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v4l2loopback.c
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v4l2loopback.c
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/* -*- c-file-style: "linux" -*- */
/*
* v4l2loopback.c -- video4linux2 loopback driver
*
* Copyright (C) 2005-2009 Vasily Levin (vasaka@gmail.com)
* Copyright (C) 2010-2023 IOhannes m zmoelnig (zmoelnig@iem.at)
* Copyright (C) 2011 Stefan Diewald (stefan.diewald@mytum.de)
* Copyright (C) 2012 Anton Novikov (random.plant@gmail.com)
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
*/
#include <linux/version.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/time.h>
#include <linux/module.h>
#include <linux/videodev2.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/capability.h>
#include <linux/eventpoll.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-common.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ctrls.h>
#include <media/v4l2-event.h>
#include <linux/miscdevice.h>
#include "v4l2loopback.h"
#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 0, 0)
#error This module is not supported on kernels before 4.0.0.
#endif
#if defined(timer_setup) && defined(from_timer)
#define HAVE_TIMER_SETUP
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 7, 0)
#define VFL_TYPE_VIDEO VFL_TYPE_GRABBER
#endif
#define V4L2LOOPBACK_VERSION_CODE \
KERNEL_VERSION(V4L2LOOPBACK_VERSION_MAJOR, V4L2LOOPBACK_VERSION_MINOR, \
V4L2LOOPBACK_VERSION_BUGFIX)
MODULE_DESCRIPTION("V4L2 loopback video device");
MODULE_AUTHOR("Vasily Levin, "
"IOhannes m zmoelnig <zmoelnig@iem.at>,"
"Stefan Diewald,"
"Anton Novikov"
"et al.");
#ifdef SNAPSHOT_VERSION
MODULE_VERSION(__stringify(SNAPSHOT_VERSION));
#else
MODULE_VERSION("" __stringify(V4L2LOOPBACK_VERSION_MAJOR) "." __stringify(
V4L2LOOPBACK_VERSION_MINOR) "." __stringify(V4L2LOOPBACK_VERSION_BUGFIX));
#endif
MODULE_LICENSE("GPL");
/*
* helpers
*/
#define dprintk(fmt, args...) \
do { \
if (debug > 0) { \
printk(KERN_INFO "v4l2-loopback[" __stringify( \
__LINE__) "], pid(%d): " fmt, \
task_pid_nr(current), ##args); \
} \
} while (0)
#define MARK() \
do { \
if (debug > 1) { \
printk(KERN_INFO "%s:%d[%s], pid(%d)\n", __FILE__, \
__LINE__, __func__, task_pid_nr(current)); \
} \
} while (0)
#define dprintkrw(fmt, args...) \
do { \
if (debug > 2) { \
printk(KERN_INFO "v4l2-loopback[" __stringify( \
__LINE__) "], pid(%d): " fmt, \
task_pid_nr(current), ##args); \
} \
} while (0)
static inline void v4l2l_get_timestamp(struct v4l2_buffer *b)
{
struct timespec64 ts;
ktime_get_ts64(&ts);
b->timestamp.tv_sec = ts.tv_sec;
b->timestamp.tv_usec = (ts.tv_nsec / NSEC_PER_USEC);
b->flags |= V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
}
#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 16, 0)
typedef unsigned __poll_t;
#endif
/* module constants
* can be overridden during he build process using something like
* make KCPPFLAGS="-DMAX_DEVICES=100"
*/
/* maximum number of v4l2loopback devices that can be created */
#ifndef MAX_DEVICES
#define MAX_DEVICES 10
#endif
/* whether the default is to announce capabilities exclusively or not */
#ifndef V4L2LOOPBACK_DEFAULT_EXCLUSIVECAPS
#define V4L2LOOPBACK_DEFAULT_EXCLUSIVECAPS 0
#endif
/* when a producer is considered to have gone stale */
#ifndef MAX_TIMEOUT
#define MAX_TIMEOUT (100 * 1000) /* in msecs */
#endif
/* max buffers that can be mapped, actually they
* are all mapped to max_buffers buffers */
