]> git.proxmox.com Git - mirror_ubuntu-hirsute-kernel.git/blob - arch/arm/mach-rpc/time.c
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500
[mirror_ubuntu-hirsute-kernel.git] / arch / arm / mach-rpc / time.c
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/timex.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
27 static u32 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 -= RPC_LATCH;
50 } else if (count2 > count1) {
51 /*
52 * We have just had another interrupt between reading
53 * count1 and count2.
54 */
55 offset -= RPC_LATCH;
56 }
57
58 offset = (RPC_LATCH - offset) * (tick_nsec / 1000);
59 return DIV_ROUND_CLOSEST(offset, RPC_LATCH) * 1000;
60 }
61
62 void __init ioctime_init(void)
63 {
64 ioc_writeb(RPC_LATCH & 255, IOC_T0LTCHL);
65 ioc_writeb(RPC_LATCH >> 8, IOC_T0LTCHH);
66 ioc_writeb(0, IOC_T0GO);
67 }
68
69 static irqreturn_t
70 ioc_timer_interrupt(int irq, void *dev_id)
71 {
72 timer_tick();
73 return IRQ_HANDLED;
74 }
75
76 static struct irqaction ioc_timer_irq = {
77 .name = "timer",
78 .handler = ioc_timer_interrupt
79 };
80
81 /*
82 * Set up timer interrupt.
83 */
84 void __init ioc_timer_init(void)
85 {
86 arch_gettimeoffset = ioc_timer_gettimeoffset;
87 ioctime_init();
88 setup_irq(IRQ_TIMER0, &ioc_timer_irq);
89 }