| 1 |
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| 2 | |
| 3 | * Copyright (C) 2008 Michal Simek
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| 4 | * Copyright (C) 2007 John Williams
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| 5 | * Copyright (C) 2006 Atmark Techno, Inc.
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| 6 |
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| 7 |
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| 8 | #ifndef _ASM_MICROBLAZE_DELAY_H
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| 9 | #define _ASM_MICROBLAZE_DELAY_H
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| 10 |
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| 11 | #include <linux/param.h>
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| 12 |
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| 13 | static inline void __delay(unsigned long loops)
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| 14 | {
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| 15 | asm volatile ("# __delay \n\t" \
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| 16 | "1: addi %0, %0, -1\t\n" \
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| 17 | "bneid %0, 1b \t\n" \
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| 18 | "nop \t\n"
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| 19 | : "=r" (loops)
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| 20 | : "0" (loops));
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| 21 | }
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| 22 |
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| 23 | |
| 24 | * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so
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| 25 | * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32.
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| 26 | *
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| 27 | * The mul instruction gives us loops = (a * b) / 2^32.
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| 28 | * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226
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| 29 | * because this lets us support a wide range of HZ and
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| 30 | * loops_per_jiffy values without either a or b overflowing 2^32.
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| 31 | * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and
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| 32 | * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280
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| 33 | * (which corresponds to ~3800 bogomips at HZ = 100).
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| 34 | * -- paulus
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| 35 |
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| 36 | #define __MAX_UDELAY (226050910UL/HZ)
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| 37 | #define __MAX_NDELAY (4294967295UL/HZ)
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| 38 |
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| 39 | extern unsigned long loops_per_jiffy;
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| 40 |
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| 41 | static inline void __udelay(unsigned int x)
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| 42 | {
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| 43 |
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| 44 | unsigned long long tmp =
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| 45 | (unsigned long long)x * (unsigned long long)loops_per_jiffy \
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| 46 | * 226LL;
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| 47 | unsigned loops = tmp >> 32;
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| 48 |
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| 49 | |
| 50 | __asm__("mulxuu %0,%1,%2" : "=r" (loops) :
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| 51 | "r" (x), "r" (loops_per_jiffy * 226));
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| 52 |
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| 53 | __delay(loops);
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| 54 | }
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| 55 |
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| 56 | extern void __bad_udelay(void);
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| 57 | extern void __bad_ndelay(void);
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| 58 |
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| 59 | #define udelay(n) \
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| 60 | ({ \
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| 61 | if (__builtin_constant_p(n)) { \
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| 62 | if ((n) / __MAX_UDELAY >= 1) \
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| 63 | __bad_udelay(); \
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| 64 | else \
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| 65 | __udelay((n) * (19 * HZ)); \
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| 66 | } else { \
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| 67 | __udelay((n) * (19 * HZ)); \
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| 68 | } \
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| 69 | })
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| 70 |
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| 71 | #define ndelay(n) \
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| 72 | ({ \
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| 73 | if (__builtin_constant_p(n)) { \
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| 74 | if ((n) / __MAX_NDELAY >= 1) \
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| 75 | __bad_ndelay(); \
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| 76 | else \
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| 77 | __udelay((n) * HZ); \
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| 78 | } else { \
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| 79 | __udelay((n) * HZ); \
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| 80 | } \
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| 81 | })
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| 82 |
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| 83 | #define muldiv(a, b, c) (((a)*(b))/(c))
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| 84 |
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| 85 | #endif
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