| Michal Simek | 216f034 | 2009-03-27 14:25:27 +0100 | [diff] [blame] | 1 | /* |
| 2 | * include/asm-microblaze/delay.h |
| 3 | * |
| 4 | * This file is subject to the terms and conditions of the GNU General Public |
| 5 | * License. See the file "COPYING" in the main directory of this archive |
| 6 | * for more details. |
| 7 | * |
| 8 | * Copyright (C) 2008 Michal Simek |
| 9 | * Copyright (C) 2007 John Williams |
| 10 | * Copyright (C) 2006 Atmark Techno, Inc. |
| 11 | */ |
| 12 | |
| 13 | #ifndef _ASM_MICROBLAZE_DELAY_H |
| 14 | #define _ASM_MICROBLAZE_DELAY_H |
| 15 | |
| 16 | extern inline void __delay(unsigned long loops) |
| 17 | { |
| 18 | asm volatile ("# __delay \n\t" \ |
| 19 | "1: addi %0, %0, -1\t\n" \ |
| 20 | "bneid %0, 1b \t\n" \ |
| 21 | "nop \t\n" |
| 22 | : "=r" (loops) |
| 23 | : "0" (loops)); |
| 24 | } |
| 25 | |
| 26 | /* |
| 27 | * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so |
| 28 | * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32. |
| 29 | * |
| 30 | * The mul instruction gives us loops = (a * b) / 2^32. |
| 31 | * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226 |
| 32 | * because this lets us support a wide range of HZ and |
| 33 | * loops_per_jiffy values without either a or b overflowing 2^32. |
| 34 | * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and |
| 35 | * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280 |
| 36 | * (which corresponds to ~3800 bogomips at HZ = 100). |
| 37 | * -- paulus |
| 38 | */ |
| 39 | #define __MAX_UDELAY (226050910UL/HZ) /* maximum udelay argument */ |
| 40 | #define __MAX_NDELAY (4294967295UL/HZ) /* maximum ndelay argument */ |
| 41 | |
| 42 | extern unsigned long loops_per_jiffy; |
| 43 | |
| 44 | extern inline void __udelay(unsigned int x) |
| 45 | { |
| 46 | |
| 47 | unsigned long long tmp = |
| 48 | (unsigned long long)x * (unsigned long long)loops_per_jiffy \ |
| 49 | * 226LL; |
| 50 | unsigned loops = tmp >> 32; |
| 51 | |
| 52 | /* |
| 53 | __asm__("mulxuu %0,%1,%2" : "=r" (loops) : |
| 54 | "r" (x), "r" (loops_per_jiffy * 226)); |
| 55 | */ |
| 56 | __delay(loops); |
| 57 | } |
| 58 | |
| 59 | extern void __bad_udelay(void); /* deliberately undefined */ |
| 60 | extern void __bad_ndelay(void); /* deliberately undefined */ |
| 61 | |
| 62 | #define udelay(n) (__builtin_constant_p(n) ? \ |
| 63 | ((n) > __MAX_UDELAY ? __bad_udelay() : __udelay((n) * (19 * HZ))) : \ |
| 64 | __udelay((n) * (19 * HZ))) |
| 65 | |
| 66 | #define ndelay(n) (__builtin_constant_p(n) ? \ |
| 67 | ((n) > __MAX_NDELAY ? __bad_ndelay() : __udelay((n) * HZ)) : \ |
| 68 | __udelay((n) * HZ)) |
| 69 | |
| 70 | #define muldiv(a, b, c) (((a)*(b))/(c)) |
| 71 | |
| 72 | #endif /* _ASM_MICROBLAZE_DELAY_H */ |