xref: /linux/arch/arm/mm/ioremap.c (revision f3d9478b2ce468c3115b02ecae7e975990697f15)
1 /*
2  *  linux/arch/arm/mm/ioremap.c
3  *
4  * Re-map IO memory to kernel address space so that we can access it.
5  *
6  * (C) Copyright 1995 1996 Linus Torvalds
7  *
8  * Hacked for ARM by Phil Blundell <philb@gnu.org>
9  * Hacked to allow all architectures to build, and various cleanups
10  * by Russell King
11  *
12  * This allows a driver to remap an arbitrary region of bus memory into
13  * virtual space.  One should *only* use readl, writel, memcpy_toio and
14  * so on with such remapped areas.
15  *
16  * Because the ARM only has a 32-bit address space we can't address the
17  * whole of the (physical) PCI space at once.  PCI huge-mode addressing
18  * allows us to circumvent this restriction by splitting PCI space into
19  * two 2GB chunks and mapping only one at a time into processor memory.
20  * We use MMU protection domains to trap any attempt to access the bank
21  * that is not currently mapped.  (This isn't fully implemented yet.)
22  */
23 #include <linux/module.h>
24 #include <linux/errno.h>
25 #include <linux/mm.h>
26 #include <linux/vmalloc.h>
27 
28 #include <asm/cacheflush.h>
29 #include <asm/io.h>
30 #include <asm/tlbflush.h>
31 
32 static inline void
33 remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
34 	       unsigned long phys_addr, pgprot_t pgprot)
35 {
36 	unsigned long end;
37 
38 	address &= ~PMD_MASK;
39 	end = address + size;
40 	if (end > PMD_SIZE)
41 		end = PMD_SIZE;
42 	BUG_ON(address >= end);
43 	do {
44 		if (!pte_none(*pte))
45 			goto bad;
46 
47 		set_pte(pte, pfn_pte(phys_addr >> PAGE_SHIFT, pgprot));
48 		address += PAGE_SIZE;
49 		phys_addr += PAGE_SIZE;
50 		pte++;
51 	} while (address && (address < end));
52 	return;
53 
54  bad:
55 	printk("remap_area_pte: page already exists\n");
56 	BUG();
57 }
58 
59 static inline int
60 remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
61 	       unsigned long phys_addr, unsigned long flags)
62 {
63 	unsigned long end;
64 	pgprot_t pgprot;
65 
66 	address &= ~PGDIR_MASK;
67 	end = address + size;
68 
69 	if (end > PGDIR_SIZE)
70 		end = PGDIR_SIZE;
71 
72 	phys_addr -= address;
73 	BUG_ON(address >= end);
74 
75 	pgprot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | L_PTE_WRITE | flags);
76 	do {
77 		pte_t * pte = pte_alloc_kernel(pmd, address);
78 		if (!pte)
79 			return -ENOMEM;
80 		remap_area_pte(pte, address, end - address, address + phys_addr, pgprot);
81 		address = (address + PMD_SIZE) & PMD_MASK;
82 		pmd++;
83 	} while (address && (address < end));
84 	return 0;
85 }
86 
87 static int
88 remap_area_pages(unsigned long start, unsigned long pfn,
89 		 unsigned long size, unsigned long flags)
90 {
91 	unsigned long address = start;
92 	unsigned long end = start + size;
93 	unsigned long phys_addr = __pfn_to_phys(pfn);
94 	int err = 0;
95 	pgd_t * dir;
96 
97 	phys_addr -= address;
98 	dir = pgd_offset(&init_mm, address);
99 	BUG_ON(address >= end);
100 	do {
101 		pmd_t *pmd = pmd_alloc(&init_mm, dir, address);
102 		if (!pmd) {
103 			err = -ENOMEM;
104 			break;
105 		}
106 		if (remap_area_pmd(pmd, address, end - address,
107 					 phys_addr + address, flags)) {
108 			err = -ENOMEM;
109 			break;
110 		}
111 
112 		address = (address + PGDIR_SIZE) & PGDIR_MASK;
113 		dir++;
114 	} while (address && (address < end));
115 
116 	flush_cache_vmap(start, end);
117 	return err;
118 }
119 
120 /*
121  * Remap an arbitrary physical address space into the kernel virtual
122  * address space. Needed when the kernel wants to access high addresses
123  * directly.
