// SPDX-License-Identifier: GPL-2.0-only
// SPDX-FileCopyrightText: Copyright (c) 2022-2024 NVIDIA CORPORATION & AFFILIATES. All rights reserved.

#include <linux/notifier.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform/tegra/ptp-notifier.h>

static int (*get_systime[MAX_MAC_INSTANCES])(struct net_device *, void *, int);
static struct net_device *registered_ndev[MAX_MAC_INSTANCES];
static DEFINE_RAW_SPINLOCK(ptp_notifier_lock);
static ATOMIC_NOTIFIER_HEAD(tegra_hwtime_chain_head);

/* Clients register for notification of hwtime change events */
int tegra_register_hwtime_notifier(struct notifier_block *nb)
{
	return atomic_notifier_chain_register(&tegra_hwtime_chain_head, nb);
}
EXPORT_SYMBOL(tegra_register_hwtime_notifier);

/* Clients unregister for notification of hwtime change events */
int tegra_unregister_hwtime_notifier(struct notifier_block *nb)
{
	return atomic_notifier_chain_unregister(&tegra_hwtime_chain_head, nb);
}
EXPORT_SYMBOL(tegra_unregister_hwtime_notifier);

/* Trigger notification of hwtime change to all registered clients */
int tegra_hwtime_notifier_call_chain(unsigned int val, void *v)
{
	int ret = atomic_notifier_call_chain(&tegra_hwtime_chain_head, val, v);

	return notifier_to_errno(ret);
}

void tegra_register_hwtime_source(int (*func)(struct net_device *, void *, int),
				  struct net_device *ndev)
{
	unsigned long flags;
	int index = 0;

	for (index = 0; index < MAX_MAC_INSTANCES; index++) {
		if (registered_ndev[index] == ndev) {
			pr_debug("source is already registered for this intf\n");
			/* Didn't call the notifier as we are not using
			 * tegra_register_hwtime_notifier anywhere
			 */
			return;
		}
	}
	raw_spin_lock_irqsave(&ptp_notifier_lock, flags);
	for (index = 0; index < MAX_MAC_INSTANCES; index++) {
		if (get_systime[index] == NULL) {
			get_systime[index] = func;
			registered_ndev[index] = ndev;
			break;
		}
	}
	if (index ==  MAX_MAC_INSTANCES)
		pr_err("Maximum registrations reached\n");

	raw_spin_unlock_irqrestore(&ptp_notifier_lock, flags);

	/* Notify HW time stamp update to registered clients.
	 * NULL callback parameter. We use a separate timestamp
	 * function to peek MAC time.
	 */
	tegra_hwtime_notifier_call_chain(0, NULL);
}
EXPORT_SYMBOL(tegra_register_hwtime_source);

void tegra_unregister_hwtime_source(struct net_device *dev)
{
	unsigned long flags;
	int index = 0;

	raw_spin_lock_irqsave(&ptp_notifier_lock, flags);
	for (index = 0; index < MAX_MAC_INSTANCES; index++) {
		if (dev == registered_ndev[index])
			break;
	}
	if (index == MAX_MAC_INSTANCES) {
		pr_debug("Trying to unregister non-registered hwtime source");
		raw_spin_unlock_irqrestore(&ptp_notifier_lock, flags);
		return;
	}
	get_systime[index] = NULL;
	registered_ndev[index] = NULL;
	raw_spin_unlock_irqrestore(&ptp_notifier_lock, flags);
}
EXPORT_SYMBOL(tegra_unregister_hwtime_source);

int tegra_get_hwtime(const struct device_node *emac_node, void *ts, int ts_type)
{
	unsigned long flags;
	int ret = 0, index = 0;
	struct net_device *dev = NULL;
	struct net_device *intf_dev = NULL;
	const char *intf_name = "eth0";

	if (!ts) {
		pr_err("%s: time-stamp ptr is NULL\n", __func__);
		return -EINVAL;
	}

	if (emac_node == NULL) {
		pr_debug("EMAC node is invalid, using default interface %s\n", intf_name);
		intf_dev = dev_get_by_name(&init_net, intf_name);
		if (!intf_dev || !(intf_dev->flags & IFF_UP)) {
			pr_debug("Network interface %s is not %s", intf_name,
									!intf_dev ? "found":"up");
			ret = -EINVAL;
			goto out;
		}
	}

	raw_spin_lock_irqsave(&ptp_notifier_lock, flags);
	for (index = 0; index < MAX_MAC_INSTANCES; index++) {
		dev = registered_ndev[index];
		if (dev == NULL) {
			pr_debug("No registered net device for index %d\n", index);
			continue;
		}
		if (emac_node == dev->dev.parent->of_node) {
			pr_debug("found emac name (%s)\n", emac_node->full_name);
			break;
		} else if (intf_dev && intf_dev == dev) {
			pr_debug("found ethenet interface (%s)\n", intf_name);
			break;
		}

	}
	if (index == MAX_MAC_INSTANCES) {
		pr_debug("%s: ethernet device %s is not registered!\n", __func__,
						!emac_node ? intf_name : emac_node->full_name);
		ret = -EINVAL;
		goto unlock;
	}

	if (get_systime[index])
		ret = (get_systime[index])(dev, ts, ts_type);
	else
		ret = -EINVAL;
unlock:
	raw_spin_unlock_irqrestore(&ptp_notifier_lock, flags);
out:
	if (intf_dev)
		dev_put(intf_dev);

	return ret;
}
EXPORT_SYMBOL(tegra_get_hwtime);

MODULE_LICENSE("GPL v2");