mse_ptp_dummy.c

/*************************************************************************/ /*
 avb-mse

 Copyright (C) 2016-2017 Renesas Electronics Corporation

 License        Dual MIT/GPLv2

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 GPLv2:
 If you wish to use this file under the terms of GPL, following terms are
 effective.

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; version 2 of the License.

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 but WITHOUT ANY WARRANTY; without even the implied warranty of
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*/ /*************************************************************************/

#undef pr_fmt
#define pr_fmt(fmt) KBUILD_MODNAME "/" fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/hrtimer.h>

#include "ravb_mse_kernel.h"

#define MAX_PTP_DEVICES    10
#define MAX_TIMESTAMPS     100

#define PTP_DUMMY_INTERVAL 3333333  /* 3.33..ms */

#define q_next(que, pos)        (((que)->pos + 1) % (que)->len)
#define q_empty(que)            ((que)->head == (que)->tail)

/* structs */
struct ptp_queue {
	int head;
	int tail;
	int len;
	u64 *timestamps;
};

struct ptp_device {
	int			index;
	int			ch;
	struct			hrtimer timer;
	int			timer_interval;
	struct ptp_queue	que;
	/* timestamp queue lock */
	spinlock_t		qlock;
};

/* total devices */
static struct ptp_device *g_ptp_devices[MAX_PTP_DEVICES];
DECLARE_BITMAP(ptp_dummy_device_map, MAX_PTP_DEVICES);
DEFINE_SPINLOCK(ptp_dummy_lock);

static int enqueue(struct ptp_queue *que, u64 ns)
{
	mse_debug("START head=%d, tail=%d\n", que->head, que->tail);

	if (q_next(que, tail) == que->head)
		que->head = q_next(que, head);

	que->timestamps[que->tail] = ns;
	que->tail = q_next(que, tail);

	return 0;
}

static int dequeue(struct ptp_queue *que, u64 *ns)
{
	if (q_empty(que))
		return -1;

	*ns = que->timestamps[que->head];
	que->head = q_next(que, head);

	return 0;
}

static enum hrtimer_restart ptp_timestamp_callback(struct hrtimer *arg)
{
	struct ptp_device *dev;
	u64 ns;
	unsigned long flags;

	dev = container_of(arg, struct ptp_device, timer);

	if (!dev->timer_interval)
		return HRTIMER_NORESTART;

	hrtimer_add_expires_ns(&dev->timer, dev->timer_interval);

	/* Get time from system timer */
	ns = ktime_get_real_ns();

	spin_lock_irqsave(&dev->qlock, flags);

	/* add to queue */
	enqueue(&dev->que, ns);

	spin_unlock_irqrestore(&dev->qlock, flags);

	return HRTIMER_RESTART;
}

static struct ptp_device *mse_ptp_get_dev(void *ptp_handle)
{
	struct ptp_device *dev = ptp_handle;

	if (!dev)
		return NULL;

	if (g_ptp_devices[dev->index] != dev)
		return NULL;

	return dev;
}

/*
 * Public functions
 */
int mse_ptp_get_time_dummy(u64 *ns)
{
	/* Get time from system timer */
	*ns = ktime_get_real_ns();

	return 0;
}

int mse_ptp_capture_stop_dummy(void *ptp_handle)
{
	struct ptp_device *dev;

	dev = mse_ptp_get_dev(ptp_handle);
	if (!dev)
		return -EINVAL;

	/* if already capture started, return success */
	if (!dev->timer_interval)
		return 0;

	/* timer stop */
	dev->timer_interval = 0;
	hrtimer_cancel(&dev->timer);

	/* unassing and free timestamp buffer */
	kfree(dev->que.timestamps);
	dev->que.timestamps = NULL;
	dev->que.len = 0;

	return 0;
}

int mse_ptp_capture_start_dummy(void *ptp_handle,
				int ch,
				int max_count)
{
	struct ptp_device *dev;
	void *timestamps;
	int ret;

	dev = mse_ptp_get_dev(ptp_handle);
	if (!dev)
		return -EINVAL;

