drm/i915: State readout support for WRPLLs

Still tacked onto the side, but slowly getting there.

v2: Don't forget the debugfs file.

v3 (from Paulo): Don't forget to check the power domains.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index b2b555c..d20fadd 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -5922,6 +5922,7 @@
 /* WRPLL */
 #define WRPLL_CTL1			0x46040
 #define WRPLL_CTL2			0x46060
+#define WRPLL_CTL(pll)			(pll == 0 ? WRPLL_CTL1 : WRPLL_CTL2)
 #define  WRPLL_PLL_ENABLE		(1<<31)
 #define  WRPLL_PLL_SSC			(1<<28)
 #define  WRPLL_PLL_NON_SSC		(2<<28)