aboutsummaryrefslogtreecommitdiff
path: root/include/asm-mips/io.h
blob: a9fa1254894aa0eb08cb2df1fdede646a3458fe9 (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
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1994, 1995 Waldorf GmbH
 * Copyright (C) 1994 - 2000 Ralf Baechle
 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
 * Copyright (C) 2004, 2005  MIPS Technologies, Inc.  All rights reserved.
 *	Author:	Maciej W. Rozycki <macro@mips.com>
 */
#ifndef _ASM_IO_H
#define _ASM_IO_H

#include <linux/config.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/types.h>

#include <asm/addrspace.h>
#include <asm/byteorder.h>
#include <asm/cpu.h>
#include <asm/cpu-features.h>
#include <asm/page.h>
#include <asm/pgtable-bits.h>
#include <asm/processor.h>
#include <asm/string.h>

#include <ioremap.h>
#include <mangle-port.h>

/*
 * Slowdown I/O port space accesses for antique hardware.
 */
#undef CONF_SLOWDOWN_IO

/*
 * Raw operations are never swapped in software.  OTOH values that raw
 * operations are working on may or may not have been swapped by the bus
 * hardware.  An example use would be for flash memory that's used for
 * execute in place.
 */
# define __raw_ioswabb(x)	(x)
# define __raw_ioswabw(x)	(x)
# define __raw_ioswabl(x)	(x)
# define __raw_ioswabq(x)	(x)
# define ____raw_ioswabq(x)	(x)

/*
 * Sane hardware offers swapping of PCI/ISA I/O space accesses in hardware;
 * less sane hardware forces software to fiddle with this...
 *
 * Regardless, if the host bus endianness mismatches that of PCI/ISA, then
 * you can't have the numerical value of data and byte addresses within
 * multibyte quantities both preserved at the same time.  Hence two
 * variations of functions: non-prefixed ones that preserve the value
 * and prefixed ones that preserve byte addresses.  The latters are
 * typically used for moving raw data between a peripheral and memory (cf.
 * string I/O functions), hence the "mem_" prefix.
 */
#if defined(CONFIG_SWAP_IO_SPACE)

# define ioswabb(x)		(x)
# define mem_ioswabb(x)		(x)
# ifdef CONFIG_SGI_IP22
/*
 * IP22 seems braindead enough to swap 16bits values in hardware, but
 * not 32bits.  Go figure... Can't tell without documentation.
 */
#  define ioswabw(x)		(x)
#  define mem_ioswabw(x)	le16_to_cpu(x)
# else
#  define ioswabw(x)		le16_to_cpu(x)
#  define mem_ioswabw(x)	(x)
# endif
# define ioswabl(x)		le32_to_cpu(x)
# define mem_ioswabl(x)		(x)
# define ioswabq(x)		le64_to_cpu(x)
# define mem_ioswabq(x)		(x)

#else

# define ioswabb(x)		(x)
# define mem_ioswabb(x)		(x)
# define ioswabw(x)		(x)
# define mem_ioswabw(x)		cpu_to_le16(x)
# define ioswabl(x)		(x)
# define mem_ioswabl(x)		cpu_to_le32(x)
# define ioswabq(x)		(x)
# define mem_ioswabq(x)		cpu_to_le32(x)

#endif

#define IO_SPACE_LIMIT 0xffff

/*
 * On MIPS I/O ports are memory mapped, so we access them using normal
 * load/store instructions. mips_io_port_base is the virtual address to
 * which all ports are being mapped.  For sake of efficiency some code
 * assumes that this is an address that can be loaded with a single lui
 * instruction, so the lower 16 bits must be zero.  Should be true on
 * on any sane architecture; generic code does not use this assumption.
 */
extern const unsigned long mips_io_port_base;

#define set_io_port_base(base)	\
	do { * (unsigned long *) &mips_io_port_base = (base); } while (0)

/*
 * Thanks to James van Artsdalen for a better timing-fix than
 * the two short jumps: using outb's to a nonexistent port seems
 * to guarantee better timings even on fast machines.
 *
 * On the other hand, I'd like to be sure of a non-existent port:
 * I feel a bit unsafe about using 0x80 (should be safe, though)
 *
 *		Linus
 *
 */

