From 23af368e9a904f59256c27d371ce223d6cee0430 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 11 Nov 2009 14:05:25 +0000
Subject: clockevents: Use u32 for mult and shift factors
The mult and shift factors of clock events differ in their data type
from those of clock sources for no reason. u32 is sufficient for
both. shift is always <= 32 and mult is limited to 2^32-1 to avoid
64bit multiplication overflows in the conversion.
Preparatory patch for a generic mult/shift factor calculation
function.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Mikael Pettersson <mikpe@it.uu.se>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Cc: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <20091111134229.725664788@linutronix.de>
---
include/linux/clockchips.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
(limited to 'include/linux/clockchips.h')
diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index 3a1dbba..3b58410 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -79,8 +79,8 @@ struct clock_event_device {
unsigned int features;
unsigned long max_delta_ns;
unsigned long min_delta_ns;
- unsigned long mult;
- int shift;
+ u32 mult;
+ u32 shift;
int rating;
int irq;
const struct cpumask *cpumask;
--
cgit v1.1
From 7d2f944a2b836c69a9d260a0a5f0d1720d57fdff Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 11 Nov 2009 14:05:29 +0000
Subject: clocksource: Provide a generic mult/shift factor calculation
MIPS has two functions to calculcate the mult/shift factors for clock
sources and clock events at run time. ARM needs such functions as
well.
Implement a function which calculates the mult/shift factors based on
the frequencies to which and from which is converted. The function
also has a parameter to specify the minimum conversion range in
seconds. This range is guaranteed not to produce a 64bit overflow when
a value is multiplied with the calculated mult factor. The larger the
conversion range the less becomes the conversion accuracy.
Provide two inline wrappers which handle clock events and clock
sources. For clock events the "from" frequency is nano seconds per
second which corresponds to 1GHz and "to" is the device frequency. For
clock sources "from" is the device frequency and "to" is nano seconds
per second.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Mikael Pettersson <mikpe@it.uu.se>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Cc: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <20091111134229.766673305@linutronix.de>
---
include/linux/clockchips.h | 7 +++++++
1 file changed, 7 insertions(+)
(limited to 'include/linux/clockchips.h')
diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index 3b58410..4d438b0 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -130,6 +130,13 @@ extern int clockevents_program_event(struct clock_event_device *dev,
extern void clockevents_handle_noop(struct clock_event_device *dev);
+static inline void
+clockevents_calc_mult_shift(struct clock_event_device *ce, u32 freq, u32 minsec)
+{
+ return clocks_calc_mult_shift(&ce->mult, &ce->shift, NSEC_PER_SEC,
+ freq, minsec);
+}
+
#ifdef CONFIG_GENERIC_CLOCKEVENTS
extern void clockevents_notify(unsigned long reason, void *arg);
#else
--
cgit v1.1
From 97813f2fe77804a4464564c75ba8d8826377feea Mon Sep 17 00:00:00 2001
From: Jon Hunter <jon-hunter@ti.com>
Date: Tue, 18 Aug 2009 12:45:11 -0500
Subject: nohz: Allow 32-bit machines to sleep for more than 2.15 seconds
In the dynamic tick code, "max_delta_ns" (member of the
"clock_event_device" structure) represents the maximum sleep time
that can occur between timer events in nanoseconds.
The variable, "max_delta_ns", is defined as an unsigned long
which is a 32-bit integer for 32-bit machines and a 64-bit
integer for 64-bit machines (if -m64 option is used for gcc).
The value of max_delta_ns is set by calling the function
"clockevent_delta2ns()" which returns a maximum value of LONG_MAX.
For a 32-bit machine LONG_MAX is equal to 0x7fffffff and in
nanoseconds this equates to ~2.15 seconds. Hence, the maximum
sleep time for a 32-bit machine is ~2.15 seconds, where as for
a 64-bit machine it will be many years.
This patch changes the type of max_delta_ns to be "u64" instead of
"unsigned long" so that this variable is a 64-bit type for both 32-bit
and 64-bit machines. It also changes the maximum value returned by
clockevent_delta2ns() to KTIME_MAX. Hence this allows a 32-bit
machine to sleep for longer than ~2.15 seconds. Please note that this
patch also changes "min_delta_ns" to be "u64" too and although this is
unnecessary, it makes the patch simpler as it avoids to fixup all
callers of clockevent_delta2ns().
[ tglx: changed "unsigned long long" to u64 as we use this data type
through out the time code ]
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Cc: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1250617512-23567-3-git-send-email-jon-hunter@ti.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/clockchips.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
(limited to 'include/linux/clockchips.h')
diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index 4d438b0..0cf725b 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -77,8 +77,8 @@ enum clock_event_nofitiers {
struct clock_event_device {
const char *name;
unsigned int features;
- unsigned long max_delta_ns;
- unsigned long min_delta_ns;
+ u64 max_delta_ns;
+ u64 min_delta_ns;
u32 mult;
u32 shift;
int rating;
@@ -116,8 +116,8 @@ static inline unsigned long div_sc(unsigned long ticks, unsigned long nsec,
}
/* Clock event layer functions */
-extern unsigned long clockevent_delta2ns(unsigned long latch,
- struct clock_event_device *evt);
+extern u64 clockevent_delta2ns(unsigned long latch,
+ struct clock_event_device *evt);
extern void clockevents_register_device(struct clock_event_device *dev);
extern void clockevents_exchange_device(struct clock_event_device *old,
--
cgit v1.1