diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/iio/trigger/iio-trig-hrtimer.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/drivers/iio/trigger/iio-trig-hrtimer.c b/drivers/iio/trigger/iio-trig-hrtimer.c new file mode 100644 index 000000000..7accd0187 --- /dev/null +++ b/drivers/iio/trigger/iio-trig-hrtimer.c @@ -0,0 +1,191 @@ +/** + * The industrial I/O periodic hrtimer trigger driver + * + * Copyright (C) Intuitive Aerial AB + * Written by Marten Svanfeldt, marten@intuitiveaerial.com + * Copyright (C) 2012, Analog Device Inc. + * Author: Lars-Peter Clausen <lars@metafoo.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 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 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 = 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 = { + .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 = 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; +} + +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 <marten@intuitiveaerial.com>"); +MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>"); +MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem"); +MODULE_LICENSE("GPL v2"); |