include/asm-arm/arch-ixp4xx/fast_timer.h

   1 #ifndef __ASM_ARM_MACH_FAST_TIMER_H
   2 #define __ASM_ARM_MACH_FAST_TIMER_H
   3
   4 #include <linux/sched.h>
   5 #include <linux/timex.h>
   6 #include <linux/interrupt.h>
   7 #include <asm/hardware.h>
   8 #include <asm/irq.h>
   9
  10 static irqreturn_t
  11 fast_timer_interrupt(int irq, void *dev_id)
  12 {
  13         /* Clear Pending Interrupt by writing '1' to it */
  14         *IXP4XX_OSST = IXP4XX_OSST_TIMER_2_PEND;
  15
  16         do_fast_timer();
  17         return IRQ_HANDLED;
  18 }
  19
  20 static void fast_timer_set(void)
  21 {
  22         unsigned long interval;
  23
  24         /* Setup the Timer counter value */
  25         interval = (CLOCK_TICK_RATE + fast_timer_rate/2) / fast_timer_rate;
  26         *IXP4XX_OSRT2 = (interval & ~IXP4XX_OST_RELOAD_MASK) | IXP4XX_OST_ENABLE;
  27 }
  28
  29 static int __init fast_timer_setup(void)
  30 {
  31         /* Clear Pending Interrupt by writing '1' to it */
  32         *IXP4XX_OSST = IXP4XX_OSST_TIMER_2_PEND;
  33
  34         /* Connect the interrupt handler and enable the interrupt */
  35         if (request_irq(IRQ_IXP4XX_TIMER2, fast_timer_interrupt, SA_INTERRUPT,
  36                         "fast timer", NULL))
  37                 return -EBUSY;
  38
  39         fast_timer_rate = 5000;
  40         fast_timer_set();
  41
  42         printk("fast timer: %d Hz, IRQ %d\n", fast_timer_rate,
  43                         IRQ_IXP4XX_TIMER2);
  44         return 0;
  45 }
  46
  47 static void __exit fast_timer_cleanup(void)
  48 {
  49         *IXP4XX_OSRT2 = IXP4XX_OST_DISABLED;
  50         free_irq(IRQ_IXP4XX_TIMER2, NULL);
  51 }
  52
  53 #endif