1 /* 2 * include/asm-xtensa/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) 2001 - 2005 Tensilica Inc. 9 * 10 */ 11 12 #ifndef _XTENSA_DELAY_H 13 #define _XTENSA_DELAY_H 14 15 #include <asm/timex.h> 16 #include <asm/param.h> 17 18 extern unsigned long loops_per_jiffy; 19 20 static inline void __delay(unsigned long loops) 21 { 22 if (__builtin_constant_p(loops) && loops < 2) 23 __asm__ __volatile__ ("nop"); 24 else if (loops >= 2) 25 /* 2 cycles per loop. */ 26 __asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b" 27 : "+r" (loops)); 28 } 29 30 /* Undefined function to get compile-time error */ 31 void __bad_udelay(void); 32 void __bad_ndelay(void); 33 34 #define __MAX_UDELAY 30000 35 #define __MAX_NDELAY 30000 36 37 static inline void __udelay(unsigned long usecs) 38 { 39 unsigned long start = get_ccount(); 40 unsigned long cycles = (usecs * (ccount_freq >> 15)) >> 5; 41 42 /* Note: all variables are unsigned (can wrap around)! */ 43 while (((unsigned long)get_ccount()) - start < cycles) 44 cpu_relax(); 45 } 46 47 static inline void udelay(unsigned long usec) 48 { 49 if (__builtin_constant_p(usec) && usec >= __MAX_UDELAY) 50 __bad_udelay(); 51 else 52 __udelay(usec); 53 } 54 55 static inline void __ndelay(unsigned long nsec) 56 { 57 /* 58 * Inner shift makes sure multiplication doesn't overflow 59 * for legitimate nsec values 60 */ 61 unsigned long cycles = (nsec * (ccount_freq >> 15)) >> 15; 62 __delay(cycles); 63 } 64 65 #define ndelay(n) ndelay(n) 66 67 static inline void ndelay(unsigned long nsec) 68 { 69 if (__builtin_constant_p(nsec) && nsec >= __MAX_NDELAY) 70 __bad_ndelay(); 71 else 72 __ndelay(nsec); 73 } 74 75 #endif 76