arch/cris/arch-v32/lib/delay.c

   1 /*
   2  * Precise Delay Loops for ETRAX FS
   3  *
   4  * Copyright (C) 2006 Axis Communications AB.
   5  *
   6  */
   7
   8 #include <hwregs/reg_map.h>
   9 #include <hwregs/reg_rdwr.h>
  10 #include <hwregs/timer_defs.h>
  11 #include <linux/types.h>
  12 #include <linux/delay.h>
  13 #include <linux/module.h>
  14
  15 /*
  16  * On ETRAX FS, we can check the free-running read-only 100MHz timer
  17  * getting 32-bit 10ns precision, theoretically good for 42.94967295
  18  * seconds.  Unsigned arithmetic and careful expression handles
  19  * wrapping.
  20  */
  21
  22 void cris_delay10ns(u32 n10ns)
  23 {
  24         u32 t0 = REG_RD(timer, regi_timer0, r_time);
  25         while (REG_RD(timer, regi_timer0, r_time) - t0 < n10ns)
  26                 ;
  27 }
  28 EXPORT_SYMBOL(cris_delay10ns);