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
|
/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2007 MIPS Technologies, Inc.
* Copyright (C) 2007 Ralf Baechle <ralf@linux-mips.org>
*/
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/irq.h>
#include <asm/smtc_ipi.h>
#include <asm/time.h>
#include <asm/cevt-r4k.h>
#include <asm/gic.h>
/*
* The SMTC Kernel for the 34K, 1004K, et. al. replaces several
* of these routines with SMTC-specific variants.
*/
#ifndef CONFIG_MIPS_MT_SMTC
static int mips_next_event(unsigned long delta,
struct clock_event_device *evt)
{
unsigned int cnt;
int res;
cnt = read_c0_count();
cnt += delta;
write_c0_compare(cnt);
res = ((int)(read_c0_count() - cnt) >= 0) ? -ETIME : 0;
return res;
}
#endif /* CONFIG_MIPS_MT_SMTC */
void mips_set_clock_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
/* Nothing to do ... */
}
DEFINE_PER_CPU(struct clock_event_device, mips_clockevent_device);
int cp0_timer_irq_installed;
#ifndef CONFIG_MIPS_MT_SMTC
irqreturn_t c0_compare_interrupt(int irq, void *dev_id)
{
const int r2 = cpu_has_mips_r2;
struct clock_event_device *cd;
int cpu = smp_processor_id();
/*
* Suckage alert:
* Before R2 of the architecture there was no way to see if a
* performance counter interrupt was pending, so we have to run
* the performance counter interrupt handler anyway.
*/
if (handle_perf_irq(r2))
goto out;
/*
* The same applies to performance counter interrupts. But with the
* above we now know that the reason we got here must be a timer
* interrupt. Being the paranoiacs we are we check anyway.
*/
if (!r2 || (read_c0_cause() & (1 << 30))) {
/* Clear Count/Compare Interrupt */
write_c0_compare(read_c0_compare());
cd = &per_cpu(mips_clockevent_device, cpu);
cd->event_handler(cd);
}
out:
return IRQ_HANDLED;
}
#endif /* Not CONFIG_MIPS_MT_SMTC */
struct irqaction c0_compare_irqaction = {
.handler = c0_compare_interrupt,
.flags = IRQF_PERCPU | IRQF_TIMER,
.name = "timer",
};
void mips_event_handler(struct clock_event_device *dev)
{
}
/*
* FIXME: This doesn't hold for the relocated E9000 compare interrupt.
*/
static int c0_compare_int_pending(void)
{
#ifdef CONFIG_IRQ_GIC
if (cpu_has_veic)
return gic_get_timer_pending();
#endif
return (read_c0_cause() >> cp0_compare_irq_shift) & (1ul << CAUSEB_IP);
}
/*
* Compare interrupt can be routed and latched outside the core,
* so wait up to worst case number of cycle counter ticks for timer interrupt
* changes to propagate to the cause register.
*/
#define COMPARE_INT_SEEN_TICKS 50
int c0_compare_int_usable(void)
{
unsigned int delta;
unsigned int cnt;
/*
* IP7 already pending? Try to clear it by acking the timer.
*/
if (c0_compare_int_pending()) {
cnt = read_c0_count();
write_c0_compare(cnt);
back_to_back_c0_hazard();
while (read_c0_count() < (cnt + COMPARE_INT_SEEN_TICKS))
if (!c0_compare_int_pending())
break;
if (c0_compare_int_pending())
return 0;
}
for (delta = 0x10; delta <= 0x400000; delta <<= 1) {
cnt = read_c0_count();
cnt += delta;
write_c0_compare(cnt);
back_to_back_c0_hazard();
if ((int)(read_c0_count() - cnt) < 0)
break;
/* increase delta if the timer was already expired */
}
while ((int)(read_c0_count() - cnt) <= 0)
; /* Wait for expiry */
while (read_c0_count() < (cnt + COMPARE_INT_SEEN_TICKS))
if (c0_compare_int_pending())
break;
if (!c0_compare_int_pending())
return 0;
cnt = read_c0_count();
write_c0_compare(cnt);
back_to_back_c0_hazard();
while (read_c0_count() < (cnt + COMPARE_INT_SEEN_TICKS))
if (!c0_compare_int_pending())
break;
if (c0_compare_int_pending())
return 0;
/*
* Feels like a real count / compare timer.
*/
return 1;
}
#ifndef CONFIG_MIPS_MT_SMTC
int __cpuinit r4k_clockevent_init(void)
{
unsigned int cpu = smp_processor_id();
struct clock_event_device *cd;
unsigned int irq;
if (!cpu_has_counter || !mips_hpt_frequency)
return -ENXIO;
if (!c0_compare_int_usable())
return -ENXIO;
/*
* With vectored interrupts things are getting platform specific.
* get_c0_compare_int is a hook to allow a platform to return the
* interrupt number of it's liking.
*/
irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
if (get_c0_compare_int)
irq = get_c0_compare_int();
cd = &per_cpu(mips_clockevent_device, cpu);
cd->name = "MIPS";
cd->features = CLOCK_EVT_FEAT_ONESHOT;
clockevent_set_clock(cd, mips_hpt_frequency);
/* Calculate the min / max delta */
cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
cd->min_delta_ns = clockevent_delta2ns(0x300, cd);
cd->rating = 300;
cd->irq = irq;
cd->cpumask = cpumask_of(cpu);
cd->set_next_event = mips_next_event;
cd->set_mode = mips_set_clock_mode;
cd->event_handler = mips_event_handler;
clockevents_register_device(cd);
if (cp0_timer_irq_installed)
return 0;
cp0_timer_irq_installed = 1;
setup_irq(irq, &c0_compare_irqaction);
return 0;
}
#endif /* Not CONFIG_MIPS_MT_SMTC */
|
