1 /* 2 * OpenRISC Linux 3 * 4 * Linux architectural port borrowing liberally from similar works of 5 * others. All original copyrights apply as per the original source 6 * declaration. 7 * 8 * OpenRISC implementation: 9 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> 10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> 11 * et al. 12 * 13 * This program is free software; you can redistribute it and/or modify 14 * it under the terms of the GNU General Public License as published by 15 * the Free Software Foundation; either version 2 of the License, or 16 * (at your option) any later version. 17 */ 18 19 #ifndef __ASM_OPENRISC_FIXMAP_H 20 #define __ASM_OPENRISC_FIXMAP_H 21 22 /* Why exactly do we need 2 empty pages between the top of the fixed 23 * addresses and the top of virtual memory? Something is using that 24 * memory space but not sure what right now... If you find it, leave 25 * a comment here. 26 */ 27 #define FIXADDR_TOP ((unsigned long) (-2*PAGE_SIZE)) 28 29 #include <linux/kernel.h> 30 #include <linux/bug.h> 31 #include <asm/page.h> 32 33 /* 34 * On OpenRISC we use these special fixed_addresses for doing ioremap 35 * early in the boot process before memory initialization is complete. 36 * This is used, in particular, by the early serial console code. 37 * 38 * It's not really 'fixmap', per se, but fits loosely into the same 39 * paradigm. 40 */ 41 enum fixed_addresses { 42 /* 43 * FIX_IOREMAP entries are useful for mapping physical address 44 * space before ioremap() is useable, e.g. really early in boot 45 * before kmalloc() is working. 46 */ 47 #define FIX_N_IOREMAPS 32 48 FIX_IOREMAP_BEGIN, 49 FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1, 50 __end_of_fixed_addresses 51 }; 52 53 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 54 /* FIXADDR_BOTTOM might be a better name here... */ 55 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 56 57 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 58 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) 59 60 /* 61 * 'index to address' translation. If anyone tries to use the idx 62 * directly without tranlation, we catch the bug with a NULL-deference 63 * kernel oops. Illegal ranges of incoming indices are caught too. 64 */ 65 static __always_inline unsigned long fix_to_virt(const unsigned int idx) 66 { 67 /* 68 * this branch gets completely eliminated after inlining, 69 * except when someone tries to use fixaddr indices in an 70 * illegal way. (such as mixing up address types or using 71 * out-of-range indices). 72 * 73 * If it doesn't get removed, the linker will complain 74 * loudly with a reasonably clear error message.. 75 */ 76 if (idx >= __end_of_fixed_addresses) 77 BUG(); 78 79 return __fix_to_virt(idx); 80 } 81 82 static inline unsigned long virt_to_fix(const unsigned long vaddr) 83 { 84 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); 85 return __virt_to_fix(vaddr); 86 } 87 88 #endif 89