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 Device 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
22 struct iio_hrtimer_info {
23 struct iio_sw_trigger swt;
24 struct hrtimer timer;
25 unsigned long sampling_frequency;
26 ktime_t period;
27 };
28
29 static const struct config_item_type iio_hrtimer_type = {
30 .ct_owner = THIS_MODULE,
31 };
32
33 static
iio_hrtimer_show_sampling_frequency(struct device * dev,struct device_attribute * attr,char * buf)34 ssize_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
44 static
iio_hrtimer_store_sampling_frequency(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)45 ssize_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
67 static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
68 iio_hrtimer_show_sampling_frequency,
69 iio_hrtimer_store_sampling_frequency);
70
71 static struct attribute *iio_hrtimer_attrs[] = {
72 &dev_attr_sampling_frequency.attr,
73 NULL
74 };
75
76 static const struct attribute_group iio_hrtimer_attr_group = {
77 .attrs = iio_hrtimer_attrs,
78 };
79
80 static const struct attribute_group *iio_hrtimer_attr_groups[] = {
81 &iio_hrtimer_attr_group,
82 NULL
83 };
84
iio_hrtimer_trig_handler(struct hrtimer * timer)85 static 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
iio_trig_hrtimer_set_state(struct iio_trigger * trig,bool state)97 static 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);
106 else
107 hrtimer_cancel(&trig_info->timer);
108
109 return 0;
110 }
111
112 static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
113 .set_trigger_state = iio_trig_hrtimer_set_state,
114 };
115
iio_trig_hrtimer_probe(const char * name)116 static 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);
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;
147 err_free_trigger:
148 iio_trigger_free(trig_info->swt.trigger);
149 err_free_trig_info:
150 kfree(trig_info);
151
152 return ERR_PTR(ret);
153 }
154
iio_trig_hrtimer_remove(struct iio_sw_trigger * swt)155 static 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
171 static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
172 .probe = iio_trig_hrtimer_probe,
173 .remove = iio_trig_hrtimer_remove,
174 };
175
176 static struct iio_sw_trigger_type iio_trig_hrtimer = {
177 .name = "hrtimer",
178 .owner = THIS_MODULE,
179 .ops = &iio_trig_hrtimer_ops,
180 };
181
182 module_iio_sw_trigger_driver(iio_trig_hrtimer);
183
184 MODULE_AUTHOR("Marten Svanfeldt <marten@intuitiveaerial.com>");
185 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
186 MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
187 MODULE_LICENSE("GPL v2");
188
