// SPDX-License-Identifier: GPL-2.0
/*
 * AD7606 SPI ADC driver
 *
 * Copyright 2011 Analog Devices Inc.
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/util_macros.h>

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

#include "ad7606.h"

/*
 * Scales are computed as 5000/32768 and 10000/32768 respectively,
 * so that when applied to the raw values they provide mV values
 */
static const unsigned int ad7606_scale_avail[2] = {
        152588, 305176
};

static const unsigned int ad7606_oversampling_avail[7] = {
        1, 2, 4, 8, 16, 32, 64,
};

static const unsigned int ad7616_oversampling_avail[8] = {
        1, 2, 4, 8, 16, 32, 64, 128,
};

static int ad7606_reset(struct ad7606_state *st)
{
        if (st->gpio_reset) {
                gpiod_set_value(st->gpio_reset, 1);
                ndelay(100); /* t_reset >= 100ns */
                gpiod_set_value(st->gpio_reset, 0);
                return 0;
        }

        return -ENODEV;
}

static int ad7606_read_samples(struct ad7606_state *st)
{
        unsigned int num = st->chip_info->num_channels;
        u16 *data = st->data;
        int ret;

        /*
         * The frstdata signal is set to high while and after reading the sample
         * of the first channel and low for all other channels. This can be used
         * to check that the incoming data is correctly aligned. During normal
         * operation the data should never become unaligned, but some glitch or
         * electrostatic discharge might cause an extra read or clock cycle.
         * Monitoring the frstdata signal allows to recover from such failure
         * situations.
         */

        if (st->gpio_frstdata) {
                ret = st->bops->read_block(st->dev, 1, data);
                if (ret)
                        return ret;

                if (!gpiod_get_value(st->gpio_frstdata)) {
                        ad7606_reset(st);
                        return -EIO;
                }

                data++;
                num--;
        }

        return st->bops->read_block(st->dev, num, data);
}

static irqreturn_t ad7606_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct ad7606_state *st = iio_priv(indio_dev);
        int ret;

        mutex_lock(&st->lock);

        ret = ad7606_read_samples(st);
        if (ret == 0)
                iio_push_to_buffers_with_timestamp(indio_dev, st->data,
                                                   iio_get_time_ns(indio_dev));

        iio_trigger_notify_done(indio_dev->trig);
        /* The rising edge of the CONVST signal starts a new conversion. */
        gpiod_set_value(st->gpio_convst, 1);

        mutex_unlock(&st->lock);

        return IRQ_HANDLED;
}

static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch)
{
        struct ad7606_state *st = iio_priv(indio_dev);
        int ret;

        gpiod_set_value(st->gpio_convst, 1);
        ret = wait_for_completion_timeout(&st->completion,
                                          msecs_to_jiffies(1000));
        if (!ret) {
                ret = -ETIMEDOUT;
                goto error_ret;
        }

        ret = ad7606_read_samples(st);
        if (ret == 0)
                ret = st->data[ch];

error_ret:
        gpiod_set_value(st->gpio_convst, 0);

        return ret;
}

static int ad7606_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val,
                           int *val2,
                           long m)
{
        int ret, ch = 0;
        struct ad7606_state *st = iio_priv(indio_dev);

        switch (m) {
        case IIO_CHAN_INFO_RAW:
                ret = iio_device_claim_direct_mode(indio_dev);
                if (ret)
                        return ret;

                ret = ad7606_scan_direct(indio_dev, chan->address);
                iio_device_release_direct_mode(indio_dev);

                if (ret < 0)
                        return ret;
                *val = (short)ret;
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                if (st->sw_mode_en)
                        ch = chan->address;
                *val = 0;
                *val2 = st->scale_avail[st->range[ch]];
                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                *val = st->oversampling;
                return IIO_VAL_INT;
        }
        return -EINVAL;
}

static ssize_t ad7606_show_avail(char *buf, const unsigned int *vals,
                                 unsigned int n, bool micros)
{
        size_t len = 0;
        int i;

        for (i = 0; i < n; i++) {
                len += scnprintf(buf + len, PAGE_SIZE - len,
                        micros ? "0.%06u " : "%u ", vals[i]);
        }
        buf[len - 1] = '\n';

