1/**
  2 * The industrial I/O periodic hrtimer trigger driver
  3 *
  4 * Copyright (C) Intuitive Aerial AB
  5 * Written by Marten Svanfeldt, marten@intuitiveaerial.com
  6 * Copyright (C) 2012, Analog Device Inc.
  7 *	Author: Lars-Peter Clausen <lars@metafoo.de>
  8 * Copyright (C) 2015, Intel Corporation
  9 *
 10 * This program is free software; you can redistribute it and/or modify it
 11 * under the terms of the GNU General Public License version 2 as published by
 12 * the Free Software Foundation.
 13 *
 14 */
 15#include <linux/kernel.h>
 16#include <linux/slab.h>
 17#include <linux/hrtimer.h>
 18
 19#include <linux/iio/iio.h>
 20#include <linux/iio/trigger.h>
 21#include <linux/iio/sw_trigger.h>
 22
 23/* default sampling frequency - 100Hz */
 24#define HRTIMER_DEFAULT_SAMPLING_FREQUENCY 100
 25
 26struct iio_hrtimer_info {
 27	struct iio_sw_trigger swt;
 28	struct hrtimer timer;
 29	unsigned long sampling_frequency;
 30	ktime_t period;
 31};
 32
 33static const struct config_item_type iio_hrtimer_type = {
 34	.ct_owner = THIS_MODULE,
 35};
 36
 37static
 38ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev,
 39					    struct device_attribute *attr,
 40					    char *buf)
 41{
 42	struct iio_trigger *trig = to_iio_trigger(dev);
 43	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
 44
 45	return snprintf(buf, PAGE_SIZE, "%lu\n", info->sampling_frequency);
 46}
 47
 48static
 49ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev,
 50					     struct device_attribute *attr,
 51					     const char *buf, size_t len)
 52{
 53	struct iio_trigger *trig = to_iio_trigger(dev);
 54	struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
 55	unsigned long val;
 56	int ret;
 57
 58	ret = kstrtoul(buf, 10, &val);
 59	if (ret)
 60		return ret;
 61
 62	if (!val || val > NSEC_PER_SEC)
 63		return -EINVAL;
 64
 65	info->sampling_frequency = val;
 66	info->period = NSEC_PER_SEC / val;
 67
 68	return len;
 69}
 70
 71static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
 72		   iio_hrtimer_show_sampling_frequency,
 73		   iio_hrtimer_store_sampling_frequency);
 74
 75static struct attribute *iio_hrtimer_attrs[] = {
 76	&dev_attr_sampling_frequency.attr,
 77	NULL
 78};
 79
 80static const struct attribute_group iio_hrtimer_attr_group = {
 81	.attrs = iio_hrtimer_attrs,
 82};
 83
 84static const struct attribute_group *iio_hrtimer_attr_groups[] = {
 85	&iio_hrtimer_attr_group,
 86	NULL
 87};
 88
 89static enum hrtimer_restart iio_hrtimer_trig_handler(struct hrtimer *timer)
 90{
 91	struct iio_hrtimer_info *info;
 92
 93	info = container_of(timer, struct iio_hrtimer_info, timer);
 94
 95	hrtimer_forward_now(timer, info->period);
 96	iio_trigger_poll(info->swt.trigger);
 97
 98	return HRTIMER_RESTART;
 99}
100
101static int iio_trig_hrtimer_set_state(struct iio_trigger *trig, bool state)
102{
103	struct iio_hrtimer_info *trig_info;
104
105	trig_info = iio_trigger_get_drvdata(trig);
106
107	if (state)
108		hrtimer_start(&trig_info->timer, trig_info->period,
109			      HRTIMER_MODE_REL);
110	else
111		hrtimer_cancel(&trig_info->timer);
112
113	return 0;
114}
115
116static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
117	.set_trigger_state = iio_trig_hrtimer_set_state,
118};
119
120static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
121{
122	struct iio_hrtimer_info *trig_info;
123	int ret;
124
125	trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
126	if (!trig_info)
127		return ERR_PTR(-ENOMEM);
128
129	trig_info->swt.trigger = iio_trigger_alloc("%s", name);
130	if (!trig_info->swt.trigger) {
131		ret = -ENOMEM;
132		goto err_free_trig_info;
133	}
134
135	iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
136	trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
137	trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;
138
139	hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
140	trig_info->timer.function = iio_hrtimer_trig_handler;
141
142	trig_info->sampling_frequency = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
143	trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency;
144
145	ret = iio_trigger_register(trig_info->swt.trigger);
146	if (ret)
147		goto err_free_trigger;
148
149	iio_swt_group_init_type_name(&trig_info->swt, name, &iio_hrtimer_type);
150	return &trig_info->swt;
151err_free_trigger:
152	iio_trigger_free(trig_info->swt.trigger);
153err_free_trig_info:
154	kfree(trig_info);
155
156	return ERR_PTR(ret);
157}
158
159static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
160{
161	struct iio_hrtimer_info *trig_info;
162
163	trig_info = iio_trigger_get_drvdata(swt->trigger);
164
165	iio_trigger_unregister(swt->trigger);
166
167	/* cancel the timer after unreg to make sure no one rearms it */
168	hrtimer_cancel(&trig_info->timer);
169	iio_trigger_free(swt->trigger);
170	kfree(trig_info);
171
172	return 0;
173}
174
175static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
176	.probe		= iio_trig_hrtimer_probe,
177	.remove		= iio_trig_hrtimer_remove,
178};
179
180static struct iio_sw_trigger_type iio_trig_hrtimer = {
181	.name = "hrtimer",
182	.owner = THIS_MODULE,
183	.ops = &iio_trig_hrtimer_ops,
184};
185
186module_iio_sw_trigger_driver(iio_trig_hrtimer);
187
188MODULE_AUTHOR("Marten Svanfeldt <marten@intuitiveaerial.com>");
189MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
190MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
191MODULE_LICENSE("GPL v2");