drm/i915: BDW clock change support

Add support for changing cdclk frequency during runtime on BDW.

Also with IPS enabled the actual pixel rate mustn't exceed 95% of cdclk,
so take that into account when computing the max pixel rate.

v2: Grab rps.hw_lock around sandybridge_pcode_write()
v3: Rebase due to power well vs. .global_resources() reordering
v4: Rebased to the latest
v5: Rebased to the latest
v6: Patch order shuffle so that Broadwell CD clock change is
    applied before the patch for Haswell CD clock change
v7: Fix for patch style problems

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 00cec1f..89fd7c8 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -6705,6 +6705,7 @@
 #define	  GEN6_PCODE_READ_RC6VIDS		0x5
 #define     GEN6_ENCODE_RC6_VID(mv)		(((mv) - 245) / 5)
 #define     GEN6_DECODE_RC6_VID(vids)		(((vids) * 5) + 245)
+#define   BDW_PCODE_DISPLAY_FREQ_CHANGE_REQ	0x18
 #define   GEN9_PCODE_READ_MEM_LATENCY		0x6
 #define     GEN9_MEM_LATENCY_LEVEL_MASK		0xFF
 #define     GEN9_MEM_LATENCY_LEVEL_1_5_SHIFT	8
@@ -7167,6 +7168,7 @@
 #define  LCPLL_CLK_FREQ_337_5_BDW	(2<<26)
 #define  LCPLL_CLK_FREQ_675_BDW		(3<<26)
 #define  LCPLL_CD_CLOCK_DISABLE		(1<<25)
+#define  LCPLL_ROOT_CD_CLOCK_DISABLE	(1<<24)
 #define  LCPLL_CD2X_CLOCK_DISABLE	(1<<23)
 #define  LCPLL_POWER_DOWN_ALLOW		(1<<22)
 #define  LCPLL_CD_SOURCE_FCLK		(1<<21)