Uvc camera code parsing 5

8. initialize uvc control 8.1 important struct [cpp] struct uvc_control {// uvc controls struct uvc_entity * entity; // uvc entity struct uvc_control_info info; // uvc control information _ u8 index; // index value _ u8 dirty: 1, loaded: 1, modified: 1, cached: 1, initialized: 1; // initialization flag _ u8 * uvc_data; // uvc control data}; 8.2 initialize uvc control device [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) {// traverse uvc device entity linked list struct uvc_control * ctrl; // uvc controls unsigned int bControlSize = 0, ncontrols = 0; _ u8 * bmControls = NULL; if (UVC_ENTITY_TYPE (entity) = UVC_VC_EXTENSION_UNIT) {// extended Unit bmControls = entity-> extension. bmControls; // controls the bitmap bControlSize = entity-> extension. bControlSize; // control bit domain size} else if (UVC_ENTITY_TYPE (entity) = UVC_VC_PROCESSING_UNIT) {// process Unit bmControls = entity-> processing. bmControls; // controls the bitmap bControlSize = entity-> processing. bControlSize; // control bit domain size} else if (UVC_ENTITY_TYPE (entity) = UVC_ITT_CAMERA) {// enter Terminal Camera bmControls = entity-> camera. bmControls; // controls the bitmap bControlSize = entity-> camera. bControlSize; // control bit domain size}/* Remove bogus/blacklisted controls Remove the false/blacklist control component */uvc_ctrl_prune_entity (dev, Entity);/* Count supported controls and allocate the controls array */for (I = 0; I <bControlSize; ++ I) ncontrols + = hweight8 (bmControls [I]); // The number of statistical control components if (ncontrols = 0) continue; entity-> controls = kzarloc (ncontrols * sizeof (* ctrl), GFP_KERNEL ); // allocate ncontrols uvc control memory if (entity-> controls = NULL) return-ENOMEM; entity-> ncontrols = ncontrols; // set the number of uvc controls/* Initialize all supported controls */Ctrl = entity-> controls; // point to the uvc control array for (I = 0; I <bControlSize * 8; ++ I) {if (uvc_test_bit (bmControls, I) = 0) // skip the continue where 1 is not set for the control bit field; ctrl-> entity = entity; // bind the uvc object and uvc control ctrl-> index = I; // set the control bit domain index uvc_ctrl_init_ctrl (dev, ctrl); // 9 initialize the uvc control ctrl ++; // uvc control points to the next uvc control array item} return 0 ;} 9 initialize the uvc control 9.1 struct 9.1.1 uvc control information [cpp] struct uvc_control_info {// uvc control information struct list_head mappings ;/ /Uvc controls the bitmap linked list header _ u8 entity [16]; _ u8 index;/* Bit index in bmControls */_ u8 selector; _ 002 size; _ u32 flags;}; 9.1.2 uvc-controlled bitmap [cpp] struct uvc_control_mapping {// uvc-controlled bitmap struct list_head list; // chain table struct uvc_control_info * ctrl; // uvc control information _ u32 id; _ u8 name [32]; _ u8 entity [16]; _ u8 selector; _ u8 size; _ u8 offset; enum v4l2_ctrl_type v4l2_type; // v4l2 control type _ u32 data_type; struct uvc_menu_inf O * menu_info; // uvc menu Information _ u32 menu_count; // uvc menu number _ 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 initialize uvc control [cpp] static void uvc_ctrl_init_ctrl (struct uvc_device * dev, struct uvc_control * ctrl) {const struct uvc_control_info * info = uvc_ctrls; // point to the Global static uvc control information array const struct uvc_cont Rol_info * iend = info + ARRAY_SIZE (uvc_ctrls); // point to the array End const struct uvc_control_mapping * mapping = uvc_ctrl_mappings; // point to the Global static uvc control bitmap array const struct uvc_control_mapping * mend = mapping + ARRAY_SIZE (uvc_ctrl_mappings); // point to the array End if (UVC_ENTITY_TYPE (ctrl-> entity) = warning) // ctrl-> entity-> type is extended Unit (Extended Unit is initialized until it is used for the first time) return; for (; info <iend; ++ info) {// traverse the entire uvc control information data if (uvc _ Entity_match_guid (ctrl-> entity, info-> entity) & ctrl-> index = info-> index) {// match condition uvc_ctrl_add_info (dev, ctrl, info ); // Add uvc control information break;} if (! Ctrl-> initialized) // The initialization return has been given; for (; mapping <mend; ++ mapping) {// traverse the entire uvc control bitmap array if (uvc_entity_match_guid (ctrl-> entity, mapping-> entity) & ctrl-> info. selector = mapping-> selector) // match condition _ uvc_ctrl_add_mapping (dev, ctrl, mapping); // Add control bitmap}