#define __SLOW_DOWN_IO \
	__asm__ __volatile__( \
		"sb\t$0,0x80(%0)" \
		: : "r" (mips_io_port_base));

#ifdef CONF_SLOWDOWN_IO
#ifdef REALLY_SLOW_IO
#define SLOW_DOWN_IO { __SLOW_DOWN_IO; __SLOW_DOWN_IO; __SLOW_DOWN_IO; __SLOW_DOWN_IO; }
#else
#define SLOW_DOWN_IO __SLOW_DOWN_IO
#endif
#else
#define SLOW_DOWN_IO
#endif

/*
 *     virt_to_phys    -       map virtual addresses to physical
 *     @address: address to remap
 *
 *     The returned physical address is the physical (CPU) mapping for
 *     the memory address given. It is only valid to use this function on
 *     addresses directly mapped or allocated via kmalloc.
 *
 *     This function does not give bus mappings for DMA transfers. In
 *     almost all conceivable cases a device driver should not be using
 *     this function
 */
static inline unsigned long virt_to_phys(volatile void * address)
{
	return (unsigned long)address - PAGE_OFFSET;
}

/*
 *     phys_to_virt    -       map physical address to virtual
 *     @address: address to remap
 *
 *     The returned virtual address is a current CPU mapping for
 *     the memory address given. It is only valid to use this function on
 *     addresses that have a kernel mapping
 *
 *     This function does not handle bus mappings for DMA transfers. In
 *     almost all conceivable cases a device driver should not be using
 *     this function
 */
static inline void * phys_to_virt(unsigned long address)
{
	return (void *)(address + PAGE_OFFSET);
}

/*
 * ISA I/O bus memory addresses are 1:1 with the physical address.
 */
static inline unsigned long isa_virt_to_bus(volatile void * address)
{
	return (unsigned long)address - PAGE_OFFSET;
}

static inline void * isa_bus_to_virt(unsigned long address)
{
	return (void *)(address + PAGE_OFFSET);
}

#define isa_page_to_bus page_to_phys

/*
 * However PCI ones are not necessarily 1:1 and therefore these interfaces
 * are forbidden in portable PCI drivers.
 *
 * Allow them for x86 for legacy drivers, though.
 */
#define virt_to_bus virt_to_phys
#define bus_to_virt phys_to_virt

/*
 * isa_slot_offset is the address where E(ISA) busaddress 0 is mapped
 * for the processor.  This implies the assumption that there is only
 * one of these busses.
 */
extern unsigned long isa_slot_offset;

/*
 * Change "struct page" to physical address.
 */
#define page_to_phys(page)	((dma_addr_t)page_to_pfn(page) << PAGE_SHIFT)

extern void __iomem * __ioremap(phys_t offset, phys_t size, unsigned long flags);
extern void __iounmap(volatile void __iomem *addr);

static inline void __iomem * __ioremap_mode(phys_t offset, unsigned long size,
	unsigned long flags)
{
#define __IS_LOW512(addr) (!((phys_t)(addr) & (phys_t) ~0x1fffffffULL))

	if (cpu_has_64bit_addresses) {
		u64 base = UNCAC_BASE;

		/*
		 * R10000 supports a 2 bit uncached attribute therefore
		 * UNCAC_BASE may not equal IO_BASE.
		 */
		if (flags == _CACHE_UNCACHED)
			base = (u64) IO_BASE;
		return (void __iomem *) (unsigned long) (base + offset);
	} else if (__builtin_constant_p(offset) &&
		   __builtin_constant_p(size) && __builtin_constant_p(flags)) {
		phys_t phys_addr, last_addr;

		phys_addr = fixup_bigphys_addr(offset, size);

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

		/*
		 * Map uncached objects in the low 512MB of address
		 * space using KSEG1.
		 */
		if (__IS_LOW512(phys_addr) && __IS_LOW512(last_addr) &&
		    flags == _CACHE_UNCACHED)
			return (void __iomem *)CKSEG1ADDR(phys_addr);
	}

	return __ioremap(offset, size, flags);

