arch/mips/kernel/csrc-gic.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) 2012 MIPS Technologies, Inc.  All rights reserved.
   7  */
   8 #include <linux/init.h>
   9 #include <linux/time.h>
  10
  11 #include <asm/gic.h>
  12
  13 static cycle_t gic_hpt_read(struct clocksource *cs)
  14 {
  15         return gic_read_count();
  16 }
  17
  18 static struct clocksource gic_clocksource = {
  19         .name   = "GIC",
  20         .read   = gic_hpt_read,
  21         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
  22 };
  23
  24 void __init gic_clocksource_init(unsigned int frequency)
  25 {
  26         unsigned int config, bits;
  27
  28         /* Calculate the clocksource mask. */
  29         GICREAD(GIC_REG(SHARED, GIC_SH_CONFIG), config);
  30         bits = 32 + ((config & GIC_SH_CONFIG_COUNTBITS_MSK) >>
  31                 (GIC_SH_CONFIG_COUNTBITS_SHF - 2));
  32
  33         /* Set clocksource mask. */
  34         gic_clocksource.mask = CLOCKSOURCE_MASK(bits);
  35
  36         /* Calculate a somewhat reasonable rating value. */
  37         gic_clocksource.rating = 200 + frequency / 10000000;
  38
  39         clocksource_register_hz(&gic_clocksource, frequency);
  40 }