LXR linux/drivers/staging/iio/adc/ad7606

   1/*
   2 * Copyright 2011-2012 Analog Devices Inc.
   3 *
   4 * Licensed under the GPL-2.
   5 *
   6 */
   7
   8#include <linux/interrupt.h>
   9#include <linux/gpio.h>
  10#include <linux/device.h>
  11#include <linux/kernel.h>
  12#include <linux/slab.h>
  13
  14#include <linux/iio/iio.h>
  15#include <linux/iio/buffer.h>
  16#include <linux/iio/trigger_consumer.h>
  17#include <linux/iio/triggered_buffer.h>
  18
  19#include "ad7606.h"
  20
  21/**
  22 * ad7606_trigger_handler_th() th/bh of trigger launched polling to ring buffer
  23 *
  24 **/
  25static irqreturn_t ad7606_trigger_handler_th_bh(int irq, void *p)
  26{
  27        struct iio_poll_func *pf = p;
  28        struct ad7606_state *st = iio_priv(pf->indio_dev);
  29
  30        gpio_set_value(st->pdata->gpio_convst, 1);
  31
  32        return IRQ_HANDLED;
  33}
  34
  35/**
  36 * ad7606_poll_bh_to_ring() bh of trigger launched polling to ring buffer
  37 * @work_s:     the work struct through which this was scheduled
  38 *
  39 * Currently there is no option in this driver to disable the saving of
  40 * timestamps within the ring.
  41 * I think the one copy of this at a time was to avoid problems if the
  42 * trigger was set far too high and the reads then locked up the computer.
  43 **/
  44static void ad7606_poll_bh_to_ring(struct work_struct *work_s)
  45{
  46        struct ad7606_state *st = container_of(work_s, struct ad7606_state,
  47                                                poll_work);
  48        struct iio_dev *indio_dev = iio_priv_to_dev(st);
  49        s64 time_ns;
  50        __u8 *buf;
  51        int ret;
  52
  53        buf = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
  54        if (buf == NULL)
  55                return;
  56
  57        if (gpio_is_valid(st->pdata->gpio_frstdata)) {
  58                ret = st->bops->read_block(st->dev, 1, buf);
  59                if (ret)
  60                        goto done;
  61                if (!gpio_get_value(st->pdata->gpio_frstdata)) {
  62                        /* This should never happen. However
  63                         * some signal glitch caused by bad PCB desgin or
  64                         * electrostatic discharge, could cause an extra read
  65                         * or clock. This allows recovery.
  66                         */
  67                        ad7606_reset(st);
  68                        goto done;
  69                }
  70                ret = st->bops->read_block(st->dev,
  71                        st->chip_info->num_channels - 1, buf + 2);
  72                if (ret)
  73                        goto done;
  74        } else {
  75                ret = st->bops->read_block(st->dev,
  76                        st->chip_info->num_channels, buf);
  77                if (ret)
  78                        goto done;
  79        }
  80
  81        time_ns = iio_get_time_ns();
  82
  83        if (indio_dev->scan_timestamp)
  84                *((s64 *)(buf + indio_dev->scan_bytes - sizeof(s64))) = time_ns;
  85
  86        iio_push_to_buffers(indio_dev, buf);
  87done:
  88        gpio_set_value(st->pdata->gpio_convst, 0);
  89        iio_trigger_notify_done(indio_dev->trig);
  90        kfree(buf);
  91}
  92
  93int ad7606_register_ring_funcs_and_init(struct iio_dev *indio_dev)
  94{
  95        struct ad7606_state *st = iio_priv(indio_dev);
  96
  97        INIT_WORK(&st->poll_work, &ad7606_poll_bh_to_ring);
  98
  99        return iio_triggered_buffer_setup(indio_dev,
 100                &ad7606_trigger_handler_th_bh, &ad7606_trigger_handler_th_bh,
 101                NULL);
 102}
 103
 104void ad7606_ring_cleanup(struct iio_dev *indio_dev)
 105{
 106        iio_triggered_buffer_cleanup(indio_dev);
 107}
 108