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192.168.1.100 / R306 / 0d38ff9c7afa1207beebf9fa0886f87741dfb64a / . / ap / os / linux / linux-3.4.x / arch / arm / mach-pxa / time.c
blob: 3d6c9bd90de6b183cd741e891c926a4bcb841c7e [file] [log] [blame]
yuezonghe824eb0c2024-06-27 02:32:26 -0700[diff] [blame]1/*
2 * arch/arm/mach-pxa/time.c
3 *
4 * PXA clocksource, clockevents, and OST interrupt handlers.
5 * Copyright (c) 2007 by Bill Gatliff <bgat@billgatliff.com>.
6 *
7 * Derived from Nicolas Pitre's PXA timer handler Copyright (c) 2001
8 * by MontaVista Software, Inc. (Nico, your code rocks!)
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14
15#include <linux/kernel.h>
16#include <linux/init.h>
17#include <linux/interrupt.h>
18#include <linux/clockchips.h>
19
20#include <asm/div64.h>
21#include <asm/mach/irq.h>
22#include <asm/mach/time.h>
23#include <asm/sched_clock.h>
24#include <mach/regs-ost.h>
25#include <mach/irqs.h>
26
27/*
28 * This is PXA's sched_clock implementation. This has a resolution
29 * of at least 308 ns and a maximum value of 208 days.
30 *
31 * The return value is guaranteed to be monotonic in that range as
32 * long as there is always less than 582 seconds between successive
33 * calls to sched_clock() which should always be the case in practice.
34 */
35
36static u32 notrace pxa_read_sched_clock(void)
37{
38 return OSCR;
39}
40
41
42#define MIN_OSCR_DELTA 16
43
44static irqreturn_t
45pxa_ost0_interrupt(int irq, void *dev_id)
46{
47 struct clock_event_device *c = dev_id;
48
49 /* Disarm the compare/match, signal the event. */
50 OIER &= ~OIER_E0;
51 OSSR = OSSR_M0;
52 c->event_handler(c);
53
54 return IRQ_HANDLED;
55}
56
57static int
58pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev)
59{
60 unsigned long next, oscr;
61
62 OIER |= OIER_E0;
63 next = OSCR + delta;
64 OSMR0 = next;
65 oscr = OSCR;
66
67 return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
68}
69
70static void
71pxa_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *dev)
72{
73 switch (mode) {
74 case CLOCK_EVT_MODE_ONESHOT:
75 OIER &= ~OIER_E0;
76 OSSR = OSSR_M0;
77 break;
78
79 case CLOCK_EVT_MODE_UNUSED:
80 case CLOCK_EVT_MODE_SHUTDOWN:
81 /* initializing, released, or preparing for suspend */
82 OIER &= ~OIER_E0;
83 OSSR = OSSR_M0;
84 break;
85
86 case CLOCK_EVT_MODE_RESUME:
87 case CLOCK_EVT_MODE_PERIODIC:
88 break;
89 }
90}
91
92static struct clock_event_device ckevt_pxa_osmr0 = {
93 .name = "osmr0",
94 .features = CLOCK_EVT_FEAT_ONESHOT,
95 .rating = 200,
96 .set_next_event = pxa_osmr0_set_next_event,
97 .set_mode = pxa_osmr0_set_mode,
98};
99
100static struct irqaction pxa_ost0_irq = {
101 .name = "ost0",
102 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
103 .handler = pxa_ost0_interrupt,
104 .dev_id = &ckevt_pxa_osmr0,
105};
106
107static void __init pxa_timer_init(void)
108{
109 unsigned long clock_tick_rate = get_clock_tick_rate();
110
111 OIER = 0;
112 OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3;
113
114 setup_sched_clock(pxa_read_sched_clock, 32, clock_tick_rate);
115
116 clockevents_calc_mult_shift(&ckevt_pxa_osmr0, clock_tick_rate, 4);
117 ckevt_pxa_osmr0.max_delta_ns =
118 clockevent_delta2ns(0x7fffffff, &ckevt_pxa_osmr0);
119 ckevt_pxa_osmr0.min_delta_ns =
120 clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_pxa_osmr0) + 1;
121 ckevt_pxa_osmr0.cpumask = cpumask_of(0);
122
123 setup_irq(IRQ_OST0, &pxa_ost0_irq);
124
125 clocksource_mmio_init(&OSCR, "oscr0", clock_tick_rate, 200, 32,
126 clocksource_mmio_readl_up);
127 clockevents_register_device(&ckevt_pxa_osmr0);
128}
129
130#ifdef CONFIG_PM
131static unsigned long osmr[4], oier, oscr;
132
133static void pxa_timer_suspend(void)
134{
135 osmr[0] = OSMR0;
136 osmr[1] = OSMR1;
137 osmr[2] = OSMR2;
138 osmr[3] = OSMR3;
139 oier = OIER;
140 oscr = OSCR;
141}
142
143static void pxa_timer_resume(void)
144{
145 /*
146 * Ensure that we have at least MIN_OSCR_DELTA between match
147 * register 0 and the OSCR, to guarantee that we will receive
148 * the one-shot timer interrupt. We adjust OSMR0 in preference
149 * to OSCR to guarantee that OSCR is monotonically incrementing.
150 */
151 if (osmr[0] - oscr < MIN_OSCR_DELTA)
152 osmr[0] += MIN_OSCR_DELTA;
153
154 OSMR0 = osmr[0];
155 OSMR1 = osmr[1];
156 OSMR2 = osmr[2];
157 OSMR3 = osmr[3];
158 OIER = oier;
159 OSCR = oscr;
160}
161#else
162#define pxa_timer_suspend NULL
163#define pxa_timer_resume NULL
164#endif
165
166struct sys_timer pxa_timer = {
167 .init = pxa_timer_init,
168 .suspend = pxa_timer_suspend,
169 .resume = pxa_timer_resume,
170};