v4.19.13 snapshot.
diff --git a/arch/powerpc/include/asm/dcr-mmio.h b/arch/powerpc/include/asm/dcr-mmio.h
new file mode 100644
index 0000000..93a68b2
--- /dev/null
+++ b/arch/powerpc/include/asm/dcr-mmio.h
@@ -0,0 +1,57 @@
+/*
+ * (c) Copyright 2006 Benjamin Herrenschmidt, IBM Corp.
+ *                    <benh@kernel.crashing.org>
+ *
+ *   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.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+ *   the GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program;  if not, write to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _ASM_POWERPC_DCR_MMIO_H
+#define _ASM_POWERPC_DCR_MMIO_H
+#ifdef __KERNEL__
+
+#include <asm/io.h>
+
+typedef struct {
+	void __iomem *token;
+	unsigned int stride;
+	unsigned int base;
+} dcr_host_mmio_t;
+
+static inline bool dcr_map_ok_mmio(dcr_host_mmio_t host)
+{
+	return host.token != NULL;
+}
+
+extern dcr_host_mmio_t dcr_map_mmio(struct device_node *dev,
+				    unsigned int dcr_n,
+				    unsigned int dcr_c);
+extern void dcr_unmap_mmio(dcr_host_mmio_t host, unsigned int dcr_c);
+
+static inline u32 dcr_read_mmio(dcr_host_mmio_t host, unsigned int dcr_n)
+{
+	return in_be32(host.token + ((host.base + dcr_n) * host.stride));
+}
+
+static inline void dcr_write_mmio(dcr_host_mmio_t host,
+				  unsigned int dcr_n,
+				  u32 value)
+{
+	out_be32(host.token + ((host.base + dcr_n) * host.stride), value);
+}
+
+#endif /* __KERNEL__ */
+#endif /* _ASM_POWERPC_DCR_MMIO_H */
+
+