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>
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)
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
)
50 * Convert the ticks to usecs
52 return (1000000 / CLK32
) * ticks
;
56 * IRQ handler for the timer
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;
68 write_sequnlock(&xtime_lock
);
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
,