xref: /openbmc/linux/arch/openrisc/mm/ioremap.c (revision 002dff36)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * OpenRISC ioremap.c
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  * Modifications for the OpenRISC architecture:
10  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
11  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
12  */
13 
14 #include <linux/vmalloc.h>
15 #include <linux/io.h>
16 #include <linux/pgtable.h>
17 #include <asm/pgalloc.h>
18 #include <asm/kmap_types.h>
19 #include <asm/fixmap.h>
20 #include <asm/bug.h>
21 #include <linux/sched.h>
22 #include <asm/tlbflush.h>
23 
24 extern int mem_init_done;
25 
26 static unsigned int fixmaps_used __initdata;
27 
28 /*
29  * Remap an arbitrary physical address space into the kernel virtual
30  * address space. Needed when the kernel wants to access high addresses
31  * directly.
32  *
33  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
34  * have to convert them into an offset in a page-aligned mapping, but the
35  * caller shouldn't need to know that small detail.
36  */
37 void __iomem *__ref ioremap(phys_addr_t addr, unsigned long size)
38 {
39 	phys_addr_t p;
40 	unsigned long v;
41 	unsigned long offset, last_addr;
42 	struct vm_struct *area = NULL;
43 
44 	/* Don't allow wraparound or zero size */
45 	last_addr = addr + size - 1;
46 	if (!size || last_addr < addr)
47 		return NULL;
48 
49 	/*
50 	 * Mappings have to be page-aligned
51 	 */
52 	offset = addr & ~PAGE_MASK;
53 	p = addr & PAGE_MASK;
54 	size = PAGE_ALIGN(last_addr + 1) - p;
55 
56 	if (likely(mem_init_done)) {
57 		area = get_vm_area(size, VM_IOREMAP);
58 		if (!area)
59 			return NULL;
60 		v = (unsigned long)area->addr;
61 	} else {
62 		if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
63 			return NULL;
64 		v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
65 		fixmaps_used += (size >> PAGE_SHIFT);
66 	}
67 
68 	if (ioremap_page_range(v, v + size, p,
69 			__pgprot(pgprot_val(PAGE_KERNEL) | _PAGE_CI))) {
70 		if (likely(mem_init_done))
71 			vfree(area->addr);
72 		else
73 			fixmaps_used -= (size >> PAGE_SHIFT);
74 		return NULL;
75 	}
76 
77 	return (void __iomem *)(offset + (char *)v);
78 }
79 EXPORT_SYMBOL(ioremap);
80 
81 void iounmap(void *addr)
82 {
83 	/* If the page is from the fixmap pool then we just clear out
84 	 * the fixmap mapping.
85 	 */
86 	if (unlikely((unsigned long)addr > FIXADDR_START)) {
87 		/* This is a bit broken... we don't really know
88 		 * how big the area is so it's difficult to know
89 		 * how many fixed pages to invalidate...
90 		 * just flush tlb and hope for the best...
91 		 * consider this a FIXME
92 		 *
93 		 * Really we should be clearing out one or more page
94 		 * table entries for these virtual addresses so that
95 		 * future references cause a page fault... for now, we
96 		 * rely on two things:
97 		 *   i)  this code never gets called on known boards
98 		 *   ii) invalid accesses to the freed areas aren't made
99 		 */
100 		flush_tlb_all();
101 		return;
102 	}
103 
104 	return vfree((void *)(PAGE_MASK & (unsigned long)addr));
105 }
106 EXPORT_SYMBOL(iounmap);
107 
108 /**
109  * OK, this one's a bit tricky... ioremap can get called before memory is
110  * initialized (early serial console does this) and will want to alloc a page
111  * for its mapping.  No userspace pages will ever get allocated before memory
112  * is initialized so this applies only to kernel pages.  In the event that
113  * this is called before memory is initialized we allocate the page using
114  * the memblock infrastructure.
115  */
116 
117 pte_t __ref *pte_alloc_one_kernel(struct mm_struct *mm)
118 {
119 	pte_t *pte;
120 
121 	if (likely(mem_init_done)) {
122 		pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
123 	} else {
124 		pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
125 		if (!pte)
126 			panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
127 			      __func__, PAGE_SIZE, PAGE_SIZE);
128 	}
129 
130 	return pte;
131 }
132