// 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_obj(*trig_info);
        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 <marten@intuitiveaerial.com>");
MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
MODULE_LICENSE("GPL v2");