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 
26 struct iio_hrtimer_info {
27 	struct iio_sw_trigger swt;
28 	struct hrtimer timer;
29 	unsigned long sampling_frequency;
30 	ktime_t period;
31 };
32 
33 static const struct config_item_type iio_hrtimer_type = {
34 	.ct_owner = THIS_MODULE,
35 };
36 
37 static
38 ssize_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 
48 static
49 ssize_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 
71 static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
72 		   iio_hrtimer_show_sampling_frequency,
73 		   iio_hrtimer_store_sampling_frequency);
74 
75 static struct attribute *iio_hrtimer_attrs[] = {
76 	&dev_attr_sampling_frequency.attr,
77 	NULL
78 };
79 
80 static const struct attribute_group iio_hrtimer_attr_group = {
81 	.attrs = iio_hrtimer_attrs,
82 };
83 
84 static const struct attribute_group *iio_hrtimer_attr_groups[] = {
85 	&iio_hrtimer_attr_group,
86 	NULL
87 };
88 
89 static 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 
101 static 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 
116 static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
117 	.set_trigger_state = iio_trig_hrtimer_set_state,
118 };
119 
120 static 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;
151 err_free_trigger:
152 	iio_trigger_free(trig_info->swt.trigger);
153 err_free_trig_info:
154 	kfree(trig_info);
155 
156 	return ERR_PTR(ret);
157 }
158 
159 static 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 
175 static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
176 	.probe		= iio_trig_hrtimer_probe,
177 	.remove		= iio_trig_hrtimer_remove,
178 };
179 
180 static struct iio_sw_trigger_type iio_trig_hrtimer = {
181 	.name = "hrtimer",
182 	.owner = THIS_MODULE,
183 	.ops = &iio_trig_hrtimer_ops,
184 };
185 
186 module_iio_sw_trigger_driver(iio_trig_hrtimer);
187 
188 MODULE_AUTHOR("Marten Svanfeldt <marten@intuitiveaerial.com>");
189 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
190 MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
191 MODULE_LICENSE("GPL v2");
192