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
213
214
215
|
/*
* arch/arm/mach-pxa/time.c
*
* Author: Nicolas Pitre
* Created: Jun 15, 2001
* Copyright: MontaVista Software Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <asm/system.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/leds.h>
#include <asm/irq.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
#include <asm/arch/pxa-regs.h>
static inline unsigned long pxa_get_rtc_time(void)
{
return RCNR;
}
static int pxa_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 pxa_gettimeoffset (void)
{
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;
/* don't get fooled by the workaround in pxa_timer_interrupt() */
if (elapsed <= 0)
return 0;
/* 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
pxa_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
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.
* IRQs are disabled inside the loop to ensure coherence between
* lost_ticks (updated in do_timer()) and the match reg value, so we
* can use do_gettimeofday() from interrupt handlers.
*
* HACK ALERT: it seems that the PXA timer regs aren't updated right
* away in all cases when a write occurs. We therefore compare with
* 8 instead of 0 in the while() condition below to avoid missing a
* match if OSCR has already reached the next OSMR value.
* Experience has shown that up to 6 ticks are needed to work around
* this problem, but let's use 8 to be conservative. Note that this
* affect things only when the timer IRQ has been delayed by nearly
* exactly one tick period which should be a pretty rare event.
*/
do {
timer_tick(regs);
OSSR = OSSR_M0; /* Clear match on timer 0 */
next_match = (OSMR0 += LATCH);
} while( (signed long)(next_match - OSCR) <= 8 );
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static struct irqaction pxa_timer_irq = {
.name = "PXA Timer Tick",
.flags = SA_INTERRUPT | SA_TIMER,
.handler = pxa_timer_interrupt,
};
static void __init pxa_timer_init(void)
{
struct timespec tv;
set_rtc = pxa_set_rtc;
tv.tv_nsec = 0;
tv.tv_sec = pxa_get_rtc_time();
do_settimeofday(&tv);
OSMR0 = 0; /* set initial match at 0 */
OSSR = 0xf; /* clear status on all timers */
setup_irq(IRQ_OST0, &pxa_timer_irq);
OIER |= OIER_E0; /* enable match on timer 0 to cause interrupts */
OSCR = 0; /* initialize free-running timer, force first match */
}
#ifdef CONFIG_NO_IDLE_HZ
static int pxa_dyn_tick_enable_disable(void)
{
/* nothing to do */
return 0;
}
static void pxa_dyn_tick_reprogram(unsigned long ticks)
{
if (ticks > 1) {
initial_match = OSMR0;
OSMR0 = initial_match + ticks * LATCH;
match_posponed = 1;
}
}
static irqreturn_t
pxa_dyn_tick_handler(int irq, void *dev_id, struct pt_regs *regs)
{
if (match_posponed) {
match_posponed = 0;
OSMR0 = initial_match;
if ( (signed long)(initial_match - OSCR) <= 8 )
return pxa_timer_interrupt(irq, dev_id, regs);
}
return IRQ_NONE;
}
static struct dyn_tick_timer pxa_dyn_tick = {
.enable = pxa_dyn_tick_enable_disable,
.disable = pxa_dyn_tick_enable_disable,
.reprogram = pxa_dyn_tick_reprogram,
.handler = pxa_dyn_tick_handler,
};
#endif
#ifdef CONFIG_PM
static unsigned long osmr[4], oier;
static void pxa_timer_suspend(void)
{
osmr[0] = OSMR0;
osmr[1] = OSMR1;
osmr[2] = OSMR2;
osmr[3] = OSMR3;
oier = OIER;
}
static void pxa_timer_resume(void)
{
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 pxa_timer_suspend NULL
#define pxa_timer_resume NULL
#endif
struct sys_timer pxa_timer = {
.init = pxa_timer_init,
.suspend = pxa_timer_suspend,
.resume = pxa_timer_resume,
.offset = pxa_gettimeoffset,
#ifdef CONFIG_NO_IDLE_HZ
.dyn_tick = &pxa_dyn_tick,
#endif
};
|