#ifndef MAX_BUFFERS
#define MAX_BUFFERS 32
#endif
/* module parameters */
static int debug = 0;
module_param(debug, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "debugging level (higher values == more verbose)");
#define V4L2LOOPBACK_DEFAULT_MAX_BUFFERS 2
static int max_buffers = V4L2LOOPBACK_DEFAULT_MAX_BUFFERS;
module_param(max_buffers, int, S_IRUGO);
MODULE_PARM_DESC(max_buffers,
"how many buffers should be allocated [DEFAULT: " __stringify(
V4L2LOOPBACK_DEFAULT_MAX_BUFFERS) "]");
/* how many times a device can be opened
* the per-module default value can be overridden on a per-device basis using
* the /sys/devices interface
*
* note that max_openers should be at least 2 in order to get a working system:
* one opener for the producer and one opener for the consumer
* however, we leave that to the user
*/
#define V4L2LOOPBACK_DEFAULT_MAX_OPENERS 10
static int max_openers = V4L2LOOPBACK_DEFAULT_MAX_OPENERS;
module_param(max_openers, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(
max_openers,
"how many users can open the loopback device [DEFAULT: " __stringify(
V4L2LOOPBACK_DEFAULT_MAX_OPENERS) "]");
static int devices = -1;
module_param(devices, int, 0);
MODULE_PARM_DESC(devices, "how many devices should be created");
static int video_nr[MAX_DEVICES] = { [0 ...(MAX_DEVICES - 1)] = -1 };
module_param_array(video_nr, int, NULL, 0444);
MODULE_PARM_DESC(video_nr,
"video device numbers (-1=auto, 0=/dev/video0, etc.)");
static char *card_label[MAX_DEVICES];
module_param_array(card_label, charp, NULL, 0000);
MODULE_PARM_DESC(card_label, "card labels for each device");
static bool exclusive_caps[MAX_DEVICES] = {
[0 ...(MAX_DEVICES - 1)] = V4L2LOOPBACK_DEFAULT_EXCLUSIVECAPS
};
module_param_array(exclusive_caps, bool, NULL, 0444);
/* FIXXME: wording */
MODULE_PARM_DESC(
exclusive_caps,
"whether to announce OUTPUT/CAPTURE capabilities exclusively or not [DEFAULT: " __stringify(
V4L2LOOPBACK_DEFAULT_EXCLUSIVECAPS) "]");
/* format specifications */
#define V4L2LOOPBACK_SIZE_MIN_WIDTH 48
#define V4L2LOOPBACK_SIZE_MIN_HEIGHT 32
#define V4L2LOOPBACK_SIZE_DEFAULT_MAX_WIDTH 8192
#define V4L2LOOPBACK_SIZE_DEFAULT_MAX_HEIGHT 8192
#define V4L2LOOPBACK_SIZE_DEFAULT_WIDTH 640
#define V4L2LOOPBACK_SIZE_DEFAULT_HEIGHT 480
static int max_width = V4L2LOOPBACK_SIZE_DEFAULT_MAX_WIDTH;
module_param(max_width, int, S_IRUGO);
MODULE_PARM_DESC(max_width,
"maximum allowed frame width [DEFAULT: " __stringify(
V4L2LOOPBACK_SIZE_DEFAULT_MAX_WIDTH) "]");
static int max_height = V4L2LOOPBACK_SIZE_DEFAULT_MAX_HEIGHT;
module_param(max_height, int, S_IRUGO);
MODULE_PARM_DESC(max_height,
"maximum allowed frame height [DEFAULT: " __stringify(
V4L2LOOPBACK_SIZE_DEFAULT_MAX_HEIGHT) "]");
static DEFINE_IDR(v4l2loopback_index_idr);
static DEFINE_MUTEX(v4l2loopback_ctl_mutex);
/* frame intervals */
#define V4L2LOOPBACK_FPS_MIN 0
#define V4L2LOOPBACK_FPS_MAX 1000
/* control IDs */
#define V4L2LOOPBACK_CID_BASE (V4L2_CID_USER_BASE | 0xf000)
#define CID_KEEP_FORMAT (V4L2LOOPBACK_CID_BASE + 0)
#define CID_SUSTAIN_FRAMERATE (V4L2LOOPBACK_CID_BASE + 1)
#define CID_TIMEOUT (V4L2LOOPBACK_CID_BASE + 2)
#define CID_TIMEOUT_IMAGE_IO (V4L2LOOPBACK_CID_BASE + 3)
static int v4l2loopback_s_ctrl(struct v4l2_ctrl *ctrl);
static const struct v4l2_ctrl_ops v4l2loopback_ctrl_ops = {
.s_ctrl = v4l2loopback_s_ctrl,
};
static const struct v4l2_ctrl_config v4l2loopback_ctrl_keepformat = {
