1/*
2 * arch/arm/plat-iop/time.c
3 *
4 * Timer code for IOP32x and IOP33x based systems
5 *
6 * Author: Deepak Saxena <dsaxena@mvista.com>
7 *
8 * Copyright 2002-2003 MontaVista Software Inc.
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2 of the License, or (at your
13 * option) any later version.
14 */
15
16#include <linux/kernel.h>
17#include <linux/interrupt.h>
18#include <linux/time.h>
19#include <linux/init.h>
20#include <linux/timex.h>
21#include <asm/hardware.h>
22#include <asm/io.h>
23#include <asm/irq.h>
24#include <asm/uaccess.h>
25#include <asm/mach/irq.h>
26#include <asm/mach/time.h>
27#include <asm/arch/time.h>
28
29static unsigned long ticks_per_jiffy;
30static unsigned long ticks_per_usec;
31static unsigned long next_jiffy_time;
32
33unsigned long iop_gettimeoffset(void)
34{
35	unsigned long offset, temp;
36
37	/* enable cp6, if necessary, to avoid taking the overhead of an
38	 * undefined instruction trap
39	 */
40	asm volatile (
41	"mrc	p15, 0, %0, c15, c1, 0\n\t"
42	"tst	%0, #(1 << 6)\n\t"
43	"orreq	%0, %0, #(1 << 6)\n\t"
44	"mcreq	p15, 0, %0, c15, c1, 0\n\t"
45#ifdef CONFIG_CPU_XSCALE
46	"mrceq	p15, 0, %0, c15, c1, 0\n\t"
47	"moveq	%0, %0\n\t"
48	"subeq	pc, pc, #4\n\t"
49#endif
50	: "=r"(temp) : : "cc");
51
52	offset = next_jiffy_time - read_tcr1();
53
54	return offset / ticks_per_usec;
55}
56
57static irqreturn_t
58iop_timer_interrupt(int irq, void *dev_id)
59{
60	write_seqlock(&xtime_lock);
61
62	write_tisr(1);
63
64	while ((signed long)(next_jiffy_time - read_tcr1())
65		>= ticks_per_jiffy) {
66		timer_tick();
67		next_jiffy_time -= ticks_per_jiffy;
68	}
69
70	write_sequnlock(&xtime_lock);
71
72	return IRQ_HANDLED;
73}
74
75static struct irqaction iop_timer_irq = {
76	.name		= "IOP Timer Tick",
77	.handler	= iop_timer_interrupt,
78	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
79};
80
81void __init iop_init_time(unsigned long tick_rate)
82{
83	u32 timer_ctl;
84
85	ticks_per_jiffy = (tick_rate + HZ/2) / HZ;
86	ticks_per_usec = tick_rate / 1000000;
87	next_jiffy_time = 0xffffffff;
88
89	timer_ctl = IOP_TMR_EN | IOP_TMR_PRIVILEGED |
90			IOP_TMR_RELOAD | IOP_TMR_RATIO_1_1;
91
92	/*
93	 * We use timer 0 for our timer interrupt, and timer 1 as
94	 * monotonic counter for tracking missed jiffies.
95	 */
96	write_trr0(ticks_per_jiffy - 1);
97	write_tmr0(timer_ctl);
98	write_trr1(0xffffffff);
99	write_tmr1(timer_ctl);
100
101	setup_irq(IRQ_IOP_TIMER0, &iop_timer_irq);
102}
103