8.1 重要結構體
[cpp]
struct uvc_control { //uvc控制
struct uvc_entity *entity; //uvc實體
struct uvc_control_info info; //uvc控制信息
__u8 index; //索引值
__u8 dirty:1,
loaded:1,
modified:1,
cached:1,
initialized:1; //初始化標誌
__u8 *uvc_data; //uvc控制數據
};
8.2 初始化uvc控制設備
[cpp]
int uvc_ctrl_init_device(struct uvc_device *dev)
{
struct uvc_entity *entity;
unsigned int i;
/* Walk the entities list and instantiate controls */
list_for_each_entry(entity, &dev->entities, list) { //遍歷uvc設備實體entities鏈表
struct uvc_control *ctrl; //uvc控制
unsigned int bControlSize = 0, ncontrols = 0;
__u8 *bmControls = NULL;
if (UVC_ENTITY_TYPE(entity) == UVC_VC_EXTENSION_UNIT) { //擴展Unit
bmControls = entity->extension.bmControls; //控制位圖
bControlSize = entity->extension.bControlSize; //控制位域大小
}
else if (UVC_ENTITY_TYPE(entity) == UVC_VC_PROCESSING_UNIT) { //處理Unit
bmControls = entity->processing.bmControls; //控制位圖
bControlSize = entity->processing.bControlSize; //控制位域大小
}
else if (UVC_ENTITY_TYPE(entity) == UVC_ITT_CAMERA) { //輸入Terminal Camera
bmControls = entity->camera.bmControls; //控制位圖
bControlSize = entity->camera.bControlSize; //控制位域大小
}
/* Remove bogus/blacklisted controls 移除假的/黑名單控制組件*/
uvc_ctrl_prune_entity(dev, entity);
/* Count supported controls and allocate the controls array */
for (i = 0; i < bControlSize; ++i)
ncontrols += hweight8(bmControls[i]); //統計控制組件個數
if (ncontrols == 0)
continue;
entity->controls = kzalloc(ncontrols * sizeof(*ctrl),GFP_KERNEL); //分配ncontrols個uvc控制內存
if (entity->controls == NULL)
return -ENOMEM;
entity->ncontrols = ncontrols; //設置uvc控制個數
/* Initialize all supported controls */
ctrl = entity->controls; //指向uvc控制數組
for (i = 0; i < bControlSize * 8; ++i) {
if (uvc_test_bit(bmControls, i) == 0) //跳過控制位域沒設置1的
continue;
ctrl->entity = entity; //捆綁uvc實體和uvc控制
ctrl->index = i; //設置控制位域索引
uvc_ctrl_init_ctrl(dev, ctrl); //9初始化uvc控件
ctrl++; //uvc控制 指向下一個uvc控制數組項
}
}
return 0;
}
9初始化uvc控件
9.1 相關結構體
9.1.1 uvc控制信息
[cpp]
struct uvc_control_info { //uvc控制信息
struct list_head mappings; //uvc控制位圖鏈表頭
__u8 entity[16];
__u8 index; /* Bit index in bmControls */
__u8 selector;
__u16 size;
__u32 flags;
};
9.1.2 uvc控制位圖
[cpp]
struct uvc_control_mapping { //uvc控制位圖
struct list_head list; //鏈表
struct uvc_control_info *ctrl; //uvc控制信息
__u32 id;
__u8 name[32];
__u8 entity[16];
__u8 selector;
__u8 size;
__u8 offset;
enum v4l2_ctrl_type v4l2_type; //v4l2控制類型
__u32 data_type;
struct uvc_menu_info *menu_info; //uvc菜單信息
__u32 menu_count; //uvc菜單個數
__s32 (*get) (struct uvc_control_mapping *mapping, __u8 query,const __u8 *data);
void (*set) (struct uvc_control_mapping *mapping, __s32 value,__u8 *data);
};
9.2 初始化uvc控制
[cpp]
static void uvc_ctrl_init_ctrl(struct uvc_device *dev, struct uvc_control *ctrl)
{
const struct uvc_control_info *info = uvc_ctrls; //指向全局靜態uvc控制信息數組
const struct uvc_control_info *iend = info + ARRAY_SIZE(uvc_ctrls); //指向數組末端
const struct uvc_control_mapping *mapping = uvc_ctrl_mappings; //指向全局靜態uvc控制位圖數組
const struct uvc_control_mapping *mend = mapping + ARRAY_SIZE(uvc_ctrl_mappings); //指向數組末端
if (UVC_ENTITY_TYPE(ctrl->entity) == UVC_VC_EXTENSION_UNIT) //ctrl->entity->type爲擴展Unit(延後擴展Unit的初始化到當它第一次使用)
return;
for (; info < iend; ++info) { //遍歷整個uvc控制信息數據
if (uvc_entity_match_guid(ctrl->entity, info->entity) && ctrl->index == info->index) { //匹配條件
uvc_ctrl_add_info(dev, ctrl, info); //添加uvc控制信息
break;
}
}
if (!ctrl->initialized) //已經給初始化
return;
for (; mapping < mend; ++mapping) { //遍歷整個uvc控制位圖數組
if (uvc_entity_match_guid(ctrl->entity, mapping->entity) && ctrl->info.selector == mapping->selector) //匹配條件
__uvc_ctrl_add_mapping(dev, ctrl, mapping); //添加控制位圖
}