// clang-format off
.ops = &v4l2loopback_ctrl_ops,
.id = CID_KEEP_FORMAT,
.name = "keep_format",
.type = V4L2_CTRL_TYPE_BOOLEAN,
.min = 0,
.max = 1,
.step = 1,
.def = 0,
// clang-format on
};
static const struct v4l2_ctrl_config v4l2loopback_ctrl_sustainframerate = {
// clang-format off
.ops = &v4l2loopback_ctrl_ops,
.id = CID_SUSTAIN_FRAMERATE,
.name = "sustain_framerate",
.type = V4L2_CTRL_TYPE_BOOLEAN,
.min = 0,
.max = 1,
.step = 1,
.def = 0,
// clang-format on
};
static const struct v4l2_ctrl_config v4l2loopback_ctrl_timeout = {
// clang-format off
.ops = &v4l2loopback_ctrl_ops,
.id = CID_TIMEOUT,
.name = "timeout",
.type = V4L2_CTRL_TYPE_INTEGER,
.min = 0,
.max = MAX_TIMEOUT,
.step = 1,
.def = 0,
// clang-format on
};
static const struct v4l2_ctrl_config v4l2loopback_ctrl_timeoutimageio = {
// clang-format off
.ops = &v4l2loopback_ctrl_ops,
.id = CID_TIMEOUT_IMAGE_IO,
.name = "timeout_image_io",
.type = V4L2_CTRL_TYPE_BUTTON,
.min = 0,
.max = 1,
.step = 1,
.def = 0,
// clang-format on
};
/* module structures */
struct v4l2loopback_private {
int device_nr;
};
/* TODO(vasaka) use typenames which are common to kernel, but first find out if
* it is needed */
/* struct keeping state and settings of loopback device */
struct v4l2l_buffer {
struct v4l2_buffer buffer;
struct list_head list_head;
int use_count;
};
struct v4l2_loopback_device {
struct v4l2_device v4l2_dev;
struct v4l2_ctrl_handler ctrl_handler;
struct video_device *vdev;
/* pixel and stream format */
struct v4l2_pix_format pix_format;
bool pix_format_has_valid_sizeimage;
struct v4l2_captureparm capture_param;
unsigned long frame_jiffies;
/* ctrls */
int keep_format; /* CID_KEEP_FORMAT; stay ready_for_capture even when all
openers close() the device */
int sustain_framerate; /* CID_SUSTAIN_FRAMERATE; duplicate frames to maintain
(close to) nominal framerate */
/* buffers stuff */
u8 *image; /* pointer to actual buffers data */
unsigned long int imagesize; /* size of buffers data */
int buffers_number; /* should not be big, 4 is a good choice */
struct v4l2l_buffer buffers[MAX_BUFFERS]; /* inner driver buffers */
int used_buffers; /* number of the actually used buffers */
int max_openers; /* how many times can this device be opened */
s64 write_position; /* number of last written frame + 1 */
struct list_head outbufs_list; /* buffers in output DQBUF order */
int bufpos2index
[MAX_BUFFERS]; /* mapping of (read/write_position % used_buffers)
* to inner buffer index */
long buffer_size;
/* sustain_framerate stuff */
struct timer_list sustain_timer;
unsigned int reread_count;
/* timeout stuff */
unsigned long timeout_jiffies; /* CID_TIMEOUT; 0 means disabled */
int timeout_image_io; /* CID_TIMEOUT_IMAGE_IO; next opener will
* read/write to timeout_image */
u8 *timeout_image; /* copy of it will be captured when timeout passes */
struct v4l2l_buffer timeout_image_buffer;
struct timer_list timeout_timer;
int timeout_happened;
/* sync stuff */
atomic_t open_count;
int ready_for_capture; /* set to the number of writers that opened the
* device and negotiated format. */
int ready_for_output; /* set to true when no writer is currently attached
* this differs slightly from !ready_for_capture,
* e.g. when using fallback images */
int active_readers; /* increase if any reader starts streaming */
int announce_all_caps; /* set to false, if device caps (OUTPUT/CAPTURE)
* should only be announced if the resp. "ready"
