1 files changed, 49 insertions, 0 deletions
diff --git a/drivers/gpu/drm/xe/abi/guc_communication_mmio_abi.h b/drivers/gpu/drm/xe/abi/guc_communication_mmio_abi.h
new file mode 100644
index 000000000000..ef538e34f894
--- /dev/null
+++ b/drivers/gpu/drm/xe/abi/guc_communication_mmio_abi.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2014-2021 Intel Corporation
+ */
+
+#ifndef _ABI_GUC_COMMUNICATION_MMIO_ABI_H
+#define _ABI_GUC_COMMUNICATION_MMIO_ABI_H
+
+/**
+ * DOC: GuC MMIO based communication
+ *
+ * The MMIO based communication between Host and GuC relies on special
+ * hardware registers which format could be defined by the software
+ * (so called scratch registers).
+ *
+ * Each MMIO based message, both Host to GuC (H2G) and GuC to Host (G2H)
+ * messages, which maximum length depends on number of available scratch
+ * registers, is directly written into those scratch registers.
+ *
+ * For Gen9+, there are 16 software scratch registers 0xC180-0xC1B8,
+ * but no H2G command takes more than 4 parameters and the GuC firmware
+ * itself uses an 4-element array to store the H2G message.
+ *
+ * For Gen11+, there are additional 4 registers 0x190240-0x19024C, which
+ * are, regardless on lower count, preferred over legacy ones.
+ *
+ * The MMIO based communication is mainly used during driver initialization
+ * phase to setup the `CTB based communication`_ that will be used afterwards.
+ */
+
+#define GUC_MAX_MMIO_MSG_LEN		4
+
+/**
+ * DOC: MMIO HXG Message
+ *
+ * Format of the MMIO messages follows definitions of `HXG Message`_.
+ *
+ *  +---+-------+--------------------------------------------------------------+
+ *  |   | Bits  | Description                                                  |
+ *  +===+=======+==============================================================+
+ *  | 0 |  31:0 |                                                              |
+ *  +---+-------+                                                              |
+ *  |...|       | [Embedded `HXG Message`_]                                    |
+ *  +---+-------+                                                              |
+ *  | n |  31:0 |                                                              |
+ *  +---+-------+--------------------------------------------------------------+
+ */
+
+#endif