drm: Added SDP and VSC structures for handling PSR for eDP

SDP header and SDP VSC header as per eDP 1.3 spec, section 3.5,
chapter "PSR Secondary Data Package Support".

v2: Modified and corrected the structures to be more in line for
kernel coding guidelines and rebased the code on Paulo's DP patchset
v3: removing unecessary identation at DP_RECEIVER_CAP_SIZE
v4: moving them to include/drm/drm_dp_helper.h and also already
    icluding EDP_PSR_RECEIVER_CAP_SIZE to add everything needed
    for PSR at once at drm_dp_helper.h
v5: Fix SDP VSC header and identation by (Paulo Zanoni) and
    remove i915 from title (Daniel Vetter)
v6: Fix spec version and move comments from code to commit message
    since numbers might change in the future (by Paulo Zanoni).

CC: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Sateesh Kavuri <sateesh.kavuri@intel.com>
Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

include/drm/drm_dp_helper.h

@@ -343,12 +343,41 @@ u8 drm_dp_get_adjust_request_pre_emphasis(u8 link_status[DP_LINK_STATUS_SIZE],
 					  int lane);
 
 #define DP_RECEIVER_CAP_SIZE		0xf
+#define EDP_PSR_RECEIVER_CAP_SIZE	2
+
 void drm_dp_link_train_clock_recovery_delay(u8 dpcd[DP_RECEIVER_CAP_SIZE]);
 void drm_dp_link_train_channel_eq_delay(u8 dpcd[DP_RECEIVER_CAP_SIZE]);
 
 u8 drm_dp_link_rate_to_bw_code(int link_rate);
 int drm_dp_bw_code_to_link_rate(u8 link_bw);
 
+struct edp_sdp_header {
+	u8 HB0; /* Secondary Data Packet ID */
+	u8 HB1; /* Secondary Data Packet Type */
+	u8 HB2; /* 7:5 reserved, 4:0 revision number */
+	u8 HB3; /* 7:5 reserved, 4:0 number of valid data bytes */
+} __packed;
+
+#define EDP_SDP_HEADER_REVISION_MASK		0x1F
+#define EDP_SDP_HEADER_VALID_PAYLOAD_BYTES	0x1F
+
+struct edp_vsc_psr {
+	struct edp_sdp_header sdp_header;
+	u8 DB0; /* Stereo Interface */
+	u8 DB1; /* 0 - PSR State; 1 - Update RFB; 2 - CRC Valid */
+	u8 DB2; /* CRC value bits 7:0 of the R or Cr component */
+	u8 DB3; /* CRC value bits 15:8 of the R or Cr component */
+	u8 DB4; /* CRC value bits 7:0 of the G or Y component */
+	u8 DB5; /* CRC value bits 15:8 of the G or Y component */
+	u8 DB6; /* CRC value bits 7:0 of the B or Cb component */
+	u8 DB7; /* CRC value bits 15:8 of the B or Cb component */
+	u8 DB8_31[24]; /* Reserved */
+} __packed;
+
+#define EDP_VSC_PSR_STATE_ACTIVE	(1<<0)
+#define EDP_VSC_PSR_UPDATE_RFB		(1<<1)
+#define EDP_VSC_PSR_CRC_VALUES_VALID	(1<<2)
+
 static inline int
 drm_dp_max_link_rate(u8 dpcd[DP_RECEIVER_CAP_SIZE])
 {