drivers/staging/iio/adc/max1363_ring.c

   1 /*
   2  * Copyright (C) 2008 Jonathan Cameron
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * max1363_ring.c
   9  */
  10
  11 #include <linux/interrupt.h>
  12 #include <linux/gpio.h>
  13 #include <linux/workqueue.h>
  14 #include <linux/device.h>
  15 #include <linux/slab.h>
  16 #include <linux/kernel.h>
  17 #include <linux/sysfs.h>
  18 #include <linux/list.h>
  19 #include <linux/i2c.h>
  20 #include <linux/bitops.h>
  21
  22 #include "../iio.h"
  23 #include "../ring_generic.h"
  24 #include "../ring_sw.h"
  25 #include "../trigger.h"
  26 #include "../sysfs.h"
  27
  28 #include "max1363.h"
  29
  30 /* Todo: test this */
  31 int max1363_single_channel_from_ring(long mask, struct max1363_state *st)
  32 {
  33         struct iio_ring_buffer *ring = st->indio_dev->ring;
  34         int count = 0, ret;
  35         u8 *ring_data;
  36         if (!(st->current_mode->modemask & mask)) {
  37                 ret = -EBUSY;
  38                 goto error_ret;
  39         }
  40
  41         ring_data = kmalloc(ring->access.get_bytes_per_datum(ring), GFP_KERNEL);
  42         if (ring_data == NULL) {
  43                 ret = -ENOMEM;
  44                 goto error_ret;
  45         }
  46         ret = ring->access.read_last(ring, ring_data);
  47         if (ret)
  48                 goto error_free_ring_data;
  49         /* Need a count of channels prior to this one */
  50         mask >>= 1;
  51         while (mask) {
  52                 if (mask & st->current_mode->modemask)
  53                         count++;
  54                 mask >>= 1;
  55         }
  56         if (st->chip_info->bits != 8)
  57                 ret = ((int)(ring_data[count*2 + 0] & 0x0F) << 8)
  58                         + (int)(ring_data[count*2 + 1]);
  59         else
  60                 ret = ring_data[count];
  61
  62 error_free_ring_data:
  63         kfree(ring_data);
  64 error_ret:
  65         return ret;
  66 }
  67
  68 /**
  69  * max1363_ring_preenable() - setup the parameters of the ring before enabling
  70  *
  71  * The complex nature of the setting of the nuber of bytes per datum is due
  72  * to this driver currently ensuring that the timestamp is stored at an 8
  73  * byte boundary.
  74  **/
  75 static int max1363_ring_preenable(struct iio_dev *indio_dev)
  76 {
  77         struct max1363_state *st = indio_dev->dev_data;
  78         struct iio_ring_buffer *ring = indio_dev->ring;
  79         size_t d_size = 0;
  80         unsigned long numvals;
  81
  82         /*
  83          * Need to figure out the current mode based upon the requested
  84          * scan mask in iio_dev
  85          */
  86         st->current_mode = max1363_match_mode(ring->scan_mask,
  87                                         st->chip_info);
  88         if (!st->current_mode)
  89                 return -EINVAL;
  90
  91         max1363_set_scan_mode(st);
  92
  93         numvals = hweight_long(st->current_mode->modemask);
  94         if (ring->access.set_bytes_per_datum) {
  95                 if (ring->scan_timestamp)
  96                         d_size += sizeof(s64);
  97                 if (st->chip_info->bits != 8)
  98                         d_size += numvals*2;
  99                 else
 100                         d_size += numvals;
 101                 if (ring->scan_timestamp && (d_size % 8))
 102                         d_size += 8 - (d_size % 8);
 103                 ring->access.set_bytes_per_datum(ring, d_size);
 104         }
 105
 106         return 0;
 107 }
 108
 109
 110 /**
 111  * max1363_poll_func_th() - th of trigger launched polling to ring buffer
 112  *
 113  * As sampling only occurs on i2c comms occurring, leave timestamping until
 114  * then.  Some triggers will generate their own time stamp.  Currently
 115  * there is no way of notifying them when no one cares.
 116  **/
 117 static void max1363_poll_func_th(struct iio_dev *indio_dev, s64 time)
 118 {
 119         struct max1363_state *st = indio_dev->dev_data;
 120
 121         schedule_work(&st->poll_work);
 122
 123         return;
 124 }
 125 /**
 126  * max1363_poll_bh_to_ring() - bh of trigger launched polling to ring buffer
 127  * @work_s:     the work struct through which this was scheduled
 128  *
 129  * Currently there is no option in this driver to disable the saving of
 130  * timestamps within the ring.
