Merge branch 'orion' into devel
[linux-2.6] / arch / arm / mach-sa1100 / time.c
1 /*
2  * linux/arch/arm/mach-sa1100/time.c
3  *
4  * Copyright (C) 1998 Deborah Wallach.
5  * Twiddles  (C) 1999   Hugo Fiennes <hugo@empeg.com>
6  * 
7  * 2000/03/29 (C) Nicolas Pitre <nico@cam.org>
8  *      Rewritten: big cleanup, much simpler, better HZ accuracy.
9  *
10  */
11 #include <linux/init.h>
12 #include <linux/errno.h>
13 #include <linux/interrupt.h>
14 #include <linux/irq.h>
15 #include <linux/timex.h>
16 #include <linux/signal.h>
17 #include <linux/clocksource.h>
18
19 #include <asm/mach/time.h>
20 #include <asm/hardware.h>
21
22 #define RTC_DEF_DIVIDER         (32768 - 1)
23 #define RTC_DEF_TRIM            0
24
25 static int sa1100_set_rtc(void)
26 {
27         unsigned long current_time = xtime.tv_sec;
28
29         if (RTSR & RTSR_ALE) {
30                 /* make sure not to forward the clock over an alarm */
31                 unsigned long alarm = RTAR;
32                 if (current_time >= alarm && alarm >= RCNR)
33                         return -ERESTARTSYS;
34         }
35         RCNR = current_time;
36         return 0;
37 }
38
39 #ifdef CONFIG_NO_IDLE_HZ
40 static unsigned long initial_match;
41 static int match_posponed;
42 #endif
43
44 static irqreturn_t
45 sa1100_timer_interrupt(int irq, void *dev_id)
46 {
47         unsigned int next_match;
48
49 #ifdef CONFIG_NO_IDLE_HZ
50         if (match_posponed) {
51                 match_posponed = 0;
52                 OSMR0 = initial_match;
53         }
54 #endif
55
56         /*
57          * Loop until we get ahead of the free running timer.
58          * This ensures an exact clock tick count and time accuracy.
59          * Since IRQs are disabled at this point, coherence between
60          * lost_ticks(updated in do_timer()) and the match reg value is
61          * ensured, hence we can use do_gettimeofday() from interrupt
62          * handlers.
63          */
64         do {
65                 timer_tick();
66                 OSSR = OSSR_M0;  /* Clear match on timer 0 */
67                 next_match = (OSMR0 += LATCH);
68         } while ((signed long)(next_match - OSCR) <= 0);
69
70         return IRQ_HANDLED;
71 }
72
73 static struct irqaction sa1100_timer_irq = {
74         .name           = "SA11xx Timer Tick",
75         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
76         .handler        = sa1100_timer_interrupt,
77 };
78
79 static cycle_t sa1100_read_oscr(void)
80 {
81         return OSCR;
82 }
83
84 static struct clocksource cksrc_sa1100_oscr = {
85         .name           = "oscr",
86         .rating         = 200,
87         .read           = sa1100_read_oscr,
88         .mask           = CLOCKSOURCE_MASK(32),
89         .shift          = 20,
90         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
91 };
92
93 static void __init sa1100_timer_init(void)
94 {
95         unsigned long flags;
96
97         set_rtc = sa1100_set_rtc;
98
99         OIER = 0;               /* disable any timer interrupts */
100         OSSR = 0xf;             /* clear status on all timers */
101         setup_irq(IRQ_OST0, &sa1100_timer_irq);
102         local_irq_save(flags);
103         OIER = OIER_E0;         /* enable match on timer 0 to cause interrupts */
104         OSMR0 = OSCR + LATCH;   /* set initial match */
105         local_irq_restore(flags);
106
107         cksrc_sa1100_oscr.mult =
108                 clocksource_hz2mult(CLOCK_TICK_RATE, cksrc_sa1100_oscr.shift);
109
110         clocksource_register(&cksrc_sa1100_oscr);
111 }
112
113 #ifdef CONFIG_NO_IDLE_HZ
114 static int sa1100_dyn_tick_enable_disable(void)
115 {
116         /* nothing to do */
117         return 0;
118 }
119
120 static void sa1100_dyn_tick_reprogram(unsigned long ticks)
121 {
122         if (ticks > 1) {
123                 initial_match = OSMR0;
124                 OSMR0 = initial_match + ticks * LATCH;
125                 match_posponed = 1;
126         }
127 }
128
129 static irqreturn_t
130 sa1100_dyn_tick_handler(int irq, void *dev_id)
131 {
132         if (match_posponed) {
133                 match_posponed = 0;
134                 OSMR0 = initial_match;
135                 if ((signed long)(initial_match - OSCR) <= 0)
136                         return sa1100_timer_interrupt(irq, dev_id);
137         }
138         return IRQ_NONE;
139 }
140
141 static struct dyn_tick_timer sa1100_dyn_tick = {
142         .enable         = sa1100_dyn_tick_enable_disable,
143         .disable        = sa1100_dyn_tick_enable_disable,
144         .reprogram      = sa1100_dyn_tick_reprogram,
145         .handler        = sa1100_dyn_tick_handler,
146 };
147 #endif
148
149 #ifdef CONFIG_PM
150 unsigned long osmr[4], oier;
151
152 static void sa1100_timer_suspend(void)
153 {
154         osmr[0] = OSMR0;
155         osmr[1] = OSMR1;
156         osmr[2] = OSMR2;
157         osmr[3] = OSMR3;
158         oier = OIER;
159 }
160
161 static void sa1100_timer_resume(void)
162 {
163         OSSR = 0x0f;
164         OSMR0 = osmr[0];
165         OSMR1 = osmr[1];
166         OSMR2 = osmr[2];
167         OSMR3 = osmr[3];
168         OIER = oier;
169
170         /*
171          * OSMR0 is the system timer: make sure OSCR is sufficiently behind
172          */
173         OSCR = OSMR0 - LATCH;
174 }
175 #else
176 #define sa1100_timer_suspend NULL
177 #define sa1100_timer_resume NULL
178 #endif
179
180 struct sys_timer sa1100_timer = {
181         .init           = sa1100_timer_init,
182         .suspend        = sa1100_timer_suspend,
183         .resume         = sa1100_timer_resume,
184 #ifdef CONFIG_NO_IDLE_HZ
185         .dyn_tick       = &sa1100_dyn_tick,
186 #endif
187 };