* flag is set; default=TRUE */
int min_width, max_width;
int min_height, max_height;
char card_label[32];
wait_queue_head_t read_event;
spinlock_t lock, list_lock;
};
/* types of opener shows what opener wants to do with loopback */
enum opener_type {
// clang-format off
UNNEGOTIATED = 0,
READER = 1,
WRITER = 2,
// clang-format on
};
/* struct keeping state and type of opener */
struct v4l2_loopback_opener {
enum opener_type type;
s64 read_position; /* number of last processed frame + 1 or
* write_position - 1 if reader went out of sync */
unsigned int reread_count;
struct v4l2_buffer *buffers;
int buffers_number; /* should not be big, 4 is a good choice */
int timeout_image_io;
struct v4l2_fh fh;
};
#define fh_to_opener(ptr) container_of((ptr), struct v4l2_loopback_opener, fh)
/* this is heavily inspired by the bttv driver found in the linux kernel */
struct v4l2l_format {
char *name;
int fourcc; /* video4linux 2 */
int depth; /* bit/pixel */
int flags;
};
/* set the v4l2l_format.flags to PLANAR for non-packed formats */
#define FORMAT_FLAGS_PLANAR 0x01
#define FORMAT_FLAGS_COMPRESSED 0x02
#include "v4l2loopback_formats.h"
#ifndef V4L2_TYPE_IS_CAPTURE
#define V4L2_TYPE_IS_CAPTURE(type) \
((type) == V4L2_BUF_TYPE_VIDEO_CAPTURE || \
(type) == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE)
#endif /* V4L2_TYPE_IS_CAPTURE */
#ifndef V4L2_TYPE_IS_OUTPUT
#define V4L2_TYPE_IS_OUTPUT(type) \
((type) == V4L2_BUF_TYPE_VIDEO_OUTPUT || \
(type) == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
#endif /* V4L2_TYPE_IS_OUTPUT */
/* whether the format can be changed */
/* the format is fixated if we
- have writers (ready_for_capture>0)
- and/or have readers (active_readers>0)
*/
#define V4L2LOOPBACK_IS_FIXED_FMT(device) \
(device->ready_for_capture > 0 || device->active_readers > 0 || \
device->keep_format)
static const unsigned int FORMATS = ARRAY_SIZE(formats);
static char *fourcc2str(unsigned int fourcc, char buf[4])
{
buf[0] = (fourcc >> 0) & 0xFF;
buf[1] = (fourcc >> 8) & 0xFF;
buf[2] = (fourcc >> 16) & 0xFF;
buf[3] = (fourcc >> 24) & 0xFF;
return buf;
}
static const struct v4l2l_format *format_by_fourcc(int fourcc)
{
unsigned int i;
for (i = 0; i < FORMATS; i++) {
if (formats[i].fourcc == fourcc)
return formats + i;
}
dprintk("unsupported format '%c%c%c%c'\n", (fourcc >> 0) & 0xFF,
(fourcc >> 8) & 0xFF, (fourcc >> 16) & 0xFF,
(fourcc >> 24) & 0xFF);
return NULL;
}
static void pix_format_set_size(struct v4l2_pix_format *f,
const struct v4l2l_format *fmt,
unsigned int width, unsigned int height)
{
f->width = width;
f->height = height;
if (fmt->flags & FORMAT_FLAGS_PLANAR) {
f->bytesperline = width; /* Y plane */
f->sizeimage = (width * height * fmt->depth) >> 3;
} else if (fmt->flags & FORMAT_FLAGS_COMPRESSED) {
/* doesn't make sense for compressed formats */
f->bytesperline = 0;
f->sizeimage = (width * height * fmt->depth) >> 3;
} else {
f->bytesperline = (width * fmt->depth) >> 3;
f->sizeimage = height * f->bytesperline;
}
}
static int v4l2l_fill_format(struct v4l2_format *fmt, int capture,
const u32 minwidth, const u32 maxwidth,
const u32 minheight, const u32 maxheight)
{
u32 width = fmt->fmt.pix.width, height = fmt->fmt.pix.height;
u32 pixelformat = fmt->fmt.pix.pixelformat;
struct v4l2_format fmt0 = *fmt;
u32 bytesperline = 0, sizeimage = 0;
if (!width)
width = V4L2LOOPBACK_SIZE_DEFAULT_WIDTH;
if (!height)
height = V4L2LOOPBACK_SIZE_DEFAULT_HEIGHT;
