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

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Precise Delay Loops for ETRAX FS
   4  *
   5  * Copyright (C) 2006 Axis Communications AB.
   6  *
   7  */
   8
   9 #include <hwregs/reg_map.h>
  10 #include <hwregs/reg_rdwr.h>
  11 #include <hwregs/timer_defs.h>
  12 #include <linux/types.h>
  13 #include <linux/delay.h>
  14 #include <linux/module.h>
  15
  16 /*
  17  * On ETRAX FS, we can check the free-running read-only 100MHz timer
  18  * getting 32-bit 10ns precision, theoretically good for 42.94967295
  19  * seconds.  Unsigned arithmetic and careful expression handles
  20  * wrapping.
  21  */
  22
  23 void cris_delay10ns(u32 n10ns)
  24 {
  25         u32 t0 = REG_RD(timer, regi_timer0, r_time);
  26         while (REG_RD(timer, regi_timer0, r_time) - t0 < n10ns)
  27                 ;
  28 }
  29 EXPORT_SYMBOL(cris_delay10ns);