/*
 * Support code for Analog Devices Sigma-Delta ADCs
 *
 * Copyright 2012 Analog Devices Inc.
 *  Author: Lars-Peter Clausen <lars@metafoo.de>
 *
 * Licensed under the GPL-2.
 */

#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/err.h>
#include <linux/module.h>

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

#include <asm/unaligned.h>


#define AD_SD_COMM_CHAN_MASK    0x3

#define AD_SD_REG_COMM          0x00
#define AD_SD_REG_DATA          0x03

/**
 * ad_sd_set_comm() - Set communications register
 *
 * @sigma_delta: The sigma delta device
 * @comm: New value for the communications register
 */
void ad_sd_set_comm(struct ad_sigma_delta *sigma_delta, uint8_t comm)
{
        /* Some variants use the lower two bits of the communications register
         * to select the channel */
        sigma_delta->comm = comm & AD_SD_COMM_CHAN_MASK;
}
EXPORT_SYMBOL_GPL(ad_sd_set_comm);

/**
 * ad_sd_write_reg() - Write a register
 *
 * @sigma_delta: The sigma delta device
 * @reg: Address of the register
 * @size: Size of the register (0-3)
 * @val: Value to write to the register
 *
 * Returns 0 on success, an error code otherwise.
 **/
int ad_sd_write_reg(struct ad_sigma_delta *sigma_delta, unsigned int reg,
        unsigned int size, unsigned int val)
{
        uint8_t *data = sigma_delta->data;
        struct spi_transfer t = {
                .tx_buf         = data,
                .len            = size + 1,
                .cs_change      = sigma_delta->bus_locked,
        };
        struct spi_message m;
        int ret;

        data[0] = (reg << sigma_delta->info->addr_shift) | sigma_delta->comm;

        switch (size) {
        case 3:
                data[1] = val >> 16;
                data[2] = val >> 8;
                data[3] = val;
                break;
        case 2:
                put_unaligned_be16(val, &data[1]);
                break;
        case 1:
                data[1] = val;
                break;
        case 0:
                break;
        default:
                return -EINVAL;
        }

        spi_message_init(&m);
        spi_message_add_tail(&t, &m);

        if (sigma_delta->bus_locked)
                ret = spi_sync_locked(sigma_delta->spi, &m);
        else
                ret = spi_sync(sigma_delta->spi, &m);

        return ret;
}
EXPORT_SYMBOL_GPL(ad_sd_write_reg);

static int ad_sd_read_reg_raw(struct ad_sigma_delta *sigma_delta,
        unsigned int reg, unsigned int size, uint8_t *val)
{
        uint8_t *data = sigma_delta->data;
        int ret;
        struct spi_transfer t[] = {
                {
                        .tx_buf = data,
                        .len = 1,
                }, {
                        .rx_buf = val,
                        .len = size,
                        .cs_change = sigma_delta->bus_locked,
                },
        };
        struct spi_message m;

        spi_message_init(&m);

        if (sigma_delta->info->has_registers) {
                data[0] = reg << sigma_delta->info->addr_shift;
                data[0] |= sigma_delta->info->read_mask;
                spi_message_add_tail(&t[0], &m);
        }
        spi_message_add_tail(&t[1], &m);

        if (sigma_delta->bus_locked)
                ret = spi_sync_locked(sigma_delta->spi, &m);
        else
                ret = spi_sync(sigma_delta->spi, &m);

        return ret;
}

/**
 * ad_sd_read_reg() - Read a register
 *
 * @sigma_delta: The sigma delta device
 * @reg: Address of the register
 * @size: Size of the register (1-4)
 * @val: Read value
 *
 * Returns 0 on success, an error code otherwise.
 **/
int ad_sd_read_reg(struct ad_sigma_delta *sigma_delta,
        unsigned int reg, unsigned int size, unsigned int *val)
{
        int ret;

        ret = ad_sd_read_reg_raw(sigma_delta, reg, size, sigma_delta->data);
        if (ret < 0)
                goto out;

        switch (size) {
        case 4:
                *val = get_unaligned_be32(sigma_delta->data);
                break;
        case 3:
                *val = (sigma_delta->data[0] << 16) |
                        (sigma_delta->data[1] << 8) |
                        sigma_delta->data[2];
                break;
        case 2:
                *val = get_unaligned_be16(sigma_delta->data);
                break;
        case 1:
                *val = sigma_delta->data[0];
                break;
        default:
                ret = -EINVAL;
                break;
        }

out:
        return ret;
}
EXPORT_SYMBOL_GPL(ad_sd_read_reg);

