From 4e653e04cc1c3553af539ffc81fb56d83d83c733 Mon Sep 17 00:00:00 2001 From: Michael Hennerich Date: Wed, 4 Feb 2009 16:49:45 +0800 Subject: Blackfin arch: Fix udelay implementation Avoid possible overflow during 32*32->32 multiplies. Reported-by: Marco Reppenhagen Signed-off-by: Michael Hennerich Signed-off-by: Bryan Wu --- arch/blackfin/include/asm/delay.h | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'arch/blackfin/include/asm/delay.h') diff --git a/arch/blackfin/include/asm/delay.h b/arch/blackfin/include/asm/delay.h index 0889c3abb59..47f98c5067b 100644 --- a/arch/blackfin/include/asm/delay.h +++ b/arch/blackfin/include/asm/delay.h @@ -47,16 +47,15 @@ static inline void __delay(unsigned long loops) #include /* needed for HZ */ /* - * Use only for very small delays ( < 1 msec). Should probably use a - * lookup table, really, as the multiplications take much too long with - * short delays. This is a "reasonable" implementation, though (and the - * first constant multiplications gets optimized away if the delay is - * a constant) + * close approximation borrowed from m68knommu to avoid 64-bit math */ + +#define HZSCALE (268435456 / (1000000/HZ)) + static inline void udelay(unsigned long usecs) { extern unsigned long loops_per_jiffy; - __delay(usecs * loops_per_jiffy / (1000000 / HZ)); + __delay((((usecs * HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6); } #endif -- cgit v1.2.3 From c8e674125e03c5f36ccfd61d83b933e6956074b0 Mon Sep 17 00:00:00 2001 From: Michael Hennerich Date: Wed, 4 Feb 2009 16:49:45 +0800 Subject: Blackfin arch: Remove outdated code The removed version with the loop registers saved on the stack was originally intended to workaround the missing toolchain support for LoopReg Clobbers. Since our toolchain now supports these there is no point in keeping this workaround. And since we don't touch LoopRegs anymore we're no longer subject for ANOMALY_05000312. Signed-off-by: Michael Hennerich Signed-off-by: Bryan Wu --- arch/blackfin/include/asm/delay.h | 24 +----------------------- 1 file changed, 1 insertion(+), 23 deletions(-) (limited to 'arch/blackfin/include/asm/delay.h') diff --git a/arch/blackfin/include/asm/delay.h b/arch/blackfin/include/asm/delay.h index 47f98c5067b..c31f91cc1d5 100644 --- a/arch/blackfin/include/asm/delay.h +++ b/arch/blackfin/include/asm/delay.h @@ -13,29 +13,7 @@ static inline void __delay(unsigned long loops) { - if (ANOMALY_05000312) { - /* Interrupted loads to loop registers -> bad */ - unsigned long tmp; - __asm__ __volatile__( - "[--SP] = LC0;" - "[--SP] = LT0;" - "[--SP] = LB0;" - "LSETUP (1f,1f) LC0 = %1;" - "1: NOP;" - /* We take advantage of the fact that LC0 is 0 at - * the end of the loop. Otherwise we'd need some - * NOPs after the CLI here. - */ - "CLI %0;" - "LB0 = [SP++];" - "LT0 = [SP++];" - "LC0 = [SP++];" - "STI %0;" - : "=d" (tmp) - : "a" (loops) - ); - } else - __asm__ __volatile__ ( +__asm__ __volatile__ ( "LSETUP(1f, 1f) LC0 = %0;" "1: NOP;" : -- cgit v1.2.3