1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
/*
* linux/arch/arm/mach-sa1100/time.c
*
* Copyright (C) 1998 Deborah Wallach.
* Twiddles (C) 1999 Hugo Fiennes <hugo@empeg.com>
*
* 2000/03/29 (C) Nicolas Pitre <nico@cam.org>
* Rewritten: big cleanup, much simpler, better HZ accuracy.
*
*/
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/timex.h>
#include <linux/signal.h>
#include <asm/mach/time.h>
#include <asm/hardware.h>
#define RTC_DEF_DIVIDER (32768 - 1)
#define RTC_DEF_TRIM 0
static unsigned long __init sa1100_get_rtc_time(void)
{
/*
* According to the manual we should be able to let RTTR be zero
* and then a default diviser for a 32.768KHz clock is used.
* Apparently this doesn't work, at least for my SA1110 rev 5.
* If the clock divider is uninitialized then reset it to the
* default value to get the 1Hz clock.
*/
if (RTTR == 0) {
RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
printk(KERN_WARNING "Warning: uninitialized Real Time Clock\n");
/* The current RTC value probably doesn't make sense either */
RCNR = 0;
return 0;
}
return RCNR;
}
static int sa1100_set_rtc(void)
{
unsigned long current_time = xtime.tv_sec;
if (RTSR & RTSR_ALE) {
/* make sure not to forward the clock over an alarm */
unsigned long alarm = RTAR;
if (current_time >= alarm && alarm >= RCNR)
return -ERESTARTSYS;
}
RCNR = current_time;
return 0;
}
/* IRQs are disabled before entering here from do_gettimeofday() */
static unsigned long sa1100_gettimeoffset (void)
{
unsigned long ticks_to_match, elapsed, usec;
/* Get ticks before next timer match */
ticks_to_match = OSMR0 - OSCR;
/* We need elapsed ticks since last match */
elapsed = LATCH - ticks_to_match;
/* Now convert them to usec */
usec = (unsigned long)(elapsed * (tick_nsec / 1000))/LATCH;
return usec;
}
#ifdef CONFIG_NO_IDLE_HZ
static unsigned long initial_match;
static int match_posponed;
#endif
static irqreturn_t
sa1100_timer_interrupt(int irq, void *dev_id)
{
unsigned int next_match;
write_seqlock(&xtime_lock);
#ifdef CONFIG_NO_IDLE_HZ
if (match_posponed) {
match_posponed = 0;
OSMR0 = initial_match;
}
#endif
/*
* Loop until we get ahead of the free running timer.
* This ensures an exact clock tick count and time accuracy.
* Since IRQs are disabled at this point, coherence between
* lost_ticks(updated in do_timer()) and the match reg value is
* ensured, hence we can use do_gettimeofday() from interrupt
* handlers.
*/
do {
timer_tick();
OSSR = OSSR_M0; /* Clear match on timer 0 */
next_match = (OSMR0 += LATCH);
} while ((signed long)(next_match - OSCR) <= 0);
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static struct irqaction sa1100_timer_irq = {
.name = "SA11xx Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER,
.handler = sa1100_timer_interrupt,
};
static void __init sa1100_timer_init(void)
{
struct timespec tv;
set_rtc = sa1100_set_rtc;
tv.tv_nsec = 0;
tv.tv_sec = sa1100_get_rtc_time();
do_settimeofday(&tv);
OIER = 0; /* disable any timer interrupts */
OSCR = LATCH*2; /* push OSCR out of the way */
OSMR0 = LATCH; /* set initial match */
OSSR = 0xf; /* clear status on all timers */
setup_irq(IRQ_OST0, &sa1100_timer_irq);
OIER = OIER_E0; /* enable match on timer 0 to cause interrupts */
OSCR = 0; /* initialize free-running timer */
}
#ifdef CONFIG_NO_IDLE_HZ
static int sa1100_dyn_tick_enable_disable(void)
{
/* nothing to do */
return 0;
}
static void sa1100_dyn_tick_reprogram(unsigned long ticks)
{
if (ticks > 1) {
initial_match = OSMR0;
OSMR0 = initial_match + ticks * LATCH;
match_posponed = 1;
}
}
static irqreturn_t
sa1100_dyn_tick_handler(int irq, void *dev_id)
{
if (match_posponed) {
match_posponed = 0;
OSMR0 = initial_match;
if ((signed long)(initial_match - OSCR) <= 0)
return sa1100_timer_interrupt(irq, dev_id);
}
return IRQ_NONE;
}
static struct dyn_tick_timer sa1100_dyn_tick = {
.enable = sa1100_dyn_tick_enable_disable,
.disable = sa1100_dyn_tick_enable_disable,
.reprogram = sa1100_dyn_tick_reprogram,
.handler = sa1100_dyn_tick_handler,
};
#endif
#ifdef CONFIG_PM
unsigned long osmr[4], oier;
static void sa1100_timer_suspend(void)
{
osmr[0] = OSMR0;
osmr[1] = OSMR1;
osmr[2] = OSMR2;
osmr[3] = OSMR3;
oier = OIER;
}
static void sa1100_timer_resume(void)
{
OSSR = 0x0f;
OSMR0 = osmr[0];
OSMR1 = osmr[1];
OSMR2 = osmr[2];
OSMR3 = osmr[3];
OIER = oier;
/*
* OSMR0 is the system timer: make sure OSCR is sufficiently behind
*/
OSCR = OSMR0 - LATCH;
}
#else
#define sa1100_timer_suspend NULL
#define sa1100_timer_resume NULL
#endif
struct sys_timer sa1100_timer = {
.init = sa1100_timer_init,
.suspend = sa1100_timer_suspend,
.resume = sa1100_timer_resume,
.offset = sa1100_gettimeoffset,
#ifdef CONFIG_NO_IDLE_HZ
.dyn_tick = &sa1100_dyn_tick,
#endif
};
|
