soc: aspeed: Add XDMA Engine Driver

The XDMA engine embedded in the AST2500 and AST2600 SOCs performs PCI
DMA operations between the SOC (acting as a BMC) and a host processor
in a server.

This commit adds a driver to control the XDMA engine and adds functions
to initialize the hardware and memory and start DMA operations.

OpenBMC-Staging-Count: 1
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>

1 files changed, 38 insertions, 0 deletions

diff --git a/include/uapi/linux/aspeed-xdma.h b/include/uapi/linux/aspeed-xdma.h
new file mode 100644
index 000000000000..2efaa6067c39
--- /dev/null
+++ b/include/uapi/linux/aspeed-xdma.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/* Copyright IBM Corp 2019 */
+
+#ifndef _UAPI_LINUX_ASPEED_XDMA_H_
+#define _UAPI_LINUX_ASPEED_XDMA_H_
+
+#include <linux/types.h>
+
+/*
+ * aspeed_xdma_direction
+ *
+ * ASPEED_XDMA_DIRECTION_DOWNSTREAM: transfers data from the host to the BMC
+ *
+ * ASPEED_XDMA_DIRECTION_UPSTREAM: transfers data from the BMC to the host
+ */
+enum aspeed_xdma_direction {
+	ASPEED_XDMA_DIRECTION_DOWNSTREAM = 0,
+	ASPEED_XDMA_DIRECTION_UPSTREAM,
+};
+
+/*
+ * aspeed_xdma_op
+ *
+ * host_addr: the DMA address on the host side, typically configured by PCI
+ *            subsystem
+ *
+ * len: the size of the transfer in bytes
+ *
+ * direction: an enumerator indicating the direction of the DMA operation; see
+ *            enum aspeed_xdma_direction
+ */
+struct aspeed_xdma_op {
+	__u64 host_addr;
+	__u32 len;
+	__u32 direction;
+};
+
+#endif /* _UAPI_LINUX_ASPEED_XDMA_H_ */