diff options
| author | Stephen Boyd <sboyd@codeaurora.org> | 2010-12-20 14:20:31 -0800 |
|---|---|---|
| committer | Philippe Langlais <philippe.langlais@stericsson.com> | 2012-05-22 10:59:42 +0200 |
| commit | 958c216e22e59927b49edc01bbc513b21db7611d (patch) | |
| tree | 130c9832545ab22098be0ed86e5a7cd4d56abe14 /arch/arm/lib | |
| parent | 7ad8c791b913fa602dcfeb597d566daa71dff7f9 (diff) | |
ARM: Allow machines to override __delay()
Some machines want to implement their own __delay() routine based
on fixed rate timers. Expose functionality to set the __delay()
routine at runtime. This should allow two machines with different
__delay() routines to happily co-exist within the same kernel
with minimal overhead.
Russell expressed concern that using a timer based __delay()
would cause problems when an iomapped device isn't mapped in
prior to a delay call being made (see
http://article.gmane.org/gmane.linux.ports.arm.kernel/78543 for
more info). We can sidestep that issue with this approach since
the __delay() routine _should_ only be pointed to a timer based
delay once the timer has been properly mapped. Up until that
point __delay() and udelay() will use delay_loop() which is
always safe to call.
This patch is inspired by x86's delay.c
Reviewed-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Change-Id: I269f101b40ba50c2b635dc92d50f6e82bb934b32
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/13563
Tested-by: Mattias WALLIN <mattias.wallin@stericsson.com>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>
Diffstat (limited to 'arch/arm/lib')
| -rw-r--r-- | arch/arm/lib/delay.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c index f92aca011ba..7468bc64b35 100644 --- a/arch/arm/lib/delay.c +++ b/arch/arm/lib/delay.c @@ -11,11 +11,9 @@ #include <linux/delay.h> /* - * loops = usecs * HZ * loops_per_jiffy / 1000000 - * * Oh, if only we had a cycle counter... */ -void __delay(unsigned long loops) +static void delay_loop(unsigned long loops) { asm volatile( "1: subs %0, %0, #1 \n" @@ -24,6 +22,16 @@ void __delay(unsigned long loops) : "r" (loops) ); } + +void (*delay_fn)(unsigned long) = delay_loop; + +/* + * loops = usecs * HZ * loops_per_jiffy / 1000000 + */ +void __delay(unsigned long loops) +{ + delay_fn(loops); +} EXPORT_SYMBOL(__delay); /* |