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/processor.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 /* 2 cycles per loop. */ 23 __asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b" 24 : "=r" (loops) : "0" (loops)); 25 } 26 27 static __inline__ u32 xtensa_get_ccount(void) 28 { 29 u32 ccount; 30 asm volatile ("rsr %0, ccount\n" : "=r" (ccount)); 31 return ccount; 32 } 33 34 /* For SMP/NUMA systems, change boot_cpu_data to something like 35 * local_cpu_data->... where local_cpu_data points to the current 36 * cpu. */ 37 38 static __inline__ void udelay (unsigned long usecs) 39 { 40 unsigned long start = xtensa_get_ccount(); 41 unsigned long cycles = usecs * (loops_per_jiffy / (1000000UL / HZ)); 42 43 /* Note: all variables are unsigned (can wrap around)! */ 44 while (((unsigned long)xtensa_get_ccount()) - start < cycles) 45 ; 46 } 47 48 #endif 49