1 files changed, 69 insertions, 0 deletions
diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
new file mode 100644
index 0000000000..6796abe190
--- /dev/null
+++ b/include/asm-generic/memory_model.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_MEMORY_MODEL_H
+#define __ASM_MEMORY_MODEL_H
+
+#include <linux/pfn.h>
+
+#ifndef __ASSEMBLY__
+
+/*
+ * supports 3 memory models.
+ */
+#if defined(CONFIG_FLATMEM)
+
+#ifndef ARCH_PFN_OFFSET
+#define ARCH_PFN_OFFSET		(0UL)
+#endif
+
+#define __pfn_to_page(pfn)	(mem_map + ((pfn) - ARCH_PFN_OFFSET))
+#define __page_to_pfn(page)	((unsigned long)((page) - mem_map) + \
+				 ARCH_PFN_OFFSET)
+
+#ifndef pfn_valid
+static inline int pfn_valid(unsigned long pfn)
+{
+	/* avoid <linux/mm.h> include hell */
+	extern unsigned long max_mapnr;
+	unsigned long pfn_offset = ARCH_PFN_OFFSET;
+
+	return pfn >= pfn_offset && (pfn - pfn_offset) < max_mapnr;
+}
+#define pfn_valid pfn_valid
+#endif
+
+#elif defined(CONFIG_SPARSEMEM_VMEMMAP)
+
+/* memmap is virtually contiguous.  */
+#define __pfn_to_page(pfn)	(vmemmap + (pfn))
+#define __page_to_pfn(page)	(unsigned long)((page) - vmemmap)
+
+#elif defined(CONFIG_SPARSEMEM)
+/*
+ * Note: section's mem_map is encoded to reflect its start_pfn.
+ * section[i].section_mem_map == mem_map's address - start_pfn;
+ */
+#define __page_to_pfn(pg)					\
+({	const struct page *__pg = (pg);				\
+	int __sec = page_to_section(__pg);			\
+	(unsigned long)(__pg - __section_mem_map_addr(__nr_to_section(__sec)));	\
+})
+
+#define __pfn_to_page(pfn)				\
+({	unsigned long __pfn = (pfn);			\
+	struct mem_section *__sec = __pfn_to_section(__pfn);	\
+	__section_mem_map_addr(__sec) + __pfn;		\
+})
+#endif /* CONFIG_FLATMEM/SPARSEMEM */
+
+/*
+ * Convert a physical address to a Page Frame Number and back
+ */
+#define	__phys_to_pfn(paddr)	PHYS_PFN(paddr)
+#define	__pfn_to_phys(pfn)	PFN_PHYS(pfn)
+
+#define page_to_pfn __page_to_pfn
+#define pfn_to_page __pfn_to_page
+
+#endif /* __ASSEMBLY__ */
+
+#endif