drm/i915/display/dg2: Set CD clock squashing registers

Set CD clock squashing registers based on selected CD clock.

v2: use slk_cdclk_decimal() to compute decimal values instead of a
    specific table (Ville)
    Set waveform based on CD clock table (Ville)
    Drop unnecessary local variable (Ville)
v3: Correct function naming (Ville)
    Correct if-else structure (Ville)
[v4: vsyrjala: Fix spaces vs. tabs]
[v5: vsyrjala: Fix cd2x divider calculation (Uma),
               Add warn to waveform lookup (Uma),
               Handle bypass freq in waveform lookup,
               Generalize waveform handling in bxt_set_cdclk()]

Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211119131348.725220-4-mika.kahola@intel.com

drivers/gpu/drm/i915/display/intel_cdclk.c

@@ -1638,13 +1638,35 @@ static u32 bxt_cdclk_cd2x_div_sel(struct drm_i915_private *dev_priv,
 	}
 }
 
+static u32 cdclk_squash_waveform(struct drm_i915_private *dev_priv,
+				 int cdclk)
+{
+	const struct intel_cdclk_vals *table = dev_priv->cdclk.table;
+	int i;
+
+	if (cdclk == dev_priv->cdclk.hw.bypass)
+		return 0;
+
+	for (i = 0; table[i].refclk; i++)
+		if (table[i].refclk == dev_priv->cdclk.hw.ref &&
+		    table[i].cdclk == cdclk)
+			return table[i].waveform;
+
+	drm_WARN(&dev_priv->drm, 1, "cdclk %d not valid for refclk %u\n",
+		 cdclk, dev_priv->cdclk.hw.ref);
+
+	return 0xffff;
+}
+
 static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
 			  const struct intel_cdclk_config *cdclk_config,
 			  enum pipe pipe)
 {
 	int cdclk = cdclk_config->cdclk;
 	int vco = cdclk_config->vco;
 	u32 val;
+	u16 waveform;
+	int clock;
 	int ret;
 
 	/* Inform power controller of upcoming frequency change. */
@@ -1688,7 +1710,24 @@ static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
 			bxt_de_pll_enable(dev_priv, vco);
 	}
 
-	val = bxt_cdclk_cd2x_div_sel(dev_priv, cdclk, vco) |
+	waveform = cdclk_squash_waveform(dev_priv, cdclk);
+
+	if (waveform)
+		clock = vco / 2;
+	else
+		clock = cdclk;
+
+	if (has_cdclk_squasher(dev_priv)) {
+		u32 squash_ctl = 0;
+
+		if (waveform)
+			squash_ctl = CDCLK_SQUASH_ENABLE |
+				CDCLK_SQUASH_WINDOW_SIZE(0xf) | waveform;
+
+		intel_de_write(dev_priv, CDCLK_SQUASH_CTL, squash_ctl);
+	}
+
+	val = bxt_cdclk_cd2x_div_sel(dev_priv, clock, vco) |
 		bxt_cdclk_cd2x_pipe(dev_priv, pipe) |
 		skl_cdclk_decimal(cdclk);
 

drivers/gpu/drm/i915/i915_reg.h

@@ -10543,6 +10543,14 @@ enum skl_power_gate {
 #define  BXT_CDCLK_SSA_PRECHARGE_ENABLE	(1 << 16)
 #define  CDCLK_FREQ_DECIMAL_MASK	(0x7ff)
 
+/* CDCLK_SQUASH_CTL */
+#define CDCLK_SQUASH_CTL		_MMIO(0x46008)
+#define  CDCLK_SQUASH_ENABLE		REG_BIT(31)
+#define  CDCLK_SQUASH_WINDOW_SIZE_MASK	REG_GENMASK(27, 24)
+#define  CDCLK_SQUASH_WINDOW_SIZE(x)	REG_FIELD_PREP(CDCLK_SQUASH_WINDOW_SIZE_MASK, (x))
+#define  CDCLK_SQUASH_WAVEFORM_MASK	REG_GENMASK(15, 0)
+#define  CDCLK_SQUASH_WAVEFORM(x)	REG_FIELD_PREP(CDCLK_SQUASH_WAVEFORM_MASK, (x))
+
 /* LCPLL_CTL */
 #define LCPLL1_CTL		_MMIO(0x46010)
 #define LCPLL2_CTL		_MMIO(0x46014)