1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * OpenRISC Linux 4 * 5 * Linux architectural port borrowing liberally from similar works of 6 * others. All original copyrights apply as per the original source 7 * declaration. 8 * 9 * OpenRISC implementation: 10 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> 11 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> 12 * et al. 13 */ 14 15 #ifndef __ASM_OPENRISC_FIXMAP_H 16 #define __ASM_OPENRISC_FIXMAP_H 17 18 /* Why exactly do we need 2 empty pages between the top of the fixed 19 * addresses and the top of virtual memory? Something is using that 20 * memory space but not sure what right now... If you find it, leave 21 * a comment here. 22 */ 23 #define FIXADDR_TOP ((unsigned long) (-2*PAGE_SIZE)) 24 25 #include <linux/kernel.h> 26 #include <linux/bug.h> 27 #include <asm/page.h> 28 29 /* 30 * On OpenRISC we use these special fixed_addresses for doing ioremap 31 * early in the boot process before memory initialization is complete. 32 * This is used, in particular, by the early serial console code. 33 * 34 * It's not really 'fixmap', per se, but fits loosely into the same 35 * paradigm. 36 */ 37 enum fixed_addresses { 38 /* 39 * FIX_IOREMAP entries are useful for mapping physical address 40 * space before ioremap() is useable, e.g. really early in boot 41 * before kmalloc() is working. 42 */ 43 #define FIX_N_IOREMAPS 32 44 FIX_IOREMAP_BEGIN, 45 FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1, 46 __end_of_fixed_addresses 47 }; 48 49 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 50 /* FIXADDR_BOTTOM might be a better name here... */ 51 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 52 53 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 54 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) 55 56 /* 57 * 'index to address' translation. If anyone tries to use the idx 58 * directly without tranlation, we catch the bug with a NULL-deference 59 * kernel oops. Illegal ranges of incoming indices are caught too. 60 */ 61 static __always_inline unsigned long fix_to_virt(const unsigned int idx) 62 { 63 /* 64 * this branch gets completely eliminated after inlining, 65 * except when someone tries to use fixaddr indices in an 66 * illegal way. (such as mixing up address types or using 67 * out-of-range indices). 68 * 69 * If it doesn't get removed, the linker will complain 70 * loudly with a reasonably clear error message.. 71 */ 72 if (idx >= __end_of_fixed_addresses) 73 BUG(); 74 75 return __fix_to_virt(idx); 76 } 77 78 static inline unsigned long virt_to_fix(const unsigned long vaddr) 79 { 80 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); 81 return __virt_to_fix(vaddr); 82 } 83 84 #endif 85