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/mmu_context.h>
31#include <asm/pgalloc.h>
32#include <asm/tlbflush.h>
33#include <asm/sizes.h>
34
35#include <asm/mach/map.h>
36#include "mm.h"
37
38/*
39 * Used by ioremap() and iounmap() code to mark (super)section-mapped
40 * I/O regions in vm_struct->flags field.
41 */
42#define VM_ARM_SECTION_MAPPING	0x80000000
43
44static int remap_area_pte(pmd_t *pmd, unsigned long addr, unsigned long end,
45			  unsigned long phys_addr, const struct mem_type *type)
46{
47	pgprot_t prot = __pgprot(type->prot_pte);
48	pte_t *pte;
49
50	pte = pte_alloc_kernel(pmd, addr);
51	if (!pte)
52		return -ENOMEM;
53
54	do {
55		if (!pte_none(*pte))
56			goto bad;
57
58		set_pte_ext(pte, pfn_pte(phys_addr >> PAGE_SHIFT, prot),
59			    type->prot_pte_ext);
60		phys_addr += PAGE_SIZE;
61	} while (pte++, addr += PAGE_SIZE, addr != end);
62	return 0;
63
64 bad:
65	printk(KERN_CRIT "remap_area_pte: page already exists\n");
66	BUG();
67}
68
69static inline int remap_area_pmd(pgd_t *pgd, unsigned long addr,
70				 unsigned long end, unsigned long phys_addr,
71				 const struct mem_type *type)
72{
73	unsigned long next;
74	pmd_t *pmd;
75	int ret = 0;
76
77	pmd = pmd_alloc(&init_mm, pgd, addr);
78	if (!pmd)
79		return -ENOMEM;
80
81	do {
82		next = pmd_addr_end(addr, end);
83		ret = remap_area_pte(pmd, addr, next, phys_addr, type);
84		if (ret)
85			return ret;
86		phys_addr += next - addr;
87	} while (pmd++, addr = next, addr != end);
88	return ret;
89}
90
91static int remap_area_pages(unsigned long start, unsigned long pfn,
92			    size_t size, const struct mem_type *type)
93{
94	unsigned long addr = start;
95	unsigned long next, end = start + size;
96	unsigned long phys_addr = __pfn_to_phys(pfn);
97	pgd_t *pgd;
98	int err = 0;
99
100	BUG_ON(addr >= end);
101	pgd = pgd_offset_k(addr);
102	do {
103		next = pgd_addr_end(addr, end);
104		err = remap_area_pmd(pgd, addr, next, phys_addr, type);
105		if (err)
106			break;
107		phys_addr += next - addr;
108	} while (pgd++, addr = next, addr != end);
109
110	return err;
111}
112
113
114void __check_kvm_seq(struct mm_struct *mm)
115{
116	unsigned int seq;
117
118	do {
119		seq = init_mm.context.kvm_seq;
120		memcpy(pgd_offset(mm, VMALLOC_START),
121		       pgd_offset_k(VMALLOC_START),
122		       sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
123					pgd_index(VMALLOC_START)));
124		mm->context.kvm_seq = seq;
125	} while (seq != init_mm.context.kvm_seq);
126}
127
128#ifndef CONFIG_SMP
129/*
130 * Section support is unsafe on SMP - If you iounmap and ioremap a region,
131 * the other CPUs will not see this change until their next context switch.
132 * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
133 * which requires the new ioremap'd region to be referenced, the CPU will
134 * reference the _old_ region.
135 *
136 * Note that get_vm_area() allocates a guard 4K page, so we need to mask
137 * the size back to 1MB aligned or we will overflow in the loop below.
138 */
139static void unmap_area_sections(unsigned long virt, unsigned long size)
140{
141	unsigned long addr = virt, end = virt + (size & ~SZ_1M);
142	pgd_t *pgd;
143
144	flush_cache_vunmap(addr, end);
145	pgd = pgd_offset_k(addr);
146	do {
147		pmd_t pmd, *pmdp = pmd_offset(pgd, addr);
148
149		pmd = *pmdp;
150		if (!pmd_none(pmd)) {
151			/*
152			 * Clear the PMD from the page table, and
153			 * increment the kvm sequence so others
154			 * notice this change.
155			 *
156			 * Note: this is still racy on SMP machines.
157			 */
158			pmd_clear(pmdp);
159			init_mm.context.kvm_seq++;
160
161			/*
162			 * Free the page table, if there was one.
163			 */
164			if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
165				pte_free_kernel(pmd_page_vaddr(pmd));
166		}
167
168		addr += PGDIR_SIZE;
169		pgd++;
170	} while (addr < end);
171
172	/*
173	 * Ensure that the active_mm is up to date - we want to
174	 * catch any use-after-iounmap cases.
175	 */
176	if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
177		__check_kvm_seq(current->active_mm);
178
179	flush_tlb_kernel_range(virt, end);
180}
181
182static int
183remap_area_sections(unsigned long virt, unsigned long pfn,
184		    size_t size, const struct mem_type *type)
185{
186	unsigned long addr = virt, end = virt + size;
187	pgd_t *pgd;
188
189	/*
190	 * Remove and free any PTE-based mapping, and
191	 * sync the current kernel mapping.