if (width < minwidth)
width = minwidth;
if (width > maxwidth)
width = maxwidth;
if (height < minheight)
height = minheight;
if (height > maxheight)
height = maxheight;
/* sets: width,height,pixelformat,bytesperline,sizeimage */
if (!(V4L2_TYPE_IS_MULTIPLANAR(fmt0.type))) {
fmt0.fmt.pix.bytesperline = 0;
fmt0.fmt.pix.sizeimage = 0;
}
if (0) {
;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 2, 0)
} else if (!v4l2_fill_pixfmt(&fmt0.fmt.pix, pixelformat, width,
height)) {
;
} else if (!v4l2_fill_pixfmt_mp(&fmt0.fmt.pix_mp, pixelformat, width,
height)) {
;
#endif
} else {
const struct v4l2l_format *format =
format_by_fourcc(pixelformat);
if (!format)
return -EINVAL;
pix_format_set_size(&fmt0.fmt.pix, format, width, height);
fmt0.fmt.pix.pixelformat = format->fourcc;
}
if (V4L2_TYPE_IS_MULTIPLANAR(fmt0.type)) {
*fmt = fmt0;
if ((fmt->fmt.pix_mp.colorspace == V4L2_COLORSPACE_DEFAULT) ||
(fmt->fmt.pix_mp.colorspace > V4L2_COLORSPACE_DCI_P3))
fmt->fmt.pix_mp.colorspace = V4L2_COLORSPACE_SRGB;
if (V4L2_FIELD_ANY == fmt->fmt.pix_mp.field)
fmt->fmt.pix_mp.field = V4L2_FIELD_NONE;
if (capture)
fmt->type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
else
fmt->type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
} else {
bytesperline = fmt->fmt.pix.bytesperline;
sizeimage = fmt->fmt.pix.sizeimage;
*fmt = fmt0;
if (!fmt->fmt.pix.bytesperline)
fmt->fmt.pix.bytesperline = bytesperline;
if (!fmt->fmt.pix.sizeimage)
fmt->fmt.pix.sizeimage = sizeimage;
if ((fmt->fmt.pix.colorspace == V4L2_COLORSPACE_DEFAULT) ||
(fmt->fmt.pix.colorspace > V4L2_COLORSPACE_DCI_P3))
fmt->fmt.pix.colorspace = V4L2_COLORSPACE_SRGB;
if (V4L2_FIELD_ANY == fmt->fmt.pix.field)
fmt->fmt.pix.field = V4L2_FIELD_NONE;
if (capture)
fmt->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
else
fmt->type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
}
return 0;
}
/* Checks if v4l2l_fill_format() has set a valid, fixed sizeimage val. */
static bool v4l2l_pix_format_has_valid_sizeimage(struct v4l2_format *fmt)
{
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 2, 0)
const struct v4l2_format_info *info;
info = v4l2_format_info(fmt->fmt.pix.pixelformat);
if (info && info->mem_planes == 1)
return true;
#endif
return false;
}
static int pix_format_eq(const struct v4l2_pix_format *ref,
const struct v4l2_pix_format *tgt, int strict)
{
/* check if the two formats are equivalent.
* ANY fields are handled gracefully
*/
#define _pix_format_eq0(x) \
if (ref->x != tgt->x) \
result = 0
#define _pix_format_eq1(x, def) \
do { \
if ((def != tgt->x) && (ref->x != tgt->x)) { \
printk(KERN_INFO #x " failed"); \
result = 0; \
} \
} while (0)
int result = 1;
_pix_format_eq0(width);
_pix_format_eq0(height);
_pix_format_eq0(pixelformat);
if (!strict)
return result;
_pix_format_eq1(field, V4L2_FIELD_ANY);
_pix_format_eq0(bytesperline);
_pix_format_eq0(sizeimage);
_pix_format_eq1(colorspace, V4L2_COLORSPACE_DEFAULT);
return result;
}
static struct v4l2_loopback_device *v4l2loopback_getdevice(struct file *f);
static int inner_try_setfmt(struct file *file, struct v4l2_format *fmt)
{
int capture = V4L2_TYPE_IS_CAPTURE(fmt->type);
struct v4l2_loopback_device *dev;
int needschange = 0;
char buf[5];
buf[4] = 0;
dev = v4l2loopback_getdevice(file);
needschange = !(pix_format_eq(&dev->pix_format, &fmt->fmt.pix, 0));
if (V4L2LOOPBACK_IS_FIXED_FMT(dev)) {
fmt->fmt.pix = dev->pix_format;