        return len;
}

static ssize_t in_voltage_scale_available_show(struct device *dev,
                                               struct device_attribute *attr,
                                               char *buf)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct ad7606_state *st = iio_priv(indio_dev);

        return ad7606_show_avail(buf, st->scale_avail, st->num_scales, true);
}

static IIO_DEVICE_ATTR_RO(in_voltage_scale_available, 0);

static int ad7606_write_scale_hw(struct iio_dev *indio_dev, int ch, int val)
{
        struct ad7606_state *st = iio_priv(indio_dev);

        gpiod_set_value(st->gpio_range, val);

        return 0;
}

static int ad7606_write_os_hw(struct iio_dev *indio_dev, int val)
{
        struct ad7606_state *st = iio_priv(indio_dev);
        DECLARE_BITMAP(values, 3);

        values[0] = val;

        gpiod_set_array_value(ARRAY_SIZE(values), st->gpio_os->desc,
                              st->gpio_os->info, values);

        /* AD7616 requires a reset to update value */
        if (st->chip_info->os_req_reset)
                ad7606_reset(st);

        return 0;
}

static int ad7606_write_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int val,
                            int val2,
                            long mask)
{
        struct ad7606_state *st = iio_priv(indio_dev);
        int i, ret, ch = 0;

        switch (mask) {
        case IIO_CHAN_INFO_SCALE:
                mutex_lock(&st->lock);
                i = find_closest(val2, st->scale_avail, st->num_scales);
                if (st->sw_mode_en)
                        ch = chan->address;
                ret = st->write_scale(indio_dev, ch, i);
                if (ret < 0) {
                        mutex_unlock(&st->lock);
                        return ret;
                }
                st->range[ch] = i;
                mutex_unlock(&st->lock);

                return 0;
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                if (val2)
                        return -EINVAL;
                i = find_closest(val, st->oversampling_avail,
                                 st->num_os_ratios);
                mutex_lock(&st->lock);
                ret = st->write_os(indio_dev, i);
                if (ret < 0) {
                        mutex_unlock(&st->lock);
                        return ret;
                }
                st->oversampling = st->oversampling_avail[i];
                mutex_unlock(&st->lock);

                return 0;
        default:
                return -EINVAL;
        }
}

static ssize_t ad7606_oversampling_ratio_avail(struct device *dev,
                                               struct device_attribute *attr,
                                               char *buf)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct ad7606_state *st = iio_priv(indio_dev);

        return ad7606_show_avail(buf, st->oversampling_avail,
                                 st->num_os_ratios, false);
}

static IIO_DEVICE_ATTR(oversampling_ratio_available, 0444,
                       ad7606_oversampling_ratio_avail, NULL, 0);

static struct attribute *ad7606_attributes_os_and_range[] = {
        &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
        &iio_dev_attr_oversampling_ratio_available.dev_attr.attr,
        NULL,
};

static const struct attribute_group ad7606_attribute_group_os_and_range = {
        .attrs = ad7606_attributes_os_and_range,
};

static struct attribute *ad7606_attributes_os[] = {
        &iio_dev_attr_oversampling_ratio_available.dev_attr.attr,
        NULL,
};

static const struct attribute_group ad7606_attribute_group_os = {
        .attrs = ad7606_attributes_os,
};

static struct attribute *ad7606_attributes_range[] = {
        &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
        NULL,
};

static const struct attribute_group ad7606_attribute_group_range = {
        .attrs = ad7606_attributes_range,
};

#define AD760X_CHANNEL(num, mask) {                             \
                .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),\
                .info_mask_shared_by_all = mask,                \
                .scan_index = num,                              \
                .scan_type = {                                  \
                        .sign = 's',                            \
                        .realbits = 16,                         \
                        .storagebits = 16,                      \
                        .endianness = IIO_CPU,                  \
                },                                              \
}

#define AD7605_CHANNEL(num)     \
        AD760X_CHANNEL(num, 0)

