1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * uvc_debugfs.c -- USB Video Class driver - Debugging support
4 *
5 * Copyright (C) 2011
6 * Laurent Pinchart (laurent.pinchart@ideasonboard.com)
7 */
8
9#include <linux/module.h>
10#include <linux/debugfs.h>
11#include <linux/slab.h>
12#include <linux/usb.h>
13
14#include "uvcvideo.h"
15
16/* -----------------------------------------------------------------------------
17 * Statistics
18 */
19
20#define UVC_DEBUGFS_BUF_SIZE 1024
21
22struct uvc_debugfs_buffer {
23 size_t count;
24 char data[UVC_DEBUGFS_BUF_SIZE];
25};
26
27static int uvc_debugfs_stats_open(struct inode *inode, struct file *file)
28{
29 struct uvc_streaming *stream = inode->i_private;
30 struct uvc_debugfs_buffer *buf;
31
32 buf = kmalloc(size: sizeof(*buf), GFP_KERNEL);
33 if (buf == NULL)
34 return -ENOMEM;
35
36 buf->count = uvc_video_stats_dump(stream, buf: buf->data, size: sizeof(buf->data));
37
38 file->private_data = buf;
39 return 0;
40}
41
42static ssize_t uvc_debugfs_stats_read(struct file *file, char __user *user_buf,
43 size_t nbytes, loff_t *ppos)
44{
45 struct uvc_debugfs_buffer *buf = file->private_data;
46
47 return simple_read_from_buffer(to: user_buf, count: nbytes, ppos, from: buf->data,
48 available: buf->count);
49}
50
51static int uvc_debugfs_stats_release(struct inode *inode, struct file *file)
52{
53 kfree(objp: file->private_data);
54 file->private_data = NULL;
55
56 return 0;
57}
58
59static const struct file_operations uvc_debugfs_stats_fops = {
60 .owner = THIS_MODULE,
61 .open = uvc_debugfs_stats_open,
62 .llseek = no_llseek,
63 .read = uvc_debugfs_stats_read,
64 .release = uvc_debugfs_stats_release,
65};
66
67/* -----------------------------------------------------------------------------
68 * Global and stream initialization/cleanup
69 */
70
71static struct dentry *uvc_debugfs_root_dir;
72
73void uvc_debugfs_init_stream(struct uvc_streaming *stream)
74{
75 struct usb_device *udev = stream->dev->udev;
76 char dir_name[33];
77
78 if (uvc_debugfs_root_dir == NULL)
79 return;
80
81 snprintf(buf: dir_name, size: sizeof(dir_name), fmt: "%u-%u-%u", udev->bus->busnum,
82 udev->devnum, stream->intfnum);
83
84 stream->debugfs_dir = debugfs_create_dir(name: dir_name,
85 parent: uvc_debugfs_root_dir);
86
87 debugfs_create_file(name: "stats", mode: 0444, parent: stream->debugfs_dir, data: stream,
88 fops: &uvc_debugfs_stats_fops);
89}
90
91void uvc_debugfs_cleanup_stream(struct uvc_streaming *stream)
92{
93 debugfs_remove_recursive(dentry: stream->debugfs_dir);
94 stream->debugfs_dir = NULL;
95}
96
97void uvc_debugfs_init(void)
98{
99 uvc_debugfs_root_dir = debugfs_create_dir(name: "uvcvideo", parent: usb_debug_root);
100}
101
102void uvc_debugfs_cleanup(void)
103{
104 debugfs_remove_recursive(dentry: uvc_debugfs_root_dir);
105}
106

source code of linux/drivers/media/usb/uvc/uvc_debugfs.c