1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (C) 2008 Michal Simek 4 * Copyright (C) 2007 John Williams 5 * Copyright (C) 2006 Atmark Techno, Inc. 6 */ 7 8 #ifndef _ASM_MICROBLAZE_DELAY_H 9 #define _ASM_MICROBLAZE_DELAY_H 10 11 #include <linux/param.h> 12 13 static inline void __delay(unsigned long loops) 14 { 15 asm volatile ("# __delay \n\t" \ 16 "1: addi %0, %0, -1\t\n" \ 17 "bneid %0, 1b \t\n" \ 18 "nop \t\n" 19 : "=r" (loops) 20 : "0" (loops)); 21 } 22 23 /* 24 * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so 25 * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32. 26 * 27 * The mul instruction gives us loops = (a * b) / 2^32. 28 * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226 29 * because this lets us support a wide range of HZ and 30 * loops_per_jiffy values without either a or b overflowing 2^32. 31 * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and 32 * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280 33 * (which corresponds to ~3800 bogomips at HZ = 100). 34 * -- paulus 35 */ 36 #define __MAX_UDELAY (226050910UL/HZ) /* maximum udelay argument */ 37 #define __MAX_NDELAY (4294967295UL/HZ) /* maximum ndelay argument */ 38 39 extern unsigned long loops_per_jiffy; 40 41 static inline void __udelay(unsigned int x) 42 { 43 44 unsigned long long tmp = 45 (unsigned long long)x * (unsigned long long)loops_per_jiffy \ 46 * 226LL; 47 unsigned loops = tmp >> 32; 48 49 /* 50 __asm__("mulxuu %0,%1,%2" : "=r" (loops) : 51 "r" (x), "r" (loops_per_jiffy * 226)); 52 */ 53 __delay(loops); 54 } 55 56 extern void __bad_udelay(void); /* deliberately undefined */ 57 extern void __bad_ndelay(void); /* deliberately undefined */ 58 59 #define udelay(n) \ 60 ({ \ 61 if (__builtin_constant_p(n)) { \ 62 if ((n) / __MAX_UDELAY >= 1) \ 63 __bad_udelay(); \ 64 else \ 65 __udelay((n) * (19 * HZ)); \ 66 } else { \ 67 __udelay((n) * (19 * HZ)); \ 68 } \ 69 }) 70 71 #define ndelay(n) \ 72 ({ \ 73 if (__builtin_constant_p(n)) { \ 74 if ((n) / __MAX_NDELAY >= 1) \ 75 __bad_ndelay(); \ 76 else \ 77 __udelay((n) * HZ); \ 78 } else { \ 79 __udelay((n) * HZ); \ 80 } \ 81 }) 82 83 #define muldiv(a, b, c) (((a)*(b))/(c)) 84 85 #endif /* _ASM_MICROBLAZE_DELAY_H */ 86