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
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
|
/*
* Copyright (C) 2004-2006 Atmel Corporation
*
* Based on MIPS implementation arch/mips/kernel/time.c
* Copyright 2001 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/clk.h>
#include <linux/clocksource.h>
#include <linux/time.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel_stat.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/sysdev.h>
#include <asm/div64.h>
#include <asm/sysreg.h>
#include <asm/io.h>
#include <asm/sections.h>
static cycle_t read_cycle_count(void)
{
return (cycle_t)sysreg_read(COUNT);
}
static struct clocksource clocksource_avr32 = {
.name = "avr32",
.rating = 350,
.read = read_cycle_count,
.mask = CLOCKSOURCE_MASK(32),
.shift = 16,
.is_continuous = 1,
};
/*
* By default we provide the null RTC ops
*/
static unsigned long null_rtc_get_time(void)
{
return mktime(2004, 1, 1, 0, 0, 0);
}
static int null_rtc_set_time(unsigned long sec)
{
return 0;
}
static unsigned long (*rtc_get_time)(void) = null_rtc_get_time;
static int (*rtc_set_time)(unsigned long) = null_rtc_set_time;
/* how many counter cycles in a jiffy? */
static unsigned long cycles_per_jiffy;
/* cycle counter value at the previous timer interrupt */
static unsigned int timerhi, timerlo;
/* the count value for the next timer interrupt */
static unsigned int expirelo;
static void avr32_timer_ack(void)
{
unsigned int count;
/* Ack this timer interrupt and set the next one */
expirelo += cycles_per_jiffy;
if (expirelo == 0) {
printk(KERN_DEBUG "expirelo == 0\n");
sysreg_write(COMPARE, expirelo + 1);
} else {
sysreg_write(COMPARE, expirelo);
}
/* Check to see if we have missed any timer interrupts */
count = sysreg_read(COUNT);
if ((count - expirelo) < 0x7fffffff) {
expirelo = count + cycles_per_jiffy;
sysreg_write(COMPARE, expirelo);
}
}
static unsigned int avr32_hpt_read(void)
{
return sysreg_read(COUNT);
}
/*
* Taken from MIPS c0_hpt_timer_init().
*
* Why is it so complicated, and what is "count"? My assumption is
* that `count' specifies the "reference cycle", i.e. the cycle since
* reset that should mean "zero". The reason COUNT is written twice is
* probably to make sure we don't get any timer interrupts while we
* are messing with the counter.
*/
static void avr32_hpt_init(unsigned int count)
{
count = sysreg_read(COUNT) - count;
expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy;
sysreg_write(COUNT, expirelo - cycles_per_jiffy);
sysreg_write(COMPARE, expirelo);
sysreg_write(COUNT, count);
}
/*
* Scheduler clock - returns current time in nanosec units.
*/
unsigned long long sched_clock(void)
{
/* There must be better ways...? */
return (unsigned long long)jiffies * (1000000000 / HZ);
}
/*
* local_timer_interrupt() does profiling and process accounting on a
* per-CPU basis.
*
* In UP mode, it is invoked from the (global) timer_interrupt.
*/
static void local_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
if (current->pid)
profile_tick(CPU_PROFILING, regs);
update_process_times(user_mode(regs));
}
static irqreturn_t
timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
unsigned int count;
/* ack timer interrupt and try to set next interrupt */
count = avr32_hpt_read();
avr32_timer_ack();
/* Update timerhi/timerlo for intra-jiffy calibration */
timerhi += count < timerlo; /* Wrap around */
timerlo = count;
/*
* Call the generic timer interrupt handler
*/
write_seqlock(&xtime_lock);
do_timer(1);
write_sequnlock(&xtime_lock);
/*
* In UP mode, we call local_timer_interrupt() to do profiling
* and process accounting.
*
* SMP is not supported yet.
*/
local_timer_interrupt(irq, dev_id, regs);
return IRQ_HANDLED;
}
static struct irqaction timer_irqaction = {
.handler = timer_interrupt,
.flags = IRQF_DISABLED,
.name = "timer",
};
void __init time_init(void)
{
unsigned long mult, shift, count_hz;
int ret;
xtime.tv_sec = rtc_get_time();
xtime.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
printk("Before time_init: count=%08lx, compare=%08lx\n",
(unsigned long)sysreg_read(COUNT),
(unsigned long)sysreg_read(COMPARE));
count_hz = clk_get_rate(boot_cpu_data.clk);
shift = clocksource_avr32.shift;
mult = clocksource_hz2mult(count_hz, shift);
clocksource_avr32.mult = mult;
printk("Cycle counter: mult=%lu, shift=%lu\n", mult, shift);
{
u64 tmp;
tmp = TICK_NSEC;
tmp <<= shift;
tmp += mult / 2;
do_div(tmp, mult);
cycles_per_jiffy = tmp;
}
/* This sets up the high precision timer for the first interrupt. */
avr32_hpt_init(avr32_hpt_read());
printk("After time_init: count=%08lx, compare=%08lx\n",
(unsigned long)sysreg_read(COUNT),
(unsigned long)sysreg_read(COMPARE));
ret = clocksource_register(&clocksource_avr32);
if (ret)
printk(KERN_ERR
"timer: could not register clocksource: %d\n", ret);
ret = setup_irq(0, &timer_irqaction);
if (ret)
printk("timer: could not request IRQ 0: %d\n", ret);
}
static struct sysdev_class timer_class = {
set_kset_name("timer"),
};
static struct sys_device timer_device = {
.id = 0,
.cls = &timer_class,
};
static int __init init_timer_sysfs(void)
{
int err = sysdev_class_register(&timer_class);
if (!err)
err = sysdev_register(&timer_device);
return err;
}
device_initcall(init_timer_sysfs);
|
