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Date: Fri, 1 Jul 2011 08:40:00 GMT
From: tip-bot for Thomas Gleixner <tglx@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, john.stultz@...aro.org,
hpa@...or.com, mingo@...hat.com, ralf@...ux-mips.org,
linux@....linux.org.uk, tglx@...utronix.de
Subject: [tip:timers/cleanup] i8253: Create common clockevent implementation
Commit-ID: e6220bdc9485c5ea972f9e0e6d062a05934bb74b
Gitweb: http://git.kernel.org/tip/e6220bdc9485c5ea972f9e0e6d062a05934bb74b
Author: Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Thu, 9 Jun 2011 13:08:25 +0000
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 1 Jul 2011 10:37:14 +0200
i8253: Create common clockevent implementation
arm, mips and x86 implement i8253 based clockevents. All the same code
copied. Create a common implementation in drivers/clocksource/i8253.c.
About time to rename drivers/clocksource/ to something else.
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Russell King <linux@....linux.org.uk>
Cc: Ralf Baechle <ralf@...ux-mips.org>
Cc: John Stultz <john.stultz@...aro.org>
Link: http://lkml.kernel.org/r/20110609130621.921710458@linutronix.de
---
drivers/clocksource/Kconfig | 5 ++-
drivers/clocksource/i8253.c | 101 ++++++++++++++++++++++++++++++++++++++++---
include/linux/i8253.h | 2 +
3 files changed, 100 insertions(+), 8 deletions(-)
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 330343b..d8d3e02 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -1,11 +1,14 @@
config CLKSRC_I8253
bool
+config CLKEVT_I8253
+ bool
+
config I8253_LOCK
bool
config CLKBLD_I8253
- def_bool y if CLKSRC_I8253 || I8253_LOCK
+ def_bool y if CLKSRC_I8253 || CLKEVT_I8253 || I8253_LOCK
config CLKSRC_MMIO
bool
diff --git a/drivers/clocksource/i8253.c b/drivers/clocksource/i8253.c
index e594f52..27c49e6 100644
--- a/drivers/clocksource/i8253.c
+++ b/drivers/clocksource/i8253.c
@@ -1,13 +1,14 @@
/*
* i8253 PIT clocksource
*/
-#include <linux/clocksource.h>
+#include <linux/clockchips.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <linux/timex.h>
#include <linux/module.h>
#include <linux/i8253.h>
+#include <linux/smp.h>
/*
* Protects access to I/O ports
@@ -47,15 +48,15 @@ static cycle_t i8253_read(struct clocksource *cs)
* count), it cannot be newer.
*/
jifs = jiffies;
- outb_pit(0x00, PIT_MODE); /* latch the count ASAP */
- count = inb_pit(PIT_CH0); /* read the latched count */
- count |= inb_pit(PIT_CH0) << 8;
+ outb_p(0x00, PIT_MODE); /* latch the count ASAP */
+ count = inb_p(PIT_CH0); /* read the latched count */
+ count |= inb_p(PIT_CH0) << 8;
/* VIA686a test code... reset the latch if count > max + 1 */
if (count > LATCH) {
- outb_pit(0x34, PIT_MODE);
- outb_pit(PIT_LATCH & 0xff, PIT_CH0);
- outb_pit(PIT_LATCH >> 8, PIT_CH0);
+ outb_p(0x34, PIT_MODE);
+ outb_p(PIT_LATCH & 0xff, PIT_CH0);
+ outb_p(PIT_LATCH >> 8, PIT_CH0);
count = PIT_LATCH - 1;
}
@@ -97,3 +98,89 @@ int __init clocksource_i8253_init(void)
return clocksource_register_hz(&i8253_cs, PIT_TICK_RATE);
}
#endif
+
+#ifdef CONFIG_CLKEVT_I8253
+/*
+ * Initialize the PIT timer.
+ *
+ * This is also called after resume to bring the PIT into operation again.
+ */
+static void init_pit_timer(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ raw_spin_lock(&i8253_lock);
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ /* binary, mode 2, LSB/MSB, ch 0 */
+ outb_p(0x34, PIT_MODE);
+ outb_p(LATCH & 0xff , PIT_CH0); /* LSB */
+ outb_p(LATCH >> 8 , PIT_CH0); /* MSB */
+ break;
+
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ case CLOCK_EVT_MODE_UNUSED:
+ if (evt->mode == CLOCK_EVT_MODE_PERIODIC ||
+ evt->mode == CLOCK_EVT_MODE_ONESHOT) {
+ outb_p(0x30, PIT_MODE);
+ outb_p(0, PIT_CH0);
+ outb_p(0, PIT_CH0);
+ }
+ break;
+
+ case CLOCK_EVT_MODE_ONESHOT:
+ /* One shot setup */
+ outb_p(0x38, PIT_MODE);
+ break;
+
+ case CLOCK_EVT_MODE_RESUME:
+ /* Nothing to do here */
+ break;
+ }
+ raw_spin_unlock(&i8253_lock);
+}
+
+/*
+ * Program the next event in oneshot mode
+ *
+ * Delta is given in PIT ticks
+ */
+static int pit_next_event(unsigned long delta, struct clock_event_device *evt)
+{
+ raw_spin_lock(&i8253_lock);
+ outb_p(delta & 0xff , PIT_CH0); /* LSB */
+ outb_p(delta >> 8 , PIT_CH0); /* MSB */
+ raw_spin_unlock(&i8253_lock);
+
+ return 0;
+}
+
+/*
+ * On UP the PIT can serve all of the possible timer functions. On SMP systems
+ * it can be solely used for the global tick.
+ */
+struct clock_event_device i8253_clockevent = {
+ .name = "pit",
+ .features = CLOCK_EVT_FEAT_PERIODIC,
+ .set_mode = init_pit_timer,
+ .set_next_event = pit_next_event,
+};
+
+/*
+ * Initialize the conversion factor and the min/max deltas of the clock event
+ * structure and register the clock event source with the framework.
+ */
+void __init clockevent_i8253_init(bool oneshot)
+{
+ if (oneshot)
+ i8253_clockevent.features |= CLOCK_EVT_FEAT_ONESHOT;
+ /*
+ * Start pit with the boot cpu mask. x86 might make it global
+ * when it is used as broadcast device later.
+ */
+ i8253_clockevent.cpumask = cpumask_of(smp_processor_id());
+
+ clockevents_config_and_register(&i8253_clockevent, PIT_TICK_RATE,
+ 0xF, 0x7FFF);
+}
+#endif
diff --git a/include/linux/i8253.h b/include/linux/i8253.h
index 76039c8..487d50c 100644
--- a/include/linux/i8253.h
+++ b/include/linux/i8253.h
@@ -24,6 +24,8 @@
#define outb_pit outb_p
extern raw_spinlock_t i8253_lock;
+extern struct clock_event_device i8253_clockevent;
+extern void clockevent_i8253_init(bool oneshot);
extern void setup_pit_timer(void);
--
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