[TG3]: Set minimal hw interrupt mitigation.
[linux-2.6/verdex.git] / arch / arm / mach-imx / time.c
blob11f1e56c36bc041154e995b00650c0fcb34c4eb0
1 /*
2 * linux/arch/arm/mach-imx/time.c
4 * Copyright (C) 2000-2001 Deep Blue Solutions
5 * Copyright (C) 2002 Shane Nay (shane@minirl.com)
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.
11 #include <linux/config.h>
12 #include <linux/kernel.h>
13 #include <linux/sched.h>
14 #include <linux/init.h>
15 #include <linux/interrupt.h>
16 #include <linux/time.h>
18 #include <asm/hardware.h>
19 #include <asm/io.h>
20 #include <asm/leds.h>
21 #include <asm/irq.h>
22 #include <asm/mach/time.h>
24 /* Use timer 1 as system timer */
25 #define TIMER_BASE IMX_TIM1_BASE
28 * Returns number of us since last clock interrupt. Note that interrupts
29 * will have been disabled by do_gettimeoffset()
31 static unsigned long imx_gettimeoffset(void)
33 unsigned long ticks;
36 * Get the current number of ticks. Note that there is a race
37 * condition between us reading the timer and checking for
38 * an interrupt. We get around this by ensuring that the
39 * counter has not reloaded between our two reads.
41 ticks = IMX_TCN(TIMER_BASE);
44 * Interrupt pending? If so, we've reloaded once already.
46 if (IMX_TSTAT(TIMER_BASE) & TSTAT_COMP)
47 ticks += LATCH;
50 * Convert the ticks to usecs
52 return (1000000 / CLK32) * ticks;
56 * IRQ handler for the timer
58 static irqreturn_t
59 imx_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
61 write_seqlock(&xtime_lock);
63 /* clear the interrupt */
64 if (IMX_TSTAT(TIMER_BASE))
65 IMX_TSTAT(TIMER_BASE) = 0;
67 timer_tick(regs);
68 write_sequnlock(&xtime_lock);
70 return IRQ_HANDLED;
73 static struct irqaction imx_timer_irq = {
74 .name = "i.MX Timer Tick",
75 .flags = SA_INTERRUPT,
76 .handler = imx_timer_interrupt
80 * Set up timer interrupt, and return the current time in seconds.
82 static void __init imx_timer_init(void)
85 * Initialise to a known state (all timers off, and timing reset)
87 IMX_TCTL(TIMER_BASE) = 0;
88 IMX_TPRER(TIMER_BASE) = 0;
89 IMX_TCMP(TIMER_BASE) = LATCH - 1;
90 IMX_TCTL(TIMER_BASE) = TCTL_CLK_32 | TCTL_IRQEN | TCTL_TEN;
93 * Make irqs happen for the system timer
95 setup_irq(TIM1_INT, &imx_timer_irq);
98 struct sys_timer imx_timer = {
99 .init = imx_timer_init,
100 .offset = imx_gettimeoffset,