drm/i915/cnl: Get DDI clock based on PLLs.

PLLs are the source clocks for the DDIs so in order
to determine the ddi clock we need to check the PLL
configuration.

v2: Mika pointed out that 24 was hardcoded while it
    should consider ref clock that can be either 24KHz
    or 19.2KHz on CNL.

Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1499374321-31152-1-git-send-email-rodrigo.vivi@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -8343,6 +8343,7 @@ enum {
 #define  DPLL_CFGCR0_LINK_RATE_3240	(6 << 25)
 #define  DPLL_CFGCR0_LINK_RATE_4050	(7 << 25)
 #define  DPLL_CFGCR0_DCO_FRACTION_MASK	(0x7fff << 10)
+#define  DPLL_CFGCR0_DCO_FRAC_SHIFT	(10)
 #define  DPLL_CFGCR0_DCO_FRACTION(x)	((x) << 10)
 #define  DPLL_CFGCR0_DCO_INTEGER_MASK	(0x3ff)
 #define CNL_DPLL_CFGCR0(pll)		_MMIO_PLL(pll, _CNL_DPLL0_CFGCR0, _CNL_DPLL1_CFGCR0)
@@ -8350,6 +8351,7 @@ enum {
 #define _CNL_DPLL0_CFGCR1		0x6C004
 #define _CNL_DPLL1_CFGCR1		0x6C084
 #define  DPLL_CFGCR1_QDIV_RATIO_MASK	(0xff << 10)
+#define  DPLL_CFGCR1_QDIV_RATIO_SHIFT	(10)
 #define  DPLL_CFGCR1_QDIV_RATIO(x)	((x) << 10)
 #define  DPLL_CFGCR1_QDIV_MODE(x)	((x) << 9)
 #define  DPLL_CFGCR1_KDIV_MASK		(7 << 6)

drivers/gpu/drm/i915/intel_ddi.c

@@ -1103,6 +1103,62 @@ static int skl_calc_wrpll_link(struct drm_i915_private *dev_priv,
 	return dco_freq / (p0 * p1 * p2 * 5);
 }
 
+static int cnl_calc_wrpll_link(struct drm_i915_private *dev_priv,
+			       uint32_t pll_id)
+{
+	uint32_t cfgcr0, cfgcr1;
+	uint32_t p0, p1, p2, dco_freq, ref_clock;
+
+	cfgcr0 = I915_READ(CNL_DPLL_CFGCR0(pll_id));
+	cfgcr1 = I915_READ(CNL_DPLL_CFGCR1(pll_id));
+
+	p0 = cfgcr1 & DPLL_CFGCR1_PDIV_MASK;
+	p2 = cfgcr1 & DPLL_CFGCR1_KDIV_MASK;
+
+	if (cfgcr1 & DPLL_CFGCR1_QDIV_MODE(1))
+		p1 = (cfgcr1 & DPLL_CFGCR1_QDIV_RATIO_MASK) >>
+			DPLL_CFGCR1_QDIV_RATIO_SHIFT;
+	else
+		p1 = 1;
+
+
+	switch (p0) {
+	case DPLL_CFGCR1_PDIV_2:
+		p0 = 2;
+		break;
+	case DPLL_CFGCR1_PDIV_3:
+		p0 = 3;
+		break;
+	case DPLL_CFGCR1_PDIV_5:
+		p0 = 5;
+		break;
+	case DPLL_CFGCR1_PDIV_7:
+		p0 = 7;
+		break;
+	}
+
+	switch (p2) {
+	case DPLL_CFGCR1_KDIV_1:
+		p2 = 1;
+		break;
+	case DPLL_CFGCR1_KDIV_2:
+		p2 = 2;
+		break;
+	case DPLL_CFGCR1_KDIV_4:
+		p2 = 4;
+		break;
+	}
+
+	ref_clock = dev_priv->cdclk.hw.ref;
+
+	dco_freq = (cfgcr0 & DPLL_CFGCR0_DCO_INTEGER_MASK) * ref_clock;
+
+	dco_freq += (((cfgcr0 & DPLL_CFGCR0_DCO_FRACTION_MASK) >>
+		      DPLL_CFGCR0_DCO_FRAC_SHIFT) * ref_clock) / 0x8000;
+
+	return dco_freq / (p0 * p1 * p2 * 5);
+}
+
 static void ddi_dotclock_get(struct intel_crtc_state *pipe_config)
 {
 	int dotclock;
@@ -1124,6 +1180,59 @@ static void ddi_dotclock_get(struct intel_crtc_state *pipe_config)
 	pipe_config->base.adjusted_mode.crtc_clock = dotclock;
 }
 
+static void cnl_ddi_clock_get(struct intel_encoder *encoder,
+			      struct intel_crtc_state *pipe_config)
+{
+	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
+	int link_clock = 0;
+	uint32_t cfgcr0, pll_id;
+
+	pll_id = intel_get_shared_dpll_id(dev_priv, pipe_config->shared_dpll);
+
+	cfgcr0 = I915_READ(CNL_DPLL_CFGCR0(pll_id));
+
+	if (cfgcr0 & DPLL_CFGCR0_HDMI_MODE) {
+		link_clock = cnl_calc_wrpll_link(dev_priv, pll_id);
+	} else {
+		link_clock = cfgcr0 & DPLL_CFGCR0_LINK_RATE_MASK;
+
+		switch (link_clock) {
+		case DPLL_CFGCR0_LINK_RATE_810:
+			link_clock = 81000;
+			break;
+		case DPLL_CFGCR0_LINK_RATE_1080:
+			link_clock = 108000;
+			break;
+		case DPLL_CFGCR0_LINK_RATE_1350:
+			link_clock = 135000;
+			break;
+		case DPLL_CFGCR0_LINK_RATE_1620:
+			link_clock = 162000;
+			break;
+		case DPLL_CFGCR0_LINK_RATE_2160:
+			link_clock = 216000;
+			break;
+		case DPLL_CFGCR0_LINK_RATE_2700:
+			link_clock = 270000;
+			break;
+		case DPLL_CFGCR0_LINK_RATE_3240:
+			link_clock = 324000;
+			break;
+		case DPLL_CFGCR0_LINK_RATE_4050:
+			link_clock = 405000;
+			break;
+		default:
+			WARN(1, "Unsupported link rate\n");
+			break;
+		}
+		link_clock *= 2;
+	}
+
+	pipe_config->port_clock = link_clock;
+
+	ddi_dotclock_get(pipe_config);
+}
+
 static void skl_ddi_clock_get(struct intel_encoder *encoder,
 				struct intel_crtc_state *pipe_config)
 {
@@ -1267,6 +1376,8 @@ void intel_ddi_clock_get(struct intel_encoder *encoder,
 		skl_ddi_clock_get(encoder, pipe_config);
 	else if (IS_GEN9_LP(dev_priv))
 		bxt_ddi_clock_get(encoder, pipe_config);
+	else if (IS_CANNONLAKE(dev_priv))
+		cnl_ddi_clock_get(encoder, pipe_config);
 }
 
 void intel_ddi_set_pipe_settings(const struct intel_crtc_state *crtc_state)