#define AD7606_CHANNEL(num)     \
        AD760X_CHANNEL(num, BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO))

static const struct iio_chan_spec ad7605_channels[] = {
        IIO_CHAN_SOFT_TIMESTAMP(4),
        AD7605_CHANNEL(0),
        AD7605_CHANNEL(1),
        AD7605_CHANNEL(2),
        AD7605_CHANNEL(3),
};

static const struct iio_chan_spec ad7606_channels[] = {
        IIO_CHAN_SOFT_TIMESTAMP(8),
        AD7606_CHANNEL(0),
        AD7606_CHANNEL(1),
        AD7606_CHANNEL(2),
        AD7606_CHANNEL(3),
        AD7606_CHANNEL(4),
        AD7606_CHANNEL(5),
        AD7606_CHANNEL(6),
        AD7606_CHANNEL(7),
};

/*
 * The current assumption that this driver makes for AD7616, is that it's
 * working in Hardware Mode with Serial, Burst and Sequencer modes activated.
 * To activate them, following pins must be pulled high:
 *      -SER/PAR
 *      -SEQEN
 * And following pins must be pulled low:
 *      -WR/BURST
 *      -DB4/SER1W
 */
static const struct iio_chan_spec ad7616_channels[] = {
        IIO_CHAN_SOFT_TIMESTAMP(16),
        AD7606_CHANNEL(0),
        AD7606_CHANNEL(1),
        AD7606_CHANNEL(2),
        AD7606_CHANNEL(3),
        AD7606_CHANNEL(4),
        AD7606_CHANNEL(5),
        AD7606_CHANNEL(6),
        AD7606_CHANNEL(7),
        AD7606_CHANNEL(8),
        AD7606_CHANNEL(9),
        AD7606_CHANNEL(10),
        AD7606_CHANNEL(11),
        AD7606_CHANNEL(12),
        AD7606_CHANNEL(13),
        AD7606_CHANNEL(14),
        AD7606_CHANNEL(15),
};

static const struct ad7606_chip_info ad7606_chip_info_tbl[] = {
        /* More devices added in future */
        [ID_AD7605_4] = {
                .channels = ad7605_channels,
                .num_channels = 5,
        },
        [ID_AD7606_8] = {
                .channels = ad7606_channels,
                .num_channels = 9,
                .oversampling_avail = ad7606_oversampling_avail,
                .oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
        },
        [ID_AD7606_6] = {
                .channels = ad7606_channels,
                .num_channels = 7,
                .oversampling_avail = ad7606_oversampling_avail,
                .oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
        },
        [ID_AD7606_4] = {
                .channels = ad7606_channels,
                .num_channels = 5,
                .oversampling_avail = ad7606_oversampling_avail,
                .oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
        },
        [ID_AD7616] = {
                .channels = ad7616_channels,
                .num_channels = 17,
                .oversampling_avail = ad7616_oversampling_avail,
                .oversampling_num = ARRAY_SIZE(ad7616_oversampling_avail),
                .os_req_reset = true,
        },
};

static int ad7606_request_gpios(struct ad7606_state *st)
{
        struct device *dev = st->dev;

        st->gpio_convst = devm_gpiod_get(dev, "adi,conversion-start",
                                         GPIOD_OUT_LOW);
        if (IS_ERR(st->gpio_convst))
                return PTR_ERR(st->gpio_convst);

        st->gpio_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
        if (IS_ERR(st->gpio_reset))
                return PTR_ERR(st->gpio_reset);

        st->gpio_range = devm_gpiod_get_optional(dev, "adi,range",
                                                 GPIOD_OUT_LOW);
        if (IS_ERR(st->gpio_range))
                return PTR_ERR(st->gpio_range);

        st->gpio_standby = devm_gpiod_get_optional(dev, "standby",
                                                   GPIOD_OUT_HIGH);
        if (IS_ERR(st->gpio_standby))
                return PTR_ERR(st->gpio_standby);

        st->gpio_frstdata = devm_gpiod_get_optional(dev, "adi,first-data",
                                                    GPIOD_IN);
        if (IS_ERR(st->gpio_frstdata))
                return PTR_ERR(st->gpio_frstdata);

        if (!st->chip_info->oversampling_num)
                return 0;

        st->gpio_os = devm_gpiod_get_array_optional(dev,
                                                    "adi,oversampling-ratio",
                                                    GPIOD_OUT_LOW);
        return PTR_ERR_OR_ZERO(st->gpio_os);
}

