tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright 2016 Jonathan Cameron <jic23@kernel.org>
3 *
4 * Licensed under the GPL-2.
5 *
6 * Based on a mashup of the hrtimer trigger and continuous sampling proposal of
7 * Gregor Boirie <gregor.boirie@parrot.com>
8 *
9 * Note this is still rather experimental and may eat babies.
10 *
11 * Todo
12 * * Protect against connection of devices that 'need' the top half
13 * handler.
14 * * Work out how to run top half handlers in this context if it is
15 * safe to do so (timestamp grabbing for example)
16 *
17 * Tested against a max1363. Used about 33% cpu for the thread and 20%
18 * for generic_buffer piping to /dev/null. Watermark set at 64 on a 128
19 * element kfifo buffer.
20 */
21
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/platform_device.h>
25#include <linux/slab.h>
26#include <linux/irq_work.h>
27#include <linux/kthread.h>
28#include <linux/freezer.h>
29
30#include <linux/iio/iio.h>
31#include <linux/iio/trigger.h>
32#include <linux/iio/sw_trigger.h>
33
34struct iio_loop_info {
35 struct iio_sw_trigger swt;
36 struct task_struct *task;
37};
38
39static const struct config_item_type iio_loop_type = {
40 .ct_owner = THIS_MODULE,
41};
42
43static int iio_loop_thread(void *data)
44{
45 struct iio_trigger *trig = data;
46
47 set_freezable();
48
49 do {
50 iio_trigger_poll_chained(trig);
51 } while (likely(!kthread_freezable_should_stop(NULL)));
52
53 return 0;
54}
55
56static int iio_loop_trigger_set_state(struct iio_trigger *trig, bool state)
57{
58 struct iio_loop_info *loop_trig = iio_trigger_get_drvdata(trig);
59
60 if (state) {
61 loop_trig->task = kthread_run(iio_loop_thread,
62 trig, trig->name);
63 if (IS_ERR(loop_trig->task)) {
64 dev_err(&trig->dev,
65 "failed to create trigger loop thread\n");
66 return PTR_ERR(loop_trig->task);
67 }
68 } else {
69 kthread_stop(loop_trig->task);
70 }
71
72 return 0;
73}
74
75static const struct iio_trigger_ops iio_loop_trigger_ops = {
76 .set_trigger_state = iio_loop_trigger_set_state,
77};
78
79static struct iio_sw_trigger *iio_trig_loop_probe(const char *name)
80{
81 struct iio_loop_info *trig_info;
82 int ret;
83
84 trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
85 if (!trig_info)
86 return ERR_PTR(-ENOMEM);
87
88 trig_info->swt.trigger = iio_trigger_alloc("%s", name);
89 if (!trig_info->swt.trigger) {
90 ret = -ENOMEM;
91 goto err_free_trig_info;
92 }
93
94 iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
95 trig_info->swt.trigger->ops = &iio_loop_trigger_ops;
96
97 ret = iio_trigger_register(trig_info->swt.trigger);
98 if (ret)
99 goto err_free_trigger;
100
101 iio_swt_group_init_type_name(&trig_info->swt, name, &iio_loop_type);
102
103 return &trig_info->swt;
104
105err_free_trigger:
106 iio_trigger_free(trig_info->swt.trigger);
107err_free_trig_info:
108 kfree(trig_info);
109
110 return ERR_PTR(ret);
111}
112
113static int iio_trig_loop_remove(struct iio_sw_trigger *swt)
114{
115 struct iio_loop_info *trig_info;
116
117 trig_info = iio_trigger_get_drvdata(swt->trigger);
118
119 iio_trigger_unregister(swt->trigger);
120 iio_trigger_free(swt->trigger);
121 kfree(trig_info);
122
123 return 0;
124}
125
126static const struct iio_sw_trigger_ops iio_trig_loop_ops = {
127 .probe = iio_trig_loop_probe,
128 .remove = iio_trig_loop_remove,
129};
130
131static struct iio_sw_trigger_type iio_trig_loop = {
132 .name = "loop",
133 .owner = THIS_MODULE,
134 .ops = &iio_trig_loop_ops,
135};
136
137module_iio_sw_trigger_driver(iio_trig_loop);
138
139MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
140MODULE_DESCRIPTION("Loop based trigger for the iio subsystem");
141MODULE_LICENSE("GPL v2");
142MODULE_ALIAS("platform:iio-trig-loop");