if (needschange) {
if (dev->active_readers > 0 && capture) {
/* cannot call fmt_cap while there are readers */
return -EBUSY;
}
if (dev->ready_for_capture > 0 && !capture) {
/* cannot call fmt_out while there are writers */
return -EBUSY;
}
}
}
if (v4l2l_fill_format(fmt, capture, dev->min_width, dev->max_width,
dev->min_height, dev->max_height) != 0) {
return -EINVAL;
}
if (1) {
char buf[5];
buf[4] = 0;
dprintk("capFOURCC=%s\n",
fourcc2str(dev->pix_format.pixelformat, buf));
}
return 0;
}
static int set_timeperframe(struct v4l2_loopback_device *dev,
struct v4l2_fract *tpf)
{
if ((tpf->denominator < 1) || (tpf->numerator < 1)) {
return -EINVAL;
}
dev->capture_param.timeperframe = *tpf;
dev->frame_jiffies = max(1UL, msecs_to_jiffies(1000) * tpf->numerator /
tpf->denominator);
return 0;
}
static struct v4l2_loopback_device *v4l2loopback_cd2dev(struct device *cd);
/* device attributes */
/* available via sysfs: /sys/devices/virtual/video4linux/video* */
static ssize_t attr_show_format(struct device *cd,
struct device_attribute *attr, char *buf)
{
/* gets the current format as "FOURCC:WxH@f/s", e.g. "YUYV:320x240@1000/30" */
struct v4l2_loopback_device *dev = v4l2loopback_cd2dev(cd);
const struct v4l2_fract *tpf;
char buf4cc[5], buf_fps[32];
if (!dev || !V4L2LOOPBACK_IS_FIXED_FMT(dev))
return 0;
tpf = &dev->capture_param.timeperframe;
fourcc2str(dev->pix_format.pixelformat, buf4cc);
buf4cc[4] = 0;
if (tpf->numerator == 1)
snprintf(buf_fps, sizeof(buf_fps), "%d", tpf->denominator);
else
snprintf(buf_fps, sizeof(buf_fps), "%d/%d", tpf->denominator,
tpf->numerator);
return sprintf(buf, "%4s:%dx%d@%s\n", buf4cc, dev->pix_format.width,
dev->pix_format.height, buf_fps);
}
static ssize_t attr_store_format(struct device *cd,
struct device_attribute *attr, const char *buf,
size_t len)
{
struct v4l2_loopback_device *dev = v4l2loopback_cd2dev(cd);
int fps_num = 0, fps_den = 1;
if (!dev)
return -ENODEV;
/* only fps changing is supported */
if (sscanf(buf, "@%d/%d", &fps_num, &fps_den) > 0) {
struct v4l2_fract f = { .numerator = fps_den,
.denominator = fps_num };
int err = 0;
if ((err = set_timeperframe(dev, &f)) < 0)
return err;
return len;
}
return -EINVAL;
}
static DEVICE_ATTR(format, S_IRUGO | S_IWUSR, attr_show_format,
attr_store_format);
static ssize_t attr_show_buffers(struct device *cd,
struct device_attribute *attr, char *buf)
{
struct v4l2_loopback_device *dev = v4l2loopback_cd2dev(cd);
if (!dev)
return -ENODEV;
return sprintf(buf, "%d\n", dev->used_buffers);
}
static DEVICE_ATTR(buffers, S_IRUGO, attr_show_buffers, NULL);
static ssize_t attr_show_maxopeners(struct device *cd,
struct device_attribute *attr, char *buf)
{
struct v4l2_loopback_device *dev = v4l2loopback_cd2dev(cd);
if (!dev)
return -ENODEV;
return sprintf(buf, "%d\n", dev->max_openers);
}
static ssize_t attr_store_maxopeners(struct device *cd,
struct device_attribute *attr,
const char *buf, size_t len)
{
struct v4l2_loopback_device *dev = NULL;
unsigned long curr = 0;
if (kstrtoul(buf, 0, &curr))
return -EINVAL;
dev = v4l2loopback_cd2dev(cd);
if (!dev)
return -ENODEV;
if (dev->max_openers == curr)
return len;
if (curr > __INT_MAX__ || dev->open_count.counter > curr) {
/* request to limit to less openers as are currently attached to us */
return -EINVAL;
}
dev->max_openers = (int)curr;
return len;
}
static DEVICE_ATTR(max_openers, S_IRUGO | S_IWUSR, attr_show_maxopeners,
attr_store_maxopeners);
