1/*
2 * OpenRISC ioremap.c
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 * Modifications for the OpenRISC architecture:
9 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
11 *
12 *      This program is free software; you can redistribute it and/or
13 *      modify it under the terms of the GNU General Public License
14 *      as published by the Free Software Foundation; either version
15 *      2 of the License, or (at your option) any later version.
16 */
17
18#include <linux/vmalloc.h>
19#include <linux/io.h>
20#include <asm/pgalloc.h>
21#include <asm/kmap_types.h>
22#include <asm/fixmap.h>
23#include <asm/bug.h>
24#include <asm/pgtable.h>
25#include <linux/sched.h>
26#include <asm/tlbflush.h>
27
28extern int mem_init_done;
29
30static unsigned int fixmaps_used __initdata;
31
32/*
33 * Remap an arbitrary physical address space into the kernel virtual
34 * address space. Needed when the kernel wants to access high addresses
35 * directly.
36 *
37 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
38 * have to convert them into an offset in a page-aligned mapping, but the
39 * caller shouldn't need to know that small detail.
40 */
41void __iomem *__init_refok
42__ioremap(phys_addr_t addr, unsigned long size, pgprot_t prot)
43{
44	phys_addr_t p;
45	unsigned long v;
46	unsigned long offset, last_addr;
47	struct vm_struct *area = NULL;
48
49	/* Don't allow wraparound or zero size */
50	last_addr = addr + size - 1;
51	if (!size || last_addr < addr)
52		return NULL;
53
54	/*
55	 * Mappings have to be page-aligned
56	 */
57	offset = addr & ~PAGE_MASK;
58	p = addr & PAGE_MASK;
59	size = PAGE_ALIGN(last_addr + 1) - p;
60
61	if (likely(mem_init_done)) {
62		area = get_vm_area(size, VM_IOREMAP);
63		if (!area)
64			return NULL;
65		v = (unsigned long)area->addr;
66	} else {
67		if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
68			return NULL;
69		v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
70		fixmaps_used += (size >> PAGE_SHIFT);
71	}
72
73	if (ioremap_page_range(v, v + size, p, prot)) {
74		if (likely(mem_init_done))
75			vfree(area->addr);
76		else
77			fixmaps_used -= (size >> PAGE_SHIFT);
78		return NULL;
79	}
80
81	return (void __iomem *)(offset + (char *)v);
82}
83
84void iounmap(void *addr)
85{
86	/* If the page is from the fixmap pool then we just clear out
87	 * the fixmap mapping.
88	 */
89	if (unlikely((unsigned long)addr > FIXADDR_START)) {
90		/* This is a bit broken... we don't really know
91		 * how big the area is so it's difficult to know
92		 * how many fixed pages to invalidate...
93		 * just flush tlb and hope for the best...
94		 * consider this a FIXME
95		 *
96		 * Really we should be clearing out one or more page
97		 * table entries for these virtual addresses so that
98		 * future references cause a page fault... for now, we
99		 * rely on two things:
100		 *   i)  this code never gets called on known boards
101		 *   ii) invalid accesses to the freed areas aren't made
102		 */
103		flush_tlb_all();
104		return;
105	}
106
107	return vfree((void *)(PAGE_MASK & (unsigned long)addr));
108}
109
110/**
111 * OK, this one's a bit tricky... ioremap can get called before memory is
112 * initialized (early serial console does this) and will want to alloc a page
113 * for its mapping.  No userspace pages will ever get allocated before memory
114 * is initialized so this applies only to kernel pages.  In the event that
115 * this is called before memory is initialized we allocate the page using
116 * the memblock infrastructure.
117 */
118
119pte_t __init_refok *pte_alloc_one_kernel(struct mm_struct *mm,
120					 unsigned long address)
121{
122	pte_t *pte;
123
124	if (likely(mem_init_done)) {
125		pte = (pte_t *) __get_free_page(GFP_KERNEL | __GFP_REPEAT);
126	} else {
127		pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
128#if 0
129		/* FIXME: use memblock... */
130		pte = (pte_t *) __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
131#endif
132	}
133
134	if (pte)
135		clear_page(pte);
136	return pte;
137}
138