;
        int device_index = 0;

        mutex_lock(&adc->lock);

        device_index = spi_get_device_id(adc->spi)->driver_data;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                ret = mcp320x_adc_conversion(adc, channel->address,
                        channel->differential, device_index, val);
                if (ret < 0)
                        goto out;

                ret = IIO_VAL_INT;
                break;

        case IIO_CHAN_INFO_SCALE:
                ret = regulator_get_voltage(adc->reg);
                if (ret < 0)
                        goto out;

                /* convert regulator output voltage to mV */
                *val = ret / 1000;
                *val2 = adc->chip_info->resolution;
                ret = IIO_VAL_FRACTIONAL_LOG2;
                break;
        }

out:
        mutex_unlock(&adc->lock);

        return ret;
}

#define MCP320X_VOLTAGE_CHANNEL(num)                            \
        {                                                       \
                .type = IIO_VOLTAGE,                            \
                .indexed = 1,                                   \
                .channel = (num),                               \
                .address = (num),                               \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
        }

#define MCP320X_VOLTAGE_CHANNEL_DIFF(chan1, chan2)              \
        {                                                       \
                .type = IIO_VOLTAGE,                            \
                .indexed = 1,                                   \
                .channel = (chan1),                             \
                .channel2 = (chan2),                            \
                .address = (chan1),                             \
                .differential = 1,                              \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
        }

static const struct iio_chan_spec mcp3201_channels[] = {
        MCP320X_VOLTAGE_CHANNEL_DIFF(0, 1),
};

static const struct iio_chan_spec mcp3202_channels[] = {
        MCP320X_VOLTAGE_CHANNEL(0),
        MCP320X_VOLTAGE_CHANNEL(1),
        MCP320X_VOLTAGE_CHANNEL_DIFF(0, 1),
        MCP320X_VOLTAGE_CHANNEL_DIFF(1, 0),
};

static const struct iio_chan_spec mcp3204_channels[] = {
        MCP320X_VOLTAGE_CHANNEL(0),
        MCP320X_VOLTAGE_CHANNEL(1),
        MCP320X_VOLTAGE_CHANNEL(2),
        MCP320X_VOLTAGE_CHANNEL(3),
        MCP320X_VOLTAGE_CHANNEL_DIFF(0, 1),
        MCP320X_VOLTAGE_CHANNEL_DIFF(1, 0),
        MCP320X_VOLTAGE_CHANNEL_DIFF(2, 3),
        MCP320X_VOLTAGE_CHANNEL_DIFF(3, 2),
};

static const struct iio_chan_spec mcp3208_channels[] = {
        MCP320X_VOLTAGE_CHANNEL(0),
        MCP320X_VOLTAGE_CHANNEL(1),
        MCP320X_VOLTAGE_CHANNEL(2),
        MCP320X_VOLTAGE_CHANNEL(3),
        MCP320X_VOLTAGE_CHANNEL(4),
        MCP320X_VOLTAGE_CHANNEL(5),
        MCP320X_VOLTAGE_CHANNEL(6),
        MCP320X_VOLTAGE_CHANNEL(7),
        MCP320X_VOLTAGE_CHANNEL_DIFF(0, 1),
        MCP320X_VOLTAGE_CHANNEL_DIFF(1, 0),
        MCP320X_VOLTAGE_CHANNEL_DIFF(2, 3),
        MCP320X_VOLTAGE_CHANNEL_DIFF(3, 2),
        MCP320X_VOLTAGE_CHANNEL_DIFF(4, 5),
        MCP320X_VOLTAGE_CHANNEL_DIFF(5, 4),
        MCP320X_VOLTAGE_CHANNEL_DIFF(6, 7),
        MCP320X_VOLTAGE_CHANNEL_DIFF(7, 6),
};

static const struct iio_info mcp320x_info = {
        .read_raw = mcp320x_read_raw,
};

static const struct mcp320x_chip_info mcp320x_chip_infos[] = {
        [mcp3001] = {
                .channels = mcp3201_channels,
                .num_channels = ARRAY_SIZE(mcp3201_channels),
                .resolution = 10
        },
        [mcp3002] = {
                .channels = mcp3202_channels,
                .num_channels = ARRAY_SIZE(mcp3202_channels),
                .resolution = 10
        },
        [mcp3004] = {
                .channels = mcp3204_channels,
                .num_channels = ARRAY_SIZE(mcp3204_channels),
                .resolution = 10
        },
        [mcp3008] = {
                .channels = mcp3208_channels,
                .num_channels = ARRAY_SIZE(mcp3208_channels),
                .resolution = 10
        },
        [mcp3201] = {
                .channels = mcp3201_channels,
                .num_channels = ARRAY_SIZE(mcp3201_channels),
                .resolution = 12
        },
        [mcp3202] = {
                .channels = mcp3202_channels,
                .num_channels = ARRAY_SIZE(mcp3202_channels),
                .resolution = 12
        },
        [mcp3204] = {
                .channels = mcp3204_channels,
                .num_channels = ARRAY_SIZE(mcp3204_channels),
                .resolution = 12
        },
        [mcp3208] = {
                .channels = mcp3208_channels,
                .num_channels = ARRAY_SIZE(mcp3208_channels),
                .resolution = 12
        },
        [mcp3301] = {
                .channels = mcp3201_channels,
                .num_channels = ARRAY_SIZE(mcp3201_channels),
                .resolution = 13
        },
        [mcp3550_50] = {
                .channels = mcp3201_channels,
                .num_channels = ARRAY_SIZE(mcp3201_channels),
                .resolution = 21,
                /* 2% max deviation + 144 clock periods to exit shutdown */
                .conv_time = 80000 * 1.02 + 144000 / 102.4,
        },
        [mcp3550_60] = {
                .channels = mcp3201_channels,
                .num_channels = ARRAY_SIZE(mcp3201_channels),
                .resolution = 21,
                .conv_time = 66670 * 1.02 + 144000 / 122.88,
        },
        [mcp3551] = {
                .channels = mcp3201_channels,
                .num_channels = ARRAY_SIZE(mcp3201_channels),
                .resolution = 21,
                .conv_time = 73100 * 1.02 + 144000 / 112.64,
        },
        [mcp3553] = {
                .channels = mcp3201_channels,
                .num_channels = ARRAY_SIZE(mcp3201_channels),
                .resolution = 21,
                .conv_time = 16670 * 1.02 + 144000 / 122.88,
        },
};

