delay.h 1.1 KB

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