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 	for_each_set_bit(j, indio_dev->active_scan_mask, indio_dev->masklength)
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 }
107