drm/i915: Add a CMD_PARSER_VERSION getparam

So userspace can query the kernel for command parser support.

v2: Add i915_cmd_parser_get_version(), history log, and kerneldoc

OTC-Tracker: AXIA-4631
Change-Id: I58af650db9f6753c2dcac9c54ab432fd31db302f
Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_cmd_parser.c

@@ -896,3 +896,22 @@ int i915_parse_cmds(struct intel_ring_buffer *ring,
 
 	return ret;
 }
+
+/**
+ * i915_cmd_parser_get_version() - get the cmd parser version number
+ *
+ * The cmd parser maintains a simple increasing integer version number suitable
+ * for passing to userspace clients to determine what operations are permitted.
+ *
+ * Return: the current version number of the cmd parser
+ */
+int i915_cmd_parser_get_version(void)
+{
+	/*
+	 * Command parser version history
+	 *
+	 * 1. Initial version. Checks batches and reports violations, but leaves
+	 *    hardware parsing enabled (so does not allow new use cases).
+	 */
+	return 1;
+}