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/kernel.h>
12 #include <linux/sched.h>
13 #include <linux/init.h>
14 #include <linux/interrupt.h>
15 #include <linux/time.h>
17 #include <asm/hardware.h>
21 #include <asm/mach/time.h>
23 /* Use timer 1 as system timer */
24 #define TIMER_BASE IMX_TIM1_BASE
27 * Returns number of us since last clock interrupt. Note that interrupts
28 * will have been disabled by do_gettimeoffset()
30 static unsigned long imx_gettimeoffset(void)
35 * Get the current number of ticks. Note that there is a race
36 * condition between us reading the timer and checking for
37 * an interrupt. We get around this by ensuring that the
38 * counter has not reloaded between our two reads.
40 ticks = IMX_TCN(TIMER_BASE);
43 * Interrupt pending? If so, we've reloaded once already.
45 if (IMX_TSTAT(TIMER_BASE) & TSTAT_COMP)
49 * Convert the ticks to usecs
51 return (1000000 / CLK32) * ticks;
55 * IRQ handler for the timer
58 imx_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
60 write_seqlock(&xtime_lock);
62 /* clear the interrupt */
63 if (IMX_TSTAT(TIMER_BASE))
64 IMX_TSTAT(TIMER_BASE) = 0;
67 write_sequnlock(&xtime_lock);
72 static struct irqaction imx_timer_irq = {
73 .name = "i.MX Timer Tick",
74 .flags = SA_INTERRUPT | SA_TIMER,
75 .handler = imx_timer_interrupt,
79 * Set up timer interrupt, and return the current time in seconds.
81 static void __init imx_timer_init(void)
84 * Initialise to a known state (all timers off, and timing reset)
86 IMX_TCTL(TIMER_BASE) = 0;
87 IMX_TPRER(TIMER_BASE) = 0;
88 IMX_TCMP(TIMER_BASE) = LATCH - 1;
89 IMX_TCTL(TIMER_BASE) = TCTL_CLK_32 | TCTL_IRQEN | TCTL_TEN;
92 * Make irqs happen for the system timer
94 setup_irq(TIM1_INT, &imx_timer_irq);
97 struct sys_timer imx_timer = {
98 .init = imx_timer_init,
99 .offset = imx_gettimeoffset,