linux/include/asm-generic/memory_model.h

/* 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 …
#endif

#define __pfn_to_page …
#define __page_to_pfn …

#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 …
#endif

#elif defined(CONFIG_SPARSEMEM_VMEMMAP)

/* memmap is virtually contiguous.  */
#define __pfn_to_page(pfn) …
#define __page_to_pfn(page) …

#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 …

#define __pfn_to_page …
#endif /* CONFIG_FLATMEM/SPARSEMEM */

/*
 * Convert a physical address to a Page Frame Number and back
 */
#define __phys_to_pfn(paddr) …
#define __pfn_to_phys(pfn) …

#define page_to_pfn …
#define pfn_to_page …

#endif /* __ASSEMBLY__ */

#endif