static void mcp320x_regulator_disable(void *reg)
{
        regulator_disable(reg);
}

static int mcp320x_probe(struct spi_device *spi)
{
        struct iio_dev *indio_dev;
        struct mcp320x *adc;
        const struct mcp320x_chip_info *chip_info;
        int ret, device_index;

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

        adc = iio_priv(indio_dev);
        adc->spi = spi;

        indio_dev->name = spi_get_device_id(spi)->name;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->info = &mcp320x_info;

        device_index = spi_get_device_id(spi)->driver_data;
        chip_info = &mcp320x_chip_infos[device_index];
        indio_dev->channels = chip_info->channels;
        indio_dev->num_channels = chip_info->num_channels;

        adc->chip_info = chip_info;

        adc->transfer[0].tx_buf = &adc->tx_buf;
        adc->transfer[0].len = sizeof(adc->tx_buf);
        adc->transfer[1].rx_buf = adc->rx_buf;
        adc->transfer[1].len = DIV_ROUND_UP(chip_info->resolution, 8);

        if (chip_info->num_channels == 1)
                /* single-channel converters are rx only (no MOSI pin) */
                spi_message_init_with_transfers(&adc->msg,
                                                &adc->transfer[1], 1);
        else
                spi_message_init_with_transfers(&adc->msg, adc->transfer,
                                                ARRAY_SIZE(adc->transfer));

        switch (device_index) {
        case mcp3550_50:
        case mcp3550_60:
        case mcp3551:
        case mcp3553:
                /* rx len increases from 24 to 25 bit in SPI mode 0,0 */
                if (!(spi->mode & SPI_CPOL))
                        adc->transfer[1].len++;

                /* conversions are started by asserting CS pin for 8 usec */
                adc->start_conv_transfer.delay.value = 8;
                adc->start_conv_transfer.delay.unit = SPI_DELAY_UNIT_USECS;
                spi_message_init_with_transfers(&adc->start_conv_msg,
                                                &adc->start_conv_transfer, 1);

                /*
                 * If CS was previously kept low (continuous conversion mode)
                 * and then changed to high, the chip is in shutdown.
                 * Sometimes it fails to wake from shutdown and clocks out
                 * only 0xffffff.  The magic sequence of performing two
                 * conversions without delay between them resets the chip
                 * and ensures all subsequent conversions succeed.
                 */
                mcp320x_adc_conversion(adc, 0, 1, device_index, &ret);
                mcp320x_adc_conversion(adc, 0, 1, device_index, &ret);
        }

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

        ret = regulator_enable(adc->reg);
        if (ret < 0)
                return ret;

        ret = devm_add_action_or_reset(&spi->dev, mcp320x_regulator_disable, adc->reg);
        if (ret < 0)
                return ret;

        mutex_init(&adc->lock);

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

static const struct of_device_id mcp320x_dt_ids[] = {
        { .compatible = "microchip,mcp3001" },
        { .compatible = "microchip,mcp3002" },
        { .compatible = "microchip,mcp3004" },
        { .compatible = "microchip,mcp3008" },
        { .compatible = "microchip,mcp3201" },
        { .compatible = "microchip,mcp3202" },
        { .compatible = "microchip,mcp3204" },
        { .compatible = "microchip,mcp3208" },
        { .compatible = "microchip,mcp3301" },
        { .compatible = "microchip,mcp3550-50" },
        { .compatible = "microchip,mcp3550-60" },
        { .compatible = "microchip,mcp3551" },
        { .compatible = "microchip,mcp3553" },
        { }
};
MODULE_DEVICE_TABLE(of, mcp320x_dt_ids);

static const struct spi_device_id mcp320x_id[] = {
        { "mcp3001", mcp3001 },
        { "mcp3002", mcp3002 },
        { "mcp3004", mcp3004 },
        { "mcp3008", mcp3008 },
        { "mcp3201", mcp3201 },
        { "mcp3202", mcp3202 },
        { "mcp3204", mcp3204 },
        { "mcp3208", mcp3208 },
        { "mcp3301", mcp3301 },
        { "mcp3550-50", mcp3550_50 },
        { "mcp3550-60", mcp3550_60 },
        { "mcp3551", mcp3551 },
        { "mcp3553", mcp3553 },
        { }
};
MODULE_DEVICE_TABLE(spi, mcp320x_id);

static struct spi_driver mcp320x_driver = {
        .driver = {
                .name = "mcp320x",
                .of_match_table = mcp320x_dt_ids,
        },
        .probe = mcp320x_probe,
        .id_table = mcp320x_id,
};
module_spi_driver(mcp320x_driver);

MODULE_AUTHOR("Oskar Andero <oskar.andero@gmail.com>");
MODULE_DESCRIPTION("Microchip Technology MCP3x01/02/04/08 and MCP3550/1/3");
MODULE_LICENSE("GPL v2");