1/*
2 * arch/arm/mach-ks8695/time.c
3 *
4 * Copyright (C) 2006 Ben Dooks <ben@simtec.co.uk>
5 * Copyright (C) 2006 Simtec Electronics
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20 */
21
22#include <linux/init.h>
23#include <linux/interrupt.h>
24#include <linux/irq.h>
25#include <linux/kernel.h>
26#include <linux/sched.h>
27
28#include <asm/io.h>
29#include <asm/mach/time.h>
30
31#include <asm/arch/regs-timer.h>
32#include <asm/arch/regs-irq.h>
33
34#include "generic.h"
35
36/*
37 * Returns number of ms since last clock interrupt.  Note that interrupts
38 * will have been disabled by do_gettimeoffset()
39 */
40static unsigned long ks8695_gettimeoffset (void)
41{
42	unsigned long elapsed, tick2, intpending;
43
44	/*
45	 * Get the current number of ticks.  Note that there is a race
46	 * condition between us reading the timer and checking for an
47	 * interrupt.  We solve this by ensuring that the counter has not
48	 * reloaded between our two reads.
49	 */
50	elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD);
51	do {
52		tick2 = elapsed;
53		intpending = __raw_readl(KS8695_IRQ_VA + KS8695_INTST) & (1 << KS8695_IRQ_TIMER1);
54		elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD);
55	} while (elapsed > tick2);
56
57	/* Convert to number of ticks expired (not remaining) */
58	elapsed = (CLOCK_TICK_RATE / HZ) - elapsed;
59
60	/* Is interrupt pending?  If so, then timer has been reloaded already. */
61	if (intpending)
62		elapsed += (CLOCK_TICK_RATE / HZ);
63
64	/* Convert ticks to usecs */
65	return (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH;
66}
67
68/*
69 * IRQ handler for the timer.
70 */
71static irqreturn_t ks8695_timer_interrupt(int irq, void *dev_id)
72{
73	write_seqlock(&xtime_lock);
74	timer_tick();
75	write_sequnlock(&xtime_lock);
76
77	return IRQ_HANDLED;
78}
79
80static struct irqaction ks8695_timer_irq = {
81	.name		= "ks8695_tick",
82	.flags		= IRQF_DISABLED | IRQF_TIMER,
83	.handler	= ks8695_timer_interrupt,
84};
85
86static void ks8695_timer_setup(void)
87{
88	unsigned long tmout = CLOCK_TICK_RATE / HZ;
89	unsigned long tmcon;
90
91	/* disable timer1 */
92	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
93	__raw_writel(tmcon & ~TMCON_T1EN, KS8695_TMR_VA + KS8695_TMCON);
94
95	__raw_writel(tmout / 2, KS8695_TMR_VA + KS8695_T1TC);
96	__raw_writel(tmout / 2, KS8695_TMR_VA + KS8695_T1PD);
97
98	/* re-enable timer1 */
99	__raw_writel(tmcon | TMCON_T1EN, KS8695_TMR_VA + KS8695_TMCON);
100}
101
102static void __init ks8695_timer_init (void)
103{
104	ks8695_timer_setup();
105
106	/* Enable timer interrupts */
107	setup_irq(KS8695_IRQ_TIMER1, &ks8695_timer_irq);
108}
109
110struct sys_timer ks8695_timer = {
111	.init		= ks8695_timer_init,
112	.offset		= ks8695_gettimeoffset,
113	.resume		= ks8695_timer_setup,
114};
115