arch/metag/kernel/clock.c

   1 /*
   2  * arch/metag/kernel/clock.c
   3  *
   4  * Copyright (C) 2012 Imagination Technologies Ltd.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/delay.h>
  12 #include <linux/io.h>
  13
  14 #include <asm/param.h>
  15 #include <asm/clock.h>
  16
  17 struct meta_clock_desc _meta_clock;
  18
  19 /* Default machine get_core_freq callback. */
  20 static unsigned long get_core_freq_default(void)
  21 {
  22 #ifdef CONFIG_METAG_META21
  23         /*
  24          * Meta 2 cores divide down the core clock for the Meta timers, so we
  25          * can estimate the core clock from the divider.
  26          */
  27         return (metag_in32(EXPAND_TIMER_DIV) + 1) * 1000000;
  28 #else
  29         /*
  30          * On Meta 1 we don't know the core clock, but assuming the Meta timer
  31          * is correct it can be estimated based on loops_per_jiffy.
  32          */
  33         return (loops_per_jiffy * HZ * 5) >> 1;
  34 #endif
  35 }
  36
  37 /**
  38  * setup_meta_clocks() - Set up the Meta clock.
  39  * @desc:       Clock descriptor usually provided by machine description
  40  *
  41  * Ensures all callbacks are valid.
  42  */
  43 void __init setup_meta_clocks(struct meta_clock_desc *desc)
  44 {
  45         /* copy callbacks */
  46         if (desc)
  47                 _meta_clock = *desc;
  48
  49         /* set fallback functions */
  50         if (!_meta_clock.get_core_freq)
  51                 _meta_clock.get_core_freq = get_core_freq_default;
  52 }
  53