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/* Defined locally, not in time64.h yet. */
 20#define PSEC_PER_SEC   1000000000000LL
 21
 22/* default sampling frequency - 100Hz */
 23#define HRTIMER_DEFAULT_SAMPLING_FREQUENCY 100
 24
 25struct iio_hrtimer_info {
 26	struct iio_sw_trigger swt;
 27	struct hrtimer timer;
 28	int sampling_frequency[2];
 29	ktime_t period;
 30};
 31
 32static const struct config_item_type iio_hrtimer_type = {
 33	.ct_owner = THIS_MODULE,
 34};
 35
 36static
 37ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev,
 38					    struct device_attribute *attr,
 39					    char *buf)
 40{
 41	struct iio_trigger *trig = to_iio_trigger(dev);
 42	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
 43
 44	return iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO,
 45			ARRAY_SIZE(info->sampling_frequency),
 46			info->sampling_frequency);
 47}
 48
 49static
 50ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev,
 51					     struct device_attribute *attr,
 52					     const char *buf, size_t len)
 53{
 54	struct iio_trigger *trig = to_iio_trigger(dev);
 55	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
 56	unsigned long long val;
 57	u64 period;
 58	int integer, fract, ret;
 59
 60	ret = iio_str_to_fixpoint(buf, 100, &integer, &fract);
 61	if (ret)
 62		return ret;
 63	if (integer < 0 || fract < 0)
 64		return -ERANGE;
 65
 66	val = fract + 1000ULL * integer;  /* mHz */
 67
 68	if (!val || val > UINT_MAX)
 69		return -EINVAL;
 70
 71	info->sampling_frequency[0] = integer;  /* Hz */
 72	info->sampling_frequency[1] = fract * 1000;  /* uHz */
 73	period = PSEC_PER_SEC;
 74	do_div(period, val);
 75	info->period = period;  /* nS */
 76
 77	return len;
 78}
 79
 80static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
 81		   iio_hrtimer_show_sampling_frequency,
 82		   iio_hrtimer_store_sampling_frequency);
 83
 84static struct attribute *iio_hrtimer_attrs[] = {
 85	&dev_attr_sampling_frequency.attr,
 86	NULL
 87};
 88
 89static const struct attribute_group iio_hrtimer_attr_group = {
 90	.attrs = iio_hrtimer_attrs,
 91};
 92
 93static const struct attribute_group *iio_hrtimer_attr_groups[] = {
 94	&iio_hrtimer_attr_group,
 95	NULL
 96};
 97
 98static enum hrtimer_restart iio_hrtimer_trig_handler(struct hrtimer *timer)
 99{
100	struct iio_hrtimer_info *info;
101
102	info = container_of(timer, struct iio_hrtimer_info, timer);
103
104	hrtimer_forward_now(timer, info->period);
105	iio_trigger_poll(info->swt.trigger);
106
107	return HRTIMER_RESTART;
108}
109
110static int iio_trig_hrtimer_set_state(struct iio_trigger *trig, bool state)
111{
112	struct iio_hrtimer_info *trig_info;
113
114	trig_info = iio_trigger_get_drvdata(trig);
115
116	if (state)
117		hrtimer_start(&trig_info->timer, trig_info->period,
118			      HRTIMER_MODE_REL_HARD);
119	else
120		hrtimer_cancel(&trig_info->timer);
121
122	return 0;
123}
124
125static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
126	.set_trigger_state = iio_trig_hrtimer_set_state,
127};
128
129static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
130{
131	struct iio_hrtimer_info *trig_info;
132	int ret;
133
134	trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
135	if (!trig_info)
136		return ERR_PTR(-ENOMEM);
137
138	trig_info->swt.trigger = iio_trigger_alloc(NULL, "%s", name);
139	if (!trig_info->swt.trigger) {
140		ret = -ENOMEM;
141		goto err_free_trig_info;
142	}
143
144	iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
145	trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
146	trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;
147
148	hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
149	trig_info->timer.function = iio_hrtimer_trig_handler;
150
151	trig_info->sampling_frequency[0] = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
152	trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency[0];
153
154	ret = iio_trigger_register(trig_info->swt.trigger);
155	if (ret)
156		goto err_free_trigger;
157
158	iio_swt_group_init_type_name(&trig_info->swt, name, &iio_hrtimer_type);
159	return &trig_info->swt;
160err_free_trigger:
161	iio_trigger_free(trig_info->swt.trigger);
162err_free_trig_info:
163	kfree(trig_info);
164
165	return ERR_PTR(ret);
166}
167
168static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
169{
170	struct iio_hrtimer_info *trig_info;
171
172	trig_info = iio_trigger_get_drvdata(swt->trigger);
173
174	iio_trigger_unregister(swt->trigger);
175
176	/* cancel the timer after unreg to make sure no one rearms it */
177	hrtimer_cancel(&trig_info->timer);
178	iio_trigger_free(swt->trigger);
179	kfree(trig_info);
180
181	return 0;
182}
183
184static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
185	.probe		= iio_trig_hrtimer_probe,
186	.remove		= iio_trig_hrtimer_remove,
187};
188
189static struct iio_sw_trigger_type iio_trig_hrtimer = {
190	.name = "hrtimer",
191	.owner = THIS_MODULE,
192	.ops = &iio_trig_hrtimer_ops,
193};
194
195module_iio_sw_trigger_driver(iio_trig_hrtimer);
196
197MODULE_AUTHOR("Marten Svanfeldt <marten@intuitiveaerial.com>");
198MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
199MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
200MODULE_LICENSE("GPL v2");