time.c (e5451c8f8330e03ad3cfa16048b4daf961af434f) time.c (a44c1d700c848e221d80aab1029d36a60d21a0f4)
1/*
2 * linux/arch/arm/common/time-acorn.c
3 *
4 * Copyright (c) 1996-2000 Russell King.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Changelog:
11 * 24-Sep-1996 RMK Created
12 * 10-Oct-1996 RMK Brought up to date with arch-sa110eval
13 * 04-Dec-1997 RMK Updated for new arch/arm/time.c
14 * 13=Jun-2004 DS Moved to arch/arm/common b/c shared w/CLPS7500
15 */
1/*
2 * linux/arch/arm/common/time-acorn.c
3 *
4 * Copyright (c) 1996-2000 Russell King.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Changelog:
11 * 24-Sep-1996 RMK Created
12 * 10-Oct-1996 RMK Brought up to date with arch-sa110eval
13 * 04-Dec-1997 RMK Updated for new arch/arm/time.c
14 * 13=Jun-2004 DS Moved to arch/arm/common b/c shared w/CLPS7500
15 */
16#include <linux/timex.h>
16#include <linux/clocksource.h>
17#include <linux/init.h>
18#include <linux/interrupt.h>
19#include <linux/irq.h>
20#include <linux/io.h>
21
22#include <mach/hardware.h>
23#include <asm/hardware/ioc.h>
24
25#include <asm/mach/time.h>
26
27#define RPC_CLOCK_FREQ 2000000
28#define RPC_LATCH DIV_ROUND_CLOSEST(RPC_CLOCK_FREQ, HZ)
29
17#include <linux/init.h>
18#include <linux/interrupt.h>
19#include <linux/irq.h>
20#include <linux/io.h>
21
22#include <mach/hardware.h>
23#include <asm/hardware/ioc.h>
24
25#include <asm/mach/time.h>
26
27#define RPC_CLOCK_FREQ 2000000
28#define RPC_LATCH DIV_ROUND_CLOSEST(RPC_CLOCK_FREQ, HZ)
29
30static u32 ioc_timer_gettimeoffset(void)
30static u32 ioc_time;
31
32static u64 ioc_timer_read(struct clocksource *cs)
31{
32 unsigned int count1, count2, status;
33{
34 unsigned int count1, count2, status;
33 long offset;
35 unsigned long flags;
36 u32 ticks;
34
37
38 local_irq_save(flags);
35 ioc_writeb (0, IOC_T0LATCH);
36 barrier ();
37 count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
38 barrier ();
39 status = ioc_readb(IOC_IRQREQA);
40 barrier ();
41 ioc_writeb (0, IOC_T0LATCH);
42 barrier ();
43 count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
39 ioc_writeb (0, IOC_T0LATCH);
40 barrier ();
41 count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
42 barrier ();
43 status = ioc_readb(IOC_IRQREQA);
44 barrier ();
45 ioc_writeb (0, IOC_T0LATCH);
46 barrier ();
47 count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
48 ticks = ioc_time + RPC_LATCH - count2;
49 local_irq_restore(flags);
44
50
45 offset = count2;
46 if (count2 < count1) {
47 /*
51 if (count2 < count1) {
52 /*
48 * We have not had an interrupt between reading count1
49 * and count2.
53 * The timer has not reloaded between reading count1 and
54 * count2, check whether an interrupt was actually pending.
50 */
51 if (status & (1 << 5))
55 */
56 if (status & (1 << 5))
52 offset -= RPC_LATCH;
57 ticks += RPC_LATCH;
53 } else if (count2 > count1) {
54 /*
58 } else if (count2 > count1) {
59 /*
55 * We have just had another interrupt between reading
56 * count1 and count2.
60 * The timer has reloaded, so count2 indicates the new
61 * count since the wrap. The interrupt would not have
62 * been processed, so add the missed ticks.
57 */
63 */
58 offset -= RPC_LATCH;
64 ticks += RPC_LATCH;
59 }
60
65 }
66
61 offset = (RPC_LATCH - offset) * (tick_nsec / 1000);
62 return DIV_ROUND_CLOSEST(offset, RPC_LATCH) * 1000;
67 return ticks;
63}
64
68}
69
70static struct clocksource ioctime_clocksource = {
71 .read = ioc_timer_read,
72 .mask = CLOCKSOURCE_MASK(32),
73 .rating = 100,
74};
75
65void __init ioctime_init(void)
66{
67 ioc_writeb(RPC_LATCH & 255, IOC_T0LTCHL);
68 ioc_writeb(RPC_LATCH >> 8, IOC_T0LTCHH);
69 ioc_writeb(0, IOC_T0GO);
70}
71
72static irqreturn_t
73ioc_timer_interrupt(int irq, void *dev_id)
74{
76void __init ioctime_init(void)
77{
78 ioc_writeb(RPC_LATCH & 255, IOC_T0LTCHL);
79 ioc_writeb(RPC_LATCH >> 8, IOC_T0LTCHH);
80 ioc_writeb(0, IOC_T0GO);
81}
82
83static irqreturn_t
84ioc_timer_interrupt(int irq, void *dev_id)
85{
86 ioc_time += RPC_LATCH;
75 timer_tick();
76 return IRQ_HANDLED;
77}
78
79static struct irqaction ioc_timer_irq = {
80 .name = "timer",
81 .handler = ioc_timer_interrupt
82};
83
84/*
85 * Set up timer interrupt.
86 */
87void __init ioc_timer_init(void)
88{
87 timer_tick();
88 return IRQ_HANDLED;
89}
90
91static struct irqaction ioc_timer_irq = {
92 .name = "timer",
93 .handler = ioc_timer_interrupt
94};
95
96/*
97 * Set up timer interrupt.
98 */
99void __init ioc_timer_init(void)
100{
89 arch_gettimeoffset = ioc_timer_gettimeoffset;
101 WARN_ON(clocksource_register_hz(&ioctime_clocksource, RPC_CLOCK_FREQ));
90 ioctime_init();
91 setup_irq(IRQ_TIMER0, &ioc_timer_irq);
92}
102 ioctime_init();
103 setup_irq(IRQ_TIMER0, &ioc_timer_irq);
104}