include/asm-xtensa/delay.h

   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 <linux/config.h>
  16 #include <asm/processor.h>
  17 #include <asm/param.h>
  18
  19 extern unsigned long loops_per_jiffy;
  20
  21 static inline void __delay(unsigned long loops)
  22 {
  23   /* 2 cycles per loop. */
  24   __asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b"
  25                         : "=r" (loops) : "0" (loops));
  26 }
  27
  28 static __inline__ u32 xtensa_get_ccount(void)
  29 {
  30         u32 ccount;
  31         asm volatile ("rsr %0, 234; # CCOUNT\n" : "=r" (ccount));
  32         return ccount;
  33 }
  34
  35 /* For SMP/NUMA systems, change boot_cpu_data to something like
  36  * local_cpu_data->... where local_cpu_data points to the current
  37  * cpu. */
  38
  39 static __inline__ void udelay (unsigned long usecs)
  40 {
  41         unsigned long start = xtensa_get_ccount();
  42         unsigned long cycles = usecs * (loops_per_jiffy / (1000000UL / HZ));
  43
  44         /* Note: all variables are unsigned (can wrap around)! */
  45         while (((unsigned long)xtensa_get_ccount()) - start < cycles)
  46                 ;
  47 }
  48
  49 #endif
  50