#undef __IS_LOW512
}

/*
 * ioremap     -   map bus memory into CPU space
 * @offset:    bus address of the memory
 * @size:      size of the resource to map
 *
 * ioremap performs a platform specific sequence of operations to
 * make bus memory CPU accessible via the readb/readw/readl/writeb/
 * writew/writel functions and the other mmio helpers. The returned
 * address is not guaranteed to be usable directly as a virtual
 * address.
 */
#define ioremap(offset, size)						\
	__ioremap_mode((offset), (size), _CACHE_UNCACHED)

/*
 * ioremap_nocache     -   map bus memory into CPU space
 * @offset:    bus address of the memory
 * @size:      size of the resource to map
 *
 * ioremap_nocache performs a platform specific sequence of operations to
 * make bus memory CPU accessible via the readb/readw/readl/writeb/
 * writew/writel functions and the other mmio helpers. The returned
 * address is not guaranteed to be usable directly as a virtual
 * address.
 *
 * This version of ioremap ensures that the memory is marked uncachable
 * on the CPU as well as honouring existing caching rules from things like
 * the PCI bus. Note that there are other caches and buffers on many
 * busses. In paticular driver authors should read up on PCI writes
 *
 * It's useful if some control registers are in such an area and
 * write combining or read caching is not desirable:
 */
#define ioremap_nocache(offset, size)					\
	__ioremap_mode((offset), (size), _CACHE_UNCACHED)

/*
 * These two are MIPS specific ioremap variant.  ioremap_cacheable_cow
 * requests a cachable mapping, ioremap_uncached_accelerated requests a
 * mapping using the uncached accelerated mode which isn't supported on
 * all processors.
 */
#define ioremap_cacheable_cow(offset, size)				\
	__ioremap_mode((offset), (size), _CACHE_CACHABLE_COW)
#define ioremap_uncached_accelerated(offset, size)			\
	__ioremap_mode((offset), (size), _CACHE_UNCACHED_ACCELERATED)

static inline void iounmap(volatile void __iomem *addr)
{
#define __IS_KSEG1(addr) (((unsigned long)(addr) & ~0x1fffffffUL) == CKSEG1)

	if (cpu_has_64bit_addresses ||
	    (__builtin_constant_p(addr) && __IS_KSEG1(addr)))
		return;

	__iounmap(addr);

#undef __IS_KSEG1
}

#define __BUILD_MEMORY_SINGLE(pfx, bwlq, type, irq)			\
									\
static inline void pfx##write##bwlq(type val,				\
				    volatile void __iomem *mem)		\
{									\
	volatile type *__mem;						\
	type __val;							\
									\
	__mem = (void *)__swizzle_addr_##bwlq((unsigned long)(mem));	\
									\
	__val = pfx##ioswab##bwlq(val);					\
									\
	if (sizeof(type) != sizeof(u64) || sizeof(u64) == sizeof(long))	\
		*__mem = __val;						\
	else if (cpu_has_64bits) {					\
		unsigned long __flags;					\
		type __tmp;						\
									\
		if (irq)						\
			local_irq_save(__flags);			\
		__asm__ __volatile__(					\
			".set	mips3"		"\t\t# __writeq""\n\t"	\
			"dsll32	%L0, %L0, 0"			"\n\t"	\
			"dsrl32	%L0, %L0, 0"			"\n\t"	\
			"dsll32	%M0, %M0, 0"			"\n\t"	\
			"or	%L0, %L0, %M0"			"\n\t"	\
			"sd	%L0, %2"			"\n\t"	\
			".set	mips0"				"\n"	\
			: "=r" (__tmp)					\
			: "0" (__val), "m" (*__mem));			\
		if (irq)						\
			local_irq_restore(__flags);			\
	} else								\
		BUG();							\
}									\
									\
static inline type pfx##read##bwlq(volatile void __iomem *mem)		\
{									\
	volatile type *__mem;						\
	type __val;							\
									\
	__mem = (void *)__swizzle_addr_##bwlq((unsigned long)(mem));	\
									\
	if (sizeof(type) != sizeof(u64) || sizeof(u64) == sizeof(long))	\
		__val = *__mem;						\
	else if (cpu_has_64bits) {					\
		unsigned long __flags;					\
									\
		if (irq)						\
			local_irq_save(__flags);			\
		__asm__ __volatile__(					\
			".set	mips3"		"\t\t# __readq"	"\n\t"	\
			"ld	%L0, %1"			"\n\t"	\
			"dsra32	%M0, %L0, 0"			"\n\t"	\
			"sll	%L0, %L0, 0"			"\n\t"	\
			".set	mips0"				"\n"	\
			: "=r" (__val)					\
			: "m" (*__mem));				\
		if (irq)						\
			local_irq_restore(__flags);			\
	} else {							\
		__val = 0;						\
		BUG();							\
	}								\
									\
	return pfx##ioswab##bwlq(__val);				\
}

