drm: revocation check at drm subsystem

On every hdcp revocation check request SRM is read from fw file
/lib/firmware/display_hdcp_srm.bin

SRM table is parsed and stored at drm_hdcp.c, with functions exported
for the services for revocation check from drivers (which
implements the HDCP authentication)

This patch handles the HDCP1.4 and 2.2 versions of SRM table.

v2:
  moved the uAPI to request_firmware_direct() [Daniel]
v3:
  kdoc added. [Daniel]
  srm_header unified and bit field definitions are removed. [Daniel]
  locking improved. [Daniel]
  vrl length violation is fixed. [Daniel]
v4:
  s/__swab16/be16_to_cpu [Daniel]
  be24_to_cpu is done through a global func [Daniel]
  Unused variables are removed. [Daniel]
  unchecked return values are dropped from static funcs [Daniel]

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Acked-by: Satyeshwar Singh <satyeshwar.singh@intel.com>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190507162745.25600-5-ramalingam.c@intel.com
diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index ecb7b33..18b1ac4 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -78,6 +78,7 @@ int drm_sysfs_init(void)
 	}
 
 	drm_class->devnode = drm_devnode;
+	drm_setup_hdcp_srm(drm_class);
 	return 0;
 }
 
@@ -90,6 +91,7 @@ void drm_sysfs_destroy(void)
 {
 	if (IS_ERR_OR_NULL(drm_class))
 		return;
+	drm_teardown_hdcp_srm(drm_class);
 	class_remove_file(drm_class, &class_attr_version.attr);
 	class_destroy(drm_class);
 	drm_class = NULL;