release/src-rt-6.x/linux/linux-2.6/arch/arm/mach-imx/time.c

   1 /*
   2  *  linux/arch/arm/mach-imx/time.c
   3  *
   4  *  Copyright (C) 2000-2001 Deep Blue Solutions
   5  *  Copyright (C) 2002 Shane Nay (shane@minirl.com)
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/sched.h>
  13 #include <linux/init.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/irq.h>
  16 #include <linux/time.h>
  17 #include <linux/clocksource.h>
  18
  19 #include <asm/hardware.h>
  20 #include <asm/io.h>
  21 #include <asm/leds.h>
  22 #include <asm/irq.h>
  23 #include <asm/mach/time.h>
  24
  25 /* Use timer 1 as system timer */
  26 #define TIMER_BASE IMX_TIM1_BASE
  27
  28 static unsigned long evt_diff;
  29
  30 /*
  31  * IRQ handler for the timer
  32  */
  33 static irqreturn_t
  34 imx_timer_interrupt(int irq, void *dev_id)
  35 {
  36         uint32_t tstat;
  37
  38         /* clear the interrupt */
  39         tstat = IMX_TSTAT(TIMER_BASE);
  40         IMX_TSTAT(TIMER_BASE) = 0;
  41
  42         if (tstat & TSTAT_COMP) {
  43                 do {
  44
  45                         write_seqlock(&xtime_lock);
  46                         timer_tick();
  47                         write_sequnlock(&xtime_lock);
  48                         IMX_TCMP(TIMER_BASE) += evt_diff;
  49
  50                 } while (unlikely((int32_t)(IMX_TCMP(TIMER_BASE)
  51                                         - IMX_TCN(TIMER_BASE)) < 0));
  52         }
  53
  54         return IRQ_HANDLED;
  55 }
  56
  57 static struct irqaction imx_timer_irq = {
  58         .name           = "i.MX Timer Tick",
  59         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
  60         .handler        = imx_timer_interrupt,
  61 };
  62
  63 /*
  64  * Set up timer hardware into expected mode and state.
  65  */
  66 static void __init imx_timer_hardware_init(void)
  67 {
  68         /*
  69          * Initialise to a known state (all timers off, and timing reset)
  70          */
  71         IMX_TCTL(TIMER_BASE) = 0;
  72         IMX_TPRER(TIMER_BASE) = 0;
  73         IMX_TCMP(TIMER_BASE) = LATCH - 1;
  74
  75         IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_IRQEN | TCTL_TEN;
  76         evt_diff = LATCH;
  77 }
  78
  79 cycle_t imx_get_cycles(void)
  80 {
  81         return IMX_TCN(TIMER_BASE);
  82 }
  83
  84 static struct clocksource clocksource_imx = {
  85         .name           = "imx_timer1",
  86         .rating         = 200,
  87         .read           = imx_get_cycles,
  88         .mask           = 0xFFFFFFFF,
  89         .shift          = 20,
  90         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  91 };
  92
  93 static int __init imx_clocksource_init(void)
  94 {
  95         clocksource_imx.mult =
  96                 clocksource_hz2mult(imx_get_perclk1(), clocksource_imx.shift);
  97         clocksource_register(&clocksource_imx);
  98
  99         return 0;
 100 }
 101
 102 static void __init imx_timer_init(void)
 103 {
 104         imx_timer_hardware_init();
 105         imx_clocksource_init();
 106
 107         /*
 108          * Make irqs happen for the system timer
 109          */
 110         setup_irq(TIM1_INT, &imx_timer_irq);
 111 }
 112
 113 struct sys_timer imx_timer = {
 114         .init           = imx_timer_init,
 115 };