/*
 * Copyright 2011-2012 Analog Devices Inc.
 *
 * Licensed under the GPL-2.
 *
 */

#include <linux/interrupt.h>
#include <linux/gpio.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>

#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/kfifo_buf.h>
#include <linux/iio/trigger_consumer.h>

#include "ad7606.h"

/**
 * ad7606_trigger_handler_th() th/bh of trigger launched polling to ring buffer
 *
 **/
static irqreturn_t ad7606_trigger_handler_th_bh(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct ad7606_state *st = iio_priv(pf->indio_dev);

	gpio_set_value(st->pdata->gpio_convst, 1);

	return IRQ_HANDLED;
}

/**
 * ad7606_poll_bh_to_ring() bh of trigger launched polling to ring buffer
 * @work_s:	the work struct through which this was scheduled
 *
 * Currently there is no option in this driver to disable the saving of
 * timestamps within the ring.
 * I think the one copy of this at a time was to avoid problems if the
 * trigger was set far too high and the reads then locked up the computer.
 **/
static void ad7606_poll_bh_to_ring(struct work_struct *work_s)
{
	struct ad7606_state *st = container_of(work_s, struct ad7606_state,
						poll_work);
	struct iio_dev *indio_dev = iio_priv_to_dev(st);
	struct iio_buffer *ring = indio_dev->buffer;
	s64 time_ns;
	__u8 *buf;
	int ret;

	buf = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
	if (buf == NULL)
		return;

	if (gpio_is_valid(st->pdata->gpio_frstdata)) {
		ret = st->bops->read_block(st->dev, 1, buf);
		if (ret)
			goto done;
		if (!gpio_get_value(st->pdata->gpio_frstdata)) {
			/* This should never happen. However
			 * some signal glitch caused by bad PCB desgin or
			 * electrostatic discharge, could cause an extra read
			 * or clock. This allows recovery.
			 */
			ad7606_reset(st);
			goto done;
		}
		ret = st->bops->read_block(st->dev,
			st->chip_info->num_channels - 1, buf + 2);
		if (ret)
			goto done;
	} else {
		ret = st->bops->read_block(st->dev,
			st->chip_info->num_channels, buf);
		if (ret)
			goto done;
	}

	time_ns = iio_get_time_ns();

	if (indio_dev->scan_timestamp)
		*((s64 *)(buf + indio_dev->scan_bytes - sizeof(s64))) = time_ns;

	ring->access->store_to(indio_dev->buffer, buf, time_ns);
done:
	gpio_set_value(st->pdata->gpio_convst, 0);
	iio_trigger_notify_done(indio_dev->trig);
	kfree(buf);
}

static const struct iio_buffer_setup_ops ad7606_ring_setup_ops = {
	.preenable = &iio_sw_buffer_preenable,
	.postenable = &iio_triggered_buffer_postenable,
	.predisable = &iio_triggered_buffer_predisable,
};

int ad7606_register_ring_funcs_and_init(struct iio_dev *indio_dev)
{
	struct ad7606_state *st = iio_priv(indio_dev);
	int ret;

	indio_dev->buffer = iio_kfifo_allocate(indio_dev);
	if (!indio_dev->buffer) {
		ret = -ENOMEM;
		goto error_ret;
	}

	indio_dev->pollfunc = iio_alloc_pollfunc(&ad7606_trigger_handler_th_bh,
						 &ad7606_trigger_handler_th_bh,
						 0,
						 indio_dev,
						 "%s_consumer%d",
						 indio_dev->name,
						 indio_dev->id);
	if (indio_dev->pollfunc == NULL) {
		ret = -ENOMEM;
		goto error_deallocate_kfifo;
	}

	/* Ring buffer functions - here trigger setup related */

	indio_dev->setup_ops = &ad7606_ring_setup_ops;
	indio_dev->buffer->scan_timestamp = true;

	INIT_WORK(&st->poll_work, &ad7606_poll_bh_to_ring);

	/* Flag that polled ring buffering is possible */
	indio_dev->modes |= INDIO_BUFFER_TRIGGERED;
	return 0;

error_deallocate_kfifo:
	iio_kfifo_free(indio_dev->buffer);
error_ret:
	return ret;
}

void ad7606_ring_cleanup(struct iio_dev *indio_dev)
{
	iio_dealloc_pollfunc(indio_dev->pollfunc);
	iio_kfifo_free(indio_dev->buffer);
}