drivers/staging/iio/adc/ad7606_ring.c

   1 /*
   2  * Copyright 2011 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 "../iio.h"
  15 #include "../ring_generic.h"
  16 #include "../ring_sw.h"
  17 #include "../trigger_consumer.h"
  18
  19 #include "ad7606.h"
  20
  21 int ad7606_scan_from_ring(struct iio_dev *indio_dev, unsigned ch)
  22 {
  23         struct iio_ring_buffer *ring = indio_dev->ring;
  24         int ret;
  25         u16 *ring_data;
  26
  27         ring_data = kmalloc(ring->access->get_bytes_per_datum(ring),
  28                             GFP_KERNEL);
  29         if (ring_data == NULL) {
  30                 ret = -ENOMEM;
  31                 goto error_ret;
  32         }
  33         ret = ring->access->read_last(ring, (u8 *) ring_data);
  34         if (ret)
  35                 goto error_free_ring_data;
  36
  37         ret = ring_data[ch];
  38
  39 error_free_ring_data:
  40         kfree(ring_data);
  41 error_ret:
  42         return ret;
  43 }
  44
  45 /**
  46  * ad7606_ring_preenable() setup the parameters of the ring before enabling
  47  *
  48  * The complex nature of the setting of the nuber of bytes per datum is due
  49  * to this driver currently ensuring that the timestamp is stored at an 8
  50  * byte boundary.
  51  **/
  52 static int ad7606_ring_preenable(struct iio_dev *indio_dev)
  53 {
  54         struct ad7606_state *st = iio_priv(indio_dev);
  55         struct iio_ring_buffer *ring = indio_dev->ring;
  56         size_t d_size;
  57
  58         d_size = st->chip_info->num_channels *
  59                  st->chip_info->channels[0].scan_type.storagebits / 8;
  60
  61         if (ring->scan_timestamp) {
  62                 d_size += sizeof(s64);
  63
  64                 if (d_size % sizeof(s64))
  65                         d_size += sizeof(s64) - (d_size % sizeof(s64));
  66         }
  67
  68         if (ring->access->set_bytes_per_datum)
  69                 ring->access->set_bytes_per_datum(ring, d_size);
  70
  71         st->d_size = d_size;
  72
  73         return 0;
  74 }
  75
  76 /**
  77  * ad7606_trigger_handler_th() th/bh of trigger launched polling to ring buffer
  78  *
  79  **/
  80 static irqreturn_t ad7606_trigger_handler_th_bh(int irq, void *p)
  81 {
  82         struct iio_poll_func *pf = p;
  83         struct ad7606_state *st = iio_priv(pf->indio_dev);
  84
  85         gpio_set_value(st->pdata->gpio_convst, 1);
  86
  87         return IRQ_HANDLED;
  88 }
  89
  90 /**
  91  * ad7606_poll_bh_to_ring() bh of trigger launched polling to ring buffer
  92  * @work_s:     the work struct through which this was scheduled
  93  *
  94  * Currently there is no option in this driver to disable the saving of
  95  * timestamps within the ring.
  96  * I think the one copy of this at a time was to avoid problems if the
  97  * trigger was set far too high and the reads then locked up the computer.
  98  **/
  99 static void ad7606_poll_bh_to_ring(struct work_struct *work_s)
 100 {
 101         struct ad7606_state *st = container_of(work_s, struct ad7606_state,
 102                                                 poll_work);
 103         struct iio_dev *indio_dev = iio_priv_to_dev(st);
 104         struct iio_ring_buffer *ring = indio_dev->ring;
 105         s64 time_ns;
 106         __u8 *buf;
 107         int ret;
 108
 109         buf = kzalloc(st->d_size, GFP_KERNEL);
 110         if (buf == NULL)
 111                 return;
 112
 113         if (st->have_frstdata) {
 114                 ret = st->bops->read_block(st->dev, 1, buf);
 115                 if (ret)
 116                         goto done;
 117                 if (!gpio_get_value(st->pdata->gpio_frstdata)) {
 118                         /* This should never happen. However
 119                          * some signal glitch caused by bad PCB desgin or
 120                          * electrostatic discharge, could cause an extra read
 121                          * or clock. This allows recovery.
 122                          */
 123                         ad7606_reset(st);
 124                         goto done;
 125                 }
 126                 ret = st->bops->read_block(st->dev,
 127                         st->chip_info->num_channels - 1, buf + 2);
 128                 if (ret)
 129                         goto done;
 130         } else {
 131                 ret = st->bops->read_block(st->dev,
 132                         st->chip_info->num_channels, buf);
 133                 if (ret)
 134                         goto done;
 135         }
 136
 137         time_ns = iio_get_time_ns();
 138
 139         if (ring->scan_timestamp)
 140                 memcpy(buf + st->d_size - sizeof(s64),
 141                         &time_ns, sizeof(time_ns));
 142
 143         ring->access->store_to(indio_dev->ring, buf, time_ns);
 144 done:
 145         gpio_set_value(st->pdata->gpio_convst, 0);
 146         iio_trigger_notify_done(indio_dev->trig);
 147         kfree(buf);
 148 }
 149
 150 static const struct iio_ring_setup_ops ad7606_ring_setup_ops = {
 151         .preenable = &ad7606_ring_preenable,
 152         .postenable = &iio_triggered_buffer_postenable,
 153         .predisable = &iio_triggered_buffer_predisable,
 154 };
 155
 156 int ad7606_register_ring_funcs_and_init(struct iio_dev *indio_dev)
 157 {
 158         struct ad7606_state *st = iio_priv(indio_dev);
 159         int ret;
 160
 161         indio_dev->ring = iio_sw_rb_allocate(indio_dev);
 162         if (!indio_dev->ring) {
 163                 ret = -ENOMEM;
 164                 goto error_ret;
 165         }
 166
 167         /* Effectively select the ring buffer implementation */
 168         indio_dev->ring->access = &ring_sw_access_funcs;
 169         indio_dev->pollfunc = iio_alloc_pollfunc(&ad7606_trigger_handler_th_bh,
 170                                                  &ad7606_trigger_handler_th_bh,
 171                                                  0,
 172                                                  indio_dev,
 173                                                  "%s_consumer%d",
 174                                                  indio_dev->name,
 175                                                  indio_dev->id);
 176         if (indio_dev->pollfunc == NULL) {
 177                 ret = -ENOMEM;
 178                 goto error_deallocate_sw_rb;
 179         }
 180
 181         /* Ring buffer functions - here trigger setup related */
 182
 183         indio_dev->ring->setup_ops = &ad7606_ring_setup_ops;
 184         indio_dev->ring->scan_timestamp = true ;
 185
 186         INIT_WORK(&st->poll_work, &ad7606_poll_bh_to_ring);
 187
 188         /* Flag that polled ring buffering is possible */
 189         indio_dev->modes |= INDIO_BUFFER_TRIGGERED;
 190         return 0;
 191
 192 error_deallocate_sw_rb:
 193         iio_sw_rb_free(indio_dev->ring);
 194 error_ret:
 195         return ret;
 196 }
 197
 198 void ad7606_ring_cleanup(struct iio_dev *indio_dev)
 199 {
 200         iio_dealloc_pollfunc(indio_dev->pollfunc);
 201         iio_sw_rb_free(indio_dev->ring);
 202 }