// SPDX-License-Identifier: GPL-2.0-only
/*
 * Authors:
 *   Branden Bonaby <brandonbonaby94@gmail.com>
 */

#include <linux/hyperv.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/err.h>

#include "hyperv_vmbus.h"

static struct dentry *hv_debug_root;

static int hv_debugfs_delay_get(void *data, u64 *val)
{
	*val = *(u32 *)data;
	return 0;
}

static int hv_debugfs_delay_set(void *data, u64 val)
{
	if (val > 1000)
		return -EINVAL;
	*(u32 *)data = val;
	return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(hv_debugfs_delay_fops, hv_debugfs_delay_get,
			 hv_debugfs_delay_set, "%llu\n");

static int hv_debugfs_state_get(void *data, u64 *val)
{
	*val = *(bool *)data;
	return 0;
}

static int hv_debugfs_state_set(void *data, u64 val)
{
	if (val == 1)
		*(bool *)data = true;
	else if (val == 0)
		*(bool *)data = false;
	else
		return -EINVAL;
	return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(hv_debugfs_state_fops, hv_debugfs_state_get,
			 hv_debugfs_state_set, "%llu\n");

/* Setup delay files to store test values */
static int hv_debug_delay_files(struct hv_device *dev, struct dentry *root)
{
	struct vmbus_channel *channel = dev->channel;
	char *buffer = "fuzz_test_buffer_interrupt_delay";
	char *message = "fuzz_test_message_delay";
	int *buffer_val = &channel->fuzz_testing_interrupt_delay;
	int *message_val = &channel->fuzz_testing_message_delay;
	struct dentry *buffer_file, *message_file;

	buffer_file = debugfs_create_file(buffer, 0644, root,
					  buffer_val,
					  &hv_debugfs_delay_fops);
	if (IS_ERR(buffer_file)) {
		pr_debug("debugfs_hyperv: file %s not created\n", buffer);
		return PTR_ERR(buffer_file);
	}

	message_file = debugfs_create_file(message, 0644, root,
					   message_val,
					   &hv_debugfs_delay_fops);
	if (IS_ERR(message_file)) {
		pr_debug("debugfs_hyperv: file %s not created\n", message);
		return PTR_ERR(message_file);
	}

	return 0;
}

/* Setup test state value for vmbus device */
static int hv_debug_set_test_state(struct hv_device *dev, struct dentry *root)
{
	struct vmbus_channel *channel = dev->channel;
	bool *state = &channel->fuzz_testing_state;
	char *status = "fuzz_test_state";
	struct dentry *test_state;

	test_state = debugfs_create_file(status, 0644, root,
					 state,
					 &hv_debugfs_state_fops);
	if (IS_ERR(test_state)) {
		pr_debug("debugfs_hyperv: file %s not created\n", status);
		return PTR_ERR(test_state);
	}

	return 0;
}

/* Bind hv device to a dentry for debugfs */
static void hv_debug_set_dir_dentry(struct hv_device *dev, struct dentry *root)
{
	if (hv_debug_root)
		dev->debug_dir = root;
}

/* Create all test dentry's and names for fuzz testing */
int hv_debug_add_dev_dir(struct hv_device *dev)
{
	const char *device = dev_name(&dev->device);
	char *delay_name = "delay";
	struct dentry *delay, *dev_root;
	int ret;

	if (!IS_ERR(hv_debug_root)) {
		dev_root = debugfs_create_dir(device, hv_debug_root);
		if (IS_ERR(dev_root)) {
			pr_debug("debugfs_hyperv: hyperv/%s/ not created\n",
				 device);
			return PTR_ERR(dev_root);
		}
		hv_debug_set_test_state(dev, dev_root);
		hv_debug_set_dir_dentry(dev, dev_root);
		delay = debugfs_create_dir(delay_name, dev_root);

		if (IS_ERR(delay)) {
			pr_debug("debugfs_hyperv: hyperv/%s/%s/ not created\n",
				 device, delay_name);
			return PTR_ERR(delay);
		}
		ret = hv_debug_delay_files(dev, delay);

		return ret;
	}
	pr_debug("debugfs_hyperv: hyperv/ not in root debugfs path\n");
	return PTR_ERR(hv_debug_root);
}

/* Remove dentry associated with released hv device */
void hv_debug_rm_dev_dir(struct hv_device *dev)
{
	if (!IS_ERR(hv_debug_root))
		debugfs_remove_recursive(dev->debug_dir);
}

/* Remove all dentrys associated with vmbus testing */
void hv_debug_rm_all_dir(void)
{
	debugfs_remove_recursive(hv_debug_root);
}

/* Delay buffer/message reads on a vmbus channel */
void hv_debug_delay_test(struct vmbus_channel *channel, enum delay delay_type)
{
	struct vmbus_channel *test_channel =    channel->primary_channel ?
						channel->primary_channel :
						channel;
	bool state = test_channel->fuzz_testing_state;

	if (state) {
		if (delay_type == 0)
			udelay(test_channel->fuzz_testing_interrupt_delay);
		else
			udelay(test_channel->fuzz_testing_message_delay);
	}
}

/* Initialize top dentry for vmbus testing */
int hv_debug_init(void)
{
	hv_debug_root = debugfs_create_dir("hyperv", NULL);
	if (IS_ERR(hv_debug_root)) {
		pr_debug("debugfs_hyperv: hyperv/ not created\n");
		return PTR_ERR(hv_debug_root);
	}
	return 0;
}