// SPDX-License-Identifier: GPL-2.0-only
 /*
  * iio/adc/max1027.c
  * Copyright (C) 2014 Philippe Reynes
  *
  * based on linux/drivers/iio/ad7923.c
  * Copyright 2011 Analog Devices Inc (from AD7923 Driver)
  * Copyright 2012 CS Systemes d'Information
  *
  * max1027.c
  *
  * Partial support for max1027 and similar chips.
  */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/delay.h>

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

#define MAX1027_CONV_REG  BIT(7)
#define MAX1027_SETUP_REG BIT(6)
#define MAX1027_AVG_REG   BIT(5)
#define MAX1027_RST_REG   BIT(4)

/* conversion register */
#define MAX1027_TEMP      BIT(0)
#define MAX1027_SCAN_0_N  (0x00 << 1)
#define MAX1027_SCAN_N_M  (0x01 << 1)
#define MAX1027_SCAN_N    (0x02 << 1)
#define MAX1027_NOSCAN    (0x03 << 1)
#define MAX1027_CHAN(n)   ((n) << 3)

/* setup register */
#define MAX1027_UNIPOLAR  0x02
#define MAX1027_BIPOLAR   0x03
#define MAX1027_REF_MODE0 (0x00 << 2)
#define MAX1027_REF_MODE1 (0x01 << 2)
#define MAX1027_REF_MODE2 (0x02 << 2)
#define MAX1027_REF_MODE3 (0x03 << 2)
#define MAX1027_CKS_MODE0 (0x00 << 4)
#define MAX1027_CKS_MODE1 (0x01 << 4)
#define MAX1027_CKS_MODE2 (0x02 << 4)
#define MAX1027_CKS_MODE3 (0x03 << 4)

/* averaging register */
#define MAX1027_NSCAN_4   0x00
#define MAX1027_NSCAN_8   0x01
#define MAX1027_NSCAN_12  0x02
#define MAX1027_NSCAN_16  0x03
#define MAX1027_NAVG_4    (0x00 << 2)
#define MAX1027_NAVG_8    (0x01 << 2)
#define MAX1027_NAVG_16   (0x02 << 2)
#define MAX1027_NAVG_32   (0x03 << 2)
#define MAX1027_AVG_EN    BIT(4)

/* Device can achieve 300ksps so we assume a 3.33us conversion delay */
#define MAX1027_CONVERSION_UDELAY 4

enum max1027_id {
        max1027,
        max1029,
        max1031,
        max1227,
        max1229,
        max1231,
};

static const struct spi_device_id max1027_id[] = {
        {"max1027", max1027},
        {"max1029", max1029},
        {"max1031", max1031},
        {"max1227", max1227},
        {"max1229", max1229},
        {"max1231", max1231},
        {}
};
MODULE_DEVICE_TABLE(spi, max1027_id);

static const struct of_device_id max1027_adc_dt_ids[] = {
        { .compatible = "maxim,max1027" },
        { .compatible = "maxim,max1029" },
        { .compatible = "maxim,max1031" },
        { .compatible = "maxim,max1227" },
        { .compatible = "maxim,max1229" },
        { .compatible = "maxim,max1231" },
        {},
};
MODULE_DEVICE_TABLE(of, max1027_adc_dt_ids);

#define MAX1027_V_CHAN(index, depth)                                    \
        {                                                               \
                .type = IIO_VOLTAGE,                                    \
                .indexed = 1,                                           \
                .channel = index,                                       \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
                .scan_index = index + 1,                                \
                .scan_type = {                                          \
                        .sign = 'u',                                    \
                        .realbits = depth,                              \
                        .storagebits = 16,                              \
                        .shift = (depth == 10) ? 2 : 0,                 \
                        .endianness = IIO_BE,                           \
                },                                                      \
        }

#define MAX1027_T_CHAN                                                  \
        {                                                               \
                .type = IIO_TEMP,                                       \
                .channel = 0,                                           \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
                .scan_index = 0,                                        \
                .scan_type = {                                          \
                        .sign = 'u',                                    \
                        .realbits = 12,                                 \
                        .storagebits = 16,                              \
                        .endianness = IIO_BE,                           \
                },                                                      \
        }

