drm/i915/bxt: Determine programmed frequency

Add placeholder function for calculating programmed pixel clock.
Note: Formula to back calculate link clock from dividers not
available currently.

v2:
- rebased on upstream s/crtc_config/crtc_state/ change (imre)

Signed-off-by: Satheeshakrishna M <satheeshakrishna.m@intel.com> (v1)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ddi.c

@@ -880,15 +880,43 @@ static void hsw_ddi_clock_get(struct intel_encoder *encoder,
 		pipe_config->base.adjusted_mode.crtc_clock = pipe_config->port_clock;
 }
 
+static int bxt_calc_pll_link(struct drm_i915_private *dev_priv,
+				enum intel_dpll_id dpll)
+{
+	/* FIXME formula not available in bspec */
+	return 0;
+}
+
+static void bxt_ddi_clock_get(struct intel_encoder *encoder,
+				struct intel_crtc_state *pipe_config)
+{
+	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
+	enum port port = intel_ddi_get_encoder_port(encoder);
+	uint32_t dpll = port;
+
+	pipe_config->port_clock =
+		bxt_calc_pll_link(dev_priv, dpll);
+
+	if (pipe_config->has_dp_encoder)
+		pipe_config->base.adjusted_mode.crtc_clock =
+			intel_dotclock_calculate(pipe_config->port_clock,
+							&pipe_config->dp_m_n);
+	else
+		pipe_config->base.adjusted_mode.crtc_clock =
+							pipe_config->port_clock;
+}
+
 void intel_ddi_clock_get(struct intel_encoder *encoder,
 			 struct intel_crtc_state *pipe_config)
 {
 	struct drm_device *dev = encoder->base.dev;
 
 	if (INTEL_INFO(dev)->gen <= 8)
 		hsw_ddi_clock_get(encoder, pipe_config);
-	else
+	else if (IS_SKYLAKE(dev))
 		skl_ddi_clock_get(encoder, pipe_config);
+	else if (IS_BROXTON(dev))
+		bxt_ddi_clock_get(encoder, pipe_config);
 }
 
 static void

drivers/gpu/drm/i915/intel_dp.c

@@ -1471,6 +1471,8 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 
 	if (IS_SKYLAKE(dev) && is_edp(intel_dp))
 		skl_edp_set_pll_config(pipe_config, common_rates[clock]);
+	else if (IS_BROXTON(dev))
+		/* handled in ddi */;
 	else if (IS_HASWELL(dev) || IS_BROADWELL(dev))
 		hsw_dp_set_ddi_pll_sel(pipe_config, intel_dp->link_bw);
 	else