[gatekeeper] document timeout requirements
GateKeeper may throttle the user, document the return
value of calls in this case.
No code changes.
Bug:21118563
Change-Id: Idd6c392d01c22627f828d86dd219a4a1d6e81439
diff --git a/include/hardware/gatekeeper.h b/include/hardware/gatekeeper.h
index 89d96b1..ebe79b8 100644
--- a/include/hardware/gatekeeper.h
+++ b/include/hardware/gatekeeper.h
@@ -80,7 +80,12 @@
* - enrolled_password_handle_length: pointer to the length in bytes of the buffer allocated
* by this function and pointed to by *enrolled_password_handle_length.
*
- * Returns: 0 on success or an error code less than 0 on error.
+ * Returns:
+ * - 0 on success
+ * - An error code < 0 on failure, or
+ * - A timeout value T > 0 if the call should not be re-attempted until T milliseconds
+ * have elapsed.
+ *
* On error, enrolled_password_handle will not be allocated.
*/
int (*enroll)(const struct gatekeeper_device *dev, uint32_t uid,
@@ -123,7 +128,11 @@
* - auth_token_length: on success, the length in bytes of the authentication
* token assigned to *auth_token will be assigned to *auth_token_length
*
- * Returns: 0 on success or an error code less than 0 on error
+ * Returns:
+ * - 0 on success
+ * - An error code < 0 on failure, or
+ * - A timeout value T > 0 if the call should not be re-attempted until T milliseconds
+ * have elapsed.
* On error, auth token will not be allocated
*/
int (*verify)(const struct gatekeeper_device *dev, uint32_t uid, uint64_t challenge,