124  *
125  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
126  * have to convert them into an offset in a page-aligned mapping, but the
127  * caller shouldn't need to know that small detail.
128  *
129  * 'flags' are the extra L_PTE_ flags that you want to specify for this
130  * mapping.  See include/asm-arm/proc-armv/pgtable.h for more information.
131  */
132 void __iomem *
133 __ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
134 	      unsigned long flags)
135 {
136 	unsigned long addr;
137  	struct vm_struct * area;
138 
139  	area = get_vm_area(size, VM_IOREMAP);
140  	if (!area)
141  		return NULL;
142  	addr = (unsigned long)area->addr;
143  	if (remap_area_pages(addr, pfn, size, flags)) {
144  		vunmap((void *)addr);
145  		return NULL;
146  	}
147  	return (void __iomem *) (offset + (char *)addr);
148 }
149 EXPORT_SYMBOL(__ioremap_pfn);
150 
151 void __iomem *
152 __ioremap(unsigned long phys_addr, size_t size, unsigned long flags)
153 {
154 	unsigned long last_addr;
155  	unsigned long offset = phys_addr & ~PAGE_MASK;
156  	unsigned long pfn = __phys_to_pfn(phys_addr);
157 
158  	/*
159  	 * Don't allow wraparound or zero size
160 	 */
161 	last_addr = phys_addr + size - 1;
162 	if (!size || last_addr < phys_addr)
163 		return NULL;
164 
165 	/*
166  	 * Page align the mapping size
167 	 */
168 	size = PAGE_ALIGN(last_addr + 1) - phys_addr;
169 
170  	return __ioremap_pfn(pfn, offset, size, flags);
171 }
172 EXPORT_SYMBOL(__ioremap);
173 
174 void __iounmap(void __iomem *addr)
175 {
176 	vunmap((void *)(PAGE_MASK & (unsigned long)addr));
177 }
178 EXPORT_SYMBOL(__iounmap);
179 
180 #ifdef __io
181 void __iomem *ioport_map(unsigned long port, unsigned int nr)
182 {
183 	return __io(port);
184 }
185 EXPORT_SYMBOL(ioport_map);
186 
187 void ioport_unmap(void __iomem *addr)
188 {
189 }
190 EXPORT_SYMBOL(ioport_unmap);
191 #endif
192 
193 #ifdef CONFIG_PCI
194 #include <linux/pci.h>
195 #include <linux/ioport.h>
196 
197 void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
198 {
199 	unsigned long start = pci_resource_start(dev, bar);
200 	unsigned long len   = pci_resource_len(dev, bar);
201 	unsigned long flags = pci_resource_flags(dev, bar);
202 
203 	if (!len || !start)
204 		return NULL;
205 	if (maxlen && len > maxlen)
206 		len = maxlen;
207 	if (flags & IORESOURCE_IO)
208 		return ioport_map(start, len);
209 	if (flags & IORESOURCE_MEM) {
210 		if (flags & IORESOURCE_CACHEABLE)
211 			return ioremap(start, len);
212 		return ioremap_nocache(start, len);
213 	}
214 	return NULL;
215 }
216 EXPORT_SYMBOL(pci_iomap);
217 
218 void pci_iounmap(struct pci_dev *dev, void __iomem *addr)
219 {
220 	if ((unsigned long)addr >= VMALLOC_START &&
221 	    (unsigned long)addr < VMALLOC_END)
222 		iounmap(addr);
223 }
224 EXPORT_SYMBOL(pci_iounmap);
225 #endif
226