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 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
  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
  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
  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
 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
 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
 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");