drm/i915/display: Add CDCLK Support for MTL

As per bSpec MTL has 38.4 MHz Reference clock.
Adding the cdclk tables and cdclk_funcs that MTL
will use.

v2: Revert to using bxt_get_cdclk()

BSpec: 65243

Cc: Clint Taylor <Clinton.A.Taylor@intel.com>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Reviewed-by: Clint Taylor <Clinton.A.Taylor@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221117230002.792096-3-anusha.srivatsa@intel.com

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

@@ -1346,6 +1346,16 @@ static const struct intel_cdclk_vals dg2_cdclk_table[] = {
 	{}
 };
 
+static const struct intel_cdclk_vals mtl_cdclk_table[] = {
+	{ .refclk = 38400, .cdclk = 172800, .divider = 2, .ratio = 16, .waveform = 0xad5a },
+	{ .refclk = 38400, .cdclk = 192000, .divider = 2, .ratio = 16, .waveform = 0xb6b6 },
+	{ .refclk = 38400, .cdclk = 307200, .divider = 2, .ratio = 16, .waveform = 0x0000 },
+	{ .refclk = 38400, .cdclk = 480000, .divider = 2, .ratio = 25, .waveform = 0x0000 },
+	{ .refclk = 38400, .cdclk = 556800, .divider = 2, .ratio = 29, .waveform = 0x0000 },
+	{ .refclk = 38400, .cdclk = 652800, .divider = 2, .ratio = 34, .waveform = 0x0000 },
+	{}
+};
+
 static int bxt_calc_cdclk(struct drm_i915_private *dev_priv, int min_cdclk)
 {
 	const struct intel_cdclk_vals *table = dev_priv->display.cdclk.table;
@@ -3190,6 +3200,13 @@ u32 intel_read_rawclk(struct drm_i915_private *dev_priv)
 	return freq;
 }
 
+static const struct intel_cdclk_funcs mtl_cdclk_funcs = {
+	.get_cdclk = bxt_get_cdclk,
+	.set_cdclk = bxt_set_cdclk,
+	.modeset_calc_cdclk = bxt_modeset_calc_cdclk,
+	.calc_voltage_level = tgl_calc_voltage_level,
+};
+
 static const struct intel_cdclk_funcs tgl_cdclk_funcs = {
 	.get_cdclk = bxt_get_cdclk,
 	.set_cdclk = bxt_set_cdclk,
@@ -3325,7 +3342,10 @@ static const struct intel_cdclk_funcs i830_cdclk_funcs = {
  */
 void intel_init_cdclk_hooks(struct drm_i915_private *dev_priv)
 {
-	if (IS_DG2(dev_priv)) {
+	if (IS_METEORLAKE(dev_priv)) {
+		dev_priv->display.funcs.cdclk = &mtl_cdclk_funcs;
+		dev_priv->display.cdclk.table = mtl_cdclk_table;
+	} else if (IS_DG2(dev_priv)) {
 		dev_priv->display.funcs.cdclk = &tgl_cdclk_funcs;
 		dev_priv->display.cdclk.table = dg2_cdclk_table;
 	} else if (IS_ALDERLAKE_P(dev_priv)) {