drm/i915: clock readout support for DDI v3

Read out and calculate the port and pixel clocks on DDI configs as well.
This means we have to grab the DP divider values and look at the port
mapping to figure out which clock select reg to read out.

v2: do the work from ddi_get_config (Ville)
v3: check WRPLL reference clock (Ville)
    add additional SPLL freqs (Ville)
    clean up port/crtc clock calc (Ville)
    fix up crtc_clock conditionals (Ville)
    drop superfluous dp_get_m_n from get_config (Ville)
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -5312,8 +5312,12 @@
 #define  SPLL_PLL_ENABLE		(1<<31)
 #define  SPLL_PLL_SSC			(1<<28)
 #define  SPLL_PLL_NON_SSC		(2<<28)
+#define  SPLL_PLL_LCPLL			(3<<28)
+#define  SPLL_PLL_REF_MASK		(3<<28)
 #define  SPLL_PLL_FREQ_810MHz		(0<<26)
 #define  SPLL_PLL_FREQ_1350MHz		(1<<26)
+#define  SPLL_PLL_FREQ_2700MHz		(2<<26)
+#define  SPLL_PLL_FREQ_MASK		(3<<26)
 
 /* WRPLL */
 #define WRPLL_CTL1			0x46040
@@ -5324,8 +5328,13 @@
 #define  WRPLL_PLL_SELECT_LCPLL_2700	(0x03<<28)
 /* WRPLL divider programming */
 #define  WRPLL_DIVIDER_REFERENCE(x)	((x)<<0)
+#define  WRPLL_DIVIDER_REF_MASK		(0xff)
 #define  WRPLL_DIVIDER_POST(x)		((x)<<8)
+#define  WRPLL_DIVIDER_POST_MASK	(0x3f<<8)
+#define  WRPLL_DIVIDER_POST_SHIFT	8
 #define  WRPLL_DIVIDER_FEEDBACK(x)	((x)<<16)
+#define  WRPLL_DIVIDER_FB_SHIFT		16
+#define  WRPLL_DIVIDER_FB_MASK		(0xff<<16)
 
 /* Port clock selection */
 #define PORT_CLK_SEL_A			0x46100
@@ -5338,6 +5347,7 @@
 #define  PORT_CLK_SEL_WRPLL1		(4<<29)
 #define  PORT_CLK_SEL_WRPLL2		(5<<29)
 #define  PORT_CLK_SEL_NONE		(7<<29)
+#define  PORT_CLK_SEL_MASK		(7<<29)
 
 /* Transcoder clock selection */
 #define TRANS_CLK_SEL_A			0x46140

drivers/gpu/drm/i915/intel_ddi.c

@@ -633,6 +633,96 @@ static void wrpll_update_rnp(uint64_t freq2k, unsigned budget,
 	/* Otherwise a < c && b >= d, do nothing */
 }
 
+static int intel_ddi_calc_wrpll_link(struct drm_i915_private *dev_priv,
+				     int reg)
+{
+	int refclk = LC_FREQ;
+	int n, p, r;
+	u32 wrpll;
+
+	wrpll = I915_READ(reg);
+	switch (wrpll & SPLL_PLL_REF_MASK) {
+	case SPLL_PLL_SSC:
+	case SPLL_PLL_NON_SSC:
+		/*
+		 * We could calculate spread here, but our checking
+		 * code only cares about 5% accuracy, and spread is a max of
+		 * 0.5% downspread.
+		 */
+		refclk = 135;
+		break;
+	case SPLL_PLL_LCPLL:
+		refclk = LC_FREQ;
+		break;
+	default:
+		WARN(1, "bad wrpll refclk\n");
+		return 0;
+	}
+
+	r = wrpll & WRPLL_DIVIDER_REF_MASK;
+	p = (wrpll & WRPLL_DIVIDER_POST_MASK) >> WRPLL_DIVIDER_POST_SHIFT;
+	n = (wrpll & WRPLL_DIVIDER_FB_MASK) >> WRPLL_DIVIDER_FB_SHIFT;
+
+	return (LC_FREQ * n) / (p * r);
+}
+
+static void intel_ddi_clock_get(struct intel_encoder *encoder,
+				struct intel_crtc_config *pipe_config)
+{
+	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
+	enum port port = intel_ddi_get_encoder_port(encoder);
+	int link_clock = 0;
+	u32 val, pll;
+
+	val = I915_READ(PORT_CLK_SEL(port));
+	switch (val & PORT_CLK_SEL_MASK) {
+	case PORT_CLK_SEL_LCPLL_810:
+		link_clock = 81000;
+		break;
+	case PORT_CLK_SEL_LCPLL_1350:
+		link_clock = 135000;
+		break;
+	case PORT_CLK_SEL_LCPLL_2700:
+		link_clock = 270000;
+		break;
+	case PORT_CLK_SEL_WRPLL1:
+		link_clock = intel_ddi_calc_wrpll_link(dev_priv, WRPLL_CTL1);
+		break;
+	case PORT_CLK_SEL_WRPLL2:
+		link_clock = intel_ddi_calc_wrpll_link(dev_priv, WRPLL_CTL2);
+		break;
+	case PORT_CLK_SEL_SPLL:
+		pll = I915_READ(SPLL_CTL) & SPLL_PLL_FREQ_MASK;
+		if (pll == SPLL_PLL_FREQ_810MHz)
+			link_clock = 81000;
+		else if (pll == SPLL_PLL_FREQ_1350MHz)
+			link_clock = 135000;
+		else if (pll == SPLL_PLL_FREQ_2700MHz)
+			link_clock = 270000;
+		else {
+			WARN(1, "bad spll freq\n");
+			return;
+		}
+		break;
+	default:
+		WARN(1, "bad port clock sel\n");
+		return;
+	}
+
+	pipe_config->port_clock = link_clock * 2;
+
+	if (pipe_config->has_pch_encoder)
+		pipe_config->adjusted_mode.crtc_clock =
+			intel_dotclock_calculate(pipe_config->port_clock,
+						 &pipe_config->fdi_m_n);
+	else if (pipe_config->has_dp_encoder)
+		pipe_config->adjusted_mode.crtc_clock =
+			intel_dotclock_calculate(pipe_config->port_clock,
+						 &pipe_config->dp_m_n);
+	else
+		pipe_config->adjusted_mode.crtc_clock = pipe_config->port_clock;
+}
+
 static void
 intel_ddi_calculate_wrpll(int clock /* in Hz */,
 			  unsigned *r2_out, unsigned *n2_out, unsigned *p_out)
@@ -1509,6 +1599,8 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
 			      pipe_config->pipe_bpp, dev_priv->vbt.edp_bpp);
 		dev_priv->vbt.edp_bpp = pipe_config->pipe_bpp;
 	}
+
+	intel_ddi_clock_get(encoder, pipe_config);
 }
 
 static void intel_ddi_destroy(struct drm_encoder *encoder)