arch/mips/gt64120/wrppmc/time.c

   1 /*
   2  * time.c: MIPS CPU Count/Compare timer hookup
   3  *
   4  * Author: Mark.Zhan, <rongkai.zhan@windriver.com>
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  *
  10  * Copyright (C) 1996, 1997, 2004 by Ralf Baechle (ralf@linux-mips.org)
  11  * Copyright (C) 2006, Wind River System Inc.
  12  */
  13 #include <linux/config.h>
  14 #include <linux/init.h>
  15 #include <linux/string.h>
  16 #include <linux/kernel.h>
  17 #include <linux/param.h>        /* for HZ */
  18 #include <linux/irq.h>
  19 #include <linux/timex.h>
  20 #include <linux/interrupt.h>
  21
  22 #include <asm/reboot.h>
  23 #include <asm/time.h>
  24 #include <asm/io.h>
  25 #include <asm/bootinfo.h>
  26 #include <asm/gt64120.h>
  27
  28 #define WRPPMC_CPU_CLK_FREQ 40000000 /* 40MHZ */
  29
  30 void __init wrppmc_timer_setup(struct irqaction *irq)
  31 {
  32         /* Install ISR for timer interrupt */
  33         setup_irq(WRPPMC_MIPS_TIMER_IRQ, irq);
  34 }
  35
  36 /*
  37  * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect
  38  *
  39  * NOTE: We disable all GT64120 timers, and use MIPS processor internal
  40  * timer as the source of kernel clock tick.
  41  */
  42 void __init wrppmc_time_init(void)
  43 {
  44         /* Disable GT64120 timers */
  45         GT_WRITE(GT_TC_CONTROL_OFS, 0x00);
  46         GT_WRITE(GT_TC0_OFS, 0x00);
  47         GT_WRITE(GT_TC1_OFS, 0x00);
  48         GT_WRITE(GT_TC2_OFS, 0x00);
  49         GT_WRITE(GT_TC3_OFS, 0x00);
  50
  51         /* Use MIPS compare/count internal timer */
  52         mips_hpt_frequency = WRPPMC_CPU_CLK_FREQ;
  53 }