drivers/staging/iio/adc/ad7298_ring.c

   1 /*
   2  * AD7298 SPI ADC driver
   3  *
   4  * Copyright 2011 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2.
   7  */
   8
   9 #include <linux/interrupt.h>
  10 #include <linux/workqueue.h>
  11 #include <linux/device.h>
  12 #include <linux/kernel.h>
  13 #include <linux/slab.h>
  14 #include <linux/sysfs.h>
  15 #include <linux/spi/spi.h>
  16
  17 #include "../iio.h"
  18 #include "../ring_generic.h"
  19 #include "../ring_sw.h"
  20 #include "../trigger.h"
  21 #include "../sysfs.h"
  22
  23 #include "ad7298.h"
  24
  25 static IIO_SCAN_EL_C(in0, 0, 0, NULL);
  26 static IIO_SCAN_EL_C(in1, 1, 0, NULL);
  27 static IIO_SCAN_EL_C(in2, 2, 0, NULL);
  28 static IIO_SCAN_EL_C(in3, 3, 0, NULL);
  29 static IIO_SCAN_EL_C(in4, 4, 0, NULL);
  30 static IIO_SCAN_EL_C(in5, 5, 0, NULL);
  31 static IIO_SCAN_EL_C(in6, 6, 0, NULL);
  32 static IIO_SCAN_EL_C(in7, 7, 0, NULL);
  33
  34 static IIO_SCAN_EL_TIMESTAMP(8);
  35 static IIO_CONST_ATTR_SCAN_EL_TYPE(timestamp, s, 64, 64);
  36
  37 static IIO_CONST_ATTR(in_type, "u12/16") ;
  38
  39 static struct attribute *ad7298_scan_el_attrs[] = {
  40         &iio_scan_el_in0.dev_attr.attr,
  41         &iio_const_attr_in0_index.dev_attr.attr,
  42         &iio_scan_el_in1.dev_attr.attr,
  43         &iio_const_attr_in1_index.dev_attr.attr,
  44         &iio_scan_el_in2.dev_attr.attr,
  45         &iio_const_attr_in2_index.dev_attr.attr,
  46         &iio_scan_el_in3.dev_attr.attr,
  47         &iio_const_attr_in3_index.dev_attr.attr,
  48         &iio_scan_el_in4.dev_attr.attr,
  49         &iio_const_attr_in4_index.dev_attr.attr,
  50         &iio_scan_el_in5.dev_attr.attr,
  51         &iio_const_attr_in5_index.dev_attr.attr,
  52         &iio_scan_el_in6.dev_attr.attr,
  53         &iio_const_attr_in6_index.dev_attr.attr,
  54         &iio_scan_el_in7.dev_attr.attr,
  55         &iio_const_attr_in7_index.dev_attr.attr,
  56         &iio_const_attr_timestamp_index.dev_attr.attr,
  57         &iio_scan_el_timestamp.dev_attr.attr,
  58         &iio_const_attr_timestamp_type.dev_attr.attr,
  59         &iio_const_attr_in_type.dev_attr.attr,
  60         NULL,
  61 };
  62
  63 static struct attribute_group ad7298_scan_el_group = {
  64         .name = "scan_elements",
  65         .attrs = ad7298_scan_el_attrs,
  66 };
  67
  68 int ad7298_scan_from_ring(struct ad7298_state *st, long ch)
  69 {
  70         struct iio_ring_buffer *ring = st->indio_dev->ring;
  71         int ret;
  72         u16 *ring_data;
  73
  74         if (!(ring->scan_mask & (1 << ch))) {
  75                 ret = -EBUSY;
  76                 goto error_ret;
  77         }
  78
  79         ring_data = kmalloc(ring->access.get_bytes_per_datum(ring), GFP_KERNEL);
  80         if (ring_data == NULL) {
  81                 ret = -ENOMEM;
  82                 goto error_ret;
  83         }
  84         ret = ring->access.read_last(ring, (u8 *) ring_data);
  85         if (ret)
  86                 goto error_free_ring_data;
  87
  88         ret = be16_to_cpu(ring_data[ch]);
  89
  90 error_free_ring_data:
  91         kfree(ring_data);
  92 error_ret:
  93         return ret;
  94 }
  95
  96 /**
  97  * ad7298_ring_preenable() setup the parameters of the ring before enabling
  98  *
  99  * The complex nature of the setting of the number of bytes per datum is due
 100  * to this driver currently ensuring that the timestamp is stored at an 8
 101  * byte boundary.
