drm/i915/icl: implement DVFS for ICL

ICL DVFS is almost the same as CNL, except for the CDCLK/DDICLK
table. Implement it just like CNL does.

References: commit 48469ece ("drm/i915: Use cdclk_state->voltage
 on CNL")
References: commit 53e9bf5e ("drm/i915: Adjust system agent
 voltage on CNL if required by DDI ports")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180614221018.19044-1-paulo.r.zanoni@intel.com

drivers/gpu/drm/i915/intel_cdclk.c

@@ -1871,11 +1871,35 @@ static void icl_set_cdclk(struct drm_i915_private *dev_priv,
 			      skl_cdclk_decimal(cdclk));
 
 	mutex_lock(&dev_priv->pcu_lock);
-	/* TODO: add proper DVFS support. */
-	sandybridge_pcode_write(dev_priv, SKL_PCODE_CDCLK_CONTROL, 2);
+	sandybridge_pcode_write(dev_priv, SKL_PCODE_CDCLK_CONTROL,
+				cdclk_state->voltage_level);
 	mutex_unlock(&dev_priv->pcu_lock);
 
 	intel_update_cdclk(dev_priv);
+
+	/*
+	 * Can't read out the voltage level :(
+	 * Let's just assume everything is as expected.
+	 */
+	dev_priv->cdclk.hw.voltage_level = cdclk_state->voltage_level;
+}
+
+static u8 icl_calc_voltage_level(int cdclk)
+{
+	switch (cdclk) {
+	case 50000:
+	case 307200:
+	case 312000:
+		return 0;
+	case 556800:
+	case 552000:
+		return 1;
+	default:
+		MISSING_CASE(cdclk);
+	case 652800:
+	case 648000:
+		return 2;
+	}
 }
 
 static void icl_get_cdclk(struct drm_i915_private *dev_priv,
@@ -1909,7 +1933,7 @@ static void icl_get_cdclk(struct drm_i915_private *dev_priv,
 		 */
 		cdclk_state->vco = 0;
 		cdclk_state->cdclk = cdclk_state->bypass;
-		return;
+		goto out;
 	}
 
 	cdclk_state->vco = (val & BXT_DE_PLL_RATIO_MASK) * cdclk_state->ref;
@@ -1918,6 +1942,14 @@ static void icl_get_cdclk(struct drm_i915_private *dev_priv,
 	WARN_ON((val & BXT_CDCLK_CD2X_DIV_SEL_MASK) != 0);
 
 	cdclk_state->cdclk = cdclk_state->vco / 2;
+
+out:
+	/*
+	 * Can't read this out :( Let's assume it's
+	 * at least what the CDCLK frequency requires.
+	 */
+	cdclk_state->voltage_level =
+		icl_calc_voltage_level(cdclk_state->cdclk);
 }
 
 /**
@@ -1960,6 +1992,8 @@ void icl_init_cdclk(struct drm_i915_private *dev_priv)
 	sanitized_state.cdclk = icl_calc_cdclk(0, sanitized_state.ref);
 	sanitized_state.vco = icl_calc_cdclk_pll_vco(dev_priv,
 						     sanitized_state.cdclk);
+	sanitized_state.voltage_level =
+				icl_calc_voltage_level(sanitized_state.cdclk);
 
 	icl_set_cdclk(dev_priv, &sanitized_state);
 }
@@ -1977,6 +2011,7 @@ void icl_uninit_cdclk(struct drm_i915_private *dev_priv)
 
 	cdclk_state.cdclk = cdclk_state.bypass;
 	cdclk_state.vco = 0;
+	cdclk_state.voltage_level = icl_calc_voltage_level(cdclk_state.cdclk);
 
 	icl_set_cdclk(dev_priv, &cdclk_state);
 }
@@ -2480,6 +2515,9 @@ static int icl_modeset_calc_cdclk(struct drm_atomic_state *state)
 
 	intel_state->cdclk.logical.vco = vco;
 	intel_state->cdclk.logical.cdclk = cdclk;
+	intel_state->cdclk.logical.voltage_level =
+		max(icl_calc_voltage_level(cdclk),
+		    cnl_compute_min_voltage_level(intel_state));
 
 	if (!intel_state->active_crtcs) {
 		cdclk = icl_calc_cdclk(0, ref);
@@ -2487,6 +2525,8 @@ static int icl_modeset_calc_cdclk(struct drm_atomic_state *state)
 
 		intel_state->cdclk.actual.vco = vco;
 		intel_state->cdclk.actual.cdclk = cdclk;
+		intel_state->cdclk.actual.voltage_level =
+			icl_calc_voltage_level(cdclk);
 	} else {
 		intel_state->cdclk.actual = intel_state->cdclk.logical;
 	}

drivers/gpu/drm/i915/intel_ddi.c

@@ -3078,6 +3078,8 @@ void intel_ddi_compute_min_voltage_level(struct drm_i915_private *dev_priv,
 {
 	if (IS_CANNONLAKE(dev_priv) && crtc_state->port_clock > 594000)
 		crtc_state->min_voltage_level = 2;
+	else if (IS_ICELAKE(dev_priv) && crtc_state->port_clock > 594000)
+		crtc_state->min_voltage_level = 1;
 }
 
 void intel_ddi_get_config(struct intel_encoder *encoder,