/*
 * Copyright (C) 2008 Jonathan Cameron
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * max1363_ring.c
 */

#include <linux/interrupt.h>
#include <linux/gpio.h>
#include <linux/workqueue.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/sysfs.h>
#include <linux/list.h>
#include <linux/i2c.h>
#include <linux/bitops.h>

#include "../iio.h"
#include "../ring_generic.h"
#include "../ring_sw.h"
#include "../trigger.h"
#include "../sysfs.h"

#include "max1363.h"

/* Todo: test this */
int max1363_single_channel_from_ring(long mask, struct max1363_state *st)
{
        struct iio_ring_buffer *ring = st->indio_dev->ring;
        int count = 0, ret;
        u8 *ring_data;
        if (!(st->current_mode->modemask & mask)) {
                ret = -EBUSY;
                goto error_ret;
        }

        ring_data = kmalloc(ring->access.get_bytes_per_datum(ring), GFP_KERNEL);
        if (ring_data == NULL) {
                ret = -ENOMEM;
                goto error_ret;
        }
        ret = ring->access.read_last(ring, ring_data);
        if (ret)
                goto error_free_ring_data;
        /* Need a count of channels prior to this one */
        mask >>= 1;
        while (mask) {
                if (mask & st->current_mode->modemask)
                        count++;
                mask >>= 1;
        }
        if (st->chip_info->bits != 8)
                ret = ((int)(ring_data[count*2 + 0] & 0x0F) << 8)
                        + (int)(ring_data[count*2 + 1]);
        else
                ret = ring_data[count];

error_free_ring_data:
        kfree(ring_data);
error_ret:
        return ret;
}

/**
 * max1363_ring_preenable() - setup the parameters of the ring before enabling
 *
 * The complex nature of the setting of the nuber of bytes per datum is due
 * to this driver currently ensuring that the timestamp is stored at an 8
 * byte boundary.
 **/
static int max1363_ring_preenable(struct iio_dev *indio_dev)
{
        struct max1363_state *st = indio_dev->dev_data;
        struct iio_ring_buffer *ring = indio_dev->ring;
        size_t d_size;
        unsigned long numvals;

        /*
         * Need to figure out the current mode based upon the requested
         * scan mask in iio_dev
         */
        st->current_mode = max1363_match_mode(ring->scan_mask,
                                        st->chip_info);
        if (!st->current_mode)
                return -EINVAL;

        max1363_set_scan_mode(st);

        numvals = hweight_long(st->current_mode->modemask);
        if (ring->access.set_bytes_per_datum) {
                if (st->chip_info->bits != 8)
                        d_size = numvals*2 + sizeof(s64);
                else
                        d_size = numvals + sizeof(s64);
                if (d_size % 8)
                        d_size += 8 - (d_size % 8);
                ring->access.set_bytes_per_datum(ring, d_size);
        }

        return 0;
}


/**
 * max1363_poll_func_th() - th of trigger launched polling to ring buffer
 *
 * As sampling only occurs on i2c comms occuring, leave timestamping until
 * then.  Some triggers will generate their own time stamp.  Currently
 * there is no way of notifying them when no one cares.
 **/
static void max1363_poll_func_th(struct iio_dev *indio_dev, s64 time)
{
        struct max1363_state *st = indio_dev->dev_data;

        schedule_work(&st->poll_work);

        return;
}
/**
 * max1363_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 max1363_poll_bh_to_ring(struct work_struct *work_s)
{
        struct max1363_state *st = container_of(work_s, struct max1363_state,
                                                  poll_work);
        struct iio_dev *indio_dev = st->indio_dev;
        struct iio_sw_ring_buffer *sw_ring = iio_to_sw_ring(indio_dev->ring);
        s64 time_ns;
        __u8 *rxbuf;
        int b_sent;
        size_t d_size;
        unsigned long numvals = hweight_long(st->current_mode->modemask);

        /* Ensure the timestamp is 8 byte aligned */
        if (st->chip_info->bits != 8)
                d_size = numvals*2 + sizeof(s64);
        else
                d_size = numvals + sizeof(s64);
        if (d_size % sizeof(s64))
                d_size += sizeof(s64) - (d_size % sizeof(s64));

        /* Ensure only one copy of this function running at a time */
        if (atomic_inc_return(&st->protect_ring) > 1)
                return;

        /* Monitor mode prevents reading. Whilst not currently implemented
         * might as well have this test in here in the meantime as it does
         * no harm.
         */
        if (numvals == 0)
                return;

        rxbuf = kmalloc(d_size, GFP_KERNEL);
        if (rxbuf == NULL)
                return;
        if (st->chip_info->bits != 8)
                b_sent = i2c_master_recv(st->client, rxbuf, numvals*2);
        else
                b_sent = i2c_master_recv(st->client, rxbuf, numvals);
        if (b_sent < 0)
                goto done;

        time_ns = iio_get_time_ns();

        memcpy(rxbuf + d_size - sizeof(s64), &time_ns, sizeof(time_ns));

        indio_dev->ring->access.store_to(&sw_ring->buf, rxbuf, time_ns);
done:
        kfree(rxbuf);
        atomic_dec(&st->protect_ring);
}


int max1363_register_ring_funcs_and_init(struct iio_dev *indio_dev)
{
        struct max1363_state *st = indio_dev->dev_data;
        int ret = 0;

        indio_dev->ring = iio_sw_rb_allocate(indio_dev);
        if (!indio_dev->ring) {
                ret = -ENOMEM;
                goto error_ret;
        }
        /* Effectively select the ring buffer implementation */
        iio_ring_sw_register_funcs(&indio_dev->ring->access);
        ret = iio_alloc_pollfunc(indio_dev, NULL, &max1363_poll_func_th);
        if (ret)
                goto error_deallocate_sw_rb;

        /* Ring buffer functions - here trigger setup related */
        indio_dev->ring->scan_el_attrs = st->chip_info->scan_attrs;
        indio_dev->ring->postenable = &iio_triggered_ring_postenable;
        indio_dev->ring->preenable = &max1363_ring_preenable;
        indio_dev->ring->predisable = &iio_triggered_ring_predisable;
        INIT_WORK(&st->poll_work, &max1363_poll_bh_to_ring);

        /* Flag that polled ring buffering is possible */
        indio_dev->modes |= INDIO_RING_TRIGGERED;
        return 0;
error_deallocate_sw_rb:
        iio_sw_rb_free(indio_dev->ring);
error_ret:
        return ret;
}

void max1363_ring_cleanup(struct iio_dev *indio_dev)
{
        /* ensure that the trigger has been detached */
        if (indio_dev->trig) {
                iio_put_trigger(indio_dev->trig);
                iio_trigger_dettach_poll_func(indio_dev->trig,
                                              indio_dev->pollfunc);
        }
        kfree(indio_dev->pollfunc);
        iio_sw_rb_free(indio_dev->ring);
}