 102  **/
 103 static int ad7298_ring_preenable(struct iio_dev *indio_dev)
 104 {
 105         struct ad7298_state *st = indio_dev->dev_data;
 106         struct iio_ring_buffer *ring = indio_dev->ring;
 107         size_t d_size;
 108         int i, m;
 109         unsigned short command;
 110
 111         d_size = ring->scan_count * (AD7298_STORAGE_BITS / 8);
 112
 113         if (ring->scan_timestamp) {
 114                 d_size += sizeof(s64);
 115
 116                 if (d_size % sizeof(s64))
 117                         d_size += sizeof(s64) - (d_size % sizeof(s64));
 118         }
 119
 120         if (ring->access.set_bytes_per_datum)
 121                 ring->access.set_bytes_per_datum(ring, d_size);
 122
 123         st->d_size = d_size;
 124
 125         command = AD7298_WRITE | st->ext_ref;
 126
 127         for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
 128                 if (ring->scan_mask & (1 << i))
 129                         command |= m;
 130
 131         st->tx_buf[0] = cpu_to_be16(command);
 132
 133         /* build spi ring message */
 134         st->ring_xfer[0].tx_buf = &st->tx_buf[0];
 135         st->ring_xfer[0].len = 2;
 136         st->ring_xfer[0].cs_change = 1;
 137         st->ring_xfer[1].tx_buf = &st->tx_buf[1];
 138         st->ring_xfer[1].len = 2;
 139         st->ring_xfer[1].cs_change = 1;
 140
 141         spi_message_init(&st->ring_msg);
 142         spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
 143         spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);
 144
 145         for (i = 0; i < ring->scan_count; i++) {
 146                 st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
 147                 st->ring_xfer[i + 2].len = 2;
 148                 st->ring_xfer[i + 2].cs_change = 1;
 149                 spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
 150         }
 151         /* make sure last transfer cs_change is not set */
 152         st->ring_xfer[i + 1].cs_change = 0;
 153
 154         return 0;
 155 }
 156
 157 /**
 158  * ad7298_poll_func_th() th of trigger launched polling to ring buffer
 159  *
 160  * As sampling only occurs on spi comms occurring, leave timestamping until
 161  * then.  Some triggers will generate their own time stamp.  Currently
 162  * there is no way of notifying them when no one cares.
 163  **/
 164 static void ad7298_poll_func_th(struct iio_dev *indio_dev, s64 time)
 165 {
 166         struct ad7298_state *st = indio_dev->dev_data;
 167
 168         schedule_work(&st->poll_work);
 169         return;
 170 }
 171
 172 /**
 173  * ad7298_poll_bh_to_ring() bh of trigger launched polling to ring buffer
 174  * @work_s:     the work struct through which this was scheduled
 175  *
 176  * Currently there is no option in this driver to disable the saving of
 177  * timestamps within the ring.
 178  * I think the one copy of this at a time was to avoid problems if the
 179  * trigger was set far too high and the reads then locked up the computer.
 180  **/
 181 static void ad7298_poll_bh_to_ring(struct work_struct *work_s)
 182 {
 183         struct ad7298_state *st = container_of(work_s, struct ad7298_state,
 184                                                   poll_work);
 185         struct iio_dev *indio_dev = st->indio_dev;
 186         struct iio_sw_ring_buffer *sw_ring = iio_to_sw_ring(indio_dev->ring);
 187         struct iio_ring_buffer *ring = indio_dev->ring;
 188         s64 time_ns;
 189         __u16 buf[16];
 190         int b_sent, i;
 191
 192         /* Ensure only one copy of this function running at a time */
 193         if (atomic_inc_return(&st->protect_ring) > 1)
 194                 return;
 195
 196         b_sent = spi_sync(st->spi, &st->ring_msg);
 197         if (b_sent)
 198                 goto done;
 199
 200         if (ring->scan_timestamp) {
 201                 time_ns = iio_get_time_ns();
 202                 memcpy((u8 *)buf + st->d_size - sizeof(s64),
 203                         &time_ns, sizeof(time_ns));
 204         }
 205
 206         for (i = 0; i < ring->scan_count; i++)
 207                 buf[i] = be16_to_cpu(st->rx_buf[i]);
 208
 209         indio_dev->ring->access.store_to(&sw_ring->buf, (u8 *)buf, time_ns);
 210 done:
 211         atomic_dec(&st->protect_ring);
 212 }
 213
 214 int ad7298_register_ring_funcs_and_init(struct iio_dev *indio_dev)
 215 {
 216         struct ad7298_state *st = indio_dev->dev_data;
 217         int ret;
 218
 219         indio_dev->ring = iio_sw_rb_allocate(indio_dev);
 220         if (!indio_dev->ring) {
 221                 ret = -ENOMEM;
 222                 goto error_ret;
 223         }
 224         /* Effectively select the ring buffer implementation */
 225         iio_ring_sw_register_funcs(&indio_dev->ring->access);
 226         ret = iio_alloc_pollfunc(indio_dev, NULL, &ad7298_poll_func_th);
 227         if (ret)
 228                 goto error_deallocate_sw_rb;
 229
 230         /* Ring buffer functions - here trigger setup related */
 231
 232         indio_dev->ring->preenable = &ad7298_ring_preenable;
 233         indio_dev->ring->postenable = &iio_triggered_ring_postenable;
 234         indio_dev->ring->predisable = &iio_triggered_ring_predisable;
 235         indio_dev->ring->scan_el_attrs = &ad7298_scan_el_group;
 236         indio_dev->ring->scan_timestamp = true;
 237
 238         INIT_WORK(&st->poll_work, &ad7298_poll_bh_to_ring);
 239
 240         /* Flag that polled ring buffering is possible */
 241         indio_dev->modes |= INDIO_RING_TRIGGERED;
 242         return 0;
 243 error_deallocate_sw_rb:
 244         iio_sw_rb_free(indio_dev->ring);
 245 error_ret:
 246         return ret;
 247 }
 248
 249 void ad7298_ring_cleanup(struct iio_dev *indio_dev)
 250 {
 251         if (indio_dev->trig) {
 252                 iio_put_trigger(indio_dev->trig);
 253                 iio_trigger_dettach_poll_func(indio_dev->trig,
 254                                               indio_dev->pollfunc);
 255         }
 256         kfree(indio_dev->pollfunc);
 257         iio_sw_rb_free(indio_dev->ring);
 258 }