This patch converts alpha to use GENERIC_TIME via the arch_getoffset()
infrastructure, reducing the amount of arch specific code we need to
maintain.
I suspect the alpha arch could even be further improved to provide and
rpcc() based clocksource, but not having the hardware, I don't feel
comfortable attempting the more complicated conversion (but I'd be glad
to help if anyone else is interested).
This patch applies on top of Linus' current -git tree (2.6.31-rc3).
I've taken my best swing at converting this, but I'm not 100% confident
I got it right. My cross-compiler is now too old, so I couldn't check if
it builds. So any assistance from arch maintainers or testers to get
this merged would be great.
thanks
-john
Signed-off-by: John Stultz <[email protected]>
---
Kconfig | 8 ++++++
kernel/time.c | 72 +++-------------------------------------------------------
2 files changed, 12 insertions(+), 68 deletions(-)
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 9fb8aae..4434481 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -45,6 +45,14 @@ config GENERIC_CALIBRATE_DELAY
bool
default y
+config GENERIC_TIME
+ bool
+ default y
+
+config ARCH_USES_GETTIMEOFFSET
+ bool
+ default y
+
config ZONE_DMA
bool
default y
diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c
index b04e2cb..8f7eb6d 100644
--- a/arch/alpha/kernel/time.c
+++ b/arch/alpha/kernel/time.c
@@ -408,28 +408,17 @@ time_init(void)
* part. So we can't do the "find absolute time in terms of cycles" thing
* that the other ports do.
*/
-void
-do_gettimeofday(struct timeval *tv)
+u32 arch_gettimeoffset(void)
{
- unsigned long flags;
- unsigned long sec, usec, seq;
unsigned long delta_cycles, delta_usec, partial_tick;
- do {
- seq = read_seqbegin_irqsave(&xtime_lock, flags);
-
- delta_cycles = rpcc() - state.last_time;
- sec = xtime.tv_sec;
- usec = (xtime.tv_nsec / 1000);
- partial_tick = state.partial_tick;
-
- } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
-
#ifdef CONFIG_SMP
/* Until and unless we figure out how to get cpu cycle counters
in sync and keep them there, we can't use the rpcc tricks. */
delta_usec = 0;
#else
+ delta_cycles = rpcc() - state.last_time;
+ partial_tick = state.partial_tick;
/*
* usec = cycles * ticks_per_cycle * 2**48 * 1e6 / (2**48 * ticks)
* = cycles * (s_t_p_c) * 1e6 / (2**48 * ticks)
@@ -448,62 +437,9 @@ do_gettimeofday(struct timeval *tv)
delta_usec = ((delta_usec / ((1UL << (FIX_SHIFT-6-1)) * HZ)) + 1) / 2;
#endif
- usec += delta_usec;
- if (usec >= 1000000) {
- sec += 1;
- usec -= 1000000;
- }
-
- tv->tv_sec = sec;
- tv->tv_usec = usec;
-}
-
-EXPORT_SYMBOL(do_gettimeofday);
-
-int
-do_settimeofday(struct timespec *tv)
-{
- time_t wtm_sec, sec = tv->tv_sec;
- long wtm_nsec, nsec = tv->tv_nsec;
- unsigned long delta_nsec;
-
- if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
- return -EINVAL;
-
- write_seqlock_irq(&xtime_lock);
-
- /* The offset that is added into time in do_gettimeofday above
- must be subtracted out here to keep a coherent view of the
- time. Without this, a full-tick error is possible. */
-
-#ifdef CONFIG_SMP
- delta_nsec = 0;
-#else
- delta_nsec = rpcc() - state.last_time;
- delta_nsec = (delta_nsec * state.scaled_ticks_per_cycle
- + state.partial_tick) * 15625;
- delta_nsec = ((delta_nsec / ((1UL << (FIX_SHIFT-6-1)) * HZ)) + 1) / 2;
- delta_nsec *= 1000;
-#endif
-
- nsec -= delta_nsec;
-
- wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
- wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
-
- set_normalized_timespec(&xtime, sec, nsec);
- set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
-
- ntp_clear();
-
- write_sequnlock_irq(&xtime_lock);
- clock_was_set();
- return 0;
+ return delta_usec * 1000;
}
-EXPORT_SYMBOL(do_settimeofday);
-
-
/*
* In order to set the CMOS clock precisely, set_rtc_mmss has to be
* called 500 ms after the second nowtime has started, because when
On Thu, 16 Jul 2009 17:14:07 -0700
john stultz <[email protected]> wrote:
> This patch converts alpha to use GENERIC_TIME via the arch_getoffset()
> infrastructure, reducing the amount of arch specific code we need to
> maintain.