#define MAX1X27_CHANNELS(depth)                 \
        MAX1027_T_CHAN,                         \
        MAX1027_V_CHAN(0, depth),               \
        MAX1027_V_CHAN(1, depth),               \
        MAX1027_V_CHAN(2, depth),               \
        MAX1027_V_CHAN(3, depth),               \
        MAX1027_V_CHAN(4, depth),               \
        MAX1027_V_CHAN(5, depth),               \
        MAX1027_V_CHAN(6, depth),               \
        MAX1027_V_CHAN(7, depth)

#define MAX1X29_CHANNELS(depth)                 \
        MAX1X27_CHANNELS(depth),                \
        MAX1027_V_CHAN(8, depth),               \
        MAX1027_V_CHAN(9, depth),               \
        MAX1027_V_CHAN(10, depth),              \
        MAX1027_V_CHAN(11, depth)

#define MAX1X31_CHANNELS(depth)                 \
        MAX1X29_CHANNELS(depth),                \
        MAX1027_V_CHAN(12, depth),              \
        MAX1027_V_CHAN(13, depth),              \
        MAX1027_V_CHAN(14, depth),              \
        MAX1027_V_CHAN(15, depth)

static const struct iio_chan_spec max1027_channels[] = {
        MAX1X27_CHANNELS(10),
};

static const struct iio_chan_spec max1029_channels[] = {
        MAX1X29_CHANNELS(10),
};

static const struct iio_chan_spec max1031_channels[] = {
        MAX1X31_CHANNELS(10),
};

static const struct iio_chan_spec max1227_channels[] = {
        MAX1X27_CHANNELS(12),
};

static const struct iio_chan_spec max1229_channels[] = {
        MAX1X29_CHANNELS(12),
};

static const struct iio_chan_spec max1231_channels[] = {
        MAX1X31_CHANNELS(12),
};

/*
 * These devices are able to scan from 0 to N, N being the highest voltage
 * channel requested by the user. The temperature can be included or not,
 * but cannot be retrieved alone. Based on the below
 * ->available_scan_masks, the core will select the most appropriate
 * ->active_scan_mask and the "minimum" number of channels will be
 * scanned and pushed to the buffers.
 *
 * For example, if the user wants channels 1, 4 and 5, all channels from
 * 0 to 5 will be scanned and pushed to the IIO buffers. The core will then
 * filter out the unneeded samples based on the ->active_scan_mask that has
 * been selected and only channels 1, 4 and 5 will be available to the user
 * in the shared buffer.
 */
#define MAX1X27_SCAN_MASK_TEMP BIT(0)

#define MAX1X27_SCAN_MASKS(temp)                                        \
        GENMASK(1, 1 - (temp)), GENMASK(2, 1 - (temp)),                 \
        GENMASK(3, 1 - (temp)), GENMASK(4, 1 - (temp)),                 \
        GENMASK(5, 1 - (temp)), GENMASK(6, 1 - (temp)),                 \
        GENMASK(7, 1 - (temp)), GENMASK(8, 1 - (temp))

#define MAX1X29_SCAN_MASKS(temp)                                        \
        MAX1X27_SCAN_MASKS(temp),                                       \
        GENMASK(9, 1 - (temp)), GENMASK(10, 1 - (temp)),                \
        GENMASK(11, 1 - (temp)), GENMASK(12, 1 - (temp))

#define MAX1X31_SCAN_MASKS(temp)                                        \
        MAX1X29_SCAN_MASKS(temp),                                       \
        GENMASK(13, 1 - (temp)), GENMASK(14, 1 - (temp)),               \
        GENMASK(15, 1 - (temp)), GENMASK(16, 1 - (temp))

static const unsigned long max1027_available_scan_masks[] = {
        MAX1X27_SCAN_MASKS(0),
        MAX1X27_SCAN_MASKS(1),
        0x00000000,
};

static const unsigned long max1029_available_scan_masks[] = {
        MAX1X29_SCAN_MASKS(0),
        MAX1X29_SCAN_MASKS(1),
        0x00000000,
};

static const unsigned long max1031_available_scan_masks[] = {
        MAX1X31_SCAN_MASKS(0),
        MAX1X31_SCAN_MASKS(1),
        0x00000000,
};

