drm/i915/icl: Get DDI clock for ICL for MG PLL and TBT PLL

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

For MG PHy Ports (C - F), depending on whether it is a TBT PLL or MG
PLL the link lock can be obtained from the the PLL divisors based on
the specification.

v2 (from Paulo):
 * Make the algorithm look more like what's in the spec, also document
   where we differ form the spec and why.
 * Make the code a little more consistent with our coding style.

Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180817215209.29133-2-paulo.r.zanoni@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -9397,6 +9397,7 @@ enum skl_power_gate {
 #define   MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_5		(2 << 12)
 #define   MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_7		(3 << 12)
 #define   MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO(x)		((x) << 8)
+#define   MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO_SHIFT		8
 #define   MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO_MASK		(0xf << 8)
 #define MG_CLKTOP2_HSCLKCTL(port) _MMIO_PORT((port) - PORT_C, \
 					     _MG_CLKTOP2_HSCLKCTL_PORT1, \
@@ -9407,7 +9408,10 @@ enum skl_power_gate {
 #define _MG_PLL_DIV0_PORT3				0x16AA00
 #define _MG_PLL_DIV0_PORT4				0x16BA00
 #define   MG_PLL_DIV0_FRACNEN_H				(1 << 30)
+#define   MG_PLL_DIV0_FBDIV_FRAC_MASK			(0x3fffff << 8)
+#define   MG_PLL_DIV0_FBDIV_FRAC_SHIFT			8
 #define   MG_PLL_DIV0_FBDIV_FRAC(x)			((x) << 8)
+#define   MG_PLL_DIV0_FBDIV_INT_MASK			(0xff << 0)
 #define   MG_PLL_DIV0_FBDIV_INT(x)			((x) << 0)
 #define MG_PLL_DIV0(port) _MMIO_PORT((port) - PORT_C, _MG_PLL_DIV0_PORT1, \
 				     _MG_PLL_DIV0_PORT2)
@@ -9422,6 +9426,7 @@ enum skl_power_gate {
 #define   MG_PLL_DIV1_DITHER_DIV_4			(2 << 12)
 #define   MG_PLL_DIV1_DITHER_DIV_8			(3 << 12)
 #define   MG_PLL_DIV1_NDIVRATIO(x)			((x) << 4)
+#define   MG_PLL_DIV1_FBPREDIV_MASK			(0xf << 0)
 #define   MG_PLL_DIV1_FBPREDIV(x)			((x) << 0)
 #define MG_PLL_DIV1(port) _MMIO_PORT((port) - PORT_C, _MG_PLL_DIV1_PORT1, \
 				     _MG_PLL_DIV1_PORT2)

drivers/gpu/drm/i915/intel_ddi.c

@@ -1427,6 +1427,81 @@ static int cnl_calc_wrpll_link(struct drm_i915_private *dev_priv,
 	return dco_freq / (p0 * p1 * p2 * 5);
 }
 
+static int icl_calc_tbt_pll_link(struct drm_i915_private *dev_priv,
+				 enum port port)
+{
+	u32 val = I915_READ(DDI_CLK_SEL(port)) & DDI_CLK_SEL_MASK;
+
+	switch (val) {
+	case DDI_CLK_SEL_NONE:
+		return 0;
+	case DDI_CLK_SEL_TBT_162:
+		return 162000;
+	case DDI_CLK_SEL_TBT_270:
+		return 270000;
+	case DDI_CLK_SEL_TBT_540:
+		return 540000;
+	case DDI_CLK_SEL_TBT_810:
+		return 810000;
+	default:
+		MISSING_CASE(val);
+		return 0;
+	}
+}
+
+static int icl_calc_mg_pll_link(struct drm_i915_private *dev_priv,
+				enum port port)
+{
+	u32 mg_pll_div0, mg_clktop_hsclkctl;
+	u32 m1, m2_int, m2_frac, div1, div2, refclk;
+	u64 tmp;
+
+	refclk = dev_priv->cdclk.hw.ref;
+
+	mg_pll_div0 = I915_READ(MG_PLL_DIV0(port));
+	mg_clktop_hsclkctl = I915_READ(MG_CLKTOP2_HSCLKCTL(port));
+
+	m1 = I915_READ(MG_PLL_DIV1(port)) & MG_PLL_DIV1_FBPREDIV_MASK;
+	m2_int = mg_pll_div0 & MG_PLL_DIV0_FBDIV_INT_MASK;
+	m2_frac = (mg_pll_div0 & MG_PLL_DIV0_FRACNEN_H) ?
+		  (mg_pll_div0 & MG_PLL_DIV0_FBDIV_FRAC_MASK) >>
+		  MG_PLL_DIV0_FBDIV_FRAC_SHIFT : 0;
+
+	switch (mg_clktop_hsclkctl & MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_MASK) {
+	case MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_2:
+		div1 = 2;
+		break;
+	case MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_3:
+		div1 = 3;
+		break;
+	case MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_5:
+		div1 = 5;
+		break;
+	case MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_7:
+		div1 = 7;
+		break;
+	default:
+		MISSING_CASE(mg_clktop_hsclkctl);
+		return 0;
+	}
+
+	div2 = (mg_clktop_hsclkctl & MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO_MASK) >>
+		MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO_SHIFT;
+	/* div2 value of 0 is same as 1 means no div */
+	if (div2 == 0)
+		div2 = 1;
+
+	/*
+	 * Adjust the original formula to delay the division by 2^22 in order to
+	 * minimize possible rounding errors.
+	 */
+	tmp = (u64)m1 * m2_int * refclk +
+	      (((u64)m1 * m2_frac * refclk) >> 22);
+	tmp = div_u64(tmp, 5 * div1 * div2);
+
+	return tmp;
+}
+
 static void ddi_dotclock_get(struct intel_crtc_state *pipe_config)
 {
 	int dotclock;
@@ -1467,8 +1542,10 @@ static void icl_ddi_clock_get(struct intel_encoder *encoder,
 			link_clock = icl_calc_dp_combo_pll_link(dev_priv,
 								pll_id);
 	} else {
-		/* FIXME - Add for MG PLL */
-		WARN(1, "MG PLL clock_get code not implemented yet\n");
+		if (pll_id == DPLL_ID_ICL_TBTPLL)
+			link_clock = icl_calc_tbt_pll_link(dev_priv, port);
+		else
+			link_clock = icl_calc_mg_pll_link(dev_priv, port);
 	}
 
 	pipe_config->port_clock = link_clock;