drivers/iio/dummy/iio_simple_dummy_buffer.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2011 Jonathan Cameron
   4  *
   5  * Buffer handling elements of industrial I/O reference driver.
   6  * Uses the kfifo buffer.
   7  *
   8  * To test without hardware use the sysfs trigger.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/export.h>
  13 #include <linux/slab.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/irq.h>
  16 #include <linux/bitmap.h>
  17
  18 #include <linux/iio/iio.h>
  19 #include <linux/iio/buffer.h>
  20 #include <linux/iio/trigger_consumer.h>
  21 #include <linux/iio/triggered_buffer.h>
  22
  23 #include "iio_simple_dummy.h"
  24
  25 /* Some fake data */
  26
  27 static const s16 fakedata[] = {
  28         [DUMMY_INDEX_VOLTAGE_0] = 7,
  29         [DUMMY_INDEX_DIFFVOLTAGE_1M2] = -33,
  30         [DUMMY_INDEX_DIFFVOLTAGE_3M4] = -2,
  31         [DUMMY_INDEX_ACCELX] = 344,
  32 };
  33
  34 /**
  35  * iio_simple_dummy_trigger_h() - the trigger handler function
  36  * @irq: the interrupt number
  37  * @p: private data - always a pointer to the poll func.
  38  *
  39  * This is the guts of buffered capture. On a trigger event occurring,
  40  * if the pollfunc is attached then this handler is called as a threaded
  41  * interrupt (and hence may sleep). It is responsible for grabbing data
  42  * from the device and pushing it into the associated buffer.
  43  */
  44 static irqreturn_t iio_simple_dummy_trigger_h(int irq, void *p)
  45 {
  46         struct iio_poll_func *pf = p;
  47         struct iio_dev *indio_dev = pf->indio_dev;
  48         int i = 0, j;
  49         u16 *data;
  50
  51         data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
  52         if (!data)
  53                 goto done;
  54
  55         /*
  56          * Three common options here:
  57          * hardware scans:
  58          *   certain combinations of channels make up a fast read. The capture
  59          *   will consist of all of them. Hence we just call the grab data
  60          *   function and fill the buffer without processing.
  61          * software scans:
  62          *   can be considered to be random access so efficient reading is just
  63          *   a case of minimal bus transactions.
  64          * software culled hardware scans:
  65          *   occasionally a driver may process the nearest hardware scan to avoid
  66          *   storing elements that are not desired. This is the fiddliest option
  67          *   by far.
  68          * Here let's pretend we have random access. And the values are in the
  69          * constant table fakedata.
  70          */
  71         iio_for_each_active_channel(indio_dev, j)
  72                 data[i++] = fakedata[j];
  73
  74         iio_push_to_buffers_with_timestamp(indio_dev, data,
  75                                            iio_get_time_ns(indio_dev));
  76
  77         kfree(data);
  78
  79 done:
  80         /*
  81          * Tell the core we are done with this trigger and ready for the
  82          * next one.
  83          */
  84         iio_trigger_notify_done(indio_dev->trig);
  85
  86         return IRQ_HANDLED;
  87 }
  88
  89 static const struct iio_buffer_setup_ops iio_simple_dummy_buffer_setup_ops = {
  90 };
  91
  92 int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev)
  93 {
  94         return iio_triggered_buffer_setup(indio_dev, NULL,
  95                                           iio_simple_dummy_trigger_h,
  96                                           &iio_simple_dummy_buffer_setup_ops);
  97 }
  98
  99 /**
 100  * iio_simple_dummy_unconfigure_buffer() - release buffer resources
 101  * @indio_dev: device instance state
 102  */
 103 void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev)
 104 {
 105         iio_triggered_buffer_cleanup(indio_dev);
 106 }