![Daniel Baluta](/assets/img/avatar_default.png)
This patch registers a new IIO software trigger interrupt source based on high resolution timers. Notice that if configfs is enabled we create sampling_frequency attribute allowing users to change hrtimer period (1/sampling_frequency). The IIO hrtimer trigger has a long history, this patch is based on an older version from Marten and Lars-Peter. Signed-off-by: Marten Svanfeldt <marten@intuitiveaerial.com> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Daniel Baluta <daniel.baluta@intel.com> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
194 lines
4.9 KiB
C
194 lines
4.9 KiB
C
/**
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* The industrial I/O periodic hrtimer trigger driver
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*
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* Copyright (C) Intuitive Aerial AB
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* Written by Marten Svanfeldt, marten@intuitiveaerial.com
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* Copyright (C) 2012, Analog Device Inc.
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* Author: Lars-Peter Clausen <lars@metafoo.de>
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* Copyright (C) 2015, Intel Corporation
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/hrtimer.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/trigger.h>
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#include <linux/iio/sw_trigger.h>
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/* default sampling frequency - 100Hz */
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#define HRTIMER_DEFAULT_SAMPLING_FREQUENCY 100
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struct iio_hrtimer_info {
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struct iio_sw_trigger swt;
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struct hrtimer timer;
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unsigned long sampling_frequency;
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ktime_t period;
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};
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static struct config_item_type iio_hrtimer_type = {
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.ct_owner = THIS_MODULE,
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};
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static
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ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct iio_trigger *trig = to_iio_trigger(dev);
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struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
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return snprintf(buf, PAGE_SIZE, "%lu\n", info->sampling_frequency);
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}
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static
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ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev,
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struct device_attribute *attr,
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const char *buf, size_t len)
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{
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struct iio_trigger *trig = to_iio_trigger(dev);
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struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
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unsigned long val;
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int ret;
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ret = kstrtoul(buf, 10, &val);
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if (ret)
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return ret;
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if (!val || val > NSEC_PER_SEC)
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return -EINVAL;
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info->sampling_frequency = val;
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info->period = ktime_set(0, NSEC_PER_SEC / val);
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return len;
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}
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static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
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iio_hrtimer_show_sampling_frequency,
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iio_hrtimer_store_sampling_frequency);
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static struct attribute *iio_hrtimer_attrs[] = {
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&dev_attr_sampling_frequency.attr,
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NULL
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};
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static const struct attribute_group iio_hrtimer_attr_group = {
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.attrs = iio_hrtimer_attrs,
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};
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static const struct attribute_group *iio_hrtimer_attr_groups[] = {
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&iio_hrtimer_attr_group,
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NULL
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};
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static enum hrtimer_restart iio_hrtimer_trig_handler(struct hrtimer *timer)
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{
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struct iio_hrtimer_info *info;
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info = container_of(timer, struct iio_hrtimer_info, timer);
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hrtimer_forward_now(timer, info->period);
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iio_trigger_poll(info->swt.trigger);
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return HRTIMER_RESTART;
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}
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static int iio_trig_hrtimer_set_state(struct iio_trigger *trig, bool state)
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{
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struct iio_hrtimer_info *trig_info;
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trig_info = iio_trigger_get_drvdata(trig);
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if (state)
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hrtimer_start(&trig_info->timer, trig_info->period,
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HRTIMER_MODE_REL);
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else
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hrtimer_cancel(&trig_info->timer);
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return 0;
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}
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static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
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.owner = THIS_MODULE,
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.set_trigger_state = iio_trig_hrtimer_set_state,
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};
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static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
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{
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struct iio_hrtimer_info *trig_info;
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int ret;
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trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
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if (!trig_info)
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return ERR_PTR(-ENOMEM);
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trig_info->swt.trigger = iio_trigger_alloc("%s", name);
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if (!trig_info->swt.trigger) {
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ret = -ENOMEM;
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goto err_free_trig_info;
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}
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iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
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trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
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trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;
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hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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trig_info->timer.function = iio_hrtimer_trig_handler;
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trig_info->sampling_frequency = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
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trig_info->period = ktime_set(0, NSEC_PER_SEC /
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trig_info->sampling_frequency);
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ret = iio_trigger_register(trig_info->swt.trigger);
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if (ret)
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goto err_free_trigger;
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iio_swt_group_init_type_name(&trig_info->swt, name, &iio_hrtimer_type);
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return &trig_info->swt;
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err_free_trigger:
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iio_trigger_free(trig_info->swt.trigger);
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err_free_trig_info:
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kfree(trig_info);
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return ERR_PTR(ret);
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}
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static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
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{
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struct iio_hrtimer_info *trig_info;
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trig_info = iio_trigger_get_drvdata(swt->trigger);
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iio_trigger_unregister(swt->trigger);
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/* cancel the timer after unreg to make sure no one rearms it */
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hrtimer_cancel(&trig_info->timer);
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iio_trigger_free(swt->trigger);
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kfree(trig_info);
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return 0;
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}
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static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
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.probe = iio_trig_hrtimer_probe,
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.remove = iio_trig_hrtimer_remove,
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};
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static struct iio_sw_trigger_type iio_trig_hrtimer = {
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.name = "hrtimer",
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.owner = THIS_MODULE,
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.ops = &iio_trig_hrtimer_ops,
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};
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module_iio_sw_trigger_driver(iio_trig_hrtimer);
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MODULE_AUTHOR("Marten Svanfeldt <marten@intuitiveaerial.com>");
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MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
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MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
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MODULE_LICENSE("GPL v2");
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