Skip to content

Commit 925f553

Browse files
baruchsiachczankel
baruchsiach
authored and
czankel
committed
xtensa: ccount based clockevent implementation
Reused some code from a preliminary implementation by Max Fillippov. Cc: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Baruch Siach <baruch@tkos.co.il> Signed-off-by: Chris Zankel <chris@zankel.net>
1 parent 8102f47 commit 925f553

File tree

2 files changed

+79
-32
lines changed

2 files changed

+79
-32
lines changed

‎arch/xtensa/Kconfig

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@ config XTENSA
66
select ARCH_WANT_FRAME_POINTERS
77
select HAVE_IDE
88
select GENERIC_ATOMIC64
9+
select GENERIC_CLOCKEVENTS
910
select HAVE_GENERIC_HARDIRQS
1011
select VIRT_TO_BUS
1112
select GENERIC_IRQ_SHOW

‎arch/xtensa/kernel/time.c

Lines changed: 78 additions & 32 deletions
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,7 @@
1616
#include <linux/sched.h>
1717
#include <linux/time.h>
1818
#include <linux/clocksource.h>
19+
#include <linux/clockchips.h>
1920
#include <linux/interrupt.h>
2021
#include <linux/module.h>
2122
#include <linux/init.h>
@@ -43,16 +44,80 @@ static struct clocksource ccount_clocksource = {
4344
.mask = CLOCKSOURCE_MASK(32),
4445
};
4546

47+
static int ccount_timer_set_next_event(unsigned long delta,
48+
struct clock_event_device *dev);
49+
static void ccount_timer_set_mode(enum clock_event_mode mode,
50+
struct clock_event_device *evt);
51+
static struct ccount_timer_t {
52+
struct clock_event_device evt;
53+
int irq_enabled;
54+
} ccount_timer = {
55+
.evt = {
56+
.name = "ccount_clockevent",
57+
.features = CLOCK_EVT_FEAT_ONESHOT,
58+
.rating = 300,
59+
.set_next_event = ccount_timer_set_next_event,
60+
.set_mode = ccount_timer_set_mode,
61+
},
62+
};
63+
64+
static int ccount_timer_set_next_event(unsigned long delta,
65+
struct clock_event_device *dev)
66+
{
67+
unsigned long flags, next;
68+
int ret = 0;
69+
70+
local_irq_save(flags);
71+
next = get_ccount() + delta;
72+
set_linux_timer(next);
73+
if (next - get_ccount() > delta)
74+
ret = -ETIME;
75+
local_irq_restore(flags);
76+
77+
return ret;
78+
}
79+
80+
static void ccount_timer_set_mode(enum clock_event_mode mode,
81+
struct clock_event_device *evt)
82+
{
83+
struct ccount_timer_t *timer =
84+
container_of(evt, struct ccount_timer_t, evt);
85+
86+
/*
87+
* There is no way to disable the timer interrupt at the device level,
88+
* only at the intenable register itself. Since enable_irq/disable_irq
89+
* calls are nested, we need to make sure that these calls are
90+
* balanced.
91+
*/
92+
switch (mode) {
93+
case CLOCK_EVT_MODE_SHUTDOWN:
94+
case CLOCK_EVT_MODE_UNUSED:
95+
if (timer->irq_enabled) {
96+
disable_irq(evt->irq);
97+
timer->irq_enabled = 0;
98+
}
99+
break;
100+
case CLOCK_EVT_MODE_RESUME:
101+
case CLOCK_EVT_MODE_ONESHOT:
102+
if (!timer->irq_enabled) {
103+
enable_irq(evt->irq);
104+
timer->irq_enabled = 1;
105+
}
106+
default:
107+
break;
108+
}
109+
}
110+
46111
static irqreturn_t timer_interrupt(int irq, void *dev_id);
47112
static struct irqaction timer_irqaction = {
48113
.handler = timer_interrupt,
49-
.flags = IRQF_DISABLED,
114+
.flags = IRQF_TIMER,
50115
.name = "timer",
116+
.dev_id = &ccount_timer,
51117
};
52118

53119
void __init time_init(void)
54120
{
55-
unsigned int irq;
56121
#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
57122
printk("Calibrating CPU frequency ");
58123
platform_calibrate_ccount();
@@ -61,11 +126,14 @@ void __init time_init(void)
61126
#endif
62127
clocksource_register_hz(&ccount_clocksource, CCOUNT_PER_JIFFY * HZ);
63128

64-
/* Initialize the linux timer interrupt. */
65-
66-
irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
67-
setup_irq(irq, &timer_irqaction);
68-
set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
129+
ccount_timer.evt.cpumask = cpumask_of(0);
130+
ccount_timer.evt.irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
131+
if (WARN(!ccount_timer.evt.irq, "error: can't map timer irq"))
132+
return;
133+
clockevents_config_and_register(&ccount_timer.evt, ccount_freq, 0xf,
134+
0xffffffff);
135+
setup_irq(ccount_timer.evt.irq, &timer_irqaction);
136+
ccount_timer.irq_enabled = 1;
69137
}
70138

71139
/*
@@ -74,36 +142,14 @@ void __init time_init(void)
74142

75143
irqreturn_t timer_interrupt (int irq, void *dev_id)
76144
{
145+
struct ccount_timer_t *timer = dev_id;
146+
struct clock_event_device *evt = &timer->evt;
77147

78-
unsigned long next;
79-
80-
next = get_linux_timer();
81-
82-
again:
83-
while ((signed long)(get_ccount() - next) > 0) {
84-
85-
profile_tick(CPU_PROFILING);
86-
#ifndef CONFIG_SMP
87-
update_process_times(user_mode(get_irq_regs()));
88-
#endif
89-
90-
xtime_update(1); /* Linux handler in kernel/time/timekeeping */
91-
92-
/* Note that writing CCOMPARE clears the interrupt. */
93-
94-
next += CCOUNT_PER_JIFFY;
95-
set_linux_timer(next);
96-
}
148+
evt->event_handler(evt);
97149

98150
/* Allow platform to do something useful (Wdog). */
99-
100151
platform_heartbeat();
101152

102-
/* Make sure we didn't miss any tick... */
103-
104-
if ((signed long)(get_ccount() - next) > 0)
105-
goto again;
106-
107153
return IRQ_HANDLED;
108154
}
109155

0 commit comments

Comments
 (0)