struct max1027_chip_info {
        const struct iio_chan_spec *channels;
        unsigned int num_channels;
        const unsigned long *available_scan_masks;
};

static const struct max1027_chip_info max1027_chip_info_tbl[] = {
        [max1027] = {
                .channels = max1027_channels,
                .num_channels = ARRAY_SIZE(max1027_channels),
                .available_scan_masks = max1027_available_scan_masks,
        },
        [max1029] = {
                .channels = max1029_channels,
                .num_channels = ARRAY_SIZE(max1029_channels),
                .available_scan_masks = max1029_available_scan_masks,
        },
        [max1031] = {
                .channels = max1031_channels,
                .num_channels = ARRAY_SIZE(max1031_channels),
                .available_scan_masks = max1031_available_scan_masks,
        },
        [max1227] = {
                .channels = max1227_channels,
                .num_channels = ARRAY_SIZE(max1227_channels),
                .available_scan_masks = max1027_available_scan_masks,
        },
        [max1229] = {
                .channels = max1229_channels,
                .num_channels = ARRAY_SIZE(max1229_channels),
                .available_scan_masks = max1029_available_scan_masks,
        },
        [max1231] = {
                .channels = max1231_channels,
                .num_channels = ARRAY_SIZE(max1231_channels),
                .available_scan_masks = max1031_available_scan_masks,
        },
};

struct max1027_state {
        const struct max1027_chip_info  *info;
        struct spi_device               *spi;
        struct iio_trigger              *trig;
        __be16                          *buffer;
        struct mutex                    lock;
        struct completion               complete;

        u8                              reg ____cacheline_aligned;
};

static int max1027_wait_eoc(struct iio_dev *indio_dev)
{
        struct max1027_state *st = iio_priv(indio_dev);
        unsigned int conversion_time = MAX1027_CONVERSION_UDELAY;
        int ret;

        if (st->spi->irq) {
                ret = wait_for_completion_timeout(&st->complete,
                                                  msecs_to_jiffies(1000));
                reinit_completion(&st->complete);
                if (!ret)
                        return -ETIMEDOUT;
        } else {
                if (indio_dev->active_scan_mask)
                        conversion_time *= hweight32(*indio_dev->active_scan_mask);

                usleep_range(conversion_time, conversion_time * 2);
        }

        return 0;
}

/* Scan from chan 0 to the highest requested channel. Include temperature on demand. */
static int max1027_configure_chans_and_start(struct iio_dev *indio_dev)
{
        struct max1027_state *st = iio_priv(indio_dev);

        st->reg = MAX1027_CONV_REG | MAX1027_SCAN_0_N;
        st->reg |= MAX1027_CHAN(fls(*indio_dev->active_scan_mask) - 2);
        if (*indio_dev->active_scan_mask & MAX1X27_SCAN_MASK_TEMP)
                st->reg |= MAX1027_TEMP;

        return spi_write(st->spi, &st->reg, 1);
}

static int max1027_enable_trigger(struct iio_dev *indio_dev, bool enable)
{
        struct max1027_state *st = iio_priv(indio_dev);

        st->reg = MAX1027_SETUP_REG | MAX1027_REF_MODE2;

        /*
         * Start acquisition on:
         * MODE0: external hardware trigger wired to the cnvst input pin
         * MODE2: conversion register write
         */
        if (enable)
                st->reg |= MAX1027_CKS_MODE0;
        else
                st->reg |= MAX1027_CKS_MODE2;

        return spi_write(st->spi, &st->reg, 1);
}

static int max1027_read_single_value(struct iio_dev *indio_dev,
                                     struct iio_chan_spec const *chan,
                                     int *val)
{
        int ret;
        struct max1027_state *st = iio_priv(indio_dev);

        ret = iio_device_claim_direct_mode(indio_dev);
        if (ret)
                return ret;

        /* Configure conversion register with the requested chan */
        st->reg = MAX1027_CONV_REG | MAX1027_CHAN(chan->channel) |
                  MAX1027_NOSCAN;
        if (chan->type == IIO_TEMP)
                st->reg |= MAX1027_TEMP;
        ret = spi_write(st->spi, &st->reg, 1);
        if (ret < 0) {
                dev_err(&indio_dev->dev,
                        "Failed to configure conversion register\n");
                iio_device_release_direct_mode(indio_dev);
                return ret;
        }

