drm/i915: New lock to serialize the Host2GuC actions

With the addition of new Host2GuC actions related to GuC logging, there
is a need of a lock to serialize them, as they can execute concurrently
with each other and also with other existing actions.

v2: Use mutex in place of spinlock to serialize, as sleep can happen
    while waiting for the action's response from GuC. (Tvrtko)

v3: To conform to the general rules, acquire mutex before taking the
    forcewake. (Tvrtko)

Signed-off-by: Akash Goel <akash.goel@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
index e7999dd..907d13a 100644
--- a/drivers/gpu/drm/i915/intel_guc.h
+++ b/drivers/gpu/drm/i915/intel_guc.h
@@ -157,6 +157,9 @@ struct intel_guc {
 
 	uint64_t submissions[I915_NUM_ENGINES];
 	uint32_t last_seqno[I915_NUM_ENGINES];
+
+	/* To serialize the Host2GuC actions */
+	struct mutex action_lock;
 };
 
 /* intel_guc_loader.c */