	/* alloc timestamp buffer */
	timestamps = kcalloc(max_count + 1, sizeof(u64), GFP_KERNEL);
	if (!timestamps)
		return -ENOMEM;

	/* if already capture started, so stop it */
	if (dev->timer_interval) {
		ret = mse_ptp_capture_stop_dummy(ptp_handle);
		if (ret) {
			kfree(timestamps);
			return ret;
		}
	}

	/* assign timestamp buffer to queue */
	dev->que.timestamps = timestamps;
	dev->que.len = max_count + 1;

	/* start timer */
	dev->timer_interval = PTP_DUMMY_INTERVAL;
	hrtimer_start(&dev->timer,
		      ns_to_ktime(dev->timer_interval),
		      HRTIMER_MODE_REL);

	return 0;
}

int mse_ptp_get_timestamps_dummy(void *ptp_handle,
				 int req_count,
				 u64 *timestamps)
{
	struct ptp_device *dev;
	unsigned long flags;
	int i;

	dev = mse_ptp_get_dev(ptp_handle);
	if (!dev)
		return -EINVAL;

	/* if timer is NOT started */
	if (!dev->timer_interval)
		return -EPERM;

	spin_lock_irqsave(&dev->qlock, flags);

	for (i = 0; i < req_count; i++)
		if (dequeue(&dev->que, &timestamps[i]) < 0)
			break;

	spin_unlock_irqrestore(&dev->qlock, flags);

	return i;
}

void *mse_ptp_open_dummy(void)
{
	int index;
	struct ptp_device *dev;
	unsigned long flags;

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev)
		return NULL;

	spin_lock_irqsave(&ptp_dummy_lock, flags);

	index = find_first_zero_bit(ptp_dummy_device_map, MAX_PTP_DEVICES);
	if (index >= ARRAY_SIZE(g_ptp_devices)) {
		spin_unlock_irqrestore(&ptp_dummy_lock, flags);
		mse_err("cannot register ptp dummy device\n");
		kfree(dev);
		return NULL;
	}

	set_bit(index, ptp_dummy_device_map);
	g_ptp_devices[index] = dev;
	dev->index = index;

	spin_unlock_irqrestore(&ptp_dummy_lock, flags);

	/* initialize ptp dummy device */
	spin_lock_init(&dev->qlock);

	/* init timer */
	hrtimer_init(&dev->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	dev->timer_interval = 0;
	dev->timer.function = &ptp_timestamp_callback;

	mse_debug("ptp_handle=%p\n", dev);

	return dev;
}

int mse_ptp_close_dummy(void *ptp_handle)
{
	struct ptp_device *dev;
	unsigned long flags;
	int ret;

	dev = mse_ptp_get_dev(ptp_handle);
	if (!dev)
		return -EINVAL;

	/* if already capture started, so stop it */
	if (dev->timer_interval) {
		ret = mse_ptp_capture_stop_dummy(ptp_handle);
		if (ret)
			return ret;
	}

	spin_lock_irqsave(&ptp_dummy_lock, flags);

	g_ptp_devices[dev->index] = NULL;
	clear_bit(dev->index, ptp_dummy_device_map);

	spin_unlock_irqrestore(&ptp_dummy_lock, flags);

	kfree(dev);

	return 0;
}

void *mse_ptp_timer_open_dummy(u32 (*handler)(void *),
			       void *priv)
{
	return NULL;
}

int mse_ptp_timer_close_dummy(void *timer_handle)
{
	return -EPERM;
}

int mse_ptp_timer_start_dummy(void *timer_handle, u32 start)
{
	return -EPERM;
}

int mse_ptp_timer_cancel_dummy(void *timer_handle)
{
	return -EPERM;
}