drm/i915/bxt: get DSI pixelclock

BXT's DSI PLL is different from that of VLV. So this patch
adds a new function to get the current DSI pixel clock based
on the PLL divider ratio and lane count.

This function is required for intel_dsi_get_config() function.

v2: Fixed Jani's review comments.
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dsi.c

@@ -695,7 +695,7 @@ static bool intel_dsi_get_hw_state(struct intel_encoder *encoder,
 static void intel_dsi_get_config(struct intel_encoder *encoder,
 				 struct intel_crtc_state *pipe_config)
 {
-	u32 pclk;
+	u32 pclk = 0;
 	DRM_DEBUG_KMS("\n");
 
 	/*
@@ -704,7 +704,11 @@ static void intel_dsi_get_config(struct intel_encoder *encoder,
 	 */
 	pipe_config->dpll_hw_state.dpll_md = 0;
 
+	if (IS_BROXTON(encoder->base.dev))
+		pclk = bxt_get_dsi_pclk(encoder, pipe_config->pipe_bpp);
+	else if (IS_VALLEYVIEW(encoder->base.dev))
 		pclk = vlv_get_dsi_pclk(encoder, pipe_config->pipe_bpp);
+
 	if (!pclk)
 		return;
 

drivers/gpu/drm/i915/intel_dsi.h

@@ -127,6 +127,7 @@ static inline struct intel_dsi *enc_to_intel_dsi(struct drm_encoder *encoder)
 extern void intel_enable_dsi_pll(struct intel_encoder *encoder);
 extern void intel_disable_dsi_pll(struct intel_encoder *encoder);
 extern u32 vlv_get_dsi_pclk(struct intel_encoder *encoder, int pipe_bpp);
+extern u32 bxt_get_dsi_pclk(struct intel_encoder *encoder, int pipe_bpp);
 extern void intel_dsi_reset_clocks(struct intel_encoder *encoder,
 							enum port port);
 

drivers/gpu/drm/i915/intel_dsi_pll.c

@@ -384,6 +384,41 @@ u32 vlv_get_dsi_pclk(struct intel_encoder *encoder, int pipe_bpp)
 	return pclk;
 }
 
+u32 bxt_get_dsi_pclk(struct intel_encoder *encoder, int pipe_bpp)
+{
+	u32 pclk;
+	u32 dsi_clk;
+	u32 dsi_ratio;
+	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
+	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
+
+	/* Divide by zero */
+	if (!pipe_bpp) {
+		DRM_ERROR("Invalid BPP(0)\n");
+		return 0;
+	}
+
+	dsi_ratio = I915_READ(BXT_DSI_PLL_CTL) &
+				BXT_DSI_PLL_RATIO_MASK;
+
+	/* Invalid DSI ratio ? */
+	if (dsi_ratio < BXT_DSI_PLL_RATIO_MIN ||
+			dsi_ratio > BXT_DSI_PLL_RATIO_MAX) {
+		DRM_ERROR("Invalid DSI pll ratio(%u) programmed\n", dsi_ratio);
+		return 0;
+	}
+
+	dsi_clk = (dsi_ratio * BXT_REF_CLOCK_KHZ) / 2;
+
+	/* pixel_format and pipe_bpp should agree */
+	assert_bpp_mismatch(intel_dsi->pixel_format, pipe_bpp);
+
+	pclk = DIV_ROUND_CLOSEST(dsi_clk * intel_dsi->lane_count, pipe_bpp);
+
+	DRM_DEBUG_DRIVER("Calculated pclk=%u\n", pclk);
+	return pclk;
+}
+
 void vlv_dsi_reset_clocks(struct intel_encoder *encoder, enum port port)
 {
 	u32 temp;