#define __BUILD_IOPORT_SINGLE(pfx, bwlq, type, p, slow)			\
									\
static inline void pfx##out##bwlq##p(type val, unsigned long port)	\
{									\
	volatile type *__addr;						\
	type __val;							\
									\
	port = __swizzle_addr_##bwlq(port);				\
	__addr = (void *)(mips_io_port_base + port);			\
									\
	__val = pfx##ioswab##bwlq(val);					\
									\
	/* Really, we want this to be atomic */				\
	BUILD_BUG_ON(sizeof(type) > sizeof(unsigned long));		\
									\
	*__addr = __val;						\
	slow;								\
}									\
									\
static inline type pfx##in##bwlq##p(unsigned long port)			\
{									\
	volatile type *__addr;						\
	type __val;							\
									\
	port = __swizzle_addr_##bwlq(port);				\
	__addr = (void *)(mips_io_port_base + port);			\
									\
	BUILD_BUG_ON(sizeof(type) > sizeof(unsigned long));		\
									\
	__val = *__addr;						\
	slow;								\
									\
	return pfx##ioswab##bwlq(__val);				\
}

#define __BUILD_MEMORY_PFX(bus, bwlq, type)				\
									\
__BUILD_MEMORY_SINGLE(bus, bwlq, type, 1)

#define BUILDIO_MEM(bwlq, type)						\
									\
__BUILD_MEMORY_PFX(__raw_, bwlq, type)					\
__BUILD_MEMORY_PFX(, bwlq, type)					\
__BUILD_MEMORY_PFX(mem_, bwlq, type)					\

BUILDIO_MEM(b, u8)
BUILDIO_MEM(w, u16)
BUILDIO_MEM(l, u32)
BUILDIO_MEM(q, u64)

#define __BUILD_IOPORT_PFX(bus, bwlq, type)				\
	__BUILD_IOPORT_SINGLE(bus, bwlq, type, ,)			\
	__BUILD_IOPORT_SINGLE(bus, bwlq, type, _p, SLOW_DOWN_IO)

#define BUILDIO_IOPORT(bwlq, type)					\
	__BUILD_IOPORT_PFX(, bwlq, type)				\
	__BUILD_IOPORT_PFX(mem_, bwlq, type)

BUILDIO_IOPORT(b, u8)
BUILDIO_IOPORT(w, u16)
BUILDIO_IOPORT(l, u32)
#ifdef CONFIG_64BIT
BUILDIO_IOPORT(q, u64)
#endif

#define __BUILDIO(bwlq, type)						\
									\
__BUILD_MEMORY_SINGLE(____raw_, bwlq, type, 0)

__BUILDIO(q, u64)

#define readb_relaxed			readb
#define readw_relaxed			readw
#define readl_relaxed			readl
#define readq_relaxed			readq

/*
 * Some code tests for these symbols
 */
#define readq				readq
#define writeq				writeq

