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 #include <linux/irq.h>
10 
11 #include <asm/irq.h>
12 
13 #include <asm/hardware/dec21285.h>
14 #include <asm/mach/time.h>
15 
16 #include "common.h"
17 
18 /*
19  * Footbridge timer 1 support.
20  */
21 static unsigned long timer1_latch;
22 
23 static unsigned long timer1_gettimeoffset (void)
24 {
25 	unsigned long value = timer1_latch - *CSR_TIMER1_VALUE;
26 
27 	return ((tick_nsec / 1000) * value) / timer1_latch;
28 }
29 
30 static irqreturn_t
31 timer1_interrupt(int irq, void *dev_id)
32 {
33 	write_seqlock(&xtime_lock);
34 
35 	*CSR_TIMER1_CLR = 0;
36 
37 	timer_tick();
38 
39 	write_sequnlock(&xtime_lock);
40 
41 	return IRQ_HANDLED;
42 }
43 
44 static struct irqaction footbridge_timer_irq = {
45 	.name		= "Timer1 timer tick",
46 	.handler	= timer1_interrupt,
47 	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
48 };
49 
50 /*
51  * Set up timer interrupt.
52  */
53 static void __init footbridge_timer_init(void)
54 {
55 	timer1_latch = (mem_fclk_21285 + 8 * HZ) / (16 * HZ);
56 
57 	*CSR_TIMER1_CLR  = 0;
58 	*CSR_TIMER1_LOAD = timer1_latch;
59 	*CSR_TIMER1_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD | TIMER_CNTL_DIV16;
60 
61 	setup_irq(IRQ_TIMER1, &footbridge_timer_irq);
62 
63 	isa_rtc_init();
64 }
65 
66 struct sys_timer footbridge_timer = {
67 	.init		= footbridge_timer_init,
68 	.offset		= timer1_gettimeoffset,
69 };
70