        /*
         * For an unknown reason, when we use the mode "10" (write
         * conversion register), the interrupt doesn't occur every time.
         * So we just wait the maximum conversion time and deliver the value.
         */
        ret = max1027_wait_eoc(indio_dev);
        if (ret)
                return ret;

        /* Read result */
        ret = spi_read(st->spi, st->buffer, (chan->type == IIO_TEMP) ? 4 : 2);

        iio_device_release_direct_mode(indio_dev);

        if (ret < 0)
                return ret;

        *val = be16_to_cpu(st->buffer[0]);

        return IIO_VAL_INT;
}

static int max1027_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int *val, int *val2, long mask)
{
        int ret = 0;
        struct max1027_state *st = iio_priv(indio_dev);

        mutex_lock(&st->lock);

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                ret = max1027_read_single_value(indio_dev, chan, val);
                break;
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_TEMP:
                        *val = 1;
                        *val2 = 8;
                        ret = IIO_VAL_FRACTIONAL;
                        break;
                case IIO_VOLTAGE:
                        *val = 2500;
                        *val2 = chan->scan_type.realbits;
                        ret = IIO_VAL_FRACTIONAL_LOG2;
                        break;
                default:
                        ret = -EINVAL;
                        break;
                }
                break;
        default:
                ret = -EINVAL;
                break;
        }

        mutex_unlock(&st->lock);

        return ret;
}

static int max1027_debugfs_reg_access(struct iio_dev *indio_dev,
                                      unsigned int reg, unsigned int writeval,
                                      unsigned int *readval)
{
        struct max1027_state *st = iio_priv(indio_dev);
        u8 *val = (u8 *)st->buffer;

        if (readval) {
                int ret = spi_read(st->spi, val, 2);
                *readval = be16_to_cpu(st->buffer[0]);
                return ret;
        }

        *val = (u8)writeval;
        return spi_write(st->spi, val, 1);
}

static int max1027_set_cnvst_trigger_state(struct iio_trigger *trig, bool state)
{
        struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
        int ret;

        /*
         * In order to disable the convst trigger, start acquisition on
         * conversion register write, which basically disables triggering
         * conversions upon cnvst changes and thus has the effect of disabling
         * the external hardware trigger.
         */
        ret = max1027_enable_trigger(indio_dev, state);
        if (ret)
                return ret;

        if (state) {
                ret = max1027_configure_chans_and_start(indio_dev);
                if (ret)
                        return ret;
        }

        return 0;
}

static int max1027_read_scan(struct iio_dev *indio_dev)
{
        struct max1027_state *st = iio_priv(indio_dev);
        unsigned int scanned_chans;
        int ret;

        scanned_chans = fls(*indio_dev->active_scan_mask) - 1;
        if (*indio_dev->active_scan_mask & MAX1X27_SCAN_MASK_TEMP)
                scanned_chans++;

        /* fill buffer with all channel */
        ret = spi_read(st->spi, st->buffer, scanned_chans * 2);
        if (ret < 0)
                return ret;

        iio_push_to_buffers(indio_dev, st->buffer);

        return 0;
}

static irqreturn_t max1027_handler(int irq, void *private)
{
        struct iio_dev *indio_dev = private;
        struct max1027_state *st = iio_priv(indio_dev);

        /*
         * If buffers are disabled (raw read) or when using external triggers,
         * we just need to unlock the waiters which will then handle the data.
         *
         * When using the internal trigger, we must hand-off the choice of the
         * handler to the core which will then lookup through the interrupt tree
         * for the right handler registered with iio_triggered_buffer_setup()
         * to execute, as this trigger might very well be used in conjunction
         * with another device. The core will then call the relevant handler to
         * perform the data processing step.
         */
        if (!iio_buffer_enabled(indio_dev))
                complete(&st->complete);
        else
                iio_trigger_poll(indio_dev->trig);

        return IRQ_HANDLED;
}

static irqreturn_t max1027_trigger_handler(int irq, void *private)
{
        struct iio_poll_func *pf = private;
        struct iio_dev *indio_dev = pf->indio_dev;
        int ret;

        if (!iio_trigger_using_own(indio_dev)) {
                ret = max1027_configure_chans_and_start(indio_dev);
                if (ret)
                        goto out;