/*
 * The BUSY signal indicates when conversions are in progress, so when a rising
 * edge of CONVST is applied, BUSY goes logic high and transitions low at the
 * end of the entire conversion process. The falling edge of the BUSY signal
 * triggers this interrupt.
 */
static irqreturn_t ad7606_interrupt(int irq, void *dev_id)
{
        struct iio_dev *indio_dev = dev_id;
        struct ad7606_state *st = iio_priv(indio_dev);

        if (iio_buffer_enabled(indio_dev)) {
                gpiod_set_value(st->gpio_convst, 0);
                iio_trigger_poll_chained(st->trig);
        } else {
                complete(&st->completion);
        }

        return IRQ_HANDLED;
};

static int ad7606_validate_trigger(struct iio_dev *indio_dev,
                                   struct iio_trigger *trig)
{
        struct ad7606_state *st = iio_priv(indio_dev);

        if (st->trig != trig)
                return -EINVAL;

        return 0;
}

static int ad7606_buffer_postenable(struct iio_dev *indio_dev)
{
        struct ad7606_state *st = iio_priv(indio_dev);

        iio_triggered_buffer_postenable(indio_dev);
        gpiod_set_value(st->gpio_convst, 1);

        return 0;
}

static int ad7606_buffer_predisable(struct iio_dev *indio_dev)
{
        struct ad7606_state *st = iio_priv(indio_dev);

        gpiod_set_value(st->gpio_convst, 0);

        return iio_triggered_buffer_predisable(indio_dev);
}

static const struct iio_buffer_setup_ops ad7606_buffer_ops = {
        .postenable = &ad7606_buffer_postenable,
        .predisable = &ad7606_buffer_predisable,
};

static const struct iio_info ad7606_info_no_os_or_range = {
        .read_raw = &ad7606_read_raw,
        .validate_trigger = &ad7606_validate_trigger,
};

static const struct iio_info ad7606_info_os_and_range = {
        .read_raw = &ad7606_read_raw,
        .write_raw = &ad7606_write_raw,
        .attrs = &ad7606_attribute_group_os_and_range,
        .validate_trigger = &ad7606_validate_trigger,
};

static const struct iio_info ad7606_info_os = {
        .read_raw = &ad7606_read_raw,
        .write_raw = &ad7606_write_raw,
        .attrs = &ad7606_attribute_group_os,
        .validate_trigger = &ad7606_validate_trigger,
};

static const struct iio_info ad7606_info_range = {
        .read_raw = &ad7606_read_raw,
        .write_raw = &ad7606_write_raw,
        .attrs = &ad7606_attribute_group_range,
        .validate_trigger = &ad7606_validate_trigger,
};

static const struct iio_trigger_ops ad7606_trigger_ops = {
        .validate_device = iio_trigger_validate_own_device,
};

static void ad7606_regulator_disable(void *data)
{
        struct ad7606_state *st = data;

        regulator_disable(st->reg);
}

int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
                 const char *name, unsigned int id,
                 const struct ad7606_bus_ops *bops)
{
        struct ad7606_state *st;
        int ret;
        struct iio_dev *indio_dev;

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

        st = iio_priv(indio_dev);
        dev_set_drvdata(dev, indio_dev);

        st->dev = dev;
        mutex_init(&st->lock);
        st->bops = bops;
        st->base_address = base_address;
        /* tied to logic low, analog input range is +/- 5V */
        st->range[0] = 0;
        st->oversampling = 1;
        st->scale_avail = ad7606_scale_avail;
        st->num_scales = ARRAY_SIZE(ad7606_scale_avail);

        st->reg = devm_regulator_get(dev, "avcc");
        if (IS_ERR(st->reg))
                return PTR_ERR(st->reg);

        ret = regulator_enable(st->reg);
        if (ret) {
                dev_err(dev, "Failed to enable specified AVcc supply\n");
                return ret;
        }

