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Date: Mon, 17 Aug 2015 15:45:58 +0300
From: Vladimir Barinov <vladimir.barinov@...entembedded.com>
To: Daniel Baluta <daniel.baluta@...el.com>, jic23@...nel.org,
jlbec@...lplan.org, linux-iio@...r.kernel.org,
linux-fsdevel@...r.kernel.org
CC: lars@...afoo.de, knaack.h@....de, linux-kernel@...r.kernel.org,
octavian.purdila@...el.com, pebolle@...cali.nl,
patrick.porlan@...el.com, adriana.reus@...el.com,
constantin.musca@...el.com, marten@...uitiveaerial.com,
cristina.opriceana@...il.com, pmeerw@...erw.net, hch@....de,
viro@...iv.linux.org.uk, akpm@...ux-foundation.org
Subject: Re: [PATCH v7 4/5] iio: trigger: Introduce IIO hrtimer based trigger
Hello Daniel,
I've verified that your hrtimer trigger works.
I have minor suggestions.
Will not it be useful to have ability to stop/start hrtimer polling
not only during attach/detach trigger.
f.e. writing 0 to sampling_frequency will hrtimer_cancel
and writing any valid frequency will hrtimer_start.
Regards,
Vladimir
On 11.08.2015 01:42, Daniel Baluta wrote:
> 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@...uitiveaerial.com>
> Signed-off-by: Lars-Peter Clausen <lars@...afoo.de>
> Signed-off-by: Daniel Baluta <daniel.baluta@...el.com>
> ---
> drivers/iio/trigger/Kconfig | 10 ++
> drivers/iio/trigger/Makefile | 2 +
> drivers/iio/trigger/iio-trig-hrtimer.c | 193 +++++++++++++++++++++++++++++++++
> 3 files changed, 205 insertions(+)
> create mode 100644 drivers/iio/trigger/iio-trig-hrtimer.c
>
> diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
> index 7999612..4505281 100644
> --- a/drivers/iio/trigger/Kconfig
> +++ b/drivers/iio/trigger/Kconfig
> @@ -5,6 +5,16 @@
>
> menu "Triggers - standalone"
>
> +config IIO_HRTIMER_TRIGGER
> + tristate "High resolution timer trigger"
> + select IIO_SW_TRIGGER
> + help
> + Provides a frequency based IIO trigger using high resolution
> + timers as interrupt source.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called iio-trig-hrtimer.
> +
> config IIO_INTERRUPT_TRIGGER
> tristate "Generic interrupt trigger"
> help
> diff --git a/drivers/iio/trigger/Makefile b/drivers/iio/trigger/Makefile
> index 0694dae..fe06eb5 100644
> --- a/drivers/iio/trigger/Makefile
> +++ b/drivers/iio/trigger/Makefile
> @@ -3,5 +3,7 @@
> #
>
> # When adding new entries keep the list in alphabetical order
> +
> +obj-$(CONFIG_IIO_HRTIMER_TRIGGER) += iio-trig-hrtimer.o
> obj-$(CONFIG_IIO_INTERRUPT_TRIGGER) += iio-trig-interrupt.o
> obj-$(CONFIG_IIO_SYSFS_TRIGGER) += iio-trig-sysfs.o
> diff --git a/drivers/iio/trigger/iio-trig-hrtimer.c b/drivers/iio/trigger/iio-trig-hrtimer.c
> new file mode 100644
> index 0000000..4631c7a
> --- /dev/null
> +++ b/drivers/iio/trigger/iio-trig-hrtimer.c
> @@ -0,0 +1,193 @@
> +/**
> + * The industrial I/O periodic hrtimer trigger driver
> + *
> + * Copyright (C) Intuitive Aerial AB
> + * Written by Marten Svanfeldt, marten@...uitiveaerial.com
> + * Copyright (C) 2012, Analog Device Inc.
> + * Author: Lars-Peter Clausen <lars@...afoo.de>
> + * Copyright (C) 2015, Intel Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + *
> + */
> +#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>
> +
> +/* default sampling frequency - 100Hz */
> +#define HRTIMER_DEFAULT_SAMPLING_FREQUENCY 100
> +
> +struct iio_hrtimer_info {
> + struct iio_sw_trigger swt;
> + struct hrtimer timer;
> + unsigned long sampling_frequency;
> + ktime_t period;
> +};
> +
> +static 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 snprintf(buf, PAGE_SIZE, "%lu\n", 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 val;
> + int ret;
> +
> + ret = kstrtoul(buf, 10, &val);
> + if (ret)
> + return ret;
> +
> + if (!val || val > NSEC_PER_SEC)
> + return -EINVAL;
> +
> + info->sampling_frequency = val;
> + info->period = ktime_set(0, NSEC_PER_SEC / val);
> +
> + 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);
> + else
> + hrtimer_cancel(&trig_info->timer);
> +
> + return 0;
> +}
> +
> +static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
> + .owner = THIS_MODULE,
> + .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("%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_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> + trig_info->timer.function = iio_hrtimer_trig_handler;
> +
> + trig_info->sampling_frequency = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
> + trig_info->period = ktime_set(0, NSEC_PER_SEC /
> + trig_info->sampling_frequency);
> +
> + 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;
> +}
> +
> +const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
> + .probe = iio_trig_hrtimer_probe,
> + .remove = iio_trig_hrtimer_remove,
> +};
> +
> +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 <marten@...uitiveaerial.com>");
> +MODULE_AUTHOR("Daniel Baluta <daniel.baluta@...el.com>");
> +MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
> +MODULE_LICENSE("GPL v2");
--
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