 131  * I think the one copy of this at a time was to avoid problems if the
 132  * trigger was set far too high and the reads then locked up the computer.
 133  **/
 134 static void max1363_poll_bh_to_ring(struct work_struct *work_s)
 135 {
 136         struct max1363_state *st = container_of(work_s, struct max1363_state,
 137                                                   poll_work);
 138         struct iio_dev *indio_dev = st->indio_dev;
 139         struct iio_sw_ring_buffer *sw_ring = iio_to_sw_ring(indio_dev->ring);
 140         s64 time_ns;
 141         __u8 *rxbuf;
 142         int b_sent;
 143         size_t d_size;
 144         unsigned long numvals = hweight_long(st->current_mode->modemask);
 145
 146         /* Ensure the timestamp is 8 byte aligned */
 147         if (st->chip_info->bits != 8)
 148                 d_size = numvals*2 + sizeof(s64);
 149         else
 150                 d_size = numvals + sizeof(s64);
 151         if (d_size % sizeof(s64))
 152                 d_size += sizeof(s64) - (d_size % sizeof(s64));
 153
 154         /* Ensure only one copy of this function running at a time */
 155         if (atomic_inc_return(&st->protect_ring) > 1)
 156                 return;
 157
 158         /* Monitor mode prevents reading. Whilst not currently implemented
 159          * might as well have this test in here in the meantime as it does
 160          * no harm.
 161          */
 162         if (numvals == 0)
 163                 return;
 164
 165         rxbuf = kmalloc(d_size, GFP_KERNEL);
 166         if (rxbuf == NULL)
 167                 return;
 168         if (st->chip_info->bits != 8)
 169                 b_sent = i2c_master_recv(st->client, rxbuf, numvals*2);
 170         else
 171                 b_sent = i2c_master_recv(st->client, rxbuf, numvals);
 172         if (b_sent < 0)
 173                 goto done;
 174
 175         time_ns = iio_get_time_ns();
 176
 177         memcpy(rxbuf + d_size - sizeof(s64), &time_ns, sizeof(time_ns));
 178
 179         indio_dev->ring->access.store_to(&sw_ring->buf, rxbuf, time_ns);
 180 done:
 181         kfree(rxbuf);
 182         atomic_dec(&st->protect_ring);
 183 }
 184
 185
 186 int max1363_register_ring_funcs_and_init(struct iio_dev *indio_dev)
 187 {
 188         struct max1363_state *st = indio_dev->dev_data;
 189         int ret = 0;
 190
 191         indio_dev->ring = iio_sw_rb_allocate(indio_dev);
 192         if (!indio_dev->ring) {
 193                 ret = -ENOMEM;
 194                 goto error_ret;
 195         }
 196         /* Effectively select the ring buffer implementation */
 197         iio_ring_sw_register_funcs(&indio_dev->ring->access);
 198         ret = iio_alloc_pollfunc(indio_dev, NULL, &max1363_poll_func_th);
 199         if (ret)
 200                 goto error_deallocate_sw_rb;
 201
 202         /* Ring buffer functions - here trigger setup related */
 203         indio_dev->ring->scan_el_attrs = st->chip_info->scan_attrs;
 204         indio_dev->ring->postenable = &iio_triggered_ring_postenable;
 205         indio_dev->ring->preenable = &max1363_ring_preenable;
 206         indio_dev->ring->predisable = &iio_triggered_ring_predisable;
 207         INIT_WORK(&st->poll_work, &max1363_poll_bh_to_ring);
 208
 209         /* Flag that polled ring buffering is possible */
 210         indio_dev->modes |= INDIO_RING_TRIGGERED;
 211         return 0;
 212 error_deallocate_sw_rb:
 213         iio_sw_rb_free(indio_dev->ring);
 214 error_ret:
 215         return ret;
 216 }
 217
 218 void max1363_ring_cleanup(struct iio_dev *indio_dev)
 219 {
 220         /* ensure that the trigger has been detached */
 221         if (indio_dev->trig) {
 222                 iio_put_trigger(indio_dev->trig);
 223                 iio_trigger_dettach_poll_func(indio_dev->trig,
 224                                               indio_dev->pollfunc);
 225         }
 226         kfree(indio_dev->pollfunc);
 227         iio_sw_rb_free(indio_dev->ring);
 228 }