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
ioc_timer_gettimeoffset(void)30 static 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
ioctime_init(void)65 void __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
72 static irqreturn_t
ioc_timer_interrupt(int irq,void * dev_id)73 ioc_timer_interrupt(int irq, void *dev_id)
74 {
75 timer_tick();
76 return IRQ_HANDLED;
77 }
78
79 static struct irqaction ioc_timer_irq = {
80 .name = "timer",
81 .handler = ioc_timer_interrupt
82 };
83
84 /*
85 * Set up timer interrupt.
86 */
ioc_timer_init(void)87 void __init ioc_timer_init(void)
88 {
89 arch_gettimeoffset = ioc_timer_gettimeoffset;
90 ioctime_init();
91 setup_irq(IRQ_TIMER0, &ioc_timer_irq);
92 }
93
