drm/i915/bxt: add support for HPD long/short pulse detection on HPD_PORT_A pin

This is a requirement for enabling display port HPD support on the port
A HPD pin. This support is to be added by follow-up patches.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Sonika Jindal <sonika.jindal@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 e9a95df..8cf7756 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -5985,6 +5985,11 @@
 
 /* digital port hotplug */
 #define PCH_PORT_HOTPLUG        0xc4030		/* SHOTPLUG_CTL */
+#define BXT_PORTA_HOTPLUG_ENABLE	(1 << 28)
+#define BXT_PORTA_HOTPLUG_STATUS_MASK	(0x3 << 24)
+#define  BXT_PORTA_HOTPLUG_NO_DETECT	(0 << 24)
+#define  BXT_PORTA_HOTPLUG_SHORT_DETECT	(1 << 24)
+#define  BXT_PORTA_HOTPLUG_LONG_DETECT	(2 << 24)
 #define PORTD_HOTPLUG_ENABLE            (1 << 20)
 #define PORTD_PULSE_DURATION_2ms        (0)
 #define PORTD_PULSE_DURATION_4_5ms      (1 << 18)