        ret = devm_add_action_or_reset(dev, ad7606_regulator_disable, st);
        if (ret)
                return ret;

        st->chip_info = &ad7606_chip_info_tbl[id];

        if (st->chip_info->oversampling_num) {
                st->oversampling_avail = st->chip_info->oversampling_avail;
                st->num_os_ratios = st->chip_info->oversampling_num;
        }

        ret = ad7606_request_gpios(st);
        if (ret)
                return ret;

        indio_dev->dev.parent = dev;
        if (st->gpio_os) {
                if (st->gpio_range)
                        indio_dev->info = &ad7606_info_os_and_range;
                else
                        indio_dev->info = &ad7606_info_os;
        } else {
                if (st->gpio_range)
                        indio_dev->info = &ad7606_info_range;
                else
                        indio_dev->info = &ad7606_info_no_os_or_range;
        }
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->name = name;
        indio_dev->channels = st->chip_info->channels;
        indio_dev->num_channels = st->chip_info->num_channels;

        init_completion(&st->completion);

        ret = ad7606_reset(st);
        if (ret)
                dev_warn(st->dev, "failed to RESET: no RESET GPIO specified\n");

        st->write_scale = ad7606_write_scale_hw;
        st->write_os = ad7606_write_os_hw;

        if (st->chip_info->sw_mode_config)
                st->sw_mode_en = device_property_present(st->dev,
                                                         "adi,sw-mode");

        if (st->sw_mode_en) {
                /* After reset, in software mode, ±10 V is set by default */
                memset32(st->range, 2, ARRAY_SIZE(st->range));
                indio_dev->info = &ad7606_info_os_and_range;

                /*
                 * In software mode, the range gpio has no longer its function.
                 * Instead, the scale can be configured individually for each
                 * channel from the range registers.
                 */
                if (st->chip_info->write_scale_sw)
                        st->write_scale = st->chip_info->write_scale_sw;

                /*
                 * In software mode, the oversampling is no longer configured
                 * with GPIO pins. Instead, the oversampling can be configured
                 * in configuratiion register.
                 */
                if (st->chip_info->write_os_sw)
                        st->write_os = st->chip_info->write_os_sw;

                ret = st->chip_info->sw_mode_config(indio_dev);
                if (ret < 0)
                        return ret;
        }

        st->trig = devm_iio_trigger_alloc(dev, "%s-dev%d",
                                          indio_dev->name, indio_dev->id);
        if (!st->trig)
                return -ENOMEM;

        st->trig->ops = &ad7606_trigger_ops;
        st->trig->dev.parent = dev;
        iio_trigger_set_drvdata(st->trig, indio_dev);
        ret = devm_iio_trigger_register(dev, st->trig);
        if (ret)
                return ret;

        indio_dev->trig = iio_trigger_get(st->trig);

        ret = devm_request_threaded_irq(dev, irq,
                                        NULL,
                                        &ad7606_interrupt,
                                        IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                                        name, indio_dev);
        if (ret)
                return ret;

        ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
                                              &iio_pollfunc_store_time,
                                              &ad7606_trigger_handler,
                                              &ad7606_buffer_ops);
        if (ret)
                return ret;

        return devm_iio_device_register(dev, indio_dev);
}
EXPORT_SYMBOL_GPL(ad7606_probe);

#ifdef CONFIG_PM_SLEEP

static int ad7606_suspend(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct ad7606_state *st = iio_priv(indio_dev);

        if (st->gpio_standby) {
                gpiod_set_value(st->gpio_range, 1);
                gpiod_set_value(st->gpio_standby, 0);
        }

        return 0;
}

static int ad7606_resume(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct ad7606_state *st = iio_priv(indio_dev);

        if (st->gpio_standby) {
                gpiod_set_value(st->gpio_range, st->range[0]);
                gpiod_set_value(st->gpio_standby, 1);
                ad7606_reset(st);
        }

        return 0;
}

SIMPLE_DEV_PM_OPS(ad7606_pm_ops, ad7606_suspend, ad7606_resume);
EXPORT_SYMBOL_GPL(ad7606_pm_ops);

#endif

MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD7606 ADC");
MODULE_LICENSE("GPL v2");