linux/drivers/interconnect/debugfs-client.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights reserved.
 */
#include <linux/debugfs.h>
#include <linux/interconnect.h>
#include <linux/platform_device.h>

#include "internal.h"

/*
 * This can be dangerous, therefore don't provide any real compile time
 * configuration option for this feature.
 * People who want to use this will need to modify the source code directly.
 */
#undef INTERCONNECT_ALLOW_WRITE_DEBUGFS

#if defined(INTERCONNECT_ALLOW_WRITE_DEBUGFS) && defined(CONFIG_DEBUG_FS)

static LIST_HEAD(debugfs_paths);
static DEFINE_MUTEX(debugfs_lock);

static struct platform_device *pdev;
static struct icc_path *cur_path;

static char *src_node;
static char *dst_node;
static u32 avg_bw;
static u32 peak_bw;
static u32 tag;

struct debugfs_path {
	const char *src;
	const char *dst;
	struct icc_path *path;
	struct list_head list;
};

static struct icc_path *get_path(const char *src, const char *dst)
{
	struct debugfs_path *path;

	list_for_each_entry(path, &debugfs_paths, list) {
		if (!strcmp(path->src, src) && !strcmp(path->dst, dst))
			return path->path;
	}

	return NULL;
}

static int icc_get_set(void *data, u64 val)
{
	struct debugfs_path *debugfs_path;
	char *src, *dst;
	int ret = 0;

	mutex_lock(&debugfs_lock);

	rcu_read_lock();
	src = rcu_dereference(src_node);
	dst = rcu_dereference(dst_node);

	/*
	 * If we've already looked up a path, then use the existing one instead
	 * of calling icc_get() again. This allows for updating previous BW
	 * votes when "get" is written to multiple times for multiple paths.
	 */
	cur_path = get_path(src, dst);
	if (cur_path) {
		rcu_read_unlock();
		goto out;
	}

	src = kstrdup(src, GFP_ATOMIC);
	dst = kstrdup(dst, GFP_ATOMIC);
	rcu_read_unlock();

	if (!src || !dst) {
		ret = -ENOMEM;
		goto err_free;
	}

	cur_path = icc_get(&pdev->dev, src, dst);
	if (IS_ERR(cur_path)) {
		ret = PTR_ERR(cur_path);
		goto err_free;
	}

	debugfs_path = kzalloc(sizeof(*debugfs_path), GFP_KERNEL);
	if (!debugfs_path) {
		ret = -ENOMEM;
		goto err_put;
	}

	debugfs_path->path = cur_path;
	debugfs_path->src = src;
	debugfs_path->dst = dst;
	list_add_tail(&debugfs_path->list, &debugfs_paths);

	goto out;

err_put:
	icc_put(cur_path);
err_free:
	kfree(src);
	kfree(dst);
out:
	mutex_unlock(&debugfs_lock);
	return ret;
}

DEFINE_DEBUGFS_ATTRIBUTE(icc_get_fops, NULL, icc_get_set, "%llu\n");

static int icc_commit_set(void *data, u64 val)
{
	int ret;

	mutex_lock(&debugfs_lock);

	if (IS_ERR_OR_NULL(cur_path)) {
		ret = PTR_ERR(cur_path);
		goto out;
	}

	icc_set_tag(cur_path, tag);
	ret = icc_set_bw(cur_path, avg_bw, peak_bw);
out:
	mutex_unlock(&debugfs_lock);
	return ret;
}

DEFINE_DEBUGFS_ATTRIBUTE(icc_commit_fops, NULL, icc_commit_set, "%llu\n");

int icc_debugfs_client_init(struct dentry *icc_dir)
{
	struct dentry *client_dir;
	int ret;

	pdev = platform_device_alloc("icc-debugfs-client", PLATFORM_DEVID_NONE);

	ret = platform_device_add(pdev);
	if (ret) {
		pr_err("%s: failed to add platform device: %d\n", __func__, ret);
		platform_device_put(pdev);
		return ret;
	}

	client_dir = debugfs_create_dir("test_client", icc_dir);

	debugfs_create_str("src_node", 0600, client_dir, &src_node);
	debugfs_create_str("dst_node", 0600, client_dir, &dst_node);
	debugfs_create_file("get", 0200, client_dir, NULL, &icc_get_fops);
	debugfs_create_u32("avg_bw", 0600, client_dir, &avg_bw);
	debugfs_create_u32("peak_bw", 0600, client_dir, &peak_bw);
	debugfs_create_u32("tag", 0600, client_dir, &tag);
	debugfs_create_file("commit", 0200, client_dir, NULL, &icc_commit_fops);

	return 0;
}

#else

int icc_debugfs_client_init(struct dentry *icc_dir)
{
	return 0;
}

#endif