arch/xtensa/include/asm/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 <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, 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