drm/radeon/kms/atom: add support for spread spectrum (v2)

Spread spectrum is a periodic disturbance added
to the feedback divider to change the pixel clock
periodically to reduce interference.

Only enabled on LVDS.

v2: add support for r4xx and fix DCE 3

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
index b6868fb..2ea5707 100644
--- a/drivers/gpu/drm/radeon/radeon_mode.h
+++ b/drivers/gpu/drm/radeon/radeon_mode.h
@@ -260,6 +260,16 @@
 	struct radeon_tmds_pll tmds_pll[4];
 };
 
+/* spread spectrum */
+struct radeon_atom_ss {
+	uint16_t percentage;
+	uint8_t type;
+	uint8_t step;
+	uint8_t delay;
+	uint8_t range;
+	uint8_t refdiv;
+};
+
 struct radeon_encoder_atom_dig {
 	/* atom dig */
 	bool coherent_mode;
@@ -267,6 +277,7 @@
 	/* atom lvds */
 	uint32_t lvds_misc;
 	uint16_t panel_pwr_delay;
+	struct radeon_atom_ss *ss;
 	/* panel mode */
 	struct drm_display_mode native_mode;
 };