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>
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
27unsigned long ioc_timer_gettimeoffset(void)
 
 
 
 
 
28{
29	unsigned int count1, count2, status;
30	long offset;
 
31
 
32	ioc_writeb (0, IOC_T0LATCH);
33	barrier ();
34	count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
35	barrier ();
36	status = ioc_readb(IOC_IRQREQA);
37	barrier ();
38	ioc_writeb (0, IOC_T0LATCH);
39	barrier ();
40	count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
 
 
41
42	offset = count2;
43	if (count2 < count1) {
44		/*
45		 * We have not had an interrupt between reading count1
46		 * and count2.
47		 */
48		if (status & (1 << 5))
49			offset -= LATCH;
50	} else if (count2 > count1) {
51		/*
52		 * We have just had another interrupt between reading
53		 * count1 and count2.
 
54		 */
55		offset -= LATCH;
56	}
57
58	offset = (LATCH - offset) * (tick_nsec / 1000);
59	return (offset + LATCH/2) / LATCH;
60}
61
 
 
 
 
 
 
62void __init ioctime_init(void)
63{
64	ioc_writeb(LATCH & 255, IOC_T0LTCHL);
65	ioc_writeb(LATCH >> 8, IOC_T0LTCHH);
66	ioc_writeb(0, IOC_T0GO);
67}
68
69static irqreturn_t
70ioc_timer_interrupt(int irq, void *dev_id)
71{
72	timer_tick();
 
73	return IRQ_HANDLED;
74}
75
76static struct irqaction ioc_timer_irq = {
77	.name		= "timer",
78	.flags		= IRQF_DISABLED,
79	.handler	= ioc_timer_interrupt
80};
81
82/*
83 * Set up timer interrupt.
84 */
85static void __init ioc_timer_init(void)
86{
 
87	ioctime_init();
88	setup_irq(IRQ_TIMER0, &ioc_timer_irq);
 
89}
90
91struct sys_timer ioc_timer = {
92	.init		= ioc_timer_init,
93	.offset		= ioc_timer_gettimeoffset,
94};
95

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 *  linux/arch/arm/common/time-acorn.c
 4 *
 5 *  Copyright (c) 1996-2000 Russell King.
 6 *
 
 
 
 
 7 *  Changelog:
 8 *   24-Sep-1996	RMK	Created
 9 *   10-Oct-1996	RMK	Brought up to date with arch-sa110eval
10 *   04-Dec-1997	RMK	Updated for new arch/arm/time.c
11 *   13=Jun-2004	DS	Moved to arch/arm/common b/c shared w/CLPS7500
12 */
13#include <linux/clocksource.h>
14#include <linux/init.h>
15#include <linux/interrupt.h>
16#include <linux/irq.h>
17#include <linux/io.h>
18
19#include <mach/hardware.h>
20#include <asm/hardware/ioc.h>
21
22#include <asm/mach/time.h>
23
24#define RPC_CLOCK_FREQ 2000000
25#define RPC_LATCH DIV_ROUND_CLOSEST(RPC_CLOCK_FREQ, HZ)
26
27static u32 ioc_time;
28
29static u64 ioc_timer_read(struct clocksource *cs)
30{
31	unsigned int count1, count2, status;
32	unsigned long flags;
33	u32 ticks;
34
35	local_irq_save(flags);
36	ioc_writeb (0, IOC_T0LATCH);
37	barrier ();
38	count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
39	barrier ();
40	status = ioc_readb(IOC_IRQREQA);
41	barrier ();
42	ioc_writeb (0, IOC_T0LATCH);
43	barrier ();
44	count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
45	ticks = ioc_time + RPC_LATCH - count2;
46	local_irq_restore(flags);
47
 
48	if (count2 < count1) {
49		/*
50		 * The timer has not reloaded between reading count1 and
51		 * count2, check whether an interrupt was actually pending.
52		 */
53		if (status & (1 << 5))
54			ticks += RPC_LATCH;
55	} else if (count2 > count1) {
56		/*
57		 * The timer has reloaded, so count2 indicates the new
58		 * count since the wrap.  The interrupt would not have
59		 * been processed, so add the missed ticks.
60		 */
61		ticks += RPC_LATCH;
62	}
63
64	return ticks;
 
65}
66
67static struct clocksource ioctime_clocksource = {
68	.read = ioc_timer_read,
69	.mask = CLOCKSOURCE_MASK(32),
70	.rating = 100,
71};
72
73void __init ioctime_init(void)
74{
75	ioc_writeb(RPC_LATCH & 255, IOC_T0LTCHL);
76	ioc_writeb(RPC_LATCH >> 8, IOC_T0LTCHH);
77	ioc_writeb(0, IOC_T0GO);
78}
79
80static irqreturn_t
81ioc_timer_interrupt(int irq, void *dev_id)
82{
83	ioc_time += RPC_LATCH;
84	legacy_timer_tick(1);
85	return IRQ_HANDLED;
86}
87
 
 
 
 
 
 
88/*
89 * Set up timer interrupt.
90 */
91void __init ioc_timer_init(void)
92{
93	WARN_ON(clocksource_register_hz(&ioctime_clocksource, RPC_CLOCK_FREQ));
94	ioctime_init();
95	if (request_irq(IRQ_TIMER0, ioc_timer_interrupt, 0, "timer", NULL))
96		pr_err("Failed to request irq %d (timer)\n", IRQ_TIMER0);
97}