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
|
/*
* Copyright 2001 MontaVista Software Inc.
* Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
* Copyright (c) 2003, 2004 Maciej W. Rozycki
*
* Common time service routines for MIPS machines.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
#include <linux/bug.h>
#include <linux/clockchips.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/param.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <asm/cpu-features.h>
#include <asm/div64.h>
#include <asm/smtc_ipi.h>
#include <asm/time.h>
/*
* forward reference
*/
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);
int __weak rtc_mips_set_time(unsigned long sec)
{
return 0;
}
EXPORT_SYMBOL(rtc_mips_set_time);
int __weak rtc_mips_set_mmss(unsigned long nowtime)
{
return rtc_mips_set_time(nowtime);
}
int update_persistent_clock(struct timespec now)
{
return rtc_mips_set_mmss(now.tv_sec);
}
/*
* High precision timer functions for a R4k-compatible timer.
*/
static cycle_t c0_hpt_read(void)
{
return read_c0_count();
}
int (*mips_timer_state)(void);
int null_perf_irq(void)
{
return 0;
}
EXPORT_SYMBOL(null_perf_irq);
int (*perf_irq)(void) = null_perf_irq;
EXPORT_SYMBOL(perf_irq);
/*
* time_init() - it does the following things.
*
* 1) plat_time_init() -
* a) (optional) set up RTC routines,
* b) (optional) calibrate and set the mips_hpt_frequency
* (only needed if you intended to use cpu counter as timer interrupt
* source)
* 2) calculate a couple of cached variables for later usage
*/
unsigned int mips_hpt_frequency;
static struct clocksource clocksource_mips = {
.name = "MIPS",
.read = c0_hpt_read,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static unsigned int __init calibrate_hpt(void)
{
cycle_t frequency, hpt_start, hpt_end, hpt_count, hz;
const int loops = HZ / 10;
int log_2_loops = 0;
int i;
/*
* We want to calibrate for 0.1s, but to avoid a 64-bit
* division we round the number of loops up to the nearest
* power of 2.
*/
while (loops > 1 << log_2_loops)
log_2_loops++;
i = 1 << log_2_loops;
/*
* Wait for a rising edge of the timer interrupt.
*/
while (mips_timer_state());
while (!mips_timer_state());
/*
* Now see how many high precision timer ticks happen
* during the calculated number of periods between timer
* interrupts.
*/
hpt_start = clocksource_mips.read();
do {
while (mips_timer_state());
while (!mips_timer_state());
} while (--i);
hpt_end = clocksource_mips.read();
hpt_count = (hpt_end - hpt_start) & clocksource_mips.mask;
hz = HZ;
frequency = hpt_count * hz;
return frequency >> log_2_loops;
}
void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
{
u64 temp;
u32 shift;
/* Find a shift value */
for (shift = 32; shift > 0; shift--) {
temp = (u64) NSEC_PER_SEC << shift;
do_div(temp, clock);
if ((temp >> 32) == 0)
break;
}
cs->shift = shift;
cs->mult = (u32) temp;
}
void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
unsigned int clock)
{
u64 temp;
u32 shift;
/* Find a shift value */
for (shift = 32; shift > 0; shift--) {
temp = (u64) clock << shift;
do_div(temp, NSEC_PER_SEC);
if ((temp >> 32) == 0)
break;
}
cd->shift = shift;
cd->mult = (u32) temp;
}
static void __init init_mips_clocksource(void)
{
/* Calclate a somewhat reasonable rating value */
clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
clocksource_register(&clocksource_mips);
}
void __init __weak plat_time_init(void)
{
}
/*
* This function exists in order to cause an error due to a duplicate
* definition if platform code should have its own implementation. The hook
* to use instead is plat_time_init. plat_time_init does not receive the
* irqaction pointer argument anymore. This is because any function which
* initializes an interrupt timer now takes care of its own request_irq rsp.
* setup_irq calls and each clock_event_device should use its own
* struct irqrequest.
*/
void __init plat_timer_setup(void)
{
BUG();
}
void __init time_init(void)
{
plat_time_init();
if (cpu_has_counter && (mips_hpt_frequency || mips_timer_state)) {
/* We know counter frequency. Or we can get it. */
if (!mips_hpt_frequency)
mips_hpt_frequency = calibrate_hpt();
/* Report the high precision timer rate for a reference. */
printk("Using %u.%03u MHz high precision timer.\n",
((mips_hpt_frequency + 500) / 1000) / 1000,
((mips_hpt_frequency + 500) / 1000) % 1000);
init_mips_clocksource();
}
mips_clockevent_init();
}
|