#define __BUILD_MEMORY_STRING(bwlq, type)				\
									\
static inline void writes##bwlq(volatile void __iomem *mem,		\
				const void *addr, unsigned int count)	\
{									\
	const volatile type *__addr = addr;				\
									\
	while (count--) {						\
		mem_write##bwlq(*__addr, mem);				\
		__addr++;						\
	}								\
}									\
									\
static inline void reads##bwlq(volatile void __iomem *mem, void *addr,	\
			       unsigned int count)			\
{									\
	volatile type *__addr = addr;					\
									\
	while (count--) {						\
		*__addr = mem_read##bwlq(mem);				\
		__addr++;						\
	}								\
}

#define __BUILD_IOPORT_STRING(bwlq, type)				\
									\
static inline void outs##bwlq(unsigned long port, const void *addr,	\
			      unsigned int count)			\
{									\
	const volatile type *__addr = addr;				\
									\
	while (count--) {						\
		mem_out##bwlq(*__addr, port);				\
		__addr++;						\
	}								\
}									\
									\
static inline void ins##bwlq(unsigned long port, void *addr,		\
			     unsigned int count)			\
{									\
	volatile type *__addr = addr;					\
									\
	while (count--) {						\
		*__addr = mem_in##bwlq(port);				\
		__addr++;						\
	}								\
}

#define BUILDSTRING(bwlq, type)						\
									\
__BUILD_MEMORY_STRING(bwlq, type)					\
__BUILD_IOPORT_STRING(bwlq, type)

BUILDSTRING(b, u8)
BUILDSTRING(w, u16)
BUILDSTRING(l, u32)
#ifdef CONFIG_64BIT
BUILDSTRING(q, u64)
#endif


/* Depends on MIPS II instruction set */
#define mmiowb() asm volatile ("sync" ::: "memory")

static inline void memset_io(volatile void __iomem *addr, unsigned char val, int count)
{
	memset((void __force *) addr, val, count);
}
static inline void memcpy_fromio(void *dst, const volatile void __iomem *src, int count)
{
	memcpy(dst, (void __force *) src, count);
}
static inline void memcpy_toio(volatile void __iomem *dst, const void *src, int count)
{
	memcpy((void __force *) dst, src, count);
}

/*
 * Memory Mapped I/O
 */
#define ioread8(addr)		readb(addr)
#define ioread16(addr)		readw(addr)
#define ioread32(addr)		readl(addr)

#define iowrite8(b,addr)	writeb(b,addr)
#define iowrite16(w,addr)	writew(w,addr)
#define iowrite32(l,addr)	writel(l,addr)

#define ioread8_rep(a,b,c)	readsb(a,b,c)
#define ioread16_rep(a,b,c)	readsw(a,b,c)
#define ioread32_rep(a,b,c)	readsl(a,b,c)

#define iowrite8_rep(a,b,c)	writesb(a,b,c)
#define iowrite16_rep(a,b,c)	writesw(a,b,c)
#define iowrite32_rep(a,b,c)	writesl(a,b,c)

/* Create a virtual mapping cookie for an IO port range */
extern void __iomem *ioport_map(unsigned long port, unsigned int nr);
extern void ioport_unmap(void __iomem *);

/* Create a virtual mapping cookie for a PCI BAR (memory or IO) */
struct pci_dev;
extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max);
extern void pci_iounmap(struct pci_dev *dev, void __iomem *);

/*
 * ISA space is 'always mapped' on currently supported MIPS systems, no need
 * to explicitly ioremap() it. The fact that the ISA IO space is mapped
 * to PAGE_OFFSET is pure coincidence - it does not mean ISA values
 * are physical addresses. The following constant pointer can be
 * used as the IO-area pointer (it can be iounmapped as well, so the
 * analogy with PCI is quite large):
 */
#define __ISA_IO_base ((char *)(isa_slot_offset))

#define isa_readb(a)		readb(__ISA_IO_base + (a))
#define isa_readw(a)		readw(__ISA_IO_base + (a))
#define isa_readl(a)		readl(__ISA_IO_base + (a))
#define isa_readq(a)		readq(__ISA_IO_base + (a))
#define isa_writeb(b,a)		writeb(b,__ISA_IO_base + (a))
#define isa_writew(w,a)		writew(w,__ISA_IO_base + (a))
#define isa_writel(l,a)		writel(l,__ISA_IO_base + (a))
#define isa_writeq(q,a)		writeq(q,__ISA_IO_base + (a))
#define isa_memset_io(a,b,c)	memset_io(__ISA_IO_base + (a),(b),(c))
#define isa_memcpy_fromio(a,b,c) memcpy_fromio((a),__ISA_IO_base + (b),(c))
#define isa_memcpy_toio(a,b,c)	memcpy_toio(__ISA_IO_base + (a),(b),(c))

