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 struct dummy_scan {
35 s16 data[ARRAY_SIZE(fakedata)];
36 aligned_s64 timestamp;
37 };
38
39 /**
40 * iio_simple_dummy_trigger_h() - the trigger handler function
41 * @irq: the interrupt number
42 * @p: private data - always a pointer to the poll func.
43 *
44 * This is the guts of buffered capture. On a trigger event occurring,
45 * if the pollfunc is attached then this handler is called as a threaded
46 * interrupt (and hence may sleep). It is responsible for grabbing data
47 * from the device and pushing it into the associated buffer.
48 */
iio_simple_dummy_trigger_h(int irq,void * p)49 static irqreturn_t iio_simple_dummy_trigger_h(int irq, void *p)
50 {
51 struct iio_poll_func *pf = p;
52 struct iio_dev *indio_dev = pf->indio_dev;
53 struct dummy_scan *scan;
54 int i = 0, j;
55
56 /*
57 * Note that some buses such as SPI require DMA safe buffers which
58 * cannot be on the stack. Two easy ways to do this:
59 * - Local kzalloc (as done here)
60 * - A buffer at the end of the structure accessed via iio_priv()
61 * that is marked __aligned(IIO_DMA_MINALIGN).
62 */
63 scan = kzalloc(sizeof(*scan), GFP_KERNEL);
64 if (!scan)
65 goto done;
66
67 /*
68 * Three common options here:
69 * hardware scans:
70 * certain combinations of channels make up a fast read. The capture
71 * will consist of all of them. Hence we just call the grab data
72 * function and fill the buffer without processing.
73 * software scans:
74 * can be considered to be random access so efficient reading is just
75 * a case of minimal bus transactions.
76 * software culled hardware scans:
77 * occasionally a driver may process the nearest hardware scan to avoid
78 * storing elements that are not desired. This is the fiddliest option
79 * by far.
80 * Here let's pretend we have random access. And the values are in the
81 * constant table fakedata.
82 */
83 iio_for_each_active_channel(indio_dev, j)
84 scan->data[i++] = fakedata[j];
85
86 iio_push_to_buffers_with_ts(indio_dev, scan, sizeof(*scan),
87 iio_get_time_ns(indio_dev));
88
89 kfree(scan);
90 done:
91 /*
92 * Tell the core we are done with this trigger and ready for the
93 * next one.
94 */
95 iio_trigger_notify_done(indio_dev->trig);
96
97 return IRQ_HANDLED;
98 }
99
100 static const struct iio_buffer_setup_ops iio_simple_dummy_buffer_setup_ops = {
101 };
102
iio_simple_dummy_configure_buffer(struct iio_dev * indio_dev)103 int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev)
104 {
105 return iio_triggered_buffer_setup(indio_dev, NULL,
106 iio_simple_dummy_trigger_h,
107 &iio_simple_dummy_buffer_setup_ops);
108 }
109
110 /**
111 * iio_simple_dummy_unconfigure_buffer() - release buffer resources
112 * @indio_dev: device instance state
113 */
iio_simple_dummy_unconfigure_buffer(struct iio_dev * indio_dev)114 void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev)
115 {
116 iio_triggered_buffer_cleanup(indio_dev);
117 }
118