[Intel-gfx] [PATCH 2/2] drm/i915/icl: Get DDI clock for ICL for MG PLL and TBT PLL

[Paulo Zanoni]

From: Manasi Navare <manasi.d.navare at intel.com>

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.

Cc: James Ausmus <james.ausmus at intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h  |  5 ++
 drivers/gpu/drm/i915/intel_ddi.c | 81 +++++++++++++++++++++++++++++++-
 2 files changed, 84 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e04ac47d53db..cd37e76d4d19 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -9458,6 +9458,7 @@ 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, \
@@ -9468,7 +9469,10 @@ 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)
@@ -9483,6 +9487,7 @@ 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)
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 0adc043529f2..a18d57046bcc 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/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;
-- 
2.17.1