static ssize_t attr_show_state(struct device *cd, struct device_attribute *attr,
char *buf)
{
struct v4l2_loopback_device *dev = v4l2loopback_cd2dev(cd);
if (!dev)
return -ENODEV;
if (dev->ready_for_capture)
return sprintf(buf, "capture\n");
if (dev->ready_for_output)
return sprintf(buf, "output\n");
return -EAGAIN;
}
static DEVICE_ATTR(state, S_IRUGO, attr_show_state, NULL);
static void v4l2loopback_remove_sysfs(struct video_device *vdev)
{
#define V4L2_SYSFS_DESTROY(x) device_remove_file(&vdev->dev, &dev_attr_##x)
if (vdev) {
V4L2_SYSFS_DESTROY(format);
V4L2_SYSFS_DESTROY(buffers);
V4L2_SYSFS_DESTROY(max_openers);
V4L2_SYSFS_DESTROY(state);
/* ... */
}
}
static void v4l2loopback_create_sysfs(struct video_device *vdev)
{
int res = 0;
#define V4L2_SYSFS_CREATE(x) \
res = device_create_file(&vdev->dev, &dev_attr_##x); \
if (res < 0) \
break
if (!vdev)
return;
do {
V4L2_SYSFS_CREATE(format);
V4L2_SYSFS_CREATE(buffers);
V4L2_SYSFS_CREATE(max_openers);
V4L2_SYSFS_CREATE(state);
/* ... */
} while (0);
if (res >= 0)
return;
dev_err(&vdev->dev, "%s error: %d\n", __func__, res);
}
/* Event APIs */
#define V4L2LOOPBACK_EVENT_BASE (V4L2_EVENT_PRIVATE_START)
#define V4L2LOOPBACK_EVENT_OFFSET 0x08E00000
#define V4L2_EVENT_PRI_CLIENT_USAGE \
(V4L2LOOPBACK_EVENT_BASE + V4L2LOOPBACK_EVENT_OFFSET + 1)
struct v4l2_event_client_usage {
__u32 count;
};
/* global module data */
/* find a device based on it's device-number (e.g. '3' for /dev/video3) */
struct v4l2loopback_lookup_cb_data {
int device_nr;
struct v4l2_loopback_device *device;
};
static int v4l2loopback_lookup_cb(int id, void *ptr, void *data)
{
struct v4l2_loopback_device *device = ptr;
struct v4l2loopback_lookup_cb_data *cbdata = data;
if (cbdata && device && device->vdev) {
if (device->vdev->num == cbdata->device_nr) {
cbdata->device = device;
cbdata->device_nr = id;
return 1;
}
}
return 0;
}
static int v4l2loopback_lookup(int device_nr,
struct v4l2_loopback_device **device)
{
struct v4l2loopback_lookup_cb_data data = {
.device_nr = device_nr,
.device = NULL,
};
int err = idr_for_each(&v4l2loopback_index_idr, &v4l2loopback_lookup_cb,
&data);
if (1 == err) {
if (device)
*device = data.device;
return data.device_nr;
}
return -ENODEV;
}
static struct v4l2_loopback_device *v4l2loopback_cd2dev(struct device *cd)
{
struct video_device *loopdev = to_video_device(cd);
struct v4l2loopback_private *ptr =
(struct v4l2loopback_private *)video_get_drvdata(loopdev);
int nr = ptr->device_nr;
return idr_find(&v4l2loopback_index_idr, nr);
}
static struct v4l2_loopback_device *v4l2loopback_getdevice(struct file *f)
{
struct v4l2loopback_private *ptr = video_drvdata(f);
int nr = ptr->device_nr;
return idr_find(&v4l2loopback_index_idr, nr);
}
/* forward declarations */
static void client_usage_queue_event(struct video_device *vdev);
static void init_buffers(struct v4l2_loopback_device *dev);
static int allocate_buffers(struct v4l2_loopback_device *dev);
static void free_buffers(struct v4l2_loopback_device *dev);
static void try_free_buffers(struct v4l2_loopback_device *dev);
static int allocate_timeout_image(struct v4l2_loopback_device *dev);
static void check_timers(struct v4l2_loopback_device *dev);
static const struct v4l2_file_operations v4l2_loopback_fops;
static const struct v4l2_ioctl_ops v4l2_loopback_ioctl_ops;
/* Queue helpers */
/* next functions sets buffer flags and adjusts counters accordingly */
