12874c5fdSThomas Gleixner /* SPDX-License-Identifier: GPL-2.0-or-later */
261e85e36SJonas Bonn /*
361e85e36SJonas Bonn * OpenRISC Linux
461e85e36SJonas Bonn *
561e85e36SJonas Bonn * Linux architectural port borrowing liberally from similar works of
661e85e36SJonas Bonn * others. All original copyrights apply as per the original source
761e85e36SJonas Bonn * declaration.
861e85e36SJonas Bonn *
961e85e36SJonas Bonn * OpenRISC implementation:
1061e85e36SJonas Bonn * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
1161e85e36SJonas Bonn * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
1261e85e36SJonas Bonn * et al.
1361e85e36SJonas Bonn */
1461e85e36SJonas Bonn
1561e85e36SJonas Bonn #ifndef __ASM_OPENRISC_FIXMAP_H
1661e85e36SJonas Bonn #define __ASM_OPENRISC_FIXMAP_H
1761e85e36SJonas Bonn
1861e85e36SJonas Bonn /* Why exactly do we need 2 empty pages between the top of the fixed
1961e85e36SJonas Bonn * addresses and the top of virtual memory? Something is using that
2061e85e36SJonas Bonn * memory space but not sure what right now... If you find it, leave
2161e85e36SJonas Bonn * a comment here.
2261e85e36SJonas Bonn */
2361e85e36SJonas Bonn #define FIXADDR_TOP ((unsigned long) (-2*PAGE_SIZE))
2461e85e36SJonas Bonn
2561e85e36SJonas Bonn #include <linux/kernel.h>
26e687448cSTobias Klauser #include <linux/bug.h>
2761e85e36SJonas Bonn #include <asm/page.h>
2861e85e36SJonas Bonn
2961e85e36SJonas Bonn /*
3061e85e36SJonas Bonn * On OpenRISC we use these special fixed_addresses for doing ioremap
3161e85e36SJonas Bonn * early in the boot process before memory initialization is complete.
3261e85e36SJonas Bonn * This is used, in particular, by the early serial console code.
3361e85e36SJonas Bonn *
3461e85e36SJonas Bonn * It's not really 'fixmap', per se, but fits loosely into the same
3561e85e36SJonas Bonn * paradigm.
3661e85e36SJonas Bonn */
3761e85e36SJonas Bonn enum fixed_addresses {
3861e85e36SJonas Bonn /*
3961e85e36SJonas Bonn * FIX_IOREMAP entries are useful for mapping physical address
4061e85e36SJonas Bonn * space before ioremap() is useable, e.g. really early in boot
4161e85e36SJonas Bonn * before kmalloc() is working.
4261e85e36SJonas Bonn */
4361e85e36SJonas Bonn #define FIX_N_IOREMAPS 32
4461e85e36SJonas Bonn FIX_IOREMAP_BEGIN,
4561e85e36SJonas Bonn FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
4661e85e36SJonas Bonn __end_of_fixed_addresses
4761e85e36SJonas Bonn };
4861e85e36SJonas Bonn
4961e85e36SJonas Bonn #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
5061e85e36SJonas Bonn /* FIXADDR_BOTTOM might be a better name here... */
5161e85e36SJonas Bonn #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
5261e85e36SJonas Bonn
5361e85e36SJonas Bonn #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
5461e85e36SJonas Bonn #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
5561e85e36SJonas Bonn
5661e85e36SJonas Bonn /*
5761e85e36SJonas Bonn * 'index to address' translation. If anyone tries to use the idx
5861e85e36SJonas Bonn * directly without tranlation, we catch the bug with a NULL-deference
5961e85e36SJonas Bonn * kernel oops. Illegal ranges of incoming indices are caught too.
6061e85e36SJonas Bonn */
fix_to_virt(const unsigned int idx)6161e85e36SJonas Bonn static __always_inline unsigned long fix_to_virt(const unsigned int idx)
6261e85e36SJonas Bonn {
6361e85e36SJonas Bonn /*
6461e85e36SJonas Bonn * this branch gets completely eliminated after inlining,
6561e85e36SJonas Bonn * except when someone tries to use fixaddr indices in an
6661e85e36SJonas Bonn * illegal way. (such as mixing up address types or using
6761e85e36SJonas Bonn * out-of-range indices).
6861e85e36SJonas Bonn *
6961e85e36SJonas Bonn * If it doesn't get removed, the linker will complain
7061e85e36SJonas Bonn * loudly with a reasonably clear error message..
7161e85e36SJonas Bonn */
7261e85e36SJonas Bonn if (idx >= __end_of_fixed_addresses)
7361e85e36SJonas Bonn BUG();
7461e85e36SJonas Bonn
7561e85e36SJonas Bonn return __fix_to_virt(idx);
7661e85e36SJonas Bonn }
7761e85e36SJonas Bonn
virt_to_fix(const unsigned long vaddr)7861e85e36SJonas Bonn static inline unsigned long virt_to_fix(const unsigned long vaddr)
7961e85e36SJonas Bonn {
8061e85e36SJonas Bonn BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
8161e85e36SJonas Bonn return __virt_to_fix(vaddr);
8261e85e36SJonas Bonn }
8361e85e36SJonas Bonn
8461e85e36SJonas Bonn #endif
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