summaryrefslogtreecommitdiffstats
path: root/arch/arm/mm/ioremap.c
blob: f3ade18862aaa8fd8e63488bc3eee36253c4e0f7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
/*
 *  linux/arch/arm/mm/ioremap.c
 *
 * Re-map IO memory to kernel address space so that we can access it.
 *
 * (C) Copyright 1995 1996 Linus Torvalds
 *
 * Hacked for ARM by Phil Blundell <philb@gnu.org>
 * Hacked to allow all architectures to build, and various cleanups
 * by Russell King
 *
 * This allows a driver to remap an arbitrary region of bus memory into
 * virtual space.  One should *only* use readl, writel, memcpy_toio and
 * so on with such remapped areas.
 *
 * Because the ARM only has a 32-bit address space we can't address the
 * whole of the (physical) PCI space at once.  PCI huge-mode addressing
 * allows us to circumvent this restriction by splitting PCI space into
 * two 2GB chunks and mapping only one at a time into processor memory.
 * We use MMU protection domains to trap any attempt to access the bank
 * that is not currently mapped.  (This isn't fully implemented yet.)
 */
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>

#include <asm/cacheflush.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/sizes.h>

#include <asm/mach/map.h>
#include "mm.h"

/*
 * Used by ioremap() and iounmap() code to mark (super)section-mapped
 * I/O regions in vm_struct->flags field.
 */
#define VM_ARM_SECTION_MAPPING	0x80000000

static int remap_area_pte(pmd_t *pmd, unsigned long addr, unsigned long end,
			  unsigned long phys_addr, const struct mem_type *type)
{
	pgprot_t prot = __pgprot(type->prot_pte);
	pte_t *pte;

	pte = pte_alloc_kernel(pmd, addr);
	if (!pte)
		return -ENOMEM;

	do {
		if (!pte_none(*pte))
			goto bad;

		set_pte_ext(pte, pfn_pte(phys_addr >> PAGE_SHIFT, prot),
			    type->prot_pte_ext);
		phys_addr += PAGE_SIZE;
	} while (pte++, addr += PAGE_SIZE, addr != end);
	return 0;

 bad:
	printk(KERN_CRIT "remap_area_pte: page already exists\n");
	BUG();
}

static inline int remap_area_pmd(pgd_t *pgd, unsigned long addr,
				 unsigned long end, unsigned long phys_addr,
				 const struct mem_type *type)
{
	unsigned long next;
	pmd_t *pmd;
	int ret = 0;

	pmd = pmd_alloc(&init_mm, pgd, addr);
	if (!pmd)
		return -ENOMEM;

	do {
		next = pmd_addr_end(addr, end);
		ret = remap_area_pte(pmd, addr, next, phys_addr, type);
		if (ret)
			return ret;
		phys_addr += next - addr;
	} while (pmd++, addr = next, addr != end);
	return ret;
}

static int remap_area_pages(unsigned long start, unsigned long pfn,
			    size_t size, const struct mem_type *type)
{
	unsigned long addr = start;
	unsigned long next, end = start + size;
	unsigned long phys_addr = __pfn_to_phys(pfn);
	pgd_t *pgd;
	int err = 0;

	BUG_ON(addr >= end);
	pgd = pgd_offset_k(addr);
	do {
		next = pgd_addr_end(addr, end);
		err = remap_area_pmd(pgd, addr, next, phys_addr, type);
		if (err)
			break;
		phys_addr += next - addr;
	} while (pgd++, addr = next, addr != end);

	return err;
}


void __check_kvm_seq(struct mm_struct *mm)
{
	unsigned int seq;

	do {
		seq = init_mm.context.kvm_seq;
		memcpy(pgd_offset(mm, VMALLOC_START),
		       pgd_offset_k(VMALLOC_START),
		       sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
					pgd_index(VMALLOC_START)));
		mm->context.kvm_seq = seq;
	} while (seq != init_mm.context.kvm_seq);
}

#ifndef CONFIG_SMP
/*
 * Section support is unsafe on SMP - If you iounmap and ioremap a region,
 * the other CPUs will not see this change until their next context switch.
 * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
 * which requires the new ioremap'd region to be referenced, the CPU will
 * reference the _old_ region.
 *
 * Note that get_vm_area() allocates a guard 4K page, so we need to mask
 * the size back to 1MB aligned or we will overflow in the loop below.
 */
static void unmap_area_sections(unsigned long virt, unsigned long size)
{
	unsigned long addr = virt, end = virt + (size & ~SZ_1M);
	pgd_t *pgd;

	flush_cache_vunmap(addr, end);
	pgd = pgd_offset_k(addr);
	do {
		pmd_t pmd, *pmdp = pmd_offset(pgd, addr);

		pmd = *pmdp;
		if (!pmd_none(pmd)) {
			/*
			 * Clear the PMD from the page table, and
			 * increment the kvm sequence so others
			 * notice this change.
			 *
			 * Note: this is still racy on SMP machines.
			 */
			pmd_clear(pmdp);
			init_mm.context.kvm_seq++;

			/*
			 * Free the page table, if there was one.
			 */
			if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
				pte_free_kernel(pmd_page_vaddr(pmd));
		}

		addr += PGDIR_SIZE;
		pgd++;
	} while (addr < end);

	/*
	 * Ensure that the active_mm is up to date - we want to
	 * catch any use-after-iounmap cases.
	 */
	if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
		__check_kvm_seq(current->active_mm);

	flush_tlb_kernel_range(virt, end);
}

static int
remap_area_sections(unsigned long virt, unsigned long pfn,
		    size_t size, const struct mem_type *type)
{
	unsigned long addr = virt, end = virt + size;
	pgd_t *pgd;

