cxl: Add userspace header file

This adds a header file for use by userspace programs wanting to interact with
the kernel cxl driver.  It defines structs and magic numbers required for
userspace to interact with devices in /dev/cxl/afuM.N.

Further documentation on this interface is added in a subsequent patch in
Documentation/powerpc/cxl.txt.

It also adds this new userspace header file to Kbuild so it's exported when
doing "make headers_installs".

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

include/uapi/Kbuild

@@ -12,3 +12,4 @@ header-y += video/
 header-y += drm/
 header-y += xen/
 header-y += scsi/
+header-y += misc/

include/uapi/misc/Kbuild

@@ -0,0 +1,2 @@
+# misc Header export list
+header-y += cxl.h

include/uapi/misc/cxl.h

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2014 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _UAPI_MISC_CXL_H
+#define _UAPI_MISC_CXL_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+/* Structs for IOCTLS for userspace to talk to the kernel */
+struct cxl_ioctl_start_work {
+	__u64 flags;
+	__u64 work_element_descriptor;
+	__u64 amr;
+	__s16 num_interrupts;
+	__s16 reserved1;
+	__s32 reserved2;
+	__u64 reserved3;
+	__u64 reserved4;
+	__u64 reserved5;
+	__u64 reserved6;
+};
+#define CXL_START_WORK_AMR		0x0000000000000001ULL
+#define CXL_START_WORK_NUM_IRQS		0x0000000000000002ULL
+#define CXL_START_WORK_ALL		(CXL_START_WORK_AMR |\
+					 CXL_START_WORK_NUM_IRQS)
+
+/* IOCTL numbers */
+#define CXL_MAGIC 0xCA
+#define CXL_IOCTL_START_WORK		_IOW(CXL_MAGIC, 0x00, struct cxl_ioctl_start_work)
+#define CXL_IOCTL_GET_PROCESS_ELEMENT	_IOR(CXL_MAGIC, 0x01, __u32)
+
+/* Events from read() */
+#define CXL_READ_MIN_SIZE 0x1000 /* 4K */
+
+enum cxl_event_type {
+	CXL_EVENT_RESERVED      = 0,
+	CXL_EVENT_AFU_INTERRUPT = 1,
+	CXL_EVENT_DATA_STORAGE  = 2,
+	CXL_EVENT_AFU_ERROR     = 3,
+};
+
+struct cxl_event_header {
+	__u16 type;
+	__u16 size;
+	__u16 process_element;
+	__u16 reserved1;
+};
+
+struct cxl_event_afu_interrupt {
+	__u16 flags;
+	__u16 irq; /* Raised AFU interrupt number */
+	__u32 reserved1;
+};
+
+struct cxl_event_data_storage {
+	__u16 flags;
+	__u16 reserved1;
+	__u32 reserved2;
+	__u64 addr;
+	__u64 dsisr;
+	__u64 reserved3;
+};
+
+struct cxl_event_afu_error {
+	__u16 flags;
+	__u16 reserved1;
+	__u32 reserved2;
+	__u64 error;
+};
+
+struct cxl_event {
+	struct cxl_event_header header;
+	union {
+		struct cxl_event_afu_interrupt irq;
+		struct cxl_event_data_storage fault;
+		struct cxl_event_afu_error afu_error;
+	};
+};
+
+#endif /* _UAPI_MISC_CXL_H */