drivers/iio/trigger/iio-trig-hrtimer.c

   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
  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
  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
  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
  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
 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
 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");