drm/msm/dpu: introduce the dpu_encoder_phys_* for writeback

Introduce the dpu_encoder_phys_* for the writeback interface
to handle writeback specific hardware programming.

changes in v4:
	- squash the encoder_phys_wb bits from [1]
	- since its a trivial change of a previously acked change
	  preserving the ack

[1] https://patchwork.freedesktop.org/patch/483099/?series=102964&rev=2

Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/483532/
Link: https://lore.kernel.org/r/1650984096-9964-14-git-send-email-quic_abhinavk@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/Makefile

@@ -60,6 +60,7 @@ msm-$(CONFIG_DRM_MSM_DPU) += \
 	disp/dpu1/dpu_encoder.o \
 	disp/dpu1/dpu_encoder_phys_cmd.o \
 	disp/dpu1/dpu_encoder_phys_vid.o \
+	disp/dpu1/dpu_encoder_phys_wb.o \
 	disp/dpu1/dpu_formats.o \
 	disp/dpu1/dpu_hw_catalog.o \
 	disp/dpu1/dpu_hw_ctl.o \

drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h

@@ -150,13 +150,15 @@ struct dpu_encoder_phys_ops {
  * @INTR_IDX_PINGPONG: Pingpong done unterrupt for cmd mode panel
  * @INTR_IDX_UNDERRUN: Underrun unterrupt for video and cmd mode panel
  * @INTR_IDX_RDPTR:    Readpointer done unterrupt for cmd mode panel
+ * @INTR_IDX_WB_DONE:  Writeback fone interrupt for virtual connector
  */
 enum dpu_intr_idx {
 	INTR_IDX_VSYNC,
 	INTR_IDX_PINGPONG,
 	INTR_IDX_UNDERRUN,
 	INTR_IDX_CTL_START,
 	INTR_IDX_RDPTR,
+	INTR_IDX_WB_DONE,
 	INTR_IDX_MAX,
 };
 
@@ -225,6 +227,27 @@ static inline int dpu_encoder_phys_inc_pending(struct dpu_encoder_phys *phys)
 	return atomic_inc_return(&phys->pending_kickoff_cnt);
 }
 
+/**
+ * struct dpu_encoder_phys_wb - sub-class of dpu_encoder_phys to handle command
+ *	mode specific operations
+ * @base:	Baseclass physical encoder structure
+ * @wbirq_refcount:     Reference count of writeback interrupt
+ * @wb_done_timeout_cnt: number of wb done irq timeout errors
+ * @wb_cfg:  writeback block config to store fb related details
+ * @wb_conn: backpointer to writeback connector
+ * @wb_job: backpointer to current writeback job
+ * @dest:   dpu buffer layout for current writeback output buffer
+ */
+struct dpu_encoder_phys_wb {
+	struct dpu_encoder_phys base;
+	atomic_t wbirq_refcount;
+	int wb_done_timeout_cnt;
+	struct dpu_hw_wb_cfg wb_cfg;
+	struct drm_writeback_connector *wb_conn;
+	struct drm_writeback_job *wb_job;
+	struct dpu_hw_fmt_layout dest;
+};
+
 /**
  * struct dpu_encoder_phys_cmd - sub-class of dpu_encoder_phys to handle command
  *	mode specific operations
@@ -294,6 +317,13 @@ struct dpu_encoder_phys *dpu_encoder_phys_vid_init(
 struct dpu_encoder_phys *dpu_encoder_phys_cmd_init(
 		struct dpu_enc_phys_init_params *p);
 
+/**
+ * dpu_encoder_phys_wb_init - initialize writeback encoder
+ * @init:	Pointer to init info structure with initialization params
+ */
+struct dpu_encoder_phys *dpu_encoder_phys_wb_init(
+		struct dpu_enc_phys_init_params *p);
+
 /**
  * dpu_encoder_helper_trigger_start - control start helper function
  *	This helper function may be optionally specified by physical