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Diffstat (limited to 'arch/openrisc/include/asm/fixmap.h')
| -rw-r--r-- | arch/openrisc/include/asm/fixmap.h | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/arch/openrisc/include/asm/fixmap.h b/arch/openrisc/include/asm/fixmap.h new file mode 100644 index 000000000..5a0159546 --- /dev/null +++ b/arch/openrisc/include/asm/fixmap.h @@ -0,0 +1,88 @@ +/* + * OpenRISC Linux + * + * Linux architectural port borrowing liberally from similar works of + * others. All original copyrights apply as per the original source + * declaration. + * + * OpenRISC implementation: + * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> + * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> + * et al. + * + * 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 __ASM_OPENRISC_FIXMAP_H +#define __ASM_OPENRISC_FIXMAP_H + +/* Why exactly do we need 2 empty pages between the top of the fixed + * addresses and the top of virtual memory? Something is using that + * memory space but not sure what right now... If you find it, leave + * a comment here. + */ +#define FIXADDR_TOP ((unsigned long) (-2*PAGE_SIZE)) + +#include <linux/kernel.h> +#include <linux/bug.h> +#include <asm/page.h> + +/* + * On OpenRISC we use these special fixed_addresses for doing ioremap + * early in the boot process before memory initialization is complete. + * This is used, in particular, by the early serial console code. + * + * It's not really 'fixmap', per se, but fits loosely into the same + * paradigm. + */ +enum fixed_addresses { + /* + * FIX_IOREMAP entries are useful for mapping physical address + * space before ioremap() is useable, e.g. really early in boot + * before kmalloc() is working. + */ +#define FIX_N_IOREMAPS 32 + FIX_IOREMAP_BEGIN, + FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1, + __end_of_fixed_addresses +}; + +#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) +/* FIXADDR_BOTTOM might be a better name here... */ +#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) + +/* + * '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 __always_inline unsigned long fix_to_virt(const unsigned int idx) +{ + /* + * this branch gets completely eliminated after inlining, + * except when someone tries to use fixaddr indices in an + * illegal way. (such as mixing up address types or using + * out-of-range indices). + * + * If it doesn't get removed, the linker will complain + * loudly with a reasonably clear error message.. + */ + if (idx >= __end_of_fixed_addresses) + BUG(); + + return __fix_to_virt(idx); +} + +static inline unsigned long virt_to_fix(const unsigned long vaddr) +{ + BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); + return __virt_to_fix(vaddr); +} + +#endif |