drm/i915: allow force wake at init time on VLV v2

We need to set the 'allow force wake' bit to enable forcewake handling
later on.

v2: split from clock gating patch (Jani)
    check for allowwakeack (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_gem.c

@@ -4010,7 +4010,16 @@ int i915_gem_init(struct drm_device *dev)
 	int ret;
 
 	mutex_lock(&dev->struct_mutex);
+
+	if (IS_VALLEYVIEW(dev)) {
+		/* VLVA0 (potential hack), BIOS isn't actually waking us */
+		I915_WRITE(VLV_GTLC_WAKE_CTRL, 1);
+		if (wait_for((I915_READ(VLV_GTLC_PW_STATUS) & 1) == 1, 10))
+			DRM_DEBUG_DRIVER("allow wake ack timed out\n");
+	}
+
 	i915_gem_init_global_gtt(dev);
+
 	ret = i915_gem_init_hw(dev);
 	mutex_unlock(&dev->struct_mutex);
 	if (ret) {

drivers/gpu/drm/i915/i915_reg.h

@@ -4150,6 +4150,8 @@
 #define  FORCEWAKE_ACK_VLV			0x1300b4
 #define  FORCEWAKE_ACK_HSW			0x130044
 #define  FORCEWAKE_ACK				0x130090
+#define  VLV_GTLC_WAKE_CTRL			0x130090
+#define  VLV_GTLC_PW_STATUS			0x130094
 #define  FORCEWAKE_MT				0xa188 /* multi-threaded */
 #define   FORCEWAKE_KERNEL			0x1
 #define   FORCEWAKE_USER			0x2