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Linux/arch/xtensa/include/asm/delay.h

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  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) : "" (loops));
 25 }
 26 
 27 static __inline__ u32 xtensa_get_ccount(void)
 28 {
 29         u32 ccount;
 30         asm volatile ("rsr %0, 234; # 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 
 50 

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