Loading...
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}
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
27#define RPC_CLOCK_FREQ 2000000
28#define RPC_LATCH DIV_ROUND_CLOSEST(RPC_CLOCK_FREQ, HZ)
29
30static u32 ioc_timer_gettimeoffset(void)
31{
32 unsigned int count1, count2, status;
33 long offset;
34
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);
44
45 offset = count2;
46 if (count2 < count1) {
47 /*
48 * We have not had an interrupt between reading count1
49 * and count2.
50 */
51 if (status & (1 << 5))
52 offset -= RPC_LATCH;
53 } else if (count2 > count1) {
54 /*
55 * We have just had another interrupt between reading
56 * count1 and count2.
57 */
58 offset -= RPC_LATCH;
59 }
60
61 offset = (RPC_LATCH - offset) * (tick_nsec / 1000);
62 return DIV_ROUND_CLOSEST(offset, RPC_LATCH) * 1000;
63}
64
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{
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{
89 arch_gettimeoffset = ioc_timer_gettimeoffset;
90 ioctime_init();
91 setup_irq(IRQ_TIMER0, &ioc_timer_irq);
92}