static inline void set_done(struct v4l2l_buffer *buffer)
{
buffer->buffer.flags &= ~V4L2_BUF_FLAG_QUEUED;
buffer->buffer.flags |= V4L2_BUF_FLAG_DONE;
}
static inline void set_queued(struct v4l2l_buffer *buffer)
{
buffer->buffer.flags &= ~V4L2_BUF_FLAG_DONE;
buffer->buffer.flags |= V4L2_BUF_FLAG_QUEUED;
}
static inline void unset_flags(struct v4l2l_buffer *buffer)
{
buffer->buffer.flags &= ~V4L2_BUF_FLAG_QUEUED;
buffer->buffer.flags &= ~V4L2_BUF_FLAG_DONE;
}
/* V4L2 ioctl caps and params calls */
/* returns device capabilities
* called on VIDIOC_QUERYCAP
*/
static int vidioc_querycap(struct file *file, void *priv,
struct v4l2_capability *cap)
{
struct v4l2_loopback_device *dev = v4l2loopback_getdevice(file);
int device_nr =
((struct v4l2loopback_private *)video_get_drvdata(dev->vdev))
->device_nr;
__u32 capabilities = V4L2_CAP_STREAMING | V4L2_CAP_READWRITE;
strlcpy(cap->driver, "v4l2 loopback", sizeof(cap->driver));
snprintf(cap->card, sizeof(cap->card), "%s", dev->card_label);
snprintf(cap->bus_info, sizeof(cap->bus_info),
"platform:v4l2loopback-%03d", device_nr);
if (dev->announce_all_caps) {
capabilities |= V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_OUTPUT;
} else {
if (dev->ready_for_capture) {
capabilities |= V4L2_CAP_VIDEO_CAPTURE;
}
if (dev->ready_for_output) {
capabilities |= V4L2_CAP_VIDEO_OUTPUT;
}
}
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 7, 0)
dev->vdev->device_caps =
#endif /* >=linux-4.7.0 */
cap->device_caps = cap->capabilities = capabilities;
cap->capabilities |= V4L2_CAP_DEVICE_CAPS;
memset(cap->reserved, 0, sizeof(cap->reserved));
return 0;
}
static int vidioc_enum_framesizes(struct file *file, void *fh,
struct v4l2_frmsizeenum *argp)
{
struct v4l2_loopback_device *dev;
/* there can be only one... */
if (argp->index)
return -EINVAL;
dev = v4l2loopback_getdevice(file);
if (V4L2LOOPBACK_IS_FIXED_FMT(dev)) {
/* format has already been negotiated
* cannot change during runtime
*/
if (argp->pixel_format != dev->pix_format.pixelformat)
return -EINVAL;
argp->type = V4L2_FRMSIZE_TYPE_DISCRETE;
argp->discrete.width = dev->pix_format.width;
argp->discrete.height = dev->pix_format.height;
} else {
/* if the format has not been negotiated yet, we accept anything
*/
if (NULL == format_by_fourcc(argp->pixel_format))
return -EINVAL;
if (dev->min_width == dev->max_width &&
dev->min_height == dev->max_height) {
argp->type = V4L2_FRMSIZE_TYPE_DISCRETE;
argp->discrete.width = dev->min_width;
argp->discrete.height = dev->min_height;
} else {
argp->type = V4L2_FRMSIZE_TYPE_CONTINUOUS;
argp->stepwise.min_width = dev->min_width;
argp->stepwise.min_height = dev->min_height;
argp->stepwise.max_width = dev->max_width;
argp->stepwise.max_height = dev->max_height;
argp->stepwise.step_width = 1;
argp->stepwise.step_height = 1;
}
}
return 0;
}
/* returns frameinterval (fps) for the set resolution
* called on VIDIOC_ENUM_FRAMEINTERVALS
*/
static int vidioc_enum_frameintervals(struct file *file, void *fh,
struct v4l2_frmivalenum *argp)
{
struct v4l2_loopback_device *dev = v4l2loopback_getdevice(file);
/* there can be only one... */
if (argp->index)
return -EINVAL;
if (V4L2LOOPBACK_IS_FIXED_FMT(dev)) {
if (argp->width != dev->pix_format.width ||
argp->height != dev->pix_format.height ||
argp->pixel_format != dev->pix_format.pixelformat)
return -EINVAL;
argp->type = V4L2_FRMIVAL_TYPE_DISCRETE;
argp->discrete = dev->capture_param.timeperframe;
} else {