/*
 * We don't have csum_partial_copy_fromio() yet, so we cheat here and
 * just copy it. The net code will then do the checksum later.
 */
#define eth_io_copy_and_sum(skb,src,len,unused) memcpy_fromio((skb)->data,(src),(len))
#define isa_eth_io_copy_and_sum(a,b,c,d) eth_copy_and_sum((a),(b),(c),(d))

/*
 *     check_signature         -       find BIOS signatures
 *     @io_addr: mmio address to check
 *     @signature:  signature block
 *     @length: length of signature
 *
 *     Perform a signature comparison with the mmio address io_addr. This
 *     address should have been obtained by ioremap.
 *     Returns 1 on a match.
 */
static inline int check_signature(char __iomem *io_addr,
	const unsigned char *signature, int length)
{
	int retval = 0;
	do {
		if (readb(io_addr) != *signature)
			goto out;
		io_addr++;
		signature++;
		length--;
	} while (length);
	retval = 1;
out:
	return retval;
}

/*
 * The caches on some architectures aren't dma-coherent and have need to
 * handle this in software.  There are three types of operations that
 * can be applied to dma buffers.
 *
 *  - dma_cache_wback_inv(start, size) makes caches and coherent by
 *    writing the content of the caches back to memory, if necessary.
 *    The function also invalidates the affected part of the caches as
 *    necessary before DMA transfers from outside to memory.
 *  - dma_cache_wback(start, size) makes caches and coherent by
 *    writing the content of the caches back to memory, if necessary.
 *    The function also invalidates the affected part of the caches as
 *    necessary before DMA transfers from outside to memory.
 *  - dma_cache_inv(start, size) invalidates the affected parts of the
 *    caches.  Dirty lines of the caches may be written back or simply
 *    be discarded.  This operation is necessary before dma operations
 *    to the memory.
 */
#ifdef CONFIG_DMA_NONCOHERENT

extern void (*_dma_cache_wback_inv)(unsigned long start, unsigned long size);
extern void (*_dma_cache_wback)(unsigned long start, unsigned long size);
extern void (*_dma_cache_inv)(unsigned long start, unsigned long size);

#define dma_cache_wback_inv(start, size)	_dma_cache_wback_inv(start,size)
#define dma_cache_wback(start, size)		_dma_cache_wback(start,size)
#define dma_cache_inv(start, size)		_dma_cache_inv(start,size)

#else /* Sane hardware */

#define dma_cache_wback_inv(start,size)	\
	do { (void) (start); (void) (size); } while (0)
#define dma_cache_wback(start,size)	\
	do { (void) (start); (void) (size); } while (0)
#define dma_cache_inv(start,size)	\
	do { (void) (start); (void) (size); } while (0)

#endif /* CONFIG_DMA_NONCOHERENT */

/*
 * Read a 32-bit register that requires a 64-bit read cycle on the bus.
 * Avoid interrupt mucking, just adjust the address for 4-byte access.
 * Assume the addresses are 8-byte aligned.
 */
#ifdef __MIPSEB__
#define __CSR_32_ADJUST 4
#else
#define __CSR_32_ADJUST 0
#endif

#define csr_out32(v,a) (*(volatile u32 *)((unsigned long)(a) + __CSR_32_ADJUST) = (v))
#define csr_in32(a)    (*(volatile u32 *)((unsigned long)(a) + __CSR_32_ADJUST))

/*
 * Convert a physical pointer to a virtual kernel pointer for /dev/mem
 * access
 */
#define xlate_dev_mem_ptr(p)	__va(p)

/*
 * Convert a virtual cached pointer to an uncached pointer
 */
#define xlate_dev_kmem_ptr(p)	p

#endif /* _ASM_IO_H */