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 
25 struct iio_hrtimer_info {
26 	struct iio_sw_trigger swt;
27 	struct hrtimer timer;
28 	int sampling_frequency[2];
29 	ktime_t period;
30 };
31 
32 static const struct config_item_type iio_hrtimer_type = {
33 	.ct_owner = THIS_MODULE,
34 };
35 
36 static
iio_hrtimer_show_sampling_frequency(struct device * dev,struct device_attribute * attr,char * buf)37 ssize_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 
49 static
iio_hrtimer_store_sampling_frequency(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)50 ssize_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 
80 static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
81 		   iio_hrtimer_show_sampling_frequency,
82 		   iio_hrtimer_store_sampling_frequency);
83 
84 static struct attribute *iio_hrtimer_attrs[] = {
85 	&dev_attr_sampling_frequency.attr,
86 	NULL
87 };
88 
89 static const struct attribute_group iio_hrtimer_attr_group = {
90 	.attrs = iio_hrtimer_attrs,
91 };
92 
93 static const struct attribute_group *iio_hrtimer_attr_groups[] = {
94 	&iio_hrtimer_attr_group,
95 	NULL
96 };
97 
iio_hrtimer_trig_handler(struct hrtimer * timer)98 static 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 
iio_trig_hrtimer_set_state(struct iio_trigger * trig,bool state)110 static 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 
125 static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
126 	.set_trigger_state = iio_trig_hrtimer_set_state,
127 };
128 
iio_trig_hrtimer_probe(const char * name)129 static 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;
160 err_free_trigger:
161 	iio_trigger_free(trig_info->swt.trigger);
162 err_free_trig_info:
163 	kfree(trig_info);
164 
165 	return ERR_PTR(ret);
166 }
167 
iio_trig_hrtimer_remove(struct iio_sw_trigger * swt)168 static 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 
184 static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
185 	.probe		= iio_trig_hrtimer_probe,
186 	.remove		= iio_trig_hrtimer_remove,
187 };
188 
189 static struct iio_sw_trigger_type iio_trig_hrtimer = {
190 	.name = "hrtimer",
191 	.owner = THIS_MODULE,
192 	.ops = &iio_trig_hrtimer_ops,
193 };
194 
195 module_iio_sw_trigger_driver(iio_trig_hrtimer);
196 
197 MODULE_AUTHOR("Marten Svanfeldt <marten@intuitiveaerial.com>");
198 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
199 MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
200 MODULE_LICENSE("GPL v2");
201