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 enum fixed_addresses { 30 FIX_EARLYCON_MEM_BASE, 31 __end_of_fixed_addresses 32 }; 33 34 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 35 /* FIXADDR_BOTTOM might be a better name here... */ 36 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 37 #define FIXMAP_PAGE_IO PAGE_KERNEL_NOCACHE 38 39 extern void __set_fixmap(enum fixed_addresses idx, 40 phys_addr_t phys, pgprot_t flags); 41 42 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 43 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) 44 45 /* 46 * 'index to address' translation. If anyone tries to use the idx 47 * directly without tranlation, we catch the bug with a NULL-deference 48 * kernel oops. Illegal ranges of incoming indices are caught too. 49 */ 50 static __always_inline unsigned long fix_to_virt(const unsigned int idx) 51 { 52 /* 53 * this branch gets completely eliminated after inlining, 54 * except when someone tries to use fixaddr indices in an 55 * illegal way. (such as mixing up address types or using 56 * out-of-range indices). 57 * 58 * If it doesn't get removed, the linker will complain 59 * loudly with a reasonably clear error message.. 60 */ 61 if (idx >= __end_of_fixed_addresses) 62 BUG(); 63 64 return __fix_to_virt(idx); 65 } 66 67 static inline unsigned long virt_to_fix(const unsigned long vaddr) 68 { 69 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); 70 return __virt_to_fix(vaddr); 71 } 72 73 #endif 74