arch/mips/lib/delay.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1994 by Waldorf Electronics
   7  * Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle
   8  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   9  * Copyright (C) 2007, 2014 Maciej W. Rozycki
  10  */
  11 #include <linux/delay.h>
  12 #include <linux/export.h>
  13 #include <linux/param.h>
  14 #include <linux/smp.h>
  15 #include <linux/stringify.h>
  16
  17 #include <asm/asm.h>
  18 #include <asm/compiler.h>
  19
  20 #ifndef CONFIG_CPU_DADDI_WORKAROUNDS
  21 #define GCC_DADDI_IMM_ASM() "I"
  22 #else
  23 #define GCC_DADDI_IMM_ASM() "r"
  24 #endif
  25
  26 #ifndef CONFIG_HAVE_PLAT_DELAY
  27
  28 void __delay(unsigned long loops)
  29 {
  30         __asm__ __volatile__ (
  31         "       .set    noreorder                               \n"
  32         "       .align  3                                       \n"
  33         "1:     bnez    %0, 1b                                  \n"
  34         "        " __stringify(LONG_SUBU) "     %0, %1          \n"
  35         "       .set    reorder                                 \n"
  36         : "=r" (loops)
  37         : GCC_DADDI_IMM_ASM() (1), "0" (loops));
  38 }
  39 EXPORT_SYMBOL(__delay);
  40
  41 /*
  42  * Division by multiplication: you don't have to worry about
  43  * loss of precision.
  44  *
  45  * Use only for very small delays ( < 1 msec).  Should probably use a
  46  * lookup table, really, as the multiplications take much too long with
  47  * short delays.  This is a "reasonable" implementation, though (and the
  48  * first constant multiplications gets optimized away if the delay is
  49  * a constant)
  50  */
  51
  52 void __udelay(unsigned long us)
  53 {
  54         unsigned int lpj = raw_current_cpu_data.udelay_val;
  55
  56         __delay((us * 0x000010c7ull * HZ * lpj) >> 32);
  57 }
  58 EXPORT_SYMBOL(__udelay);
  59
  60 void __ndelay(unsigned long ns)
  61 {
  62         unsigned int lpj = raw_current_cpu_data.udelay_val;
  63
  64         __delay((ns * 0x00000005ull * HZ * lpj) >> 32);
  65 }
  66 EXPORT_SYMBOL(__ndelay);
  67
  68 #endif