pds_fwctl: initial driver framework

Initial files for adding a new fwctl driver for the AMD/Pensando PDS
devices.  This sets up a simple auxiliary_bus driver that registers
with fwctl subsystem.  It expects that a pds_core device has set up
the auxiliary_device pds_core.fwctl

Link: https://patch.msgid.link/r/20250320194412.67983-5-shannon.nelson@amd.com
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

include/uapi/fwctl/fwctl.h

@@ -44,6 +44,7 @@ enum fwctl_device_type {
 	FWCTL_DEVICE_TYPE_ERROR = 0,
 	FWCTL_DEVICE_TYPE_MLX5 = 1,
 	FWCTL_DEVICE_TYPE_CXL = 2,
+	FWCTL_DEVICE_TYPE_PDS = 4,
 };
 
 /**

include/uapi/fwctl/pds.h

@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* Copyright(c) Advanced Micro Devices, Inc */
+
+/*
+ * fwctl interface info for pds_fwctl
+ */
+
+#ifndef _UAPI_FWCTL_PDS_H_
+#define _UAPI_FWCTL_PDS_H_
+
+#include <linux/types.h>
+
+/**
+ * struct fwctl_info_pds
+ * @uctx_caps:  bitmap of firmware capabilities
+ *
+ * Return basic information about the FW interface available.
+ */
+struct fwctl_info_pds {
+	__u32 uctx_caps;
+};
+
+/**
+ * enum pds_fwctl_capabilities
+ * @PDS_FWCTL_QUERY_CAP: firmware can be queried for information
+ * @PDS_FWCTL_SEND_CAP:  firmware can be sent commands
+ */
+enum pds_fwctl_capabilities {
+	PDS_FWCTL_QUERY_CAP = 0,
+	PDS_FWCTL_SEND_CAP,
+};
+#endif /* _UAPI_FWCTL_PDS_H_ */