Linux驱动分析之V4L2驱动框架

//表示一个视频设备struct video_device {#if defined(CONFIG_MEDIA_CONTROLLER);  struct media_entity entity;  struct media_intf_devnode *intf_devnode;  struct media_pipeline pipe;#endif;  const struct v4l2_file_operations *fops; //文件操作接口(dev/videoX)  u32 device_caps; //设备功能，用于v4l2_capabilities(应用层定义的结构体)  struct device dev;  struct cdev *cdev; //字符设备  struct v4l2_device *v4l2_dev; //V4L2设备  struct device *dev_parent;  struct v4l2_ctrl_handler *ctrl_handler; //设备节点对应的控制句柄  struct vb2_queue *queue;  struct v4l2_prio_state *prio;  char name[32];  //Video设备名称  enum vfl_devnode_type vfl_type; //V4L设备类型  enum vfl_devnode_direction vfl_dir; //V4L 接收者/发送者/m2m  int minor; //子设备号，主设备为81  u16 num;   unsigned long flags;  int index;  spinlock_t fh_lock;  struct list_head        fh_list;  int dev_debug;  v4l2_std_id tvnorms;  void (*release)(struct video_device *vdev); //video_device release()回调  const struct v4l2_ioctl_ops *ioctl_ops; //IOCTL回调  unsigned long valid_ioctls[BITS_TO_LONGS(BASE_VIDIOC_PRIVATE)];  struct mutex *lock;};

struct v4l2_device {  struct device *dev;  struct media_device *mdev;  struct list_head subdevs; //用于追踪已注册的subdev  spinlock_t lock;  char name[V4L2_DEVICE_NAME_SIZE]; //设备名  void (*notify)(struct v4l2_subdev *sd, unsigned int notification, void *arg);  struct v4l2_ctrl_handler *ctrl_handler; //控制句柄  struct v4l2_prio_state prio; //设备的优先状态  struct kref ref; //引用  void (*release)(struct v4l2_device *v4l2_dev);//引用计数为0后调用};

struct v4l2_subdev {#if defined(CONFIG_MEDIA_CONTROLLER);  struct media_entity entity;#endif;  struct list_head list;  //subdev列表  struct module *owner;  bool owner_v4l2_dev;  u32 flags;  struct v4l2_device *v4l2_dev;  //依附的v4l2_device  const struct v4l2_subdev_ops *ops; //subdev操作函数  const struct v4l2_subdev_internal_ops *internal_ops;  struct v4l2_ctrl_handler *ctrl_handler; //控制句柄  char name[V4L2_SUBDEV_NAME_SIZE]; //subdev名称  u32 grp_id;  void *dev_priv;  void *host_priv;  struct video_device *devnode;  struct device *dev;  struct fwnode_handle *fwnode;  struct list_head async_list;  struct v4l2_async_subdev *asd;  struct v4l2_async_notifier *notifier;  struct v4l2_async_notifier *subdev_notifier;  struct v4l2_subdev_platform_data *pdata;//subdev平台数据};

struct v4l2_fh {  struct list_head        list; //文件句柄列表  struct video_device     *vdev; //依附的video_device  struct v4l2_ctrl_handler *ctrl_handler;  enum v4l2_priority      prio; //文件句柄的优先级  wait_queue_head_t wait;  struct mutex            subscribe_lock;  struct list_head        subscribed; //订阅的事件列表  struct list_head        available; //可用的事件  unsigned int            navailable; //可用的事件数  u32 sequence;  struct v4l2_m2m_ctx     *m2m_ctx;};

//V4L2设备操作函数struct v4l2_file_operations {  struct module *owner;  ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);  ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);  __poll_t (*poll) (struct file *, struct poll_table_struct *);  long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);#ifdef CONFIG_COMPAT;  long (*compat_ioctl32) (struct file *, unsigned int, unsigned long);#endif;  unsigned long (*get_unmapped_area) (struct file *, unsigned long, unsigned long, unsigned long, unsigned long);  int (*mmap) (struct file *, struct vm_area_struct *);  int (*open) (struct file *);  int (*release) (struct file *);};

//IOCTL操作函数struct v4l2_ioctl_ops {    ......    int (*vidioc_overlay)(struct file *file, void *fh, unsigned int i);    int (*vidioc_g_fbuf)(struct file *file, void *fh, struct v4l2_framebuffer *a);    int (*vidioc_s_fbuf)(struct file *file, void *fh, const struct v4l2_framebuffer *a);    int (*vidioc_streamon)(struct file *file, void *fh, enum v4l2_buf_type i);    int (*vidioc_streamoff)(struct file *file, void *fh, enum v4l2_buf_type i);    ......    int (*vidioc_enum_framesizes)(struct file *file, void *fh, struct v4l2_frmsizeenum *fsize);    int (*vidioc_enum_frameintervals)(struct file *file, void *fh, struct v4l2_frmivalenum *fival);    int (*vidioc_s_dv_timings)(struct file *file, void *fh, struct v4l2_dv_timings *timings);    int (*vidioc_g_dv_timings)(struct file *file, void *fh, struct v4l2_dv_timings *timings);    int (*vidioc_query_dv_timings)(struct file *file, void *fh, struct v4l2_dv_timings *timings);    int (*vidioc_enum_dv_timings)(struct file *file, void *fh, struct v4l2_enum_dv_timings *timings);    int (*vidioc_dv_timings_cap)(struct file *file, void *fh, struct v4l2_dv_timings_cap *cap);    int (*vidioc_g_edid)(struct file *file, void *fh, struct v4l2_edid *edid);    int (*vidioc_s_edid)(struct file *file, void *fh, struct v4l2_edid *edid);    int (*vidioc_subscribe_event)(struct v4l2_fh *fh, const struct v4l2_event_subscription *sub);    int (*vidioc_unsubscribe_event)(struct v4l2_fh *fh, const struct v4l2_event_subscription *sub);    long (*vidioc_default)(struct file *file, void *fh, bool valid_prio, unsigned int cmd, void *arg);};

//subdev操作函数struct v4l2_subdev_ops {    const struct v4l2_subdev_core_ops       *core;     //subdev核心操作回调    const struct v4l2_subdev_tuner_ops      *tuner;    //radio模式打开v4l设备时的操作回调    const struct v4l2_subdev_audio_ops      *audio;    //音频相关设置回调    const struct v4l2_subdev_video_ops      *video;    //video模式打开v4l设备时的操作回调    const struct v4l2_subdev_vbi_ops        *vbi;    //通过vbi设备节点以video模式打开v4l设备时的操作回调    const struct v4l2_subdev_ir_ops         *ir;     //IR(红外)设备操作函数    const struct v4l2_subdev_sensor_ops     *sensor; //sensor操作函数    const struct v4l2_subdev_pad_ops        *pad;    //pad操作函数};