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

   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 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         .owner = THIS_MODULE,
 118         .set_trigger_state = iio_trig_hrtimer_set_state,
 119 };
 120
 121 static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
 122 {
 123         struct iio_hrtimer_info *trig_info;
 124         int ret;
 125
 126         trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
 127         if (!trig_info)
 128                 return ERR_PTR(-ENOMEM);
 129
 130         trig_info->swt.trigger = iio_trigger_alloc("%s", name);
 131         if (!trig_info->swt.trigger) {
 132                 ret = -ENOMEM;
 133                 goto err_free_trig_info;
 134         }
 135
 136         iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
 137         trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
 138         trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;
 139
 140         hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 141         trig_info->timer.function = iio_hrtimer_trig_handler;
 142
 143         trig_info->sampling_frequency = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
 144         trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency;
 145
 146         ret = iio_trigger_register(trig_info->swt.trigger);
 147         if (ret)
 148                 goto err_free_trigger;
 149
 150         iio_swt_group_init_type_name(&trig_info->swt, name, &iio_hrtimer_type);
 151         return &trig_info->swt;
 152 err_free_trigger:
 153         iio_trigger_free(trig_info->swt.trigger);
 154 err_free_trig_info:
 155         kfree(trig_info);
 156
 157         return ERR_PTR(ret);
 158 }
 159
 160 static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
 161 {
 162         struct iio_hrtimer_info *trig_info;
 163
 164         trig_info = iio_trigger_get_drvdata(swt->trigger);
 165
 166         iio_trigger_unregister(swt->trigger);
 167
 168         /* cancel the timer after unreg to make sure no one rearms it */
 169         hrtimer_cancel(&trig_info->timer);
 170         iio_trigger_free(swt->trigger);
 171         kfree(trig_info);
 172
 173         return 0;
 174 }
 175
 176 static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
 177         .probe          = iio_trig_hrtimer_probe,
 178         .remove         = iio_trig_hrtimer_remove,
 179 };
 180
 181 static struct iio_sw_trigger_type iio_trig_hrtimer = {
 182         .name = "hrtimer",
 183         .owner = THIS_MODULE,
 184         .ops = &iio_trig_hrtimer_ops,
 185 };
 186
 187 module_iio_sw_trigger_driver(iio_trig_hrtimer);
 188
 189 MODULE_AUTHOR("Marten Svanfeldt <marten@intuitiveaerial.com>");
 190 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
 191 MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
 192 MODULE_LICENSE("GPL v2");