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 
remap_area_pte(pte_t * pte,unsigned long address,unsigned long size,unsigned long phys_addr,unsigned long flags)22 static 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 
remap_area_pmd(pmd_t * pmd,unsigned long address,unsigned long size,unsigned long phys_addr,unsigned long flags)50 static 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 
remap_area_pages(unsigned long address,unsigned long phys_addr,unsigned long size,unsigned long flags)76 static 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 		p4d_t *p4d;
90 		pud_t *pud;
91 		pmd_t *pmd;
92 
93 		error = -ENOMEM;
94 		p4d = p4d_alloc(&init_mm, dir, address);
95 		if (!p4d)
96 			break;
97 		pud = pud_alloc(&init_mm, p4d, address);
98 		if (!pud)
99 			break;
100 		pmd = pmd_alloc(&init_mm, pud, address);
101 		if (!pmd)
102 			break;
103 		if (remap_area_pmd(pmd, address, end - address,
104 			phys_addr + address, flags))
105 			break;
106 		error = 0;
107 		address = (address + PGDIR_SIZE) & PGDIR_MASK;
108 		dir++;
109 	} while (address && (address < end));
110 	flush_tlb_all();
111 	return error;
112 }
113 
114 #define IS_MAPPABLE_UNCACHEABLE(addr) (addr < 0x20000000UL)
115 
116 /*
117  * Map some physical address range into the kernel address space.
118  */
ioremap(unsigned long phys_addr,unsigned long size)119 void __iomem *ioremap(unsigned long phys_addr, unsigned long size)
120 {
121 	struct vm_struct *area;
122 	unsigned long offset;
123 	unsigned long last_addr;
124 	void *addr;
125 
126 	/* Don't allow wraparound or zero size */
127 	last_addr = phys_addr + size - 1;
128 
129 	if (!size || last_addr < phys_addr)
130 		return NULL;
131 
132 	/* Don't allow anybody to remap normal RAM that we're using */
133 	if (phys_addr > PHYS_OFFSET && phys_addr < virt_to_phys(high_memory)) {
134 		char *t_addr, *t_end;
135 		struct page *page;
136 
137 		t_addr = __va(phys_addr);
138 		t_end = t_addr + (size - 1);
139 		for (page = virt_to_page(t_addr);
140 			page <= virt_to_page(t_end); page++)
141 			if (!PageReserved(page))
142 				return NULL;
143 	}
144 
145 	/*
146 	 * Map uncached objects in the low part of address space to
147 	 * CONFIG_NIOS2_IO_REGION_BASE
148 	 */
149 	if (IS_MAPPABLE_UNCACHEABLE(phys_addr) &&
150 	    IS_MAPPABLE_UNCACHEABLE(last_addr))
151 		return (void __iomem *)(CONFIG_NIOS2_IO_REGION_BASE + phys_addr);
152 
153 	/* Mappings have to be page-aligned */
154 	offset = phys_addr & ~PAGE_MASK;
155 	phys_addr &= PAGE_MASK;
156 	size = PAGE_ALIGN(last_addr + 1) - phys_addr;
157 
158 	/* Ok, go for it */
159 	area = get_vm_area(size, VM_IOREMAP);
160 	if (!area)
161 		return NULL;
162 	addr = area->addr;
163 	if (remap_area_pages((unsigned long) addr, phys_addr, size, 0)) {
164 		vunmap(addr);
165 		return NULL;
166 	}
167 	return (void __iomem *) (offset + (char *)addr);
168 }
169 EXPORT_SYMBOL(ioremap);
170 
171 /*
172  * iounmap unmaps nearly everything, so be careful
173  * it doesn't free currently pointer/page tables anymore but it
174  * wasn't used anyway and might be added later.
175  */
iounmap(void __iomem * addr)176 void iounmap(void __iomem *addr)
177 {
178 	struct vm_struct *p;
179 
180 	if ((unsigned long) addr > CONFIG_NIOS2_IO_REGION_BASE)
181 		return;
182 
183 	p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
184 	if (!p)
185 		pr_err("iounmap: bad address %p\n", addr);
186 	kfree(p);
187 }
188 EXPORT_SYMBOL(iounmap);
189