arch/arm/mach-lpc22xx/time.c

   1 /*
   2  *  linux/arch/arm/mach-lpc22xx/time.c
   3  *
   4  *  Copyright (C) 2004 Philips Semiconductors
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/sched.h>
   9 #include <linux/init.h>
  10 #include <linux/interrupt.h>
  11 #include <asm/system.h>
  12 #include <asm/leds.h>
  13 #include <asm/mach-types.h>
  14
  15 #include <asm/io.h>
  16 #include <asm/irq.h>
  17 #include <asm/hardware.h>
  18 #include <asm/mach/time.h>
  19 #include <asm/arch/time.h>
  20
  21 extern void     lpc22xx_unmask_irq(unsigned int);
  22
  23 unsigned long lpc22xx_gettimeoffset (void)
  24 {
  25     return (T0TC/CLOCKS_PER_USEC);
  26 }
  27
  28 static irqreturn_t
  29 lpc22xx_timer_interrupt(int irq, void *dev_id)
  30 {
  31
  32     if (!(T0IR & 0x01)) return IRQ_NONE;
  33 /*    do_timer(regs);
  34     do_profile(regs);
  35 */ timer_tick();  /* modified 20050608 for new version */
  36
  37     T0IR |= 0x01;       /* reset interrupt */
  38     return IRQ_HANDLED;
  39 }
  40
  41 static struct irqaction lpc22xx_timer_irq = {
  42         .name           = "LPC22xx Timer Tick",
  43         .flags          = IRQF_DISABLED | IRQF_TIMER,
  44         .handler        = lpc22xx_timer_interrupt
  45 };
  46
  47 /*
  48  * Set up timer interrupt, and return the current time in seconds.
  49  */
  50
  51 void __init  lpc22xx_time_init (void)
  52 {
  53         /*
  54          * disable and clear timer 0, set to
  55          */
  56         T0TCR &= ~0x01;
  57         /* initialize the timer period and prescaler */
  58         T0MR0 = MR0_INIT_VALUE;
  59         T0PR = PRESCALE_COUNTER_INIT_VALUE;
  60         T0MCR |= 0x03;                  /* generate interrupt when T0MR0 match T0TC and Reset Timer Count*/
  61
  62         /*
  63          * @todo do those really need to be function pointers ?
  64          */
  65 /*      gettimeoffset     = lpc22xx_gettimeoffset; */
  66         lpc22xx_timer_irq.handler = lpc22xx_timer_interrupt;
  67
  68         /* set up the interrupt vevtor for timer 0 match */
  69         setup_irq(LPC22xx_INTERRUPT_TIMER0, &lpc22xx_timer_irq);
  70
  71         /* enable the timer IRQ */
  72         lpc22xx_unmask_irq(LPC22xx_INTERRUPT_TIMER0);
  73
  74         /* let timer 0 run... */
  75         T0IR = 0x01; /* reset MR0 interrupt*/
  76         T0TCR = 0x02;   /* Reset timer count and prescale counter */
  77         T0TCR = 0x01;   /* enablle timer counter and prescale counter */
  78 }
  79
  80 struct sys_timer lpc22xx_timer = {
  81         .init           = lpc22xx_time_init,
  82         .offset         = lpc22xx_gettimeoffset,
  83 };