Linux-2.6.12-rc2
[linux-2.6.git] / arch / arm / mach-footbridge / dc21285-timer.c
1 /*
2  *  linux/arch/arm/mach-footbridge/dc21285-timer.c
3  *
4  *  Copyright (C) 1998 Russell King.
5  *  Copyright (C) 1998 Phil Blundell
6  */
7 #include <linux/init.h>
8 #include <linux/interrupt.h>
9
10 #include <asm/irq.h>
11
12 #include <asm/hardware/dec21285.h>
13 #include <asm/mach/time.h>
14
15 #include "common.h"
16
17 /*
18  * Footbridge timer 1 support.
19  */
20 static unsigned long timer1_latch;
21
22 static unsigned long timer1_gettimeoffset (void)
23 {
24         unsigned long value = timer1_latch - *CSR_TIMER1_VALUE;
25
26         return ((tick_nsec / 1000) * value) / timer1_latch;
27 }
28
29 static irqreturn_t
30 timer1_interrupt(int irq, void *dev_id, struct pt_regs *regs)
31 {
32         write_seqlock(&xtime_lock);
33
34         *CSR_TIMER1_CLR = 0;
35
36         timer_tick(regs);
37
38         write_sequnlock(&xtime_lock);
39
40         return IRQ_HANDLED;
41 }
42
43 static struct irqaction footbridge_timer_irq = {
44         .name           = "Timer1 timer tick",
45         .handler        = timer1_interrupt,
46         .flags          = SA_INTERRUPT,
47 };
48
49 /*
50  * Set up timer interrupt.
51  */
52 static void __init footbridge_timer_init(void)
53 {
54         isa_rtc_init();
55
56         timer1_latch = (mem_fclk_21285 + 8 * HZ) / (16 * HZ);
57
58         *CSR_TIMER1_CLR  = 0;
59         *CSR_TIMER1_LOAD = timer1_latch;
60         *CSR_TIMER1_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD | TIMER_CNTL_DIV16;
61
62         setup_irq(IRQ_TIMER1, &footbridge_timer_irq);
63 }
64
65 struct sys_timer footbridge_timer = {
66         .init           = footbridge_timer_init,
67         .offset         = timer1_gettimeoffset,
68 };