192	 */
193	unmap_area_sections(virt, size);
194
195	pgd = pgd_offset_k(addr);
196	do {
197		pmd_t *pmd = pmd_offset(pgd, addr);
198
199		pmd[0] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
200		pfn += SZ_1M >> PAGE_SHIFT;
201		pmd[1] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
202		pfn += SZ_1M >> PAGE_SHIFT;
203		flush_pmd_entry(pmd);
204
205		addr += PGDIR_SIZE;
206		pgd++;
207	} while (addr < end);
208
209	return 0;
210}
211
212static int
213remap_area_supersections(unsigned long virt, unsigned long pfn,
214			 size_t size, const struct mem_type *type)
215{
216	unsigned long addr = virt, end = virt + size;
217	pgd_t *pgd;
218
219	/*
220	 * Remove and free any PTE-based mapping, and
221	 * sync the current kernel mapping.
222	 */
223	unmap_area_sections(virt, size);
224
225	pgd = pgd_offset_k(virt);
226	do {
227		unsigned long super_pmd_val, i;
228
229		super_pmd_val = __pfn_to_phys(pfn) | type->prot_sect |
230				PMD_SECT_SUPER;
231		super_pmd_val |= ((pfn >> (32 - PAGE_SHIFT)) & 0xf) << 20;
232
233		for (i = 0; i < 8; i++) {
234			pmd_t *pmd = pmd_offset(pgd, addr);
235
236			pmd[0] = __pmd(super_pmd_val);
237			pmd[1] = __pmd(super_pmd_val);
238			flush_pmd_entry(pmd);
239
240			addr += PGDIR_SIZE;
241			pgd++;
242		}
243
244		pfn += SUPERSECTION_SIZE >> PAGE_SHIFT;
245	} while (addr < end);
246
247	return 0;
248}
249#endif
250
251
252/*
253 * Remap an arbitrary physical address space into the kernel virtual
254 * address space. Needed when the kernel wants to access high addresses
255 * directly.
256 *
257 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
258 * have to convert them into an offset in a page-aligned mapping, but the
259 * caller shouldn't need to know that small detail.
260 *
261 * 'flags' are the extra L_PTE_ flags that you want to specify for this
262 * mapping.  See include/asm-arm/proc-armv/pgtable.h for more information.
263 */
264void __iomem *
265__arm_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
266		  unsigned int mtype)
267{
268	const struct mem_type *type;
269	int err;
270	unsigned long addr;
271 	struct vm_struct * area;
272
273	/*
274	 * High mappings must be supersection aligned
275	 */
276	if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
277		return NULL;
278
279	type = get_mem_type(mtype);
280	if (!type)
281		return NULL;
282
283	size = PAGE_ALIGN(size);
284
285 	area = get_vm_area(size, VM_IOREMAP);
286 	if (!area)
287 		return NULL;
288 	addr = (unsigned long)area->addr;
289
290#ifndef CONFIG_SMP
291	if (DOMAIN_IO == 0 &&
292	    (((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) ||
293	       cpu_is_xsc3()) && pfn >= 0x100000 &&
294	       !((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
295		area->flags |= VM_ARM_SECTION_MAPPING;
296		err = remap_area_supersections(addr, pfn, size, type);
297	} else if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
298		area->flags |= VM_ARM_SECTION_MAPPING;
299		err = remap_area_sections(addr, pfn, size, type);
300	} else
301#endif
302		err = remap_area_pages(addr, pfn, size, type);
303
304	if (err) {
305 		vunmap((void *)addr);
306 		return NULL;
307 	}
308
309	flush_cache_vmap(addr, addr + size);
310	return (void __iomem *) (offset + addr);
311}
312EXPORT_SYMBOL(__arm_ioremap_pfn);
313
314void __iomem *
315__arm_ioremap(unsigned long phys_addr, size_t size, unsigned int mtype)
316{
317	unsigned long last_addr;
318 	unsigned long offset = phys_addr & ~PAGE_MASK;
319 	unsigned long pfn = __phys_to_pfn(phys_addr);
320
321 	/*
322 	 * Don't allow wraparound or zero size
323	 */
324	last_addr = phys_addr + size - 1;
325	if (!size || last_addr < phys_addr)
326		return NULL;
327
328	/*
329 	 * Page align the mapping size
330	 */
331	size = PAGE_ALIGN(last_addr + 1) - phys_addr;
332
333 	return __arm_ioremap_pfn(pfn, offset, size, mtype);
334}
335EXPORT_SYMBOL(__arm_ioremap);
336
337void __iounmap(volatile void __iomem *addr)
338{
339#ifndef CONFIG_SMP
340	struct vm_struct **p, *tmp;
341#endif
342	unsigned int section_mapping = 0;
343
344	addr = (volatile void __iomem *)(PAGE_MASK & (unsigned long)addr);
345
346#ifndef CONFIG_SMP
347	/*
348	 * If this is a section based mapping we need to handle it
349	 * specially as the VM subsystem does not know how to handle
350	 * such a beast. We need the lock here b/c we need to clear
351	 * all the mappings before the area can be reclaimed
352	 * by someone else.
353	 */
354	write_lock(&vmlist_lock);
355	for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
356		if((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
357			if (tmp->flags & VM_ARM_SECTION_MAPPING) {
358				*p = tmp->next;
359				unmap_area_sections((unsigned long)tmp->addr,
360						    tmp->size);
361				kfree(tmp);
362				section_mapping = 1;
363			}
364			break;
365		}
366	}
367	write_unlock(&vmlist_lock);
368#endif
369
370	if (!section_mapping)
371		vunmap((void __force *)addr);
372}
373EXPORT_SYMBOL(__iounmap);
374