The patch titled
clocksource: shift helper
has been added to the -mm tree. Its filename is
clocksource-shift-helper.patch
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------------------------------------------------------
Subject: clocksource: shift helper
From: Daniel Walker <dwalker@xxxxxxxxxx>
This is a little helper I pulled from the mips tree. I've seen a couple of
bogus shift values, and this helper calculates the shift. This should move
the shift selection away from the user, and systematically pick the value base
on the hz.
I also modified the acpi_pm timer to use this new interface. The original
shift was 22 , and after this patch it's increased to 23. Which should make
the clocksource slightly more accurate, but shouldn't have much of a visible
effect.
Signed-off-by: Daniel Walker <dwalker@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: john stultz <johnstul@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/clocksource/acpi_pm.c | 5 ++++-
include/linux/acpi_pmtmr.h | 5 +++--
include/linux/clocksource.h | 21 +++++++++++++++++++++
3 files changed, 28 insertions(+), 3 deletions(-)
diff -puN drivers/clocksource/acpi_pm.c~clocksource-shift-helper drivers/clocksource/acpi_pm.c
--- a/drivers/clocksource/acpi_pm.c~clocksource-shift-helper
+++ a/drivers/clocksource/acpi_pm.c
@@ -72,7 +72,7 @@ static struct clocksource clocksource_ac
.read = acpi_pm_read,
.mask = (cycle_t)ACPI_PM_MASK,
.mult = 0, /*to be calculated*/
- .shift = 22,
+ .shift = 0,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
@@ -183,6 +183,9 @@ static int __init init_acpi_pm_clocksour
if (!pmtmr_ioport)
return -ENODEV;
+ clocksource_acpi_pm.shift =
+ clocksource_hz2shift(ACPI_PM_BITS, PMTMR_TICKS_PER_SEC);
+
clocksource_acpi_pm.mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC,
clocksource_acpi_pm.shift);
diff -puN include/linux/acpi_pmtmr.h~clocksource-shift-helper include/linux/acpi_pmtmr.h
--- a/include/linux/acpi_pmtmr.h~clocksource-shift-helper
+++ a/include/linux/acpi_pmtmr.h
@@ -7,10 +7,11 @@
#define PMTMR_TICKS_PER_SEC 3579545
/* limit it to 24 bits */
-#define ACPI_PM_MASK CLOCKSOURCE_MASK(24)
+#define ACPI_PM_BITS 24
+#define ACPI_PM_MASK CLOCKSOURCE_MASK(ACPI_PM_BITS)
/* Overrun value */
-#define ACPI_PM_OVRRUN (1<<24)
+#define ACPI_PM_OVRRUN (1 << ACPI_PM_BITS)
#ifdef CONFIG_X86_PM_TIMER
diff -puN include/linux/clocksource.h~clocksource-shift-helper include/linux/clocksource.h
--- a/include/linux/clocksource.h~clocksource-shift-helper
+++ a/include/linux/clocksource.h
@@ -159,6 +159,27 @@ static inline u32 clocksource_hz2mult(u3
}
/**
+ * clocksource_hz2shift - calculates shift from hz and # of bits
+ * @bits: Number of bits this clocksource uses
+ * @hz: Clocksource frequency in Hz
+ *
+ * Helper functions that calculates the best shift value
+ * based on the hz and # of bits of any given clock.
+ */
+static inline u32 clocksource_hz2shift(u32 bits, u32 hz)
+{
+ u64 temp;
+
+ for (; bits > 0; bits--) {
+ temp = (u64) NSEC_PER_SEC << bits;
+ do_div(temp, hz);
+ if ((temp >> 32) == 0)
+ break;
+ }
+ return bits;
+}
+
+/**
* clocksource_read: - Access the clocksource's current cycle value
* @cs: pointer to clocksource being read
*
_
Patches currently in -mm which might be from dwalker@xxxxxxxxxx are
origin.patch
git-x86.patch
macintosh-therm_pm72-driver_lock-semaphore-to-mutex.patch
macintosh-qindfarm_smu_sat-semaphore-to-mutex.patch
machintosh-adb-driver-adb_handler_sem-semaphore-to-mutex.patch
clocksource-shift-helper.patch
profile-likely-unlikely-macros.patch
likely_prof-changed-to-use-proc_create.patch
likeliness-accounting-change-and-cleanup.patch
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