/**
 * ad_sd_reset() - Reset the serial interface
 *
 * @sigma_delta: The sigma delta device
 * @reset_length: Number of SCLKs with DIN = 1
 *
 * Returns 0 on success, an error code otherwise.
 **/
int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
        unsigned int reset_length)
{
        uint8_t *buf;
        unsigned int size;
        int ret;

        size = DIV_ROUND_UP(reset_length, 8);
        buf = kcalloc(size, sizeof(*buf), GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        memset(buf, 0xff, size);
        ret = spi_write(sigma_delta->spi, buf, size);
        kfree(buf);

        return ret;
}
EXPORT_SYMBOL_GPL(ad_sd_reset);

static int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
        unsigned int mode, unsigned int channel)
{
        int ret;

        ret = ad_sigma_delta_set_channel(sigma_delta, channel);
        if (ret)
                return ret;

        spi_bus_lock(sigma_delta->spi->master);
        sigma_delta->bus_locked = true;
        reinit_completion(&sigma_delta->completion);

        ret = ad_sigma_delta_set_mode(sigma_delta, mode);
        if (ret < 0)
                goto out;

        sigma_delta->irq_dis = false;
        enable_irq(sigma_delta->spi->irq);
        ret = wait_for_completion_timeout(&sigma_delta->completion, 2*HZ);
        if (ret == 0) {
                sigma_delta->irq_dis = true;
                disable_irq_nosync(sigma_delta->spi->irq);
                ret = -EIO;
        } else {
                ret = 0;
        }
out:
        sigma_delta->bus_locked = false;
        spi_bus_unlock(sigma_delta->spi->master);
        ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);

        return ret;
}

/**
 * ad_sd_calibrate_all() - Performs channel calibration
 * @sigma_delta: The sigma delta device
 * @cb: Array of channels and calibration type to perform
 * @n: Number of items in cb
 *
 * Returns 0 on success, an error code otherwise.
 **/
int ad_sd_calibrate_all(struct ad_sigma_delta *sigma_delta,
        const struct ad_sd_calib_data *cb, unsigned int n)
{
        unsigned int i;
        int ret;

        for (i = 0; i < n; i++) {
                ret = ad_sd_calibrate(sigma_delta, cb[i].mode, cb[i].channel);
                if (ret)
                        return ret;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(ad_sd_calibrate_all);

/**
 * ad_sigma_delta_single_conversion() - Performs a single data conversion
 * @indio_dev: The IIO device
 * @chan: The conversion is done for this channel
 * @val: Pointer to the location where to store the read value
 *
 * Returns: 0 on success, an error value otherwise.
 */
int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
        const struct iio_chan_spec *chan, int *val)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
        unsigned int sample, raw_sample;
        int ret = 0;

        if (iio_buffer_enabled(indio_dev))
                return -EBUSY;

        mutex_lock(&indio_dev->mlock);
        ad_sigma_delta_set_channel(sigma_delta, chan->address);

        spi_bus_lock(sigma_delta->spi->master);
        sigma_delta->bus_locked = true;
        reinit_completion(&sigma_delta->completion);

        ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_SINGLE);

        sigma_delta->irq_dis = false;
        enable_irq(sigma_delta->spi->irq);
        ret = wait_for_completion_interruptible_timeout(
                        &sigma_delta->completion, HZ);

        sigma_delta->bus_locked = false;
        spi_bus_unlock(sigma_delta->spi->master);

        if (ret == 0)
                ret = -EIO;
        if (ret < 0)
                goto out;

        ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_DATA,
                DIV_ROUND_UP(chan->scan_type.realbits + chan->scan_type.shift, 8),
                &raw_sample);

out:
        if (!sigma_delta->irq_dis) {
                disable_irq_nosync(sigma_delta->spi->irq);
                sigma_delta->irq_dis = true;
        }

        ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
        mutex_unlock(&indio_dev->mlock);

        if (ret)
                return ret;

        sample = raw_sample >> chan->scan_type.shift;
        sample &= (1 << chan->scan_type.realbits) - 1;
        *val = sample;

        ret = ad_sigma_delta_postprocess_sample(sigma_delta, raw_sample);
        if (ret)
                return ret;

        return IIO_VAL_INT;
}
EXPORT_SYMBOL_GPL(ad_sigma_delta_single_conversion);

static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
        unsigned int channel;
        int ret;

        ret = iio_triggered_buffer_postenable(indio_dev);
        if (ret < 0)
                return ret;

        channel = find_first_bit(indio_dev->active_scan_mask,
                                 indio_dev->masklength);
        ret = ad_sigma_delta_set_channel(sigma_delta,
                indio_dev->channels[channel].address);
        if (ret)
                goto err_predisable;

        spi_bus_lock(sigma_delta->spi->master);
        sigma_delta->bus_locked = true;
        ret = ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_CONTINUOUS);
        if (ret)
                goto err_unlock;

        sigma_delta->irq_dis = false;
        enable_irq(sigma_delta->spi->irq);

        return 0;

err_unlock:
        spi_bus_unlock(sigma_delta->spi->master);
err_predisable:

        return ret;
}

static int ad_sd_buffer_postdisable(struct iio_dev *indio_dev)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);

        reinit_completion(&sigma_delta->completion);
        wait_for_completion_timeout(&sigma_delta->completion, HZ);

        if (!sigma_delta->irq_dis) {
                disable_irq_nosync(sigma_delta->spi->irq);
                sigma_delta->irq_dis = true;
        }

        ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);

        sigma_delta->bus_locked = false;
        return spi_bus_unlock(sigma_delta->spi->master);
}

static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
        unsigned int reg_size;
        uint8_t data[16];
        int ret;

        memset(data, 0x00, 16);

        reg_size = indio_dev->channels[0].scan_type.realbits +
                        indio_dev->channels[0].scan_type.shift;
        reg_size = DIV_ROUND_UP(reg_size, 8);

        switch (reg_size) {
        case 4:
        case 2:
        case 1:
                ret = ad_sd_read_reg_raw(sigma_delta, AD_SD_REG_DATA,
                        reg_size, &data[0]);
                break;
        case 3:
                /* We store 24 bit samples in a 32 bit word. Keep the upper
                 * byte set to zero. */
                ret = ad_sd_read_reg_raw(sigma_delta, AD_SD_REG_DATA,
                        reg_size, &data[1]);
                break;
        }

        iio_push_to_buffers_with_timestamp(indio_dev, data, pf->timestamp);

        iio_trigger_notify_done(indio_dev->trig);
        sigma_delta->irq_dis = false;
        enable_irq(sigma_delta->spi->irq);

        return IRQ_HANDLED;
}

static const struct iio_buffer_setup_ops ad_sd_buffer_setup_ops = {
        .postenable = &ad_sd_buffer_postenable,
        .predisable = &iio_triggered_buffer_predisable,
        .postdisable = &ad_sd_buffer_postdisable,
        .validate_scan_mask = &iio_validate_scan_mask_onehot,
};

static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
{
        struct ad_sigma_delta *sigma_delta = private;

        complete(&sigma_delta->completion);
        disable_irq_nosync(irq);
        sigma_delta->irq_dis = true;
        iio_trigger_poll(sigma_delta->trig);

        return IRQ_HANDLED;
}

/**
 * ad_sd_validate_trigger() - validate_trigger callback for ad_sigma_delta devices
 * @indio_dev: The IIO device
 * @trig: The new trigger
 *
 * Returns: 0 if the 'trig' matches the trigger registered by the ad_sigma_delta
 * device, -EINVAL otherwise.
 */
int ad_sd_validate_trigger(struct iio_dev *indio_dev, struct iio_trigger *trig)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);