>
> I suspect the alpha arch could even be further improved to provide and
> rpcc() based clocksource, but not having the hardware, I don't feel
> comfortable attempting the more complicated conversion (but I'd be glad
> to help if anyone else is interested).
>
> This patch applies on top of Linus' current -git tree (2.6.31-rc3).
>
> I've taken my best swing at converting this, but I'm not 100% confident
> I got it right. My cross-compiler is now too old, so I couldn't check if
> it builds. So any assistance from arch maintainers or testers to get
> this merged would be great.
>
It breaks the build:
cc1: warnings being treated as errors
arch/alpha/kernel/time.c: In function 'arch_gettimeoffset':
arch/alpha/kernel/time.c:413: warning: unused variable 'partial_tick'
arch/alpha/kernel/time.c:413: warning: unused variable 'delta_cycles'
make[1]: *** [arch/alpha/kernel/time.o] Error 1
u32 arch_gettimeoffset(void)
{
unsigned long delta_cycles, delta_usec, partial_tick;
#ifdef CONFIG_SMP
/* Until and unless we figure out how to get cpu cycle counters
in sync and keep them there, we can't use the rpcc tricks. */
delta_usec = 0;
#else
delta_cycles = rpcc() - state.last_time;
partial_tick = state.partial_tick;
/*
* usec = cycles * ticks_per_cycle * 2**48 * 1e6 / (2**48 * ticks)
* = cycles * (s_t_p_c) * 1e6 / (2**48 * ticks)
* = cycles * (s_t_p_c) * 15625 / (2**42 * ticks)
*
* which, given a 600MHz cycle and a 1024Hz tick, has a
* dynamic range of about 1.7e17, which is less than the
* 1.8e19 in an unsigned long, so we are safe from overflow.
*
* Round, but with .5 up always, since .5 to even is harder
* with no clear gain.
*/
delta_usec = (delta_cycles * state.scaled_ticks_per_cycle
+ partial_tick) * 15625;
delta_usec = ((delta_usec / ((1UL << (FIX_SHIFT-6-1)) * HZ)) + 1) / 2;
#endif
return delta_usec * 1000;
}
I converted the CONFIG_SMP=y case into a plain old `return 0;'. Which
means that we could turn the CONFIG_SMP=y case into a static inline,
really.
From: Andrew Morton <[email protected]>
cc1: warnings being treated as errors
arch/alpha/kernel/time.c: In function 'arch_gettimeoffset':
arch/alpha/kernel/time.c:413: warning: unused variable 'partial_tick'
arch/alpha/kernel/time.c:413: warning: unused variable 'delta_cycles'
make[1]: *** [arch/alpha/kernel/time.o] Error 1
Cc: Ivan Kokshaysky <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: john stultz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
arch/alpha/kernel/time.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
--- a/arch/alpha/kernel/time.c~alpha-convert-to-use-arch_gettimeoffset-fix
+++ a/arch/alpha/kernel/time.c
@@ -410,13 +410,13 @@ time_init(void)
*/
u32 arch_gettimeoffset(void)
{
- unsigned long delta_cycles, delta_usec, partial_tick;
-
#ifdef CONFIG_SMP
/* Until and unless we figure out how to get cpu cycle counters
in sync and keep them there, we can't use the rpcc tricks. */
- delta_usec = 0;
+ return 0;
#else
+ unsigned long delta_cycles, delta_usec, partial_tick;
+
delta_cycles = rpcc() - state.last_time;
partial_tick = state.partial_tick;
/*
@@ -435,9 +435,8 @@ u32 arch_gettimeoffset(void)
delta_usec = (delta_cycles * state.scaled_ticks_per_cycle
+ partial_tick) * 15625;
delta_usec = ((delta_usec / ((1UL << (FIX_SHIFT-6-1)) * HZ)) + 1) / 2;
-#endif
-
return delta_usec * 1000;
+#endif
}
/*
_