1. 根目录:
2. arch
3. score
4. include
5. asm
6. fixmap.h

#ifndef _ASM_SCORE_FIXMAP_H
#define _ASM_SCORE_FIXMAP_H

#include <asm/page.h>

#define PHY_RAM_BASE		0x00000000
#define PHY_IO_BASE		0x10000000

#define VIRTUAL_RAM_BASE	0xa0000000
#define VIRTUAL_IO_BASE		0xb0000000

#define RAM_SPACE_SIZE		0x10000000
#define IO_SPACE_SIZE		0x10000000

/* Kernel unmapped, cached 512MB */
#define KSEG1			0xa0000000

/*
 * Here we define all the compile-time 'special' virtual
 * addresses. The point is to have a constant address at
 * compile time, but to set the physical address only
 * in the boot process. We allocate these special addresses
 * from the end of virtual memory (0xfffff000) backwards.
 * Also this lets us do fail-safe vmalloc(), we
 * can guarantee that these special addresses and
 * vmalloc()-ed addresses never overlap.
 *
 * these 'compile-time allocated' memory buffers are
 * fixed-size 4k pages. (or larger if used with an increment
 * highger than 1) use fixmap_set(idx,phys) to associate
 * physical memory with fixmap indices.
 *
 * TLB entries of such buffers will not be flushed across
 * task switches.
 */

/*
 * on UP currently we will have no trace of the fixmap mechanizm,
 * no page table allocations, etc. This might change in the
 * future, say framebuffers for the console driver(s) could be
 * fix-mapped?
 */
enum fixed_addresses {
#define FIX_N_COLOURS 8
	FIX_CMAP_BEGIN,
	FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS,
	__end_of_fixed_addresses
};

/*
 * used by vmalloc.c.
 *
 * Leave one empty page between vmalloc'ed areas and
 * the start of the fixmap, and leave one page empty
 * at the top of mem..
 */
#define FIXADDR_TOP	((unsigned long)(long)(int)0xfefe0000)
#define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_START	(FIXADDR_TOP - FIXADDR_SIZE)

#define __fix_to_virt(x)	(FIXADDR_TOP - ((x) << PAGE_SHIFT))
#define __virt_to_fix(x)	\
	((FIXADDR_TOP - ((x) & PAGE_MASK)) >> PAGE_SHIFT)

extern void __this_fixmap_does_not_exist(void);

/*
 * 'index to address' translation. If anyone tries to use the idx
 * directly without tranlation, we catch the bug with a NULL-deference
 * kernel oops. Illegal ranges of incoming indices are caught too.
 */
static inline unsigned long fix_to_virt(const unsigned int idx)
{
	return __fix_to_virt(idx);
}

static inline unsigned long virt_to_fix(const unsigned long vaddr)
{
	return __virt_to_fix(vaddr);
}

#endif /* _ASM_SCORE_FIXMAP_H */