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

        return 0;
}
EXPORT_SYMBOL_GPL(ad_sd_validate_trigger);

static const struct iio_trigger_ops ad_sd_trigger_ops = {
        .owner = THIS_MODULE,
};

static int ad_sd_probe_trigger(struct iio_dev *indio_dev)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
        int ret;

        sigma_delta->trig = iio_trigger_alloc("%s-dev%d", indio_dev->name,
                                                indio_dev->id);
        if (sigma_delta->trig == NULL) {
                ret = -ENOMEM;
                goto error_ret;
        }
        sigma_delta->trig->ops = &ad_sd_trigger_ops;
        init_completion(&sigma_delta->completion);

        ret = request_irq(sigma_delta->spi->irq,
                          ad_sd_data_rdy_trig_poll,
                          IRQF_TRIGGER_LOW,
                          indio_dev->name,
                          sigma_delta);
        if (ret)
                goto error_free_trig;

        if (!sigma_delta->irq_dis) {
                sigma_delta->irq_dis = true;
                disable_irq_nosync(sigma_delta->spi->irq);
        }
        sigma_delta->trig->dev.parent = &sigma_delta->spi->dev;
        iio_trigger_set_drvdata(sigma_delta->trig, sigma_delta);

        ret = iio_trigger_register(sigma_delta->trig);
        if (ret)
                goto error_free_irq;

        /* select default trigger */
        indio_dev->trig = iio_trigger_get(sigma_delta->trig);

        return 0;

error_free_irq:
        free_irq(sigma_delta->spi->irq, sigma_delta);
error_free_trig:
        iio_trigger_free(sigma_delta->trig);
error_ret:
        return ret;
}

static void ad_sd_remove_trigger(struct iio_dev *indio_dev)
{
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);

        iio_trigger_unregister(sigma_delta->trig);
        free_irq(sigma_delta->spi->irq, sigma_delta);
        iio_trigger_free(sigma_delta->trig);
}

/**
 * ad_sd_setup_buffer_and_trigger() -
 * @indio_dev: The IIO device
 */
int ad_sd_setup_buffer_and_trigger(struct iio_dev *indio_dev)
{
        int ret;

        ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
                        &ad_sd_trigger_handler, &ad_sd_buffer_setup_ops);
        if (ret)
                return ret;

        ret = ad_sd_probe_trigger(indio_dev);
        if (ret) {
                iio_triggered_buffer_cleanup(indio_dev);
                return ret;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(ad_sd_setup_buffer_and_trigger);

/**
 * ad_sd_cleanup_buffer_and_trigger() -
 * @indio_dev: The IIO device
 */
void ad_sd_cleanup_buffer_and_trigger(struct iio_dev *indio_dev)
{
        ad_sd_remove_trigger(indio_dev);
        iio_triggered_buffer_cleanup(indio_dev);
}
EXPORT_SYMBOL_GPL(ad_sd_cleanup_buffer_and_trigger);

/**
 * ad_sd_init() - Initializes a ad_sigma_delta struct
 * @sigma_delta: The ad_sigma_delta device
 * @indio_dev: The IIO device which the Sigma Delta device is used for
 * @spi: The SPI device for the ad_sigma_delta device
 * @info: Device specific callbacks and options
 *
 * This function needs to be called before any other operations are performed on
 * the ad_sigma_delta struct.
 */
int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
        struct spi_device *spi, const struct ad_sigma_delta_info *info)
{
        sigma_delta->spi = spi;
        sigma_delta->info = info;
        iio_device_set_drvdata(indio_dev, sigma_delta);

        return 0;
}
EXPORT_SYMBOL_GPL(ad_sd_init);

MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("Analog Devices Sigma-Delta ADCs");
MODULE_LICENSE("GPL v2");