arch/arm/mach-nuc93x/time.c

   1 /*
   2  * linux/arch/arm/mach-nuc93x/time.c
   3  *
   4  * Copyright (c) 2009 Nuvoton technology corporation.
   5  *
   6  * Wan ZongShun <mcuos.com@gmail.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  */
  14
  15 #include <linux/kernel.h>
  16 #include <linux/sched.h>
  17 #include <linux/init.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/err.h>
  20 #include <linux/clk.h>
  21 #include <linux/io.h>
  22 #include <linux/leds.h>
  23
  24 #include <asm/mach-types.h>
  25 #include <asm/mach/irq.h>
  26 #include <asm/mach/time.h>
  27
  28 #include <mach/system.h>
  29 #include <mach/map.h>
  30 #include <mach/regs-timer.h>
  31
  32 #define RESETINT        0x01
  33 #define PERIOD          (0x01 << 27)
  34 #define ONESHOT         (0x00 << 27)
  35 #define COUNTEN         (0x01 << 30)
  36 #define INTEN           (0x01 << 29)
  37
  38 #define TICKS_PER_SEC   100
  39 #define PRESCALE        0x63 /* Divider = prescale + 1 */
  40
  41 unsigned int timer0_load;
  42
  43 static unsigned long nuc93x_gettimeoffset(void)
  44 {
  45         return 0;
  46 }
  47
  48 /*IRQ handler for the timer*/
  49
  50 static irqreturn_t nuc93x_timer_interrupt(int irq, void *dev_id)
  51 {
  52         timer_tick();
  53         __raw_writel(0x01, REG_TISR); /* clear TIF0 */
  54         return IRQ_HANDLED;
  55 }
  56
  57 static struct irqaction nuc93x_timer_irq = {
  58         .name           = "nuc93x Timer Tick",
  59         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
  60         .handler        = nuc93x_timer_interrupt,
  61 };
  62
  63 /*Set up timer reg.*/
  64
  65 static void nuc93x_timer_setup(void)
  66 {
  67         struct clk *ck_ext = clk_get(NULL, "ext");
  68         struct clk *ck_timer = clk_get(NULL, "timer");
  69         unsigned int rate, val = 0;
  70
  71         BUG_ON(IS_ERR(ck_ext) || IS_ERR(ck_timer));
  72
  73         clk_enable(ck_timer);
  74         rate = clk_get_rate(ck_ext);
  75         clk_put(ck_ext);
  76         rate = rate / (PRESCALE + 0x01);
  77
  78          /* set a known state */
  79         __raw_writel(0x00, REG_TCSR0);
  80         __raw_writel(RESETINT, REG_TISR);
  81
  82         timer0_load = (rate / TICKS_PER_SEC);
  83         __raw_writel(timer0_load, REG_TICR0);
  84
  85         val |= (PERIOD | COUNTEN | INTEN | PRESCALE);
  86         __raw_writel(val, REG_TCSR0);
  87
  88 }
  89
  90 static void __init nuc93x_timer_init(void)
  91 {
  92         nuc93x_timer_setup();
  93         setup_irq(IRQ_TIMER0, &nuc93x_timer_irq);
  94 }
  95
  96 struct sys_timer nuc93x_timer = {
  97         .init           = nuc93x_timer_init,
  98         .offset         = nuc93x_gettimeoffset,
  99         .resume         = nuc93x_timer_setup
 100 };