	/*
	 * Remove and free any PTE-based mapping, and
	 * sync the current kernel mapping.
	 */
	unmap_area_sections(virt, size);

	pgd = pgd_offset_k(addr);
	do {
		pmd_t *pmd = pmd_offset(pgd, addr);

		pmd[0] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
		pfn += SZ_1M >> PAGE_SHIFT;
		pmd[1] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
		pfn += SZ_1M >> PAGE_SHIFT;
		flush_pmd_entry(pmd);

		addr += PGDIR_SIZE;
		pgd++;
	} while (addr < end);

	return 0;
}

static int
remap_area_supersections(unsigned long virt, unsigned long pfn,
			 size_t size, const struct mem_type *type)
{
	unsigned long addr = virt, end = virt + size;
	pgd_t *pgd;

	/*
	 * Remove and free any PTE-based mapping, and
	 * sync the current kernel mapping.
	 */
	unmap_area_sections(virt, size);

	pgd = pgd_offset_k(virt);
	do {
		unsigned long super_pmd_val, i;

		super_pmd_val = __pfn_to_phys(pfn) | type->prot_sect |
				PMD_SECT_SUPER;
		super_pmd_val |= ((pfn >> (32 - PAGE_SHIFT)) & 0xf) << 20;

		for (i = 0; i < 8; i++) {
			pmd_t *pmd = pmd_offset(pgd, addr);

			pmd[0] = __pmd(super_pmd_val);
			pmd[1] = __pmd(super_pmd_val);
			flush_pmd_entry(pmd);

			addr += PGDIR_SIZE;
			pgd++;
		}

		pfn += SUPERSECTION_SIZE >> PAGE_SHIFT;
	} while (addr < end);

	return 0;
}
#endif


/*
 * Remap an arbitrary physical address space into the kernel virtual
 * address space. Needed when the kernel wants to access high addresses
 * directly.
 *
 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 * have to convert them into an offset in a page-aligned mapping, but the
 * caller shouldn't need to know that small detail.
 *
 * 'flags' are the extra L_PTE_ flags that you want to specify for this
 * mapping.  See include/asm-arm/proc-armv/pgtable.h for more information.
 */
void __iomem *
__arm_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
		  unsigned int mtype)
{
	const struct mem_type *type;
	int err;
	unsigned long addr;
 	struct vm_struct * area;

	/*
	 * High mappings must be supersection aligned
	 */
	if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
		return NULL;

	type = get_mem_type(mtype);
	if (!type)
		return NULL;

	size = PAGE_ALIGN(size);

 	area = get_vm_area(size, VM_IOREMAP);
 	if (!area)
 		return NULL;
 	addr = (unsigned long)area->addr;

#ifndef CONFIG_SMP
	if (DOMAIN_IO == 0 &&
	    (((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) ||
	       cpu_is_xsc3()) && pfn >= 0x100000 &&
	       !((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
		area->flags |= VM_ARM_SECTION_MAPPING;
		err = remap_area_supersections(addr, pfn, size, type);
	} else if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
		area->flags |= VM_ARM_SECTION_MAPPING;
		err = remap_area_sections(addr, pfn, size, type);
	} else
#endif
		err = remap_area_pages(addr, pfn, size, type);

	if (err) {
 		vunmap((void *)addr);
 		return NULL;
 	}

	flush_cache_vmap(addr, addr + size);
	return (void __iomem *) (offset + addr);
}
EXPORT_SYMBOL(__arm_ioremap_pfn);

void __iomem *
__arm_ioremap(unsigned long phys_addr, size_t size, unsigned int mtype)
{
	unsigned long last_addr;
 	unsigned long offset = phys_addr & ~PAGE_MASK;
 	unsigned long pfn = __phys_to_pfn(phys_addr);

 	/*
 	 * Don't allow wraparound or zero size
	 */
	last_addr = phys_addr + size - 1;
	if (!size || last_addr < phys_addr)
		return NULL;

	/*
 	 * Page align the mapping size
	 */
	size = PAGE_ALIGN(last_addr + 1) - phys_addr;

 	return __arm_ioremap_pfn(pfn, offset, size, mtype);
}
EXPORT_SYMBOL(__arm_ioremap);

void __iounmap(volatile void __iomem *addr)
{
#ifndef CONFIG_SMP
	struct vm_struct **p, *tmp;
#endif
	unsigned int section_mapping = 0;

	addr = (volatile void __iomem *)(PAGE_MASK & (unsigned long)addr);

#ifndef CONFIG_SMP
	/*
	 * If this is a section based mapping we need to handle it
	 * specially as the VM subsystem does not know how to handle
	 * such a beast. We need the lock here b/c we need to clear
	 * all the mappings before the area can be reclaimed
	 * by someone else.
	 */
	write_lock(&vmlist_lock);
	for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
		if((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
			if (tmp->flags & VM_ARM_SECTION_MAPPING) {
				*p = tmp->next;
				unmap_area_sections((unsigned long)tmp->addr,
						    tmp->size);
				kfree(tmp);
				section_mapping = 1;
			}
			break;
		}
	}
	write_unlock(&vmlist_lock);
#endif

	if (!section_mapping)
		vunmap((void __force *)addr);
}
EXPORT_SYMBOL(__iounmap);
OpenPOWER on IntegriCloud