1// SPDX-License-Identifier: GPL-2.0-only
2/**
3 * The industrial I/O periodic hrtimer trigger driver
4 *
5 * Copyright (C) Intuitive Aerial AB
6 * Written by Marten Svanfeldt, marten@intuitiveaerial.com
7 * Copyright (C) 2012, Analog Devices Inc.
8 *	Author: Lars-Peter Clausen <lars@metafoo.de>
9 * Copyright (C) 2015, Intel Corporation
10 */
11#include <linux/kernel.h>
12#include <linux/slab.h>
13#include <linux/hrtimer.h>
14
15#include <linux/iio/iio.h>
16#include <linux/iio/trigger.h>
17#include <linux/iio/sw_trigger.h>
18
19/* default sampling frequency - 100Hz */
20#define HRTIMER_DEFAULT_SAMPLING_FREQUENCY 100
21
22struct iio_hrtimer_info {
23	struct iio_sw_trigger swt;
24	struct hrtimer timer;
25	unsigned long sampling_frequency;
26	ktime_t period;
27};
28
29static const struct config_item_type iio_hrtimer_type = {
30	.ct_owner = THIS_MODULE,
31};
32
33static
34ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev,
35					    struct device_attribute *attr,
36					    char *buf)
37{
38	struct iio_trigger *trig = to_iio_trigger(dev);
39	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
40
41	return snprintf(buf, PAGE_SIZE, "%lu\n", info->sampling_frequency);
42}
43
44static
45ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev,
46					     struct device_attribute *attr,
47					     const char *buf, size_t len)
48{
49	struct iio_trigger *trig = to_iio_trigger(dev);
50	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
51	unsigned long val;
52	int ret;
53
54	ret = kstrtoul(buf, 10, &val);
55	if (ret)
56		return ret;
57
58	if (!val || val > NSEC_PER_SEC)
59		return -EINVAL;
60
61	info->sampling_frequency = val;
62	info->period = NSEC_PER_SEC / val;
63
64	return len;
65}
66
67static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
68		   iio_hrtimer_show_sampling_frequency,
69		   iio_hrtimer_store_sampling_frequency);
70
71static struct attribute *iio_hrtimer_attrs[] = {
72	&dev_attr_sampling_frequency.attr,
73	NULL
74};
75
76static const struct attribute_group iio_hrtimer_attr_group = {
77	.attrs = iio_hrtimer_attrs,
78};
79
80static const struct attribute_group *iio_hrtimer_attr_groups[] = {
81	&iio_hrtimer_attr_group,
82	NULL
83};
84
85static enum hrtimer_restart iio_hrtimer_trig_handler(struct hrtimer *timer)
86{
87	struct iio_hrtimer_info *info;
88
89	info = container_of(timer, struct iio_hrtimer_info, timer);
90
91	hrtimer_forward_now(timer, info->period);
92	iio_trigger_poll(info->swt.trigger);
93
94	return HRTIMER_RESTART;
95}
96
97static int iio_trig_hrtimer_set_state(struct iio_trigger *trig, bool state)
98{
99	struct iio_hrtimer_info *trig_info;
100
101	trig_info = iio_trigger_get_drvdata(trig);
102
103	if (state)
104		hrtimer_start(&trig_info->timer, trig_info->period,
105			      HRTIMER_MODE_REL_HARD);
106	else
107		hrtimer_cancel(&trig_info->timer);
108
109	return 0;
110}
111
112static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
113	.set_trigger_state = iio_trig_hrtimer_set_state,
114};
115
116static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
117{
118	struct iio_hrtimer_info *trig_info;
119	int ret;
120
121	trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
122	if (!trig_info)
123		return ERR_PTR(-ENOMEM);
124
125	trig_info->swt.trigger = iio_trigger_alloc("%s", name);
126	if (!trig_info->swt.trigger) {
127		ret = -ENOMEM;
128		goto err_free_trig_info;
129	}
130
131	iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
132	trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
133	trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;
134
135	hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
136	trig_info->timer.function = iio_hrtimer_trig_handler;
137
138	trig_info->sampling_frequency = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
139	trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency;
140
141	ret = iio_trigger_register(trig_info->swt.trigger);
142	if (ret)
143		goto err_free_trigger;
144
145	iio_swt_group_init_type_name(&trig_info->swt, name, &iio_hrtimer_type);
146	return &trig_info->swt;
147err_free_trigger:
148	iio_trigger_free(trig_info->swt.trigger);
149err_free_trig_info:
150	kfree(trig_info);
151
152	return ERR_PTR(ret);
153}
154
155static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
156{
157	struct iio_hrtimer_info *trig_info;
158
159	trig_info = iio_trigger_get_drvdata(swt->trigger);
160
161	iio_trigger_unregister(swt->trigger);
162
163	/* cancel the timer after unreg to make sure no one rearms it */
164	hrtimer_cancel(&trig_info->timer);
165	iio_trigger_free(swt->trigger);
166	kfree(trig_info);
167
168	return 0;
169}
170
171static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
172	.probe		= iio_trig_hrtimer_probe,
173	.remove		= iio_trig_hrtimer_remove,
174};
175
176static struct iio_sw_trigger_type iio_trig_hrtimer = {
177	.name = "hrtimer",
178	.owner = THIS_MODULE,
179	.ops = &iio_trig_hrtimer_ops,
180};
181
182module_iio_sw_trigger_driver(iio_trig_hrtimer);
183
184MODULE_AUTHOR("Marten Svanfeldt <marten@intuitiveaerial.com>");
185MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
186MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
187MODULE_LICENSE("GPL v2");
188