arch/arm/cpu/armv7/uniphier/timer.c

   1 /*
   2  * Copyright (C) 2012-2014 Panasonic Corporation
   3  *   Author: Masahiro Yamada <yamada.m@jp.panasonic.com>
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 #include <common.h>
   9 #include <asm/io.h>
  10 #include <asm/arch/arm-mpcore.h>
  11
  12 #define PERIPHCLK (50 * 1000 * 1000) /* 50 MHz */
  13 #define PRESCALER ((PERIPHCLK) / (CONFIG_SYS_TIMER_RATE) - 1)
  14
  15 static void *get_global_timer_base(void)
  16 {
  17         void *val;
  18
  19         asm("mrc p15, 4, %0, c15, c0, 0" : "=r" (val) : : "memory");
  20
  21         return val + GLOBAL_TIMER_OFFSET;
  22 }
  23
  24 unsigned long timer_read_counter(void)
  25 {
  26         /*
  27          * ARM 64bit Global Timer is too much for our purpose.
  28          * We use only lower 32 bit of the timer counter.
  29          */
  30         return readl(get_global_timer_base() + GTIMER_CNT_L);
  31 }
  32
  33 int timer_init(void)
  34 {
  35         /* enable timer */
  36         writel(PRESCALER << 8 | 1, get_global_timer_base() + GTIMER_CTRL);
  37
  38         return 0;
  39 }