1/*
2 * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
3 * Copyright (C) 2009 Wind River Systems Inc
4 *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
5 * Copyright (C) 2004 Microtronix Datacom Ltd.
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License. See the file "COPYING" in the main directory of this archive
9 * for more details.
10 */
11
12#include <linux/export.h>
13#include <linux/sched.h>
14#include <linux/mm.h>
15#include <linux/slab.h>
16#include <linux/vmalloc.h>
17#include <linux/io.h>
18
19#include <asm/cacheflush.h>
20#include <asm/tlbflush.h>
21
22static inline void remap_area_pte(pte_t *pte, unsigned long address,
23				unsigned long size, unsigned long phys_addr,
24				unsigned long flags)
25{
26	unsigned long end;
27	unsigned long pfn;
28	pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | _PAGE_READ
29				| _PAGE_WRITE | flags);
30
31	address &= ~PMD_MASK;
32	end = address + size;
33	if (end > PMD_SIZE)
34		end = PMD_SIZE;
35	if (address >= end)
36		BUG();
37	pfn = PFN_DOWN(phys_addr);
38	do {
39		if (!pte_none(*pte)) {
40			pr_err("remap_area_pte: page already exists\n");
41			BUG();
42		}
43		set_pte(pte, pfn_pte(pfn, pgprot));
44		address += PAGE_SIZE;
45		pfn++;
46		pte++;
47	} while (address && (address < end));
48}
49
50static inline int remap_area_pmd(pmd_t *pmd, unsigned long address,
51				unsigned long size, unsigned long phys_addr,
52				unsigned long flags)
53{
54	unsigned long end;
55
56	address &= ~PGDIR_MASK;
57	end = address + size;
58	if (end > PGDIR_SIZE)
59		end = PGDIR_SIZE;
60	phys_addr -= address;
61	if (address >= end)
62		BUG();
63	do {
64		pte_t *pte = pte_alloc_kernel(pmd, address);
65
66		if (!pte)
67			return -ENOMEM;
68		remap_area_pte(pte, address, end - address, address + phys_addr,
69			flags);
70		address = (address + PMD_SIZE) & PMD_MASK;
71		pmd++;
72	} while (address && (address < end));
73	return 0;
74}
75
76static int remap_area_pages(unsigned long address, unsigned long phys_addr,
77				unsigned long size, unsigned long flags)
78{
79	int error;
80	pgd_t *dir;
81	unsigned long end = address + size;
82
83	phys_addr -= address;
84	dir = pgd_offset(&init_mm, address);
85	flush_cache_all();
86	if (address >= end)
87		BUG();
88	do {
89		pud_t *pud;
90		pmd_t *pmd;
91
92		error = -ENOMEM;
93		pud = pud_alloc(&init_mm, dir, address);
94		if (!pud)
95			break;
96		pmd = pmd_alloc(&init_mm, pud, address);
97		if (!pmd)
98			break;
99		if (remap_area_pmd(pmd, address, end - address,
100			phys_addr + address, flags))
101			break;
102		error = 0;
103		address = (address + PGDIR_SIZE) & PGDIR_MASK;
104		dir++;
105	} while (address && (address < end));
106	flush_tlb_all();
107	return error;
108}
109
110#define IS_MAPPABLE_UNCACHEABLE(addr) (addr < 0x20000000UL)
111
112/*
113 * Map some physical address range into the kernel address space.
114 */
115void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
116			unsigned long cacheflag)
117{
118	struct vm_struct *area;
119	unsigned long offset;
120	unsigned long last_addr;
121	void *addr;
122
123	/* Don't allow wraparound or zero size */
124	last_addr = phys_addr + size - 1;
125
126	if (!size || last_addr < phys_addr)
127		return NULL;
128
129	/* Don't allow anybody to remap normal RAM that we're using */
130	if (phys_addr > PHYS_OFFSET && phys_addr < virt_to_phys(high_memory)) {
131		char *t_addr, *t_end;
132		struct page *page;
133
134		t_addr = __va(phys_addr);
135		t_end = t_addr + (size - 1);
136		for (page = virt_to_page(t_addr);
137			page <= virt_to_page(t_end); page++)
138			if (!PageReserved(page))
139				return NULL;
140	}
141
142	/*
143	 * Map uncached objects in the low part of address space to
144	 * CONFIG_NIOS2_IO_REGION_BASE
145	 */
146	if (IS_MAPPABLE_UNCACHEABLE(phys_addr) &&
147	    IS_MAPPABLE_UNCACHEABLE(last_addr) &&
148	    !(cacheflag & _PAGE_CACHED))
149		return (void __iomem *)(CONFIG_NIOS2_IO_REGION_BASE + phys_addr);
150
151	/* Mappings have to be page-aligned */
152	offset = phys_addr & ~PAGE_MASK;
153	phys_addr &= PAGE_MASK;
154	size = PAGE_ALIGN(last_addr + 1) - phys_addr;
155
156	/* Ok, go for it */
157	area = get_vm_area(size, VM_IOREMAP);
158	if (!area)
159		return NULL;
160	addr = area->addr;
161	if (remap_area_pages((unsigned long) addr, phys_addr, size,
162		cacheflag)) {
163		vunmap(addr);
164		return NULL;
165	}
166	return (void __iomem *) (offset + (char *)addr);
167}
168EXPORT_SYMBOL(__ioremap);
169
170/*
171 * __iounmap unmaps nearly everything, so be careful
172 * it doesn't free currently pointer/page tables anymore but it
173 * wasn't used anyway and might be added later.
174 */
175void __iounmap(void __iomem *addr)
176{
177	struct vm_struct *p;
178
179	if ((unsigned long) addr > CONFIG_NIOS2_IO_REGION_BASE)
180		return;
181
182	p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
183	if (!p)
184		pr_err("iounmap: bad address %p\n", addr);
185	kfree(p);
186}
187EXPORT_SYMBOL(__iounmap);
188