drm/i915/icp: Get/set proper Raw clock frequency on ICP

Add register definitions for setting the rawclock.
Set the numerator,denominator and divider values.

v2: Simplify the commit message. Simplify the math.
Add  register bits for numerator. (Paulo)
v3 (from Paulo): coding style bikesheds.

Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180111180010.24357-5-paulo.r.zanoni@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -7351,6 +7351,8 @@ enum {
 #define  CNP_RAWCLK_DIV(div)	((div) << 16)
 #define  CNP_RAWCLK_FRAC_MASK	(0xf << 26)
 #define  CNP_RAWCLK_FRAC(frac)	((frac) << 26)
+#define  ICP_RAWCLK_DEN(den)	((den) << 26)
+#define  ICP_RAWCLK_NUM(num)	((num) << 11)
 
 #define PCH_DPLL_TMR_CFG        _MMIO(0xc6208)
 

drivers/gpu/drm/i915/intel_cdclk.c

@@ -2343,6 +2343,30 @@ static int cnp_rawclk(struct drm_i915_private *dev_priv)
 	return divider + fraction;
 }
 
+static int icp_rawclk(struct drm_i915_private *dev_priv)
+{
+	u32 rawclk;
+	int divider, numerator, denominator, frequency;
+
+	if (I915_READ(SFUSE_STRAP) & SFUSE_STRAP_RAW_FREQUENCY) {
+		frequency = 24000;
+		divider = 23;
+		numerator = 0;
+		denominator = 0;
+	} else {
+		frequency = 19200;
+		divider = 18;
+		numerator = 1;
+		denominator = 4;
+	}
+
+	rawclk = CNP_RAWCLK_DIV(divider) | ICP_RAWCLK_NUM(numerator) |
+		 ICP_RAWCLK_DEN(denominator);
+
+	I915_WRITE(PCH_RAWCLK_FREQ, rawclk);
+	return frequency;
+}
+
 static int pch_rawclk(struct drm_i915_private *dev_priv)
 {
 	return (I915_READ(PCH_RAWCLK_FREQ) & RAWCLK_FREQ_MASK) * 1000;
@@ -2390,8 +2414,9 @@ static int g4x_hrawclk(struct drm_i915_private *dev_priv)
  */
 void intel_update_rawclk(struct drm_i915_private *dev_priv)
 {
-
-	if (HAS_PCH_CNP(dev_priv))
+	if (HAS_PCH_ICP(dev_priv))
+		dev_priv->rawclk_freq = icp_rawclk(dev_priv);
+	else if (HAS_PCH_CNP(dev_priv))
 		dev_priv->rawclk_freq = cnp_rawclk(dev_priv);
 	else if (HAS_PCH_SPLIT(dev_priv))
 		dev_priv->rawclk_freq = pch_rawclk(dev_priv);