Quelle  iio-trig-hrtimer.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * The industrial I/O periodic hrtimer trigger driver
 *
 * Copyright (C) Intuitive Aerial AB
 * Written by Marten Svanfeldt, marten@intuitiveaerial.com
 * Copyright (C) 2012, Analog Devices Inc.
 * Author: Lars-Peter Clausen <lars@metafoo.de>
 * Copyright (C) 2015, Intel Corporation
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/hrtimer.h>

#include <linux/iio/iio.h>
#include <linux/iio/trigger.h>
#include <linux/iio/sw_trigger.h>

/* Defined locally, not in time64.h yet. */
#define PSEC_PER_SEC   1000000000000LL

/* default sampling frequency - 100Hz */
#define HRTIMER_DEFAULT_SAMPLING_FREQUENCY 100

struct iio_hrtimer_info {
 struct iio_sw_trigger swt;
 struct hrtimer timer;
 int sampling_frequency[2];
 ktime_t period;
};

static const struct config_item_type iio_hrtimer_type = {
 .ct_owner = THIS_MODULE,
};

static
ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev,
         struct device_attribute *attr,
         char *buf)
{
 struct iio_trigger *trig = to_iio_trigger(dev);
 struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);

 return iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO,
   ARRAY_SIZE(info->sampling_frequency),
   info->sampling_frequency);
}

static
ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev,
          struct device_attribute *attr,
          const char *buf, size_t len)
{
 struct iio_trigger *trig = to_iio_trigger(dev);
 struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
 unsigned long long val;
 u64 period;
 int integer, fract, ret;

 ret = iio_str_to_fixpoint(buf, 100, &integer, &fract);
 if (ret)
  return ret;
 if (integer < 0 || fract < 0)
  return -ERANGE;

 val = fract + 1000ULL * integer;  /* mHz */

 if (!val || val > UINT_MAX)
  return -EINVAL;

 info->sampling_frequency[0] = integer;  /* Hz */
 info->sampling_frequency[1] = fract * 1000;  /* uHz */
 period = PSEC_PER_SEC;
 do_div(period, val);
 info->period = period;  /* nS */

 return len;
}

static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
     iio_hrtimer_show_sampling_frequency,
     iio_hrtimer_store_sampling_frequency);

static struct attribute *iio_hrtimer_attrs[] = {
 &dev_attr_sampling_frequency.attr,
 NULL
};

static const struct attribute_group iio_hrtimer_attr_group = {
 .attrs = iio_hrtimer_attrs,
};

static const struct attribute_group *iio_hrtimer_attr_groups[] = {
 &iio_hrtimer_attr_group,
 NULL
};

static enum hrtimer_restart iio_hrtimer_trig_handler(struct hrtimer *timer)
{
 struct iio_hrtimer_info *info;

 info = container_of(timer, struct iio_hrtimer_info, timer);

 hrtimer_forward_now(timer, info->period);
 iio_trigger_poll(info->swt.trigger);

 return HRTIMER_RESTART;
}

static int iio_trig_hrtimer_set_state(struct iio_trigger *trig, bool state)
{
 struct iio_hrtimer_info *trig_info;

 trig_info = iio_trigger_get_drvdata(trig);

 if (state)
  hrtimer_start(&trig_info->timer, trig_info->period,
         HRTIMER_MODE_REL_HARD);
 else
  hrtimer_cancel(&trig_info->timer);

 return 0;
}

static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
 .set_trigger_state = iio_trig_hrtimer_set_state,
};

static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
{
 struct iio_hrtimer_info *trig_info;
 int ret;

 trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
 if (!trig_info)
  return ERR_PTR(-ENOMEM);

 trig_info->swt.trigger = iio_trigger_alloc(NULL, "%s", name);
 if (!trig_info->swt.trigger) {
  ret = -ENOMEM;
  goto err_free_trig_info;
 }

 iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
 trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
 trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;

 hrtimer_setup(&trig_info->timer, iio_hrtimer_trig_handler, CLOCK_MONOTONIC,
        HRTIMER_MODE_REL_HARD);

 trig_info->sampling_frequency[0] = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
 trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency[0];

 ret = iio_trigger_register(trig_info->swt.trigger);
 if (ret)
  goto err_free_trigger;

 iio_swt_group_init_type_name(&trig_info->swt, name, &iio_hrtimer_type);
 return &trig_info->swt;
err_free_trigger:
 iio_trigger_free(trig_info->swt.trigger);
err_free_trig_info:
 kfree(trig_info);

 return ERR_PTR(ret);
}

static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
{
 struct iio_hrtimer_info *trig_info;

 trig_info = iio_trigger_get_drvdata(swt->trigger);

 iio_trigger_unregister(swt->trigger);

 /* cancel the timer after unreg to make sure no one rearms it */
 hrtimer_cancel(&trig_info->timer);
 iio_trigger_free(swt->trigger);
 kfree(trig_info);

 return 0;
}

static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
 .probe  = iio_trig_hrtimer_probe,
 .remove  = iio_trig_hrtimer_remove,
};

static struct iio_sw_trigger_type iio_trig_hrtimer = {
 .name = "hrtimer",
 .owner = THIS_MODULE,
 .ops = &iio_trig_hrtimer_ops,
};

module_iio_sw_trigger_driver(iio_trig_hrtimer);

MODULE_AUTHOR("Marten Svanfeldt ");
MODULE_AUTHOR("Daniel Baluta ");
MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
MODULE_LICENSE("GPL v2");