                /* This is a threaded handler, it is fine to wait for an IRQ */
                ret = max1027_wait_eoc(indio_dev);
                if (ret)
                        goto out;
        }

        ret = max1027_read_scan(indio_dev);
out:
        if (ret)
                dev_err(&indio_dev->dev,
                        "Cannot read scanned values (%d)\n", ret);

        iio_trigger_notify_done(indio_dev->trig);

        return IRQ_HANDLED;
}

static const struct iio_trigger_ops max1027_trigger_ops = {
        .validate_device = &iio_trigger_validate_own_device,
        .set_trigger_state = &max1027_set_cnvst_trigger_state,
};

static const struct iio_info max1027_info = {
        .read_raw = &max1027_read_raw,
        .debugfs_reg_access = &max1027_debugfs_reg_access,
};

static int max1027_probe(struct spi_device *spi)
{
        int ret;
        struct iio_dev *indio_dev;
        struct max1027_state *st;

        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
        if (!indio_dev) {
                pr_err("Can't allocate iio device\n");
                return -ENOMEM;
        }

        st = iio_priv(indio_dev);
        st->spi = spi;
        st->info = &max1027_chip_info_tbl[spi_get_device_id(spi)->driver_data];

        mutex_init(&st->lock);
        init_completion(&st->complete);

        indio_dev->name = spi_get_device_id(spi)->name;
        indio_dev->info = &max1027_info;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = st->info->channels;
        indio_dev->num_channels = st->info->num_channels;
        indio_dev->available_scan_masks = st->info->available_scan_masks;

        st->buffer = devm_kmalloc_array(&indio_dev->dev,
                                        indio_dev->num_channels, 2,
                                        GFP_KERNEL);
        if (!st->buffer)
                return -ENOMEM;

        /* Enable triggered buffers */
        ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
                                              &iio_pollfunc_store_time,
                                              &max1027_trigger_handler,
                                              NULL);
        if (ret < 0) {
                dev_err(&indio_dev->dev, "Failed to setup buffer\n");
                return ret;
        }

        /* If there is an EOC interrupt, register the cnvst hardware trigger */
        if (spi->irq) {
                st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger",
                                                  indio_dev->name);
                if (!st->trig) {
                        ret = -ENOMEM;
                        dev_err(&indio_dev->dev,
                                "Failed to allocate iio trigger\n");
                        return ret;
                }

                st->trig->ops = &max1027_trigger_ops;
                iio_trigger_set_drvdata(st->trig, indio_dev);
                ret = devm_iio_trigger_register(&indio_dev->dev,
                                                st->trig);
                if (ret < 0) {
                        dev_err(&indio_dev->dev,
                                "Failed to register iio trigger\n");
                        return ret;
                }

                ret = devm_request_irq(&spi->dev, spi->irq, max1027_handler,
                                       IRQF_TRIGGER_FALLING,
                                       spi->dev.driver->name, indio_dev);
                if (ret < 0) {
                        dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n");
                        return ret;
                }
        }

        /* Internal reset */
        st->reg = MAX1027_RST_REG;
        ret = spi_write(st->spi, &st->reg, 1);
        if (ret < 0) {
                dev_err(&indio_dev->dev, "Failed to reset the ADC\n");
                return ret;
        }

        /* Disable averaging */
        st->reg = MAX1027_AVG_REG;
        ret = spi_write(st->spi, &st->reg, 1);
        if (ret < 0) {
                dev_err(&indio_dev->dev, "Failed to configure averaging register\n");
                return ret;
        }

        /* Assume conversion on register write for now */
        ret = max1027_enable_trigger(indio_dev, false);
        if (ret)
                return ret;

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

static struct spi_driver max1027_driver = {
        .driver = {
                .name   = "max1027",
                .of_match_table = max1027_adc_dt_ids,
        },
        .probe          = max1027_probe,
        .id_table       = max1027_id,
};
module_spi_driver(max1027_driver);

MODULE_AUTHOR("Philippe Reynes <tremyfr@yahoo.fr>");
MODULE_DESCRIPTION("MAX1X27/MAX1X29/MAX1X31 ADC");
MODULE_LICENSE("GPL v2");