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 #include <linux/param.h> 17 18 extern inline void __delay(unsigned long loops) 19 { 20 asm volatile ("# __delay \n\t" \ 21 "1: addi %0, %0, -1\t\n" \ 22 "bneid %0, 1b \t\n" \ 23 "nop \t\n" 24 : "=r" (loops) 25 : "0" (loops)); 26 } 27 28 /* 29 * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so 30 * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32. 31 * 32 * The mul instruction gives us loops = (a * b) / 2^32. 33 * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226 34 * because this lets us support a wide range of HZ and 35 * loops_per_jiffy values without either a or b overflowing 2^32. 36 * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and 37 * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280 38 * (which corresponds to ~3800 bogomips at HZ = 100). 39 * -- paulus 40 */ 41 #define __MAX_UDELAY (226050910UL/HZ) /* maximum udelay argument */ 42 #define __MAX_NDELAY (4294967295UL/HZ) /* maximum ndelay argument */ 43 44 extern unsigned long loops_per_jiffy; 45 46 extern inline void __udelay(unsigned int x) 47 { 48 49 unsigned long long tmp = 50 (unsigned long long)x * (unsigned long long)loops_per_jiffy \ 51 * 226LL; 52 unsigned loops = tmp >> 32; 53 54 /* 55 __asm__("mulxuu %0,%1,%2" : "=r" (loops) : 56 "r" (x), "r" (loops_per_jiffy * 226)); 57 */ 58 __delay(loops); 59 } 60 61 extern void __bad_udelay(void); /* deliberately undefined */ 62 extern void __bad_ndelay(void); /* deliberately undefined */ 63 64 #define udelay(n) (__builtin_constant_p(n) ? \ 65 ((n) > __MAX_UDELAY ? __bad_udelay() : __udelay((n) * (19 * HZ))) : \ 66 __udelay((n) * (19 * HZ))) 67 68 #define ndelay(n) (__builtin_constant_p(n) ? \ 69 ((n) > __MAX_NDELAY ? __bad_ndelay() : __udelay((n) * HZ)) : \ 70 __udelay((n) * HZ)) 71 72 #define muldiv(a, b, c) (((a)*(b))/(c)) 73 74 #endif /* _ASM_MICROBLAZE_DELAY_H */ 75