From 29441e94554d406b75e647b85a9753981167910f Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Fri, 27 Aug 2004 02:12:23 -0700 Subject: [PATCH] [SPARC64]: Fix delay with HZ==1000. When I moved sparc64 over to HZ==1000 this added some problems to the udelay() handling. Specifically, with slower cpus we could now get underflows to zero for things like udelay(1) due to the order of multiplies and shifts. Fix this, and move it out to arch/sparc64/lib/delay.c so it is easier to tinker with this in the future and also to optimize away one of the multiplies for the constant delay case just like other platforms do. Signed-off-by: David S. Miller --- arch/sparc64/kernel/sparc64_ksyms.c | 6 +++ arch/sparc64/lib/Makefile | 2 +- arch/sparc64/lib/delay.c | 49 ++++++++++++++++++++ include/asm-sparc64/delay.h | 69 +++++++++-------------------- 4 files changed, 78 insertions(+), 48 deletions(-) create mode 100644 arch/sparc64/lib/delay.c diff --git a/arch/sparc64/kernel/sparc64_ksyms.c b/arch/sparc64/kernel/sparc64_ksyms.c index 46df529607b3f..7bf82ab43c7d0 100644 --- a/arch/sparc64/kernel/sparc64_ksyms.c +++ b/arch/sparc64/kernel/sparc64_ksyms.c @@ -372,6 +372,12 @@ EXPORT_SYMBOL_NOVERS(memset); EXPORT_SYMBOL_NOVERS(memmove); EXPORT_SYMBOL_NOVERS(strncmp); +/* Delay routines. */ +EXPORT_SYMBOL(__udelay); +EXPORT_SYMBOL(__ndelay); +EXPORT_SYMBOL(__const_udelay); +EXPORT_SYMBOL(__delay); + void VISenter(void); /* RAID code needs this */ EXPORT_SYMBOL_NOVERS(VISenter); diff --git a/arch/sparc64/lib/Makefile b/arch/sparc64/lib/Makefile index 5f2270f343bd8..22c5b59fd8b97 100644 --- a/arch/sparc64/lib/Makefile +++ b/arch/sparc64/lib/Makefile @@ -12,7 +12,7 @@ lib-y := PeeCeeI.o copy_page.o clear_page.o strlen.o strncmp.o \ U1memcpy.o U1copy_from_user.o U1copy_to_user.o \ U3memcpy.o U3copy_from_user.o U3copy_to_user.o U3patch.o \ copy_in_user.o user_fixup.o memmove.o \ - mcount.o ipcsum.o rwsem.o xor.o splock.o find_bit.o + mcount.o ipcsum.o rwsem.o xor.o splock.o find_bit.o delay.o lib-$(CONFIG_DEBUG_SPINLOCK) += debuglocks.o lib-$(CONFIG_HAVE_DEC_LOCK) += dec_and_lock.o diff --git a/arch/sparc64/lib/delay.c b/arch/sparc64/lib/delay.c new file mode 100644 index 0000000000000..f55f528a7f6b6 --- /dev/null +++ b/arch/sparc64/lib/delay.c @@ -0,0 +1,49 @@ +/* delay.c: Delay loops for sparc64 + * + * Copyright (C) 2004 David S. Miller + * + * Based heavily upon x86 variant which is: + * Copyright (C) 1993 Linus Torvalds + * Copyright (C) 1997 Martin Mares + */ + +#include + +void __delay(unsigned long loops) +{ + __asm__ __volatile__( +" b,pt %%xcc, 1f\n" +" cmp %0, 0\n" +" .align 32\n" +"1:\n" +" bne,pt %%xcc, 1b\n" +" subcc %0, 1, %0\n" + : "=&r" (loops) + : "0" (loops) + : "cc"); +} + +/* We used to multiply by HZ after shifting down by 32 bits + * but that runs into problems for higher values of HZ and + * slow cpus. + */ +void __const_udelay(unsigned long n) +{ + n *= 4; + + n *= (cpu_data(smp_processor_id()).udelay_val * (HZ/4)); + n >>= 32; + + __delay(n + 1); +} + +void __udelay(unsigned long n) +{ + __const_udelay(n * 0x10c7UL); +} + + +void __ndelay(unsigned long n) +{ + __const_udelay(n * 0x5UL); +} diff --git a/include/asm-sparc64/delay.h b/include/asm-sparc64/delay.h index 13de4b10f7095..2901ea0c342d9 100644 --- a/include/asm-sparc64/delay.h +++ b/include/asm-sparc64/delay.h @@ -1,7 +1,11 @@ -/* $Id: delay.h,v 1.13 2002/02/02 03:33:48 kanoj Exp $ - * delay.h: Linux delay routines on the V9. +/* delay.h: Linux delay routines on sparc64. * - * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu). + * Copyright (C) 1996, 2004 David S. Miller (davem@davemloft.net). + * + * Based heavily upon x86 variant which is: + * Copyright (C) 1993 Linus Torvalds + * + * Delay routines calling functions in arch/sparc64/lib/delay.c */ #ifndef __SPARC64_DELAY_H @@ -13,50 +17,21 @@ #ifndef __ASSEMBLY__ -static __inline__ void __delay(unsigned long loops) -{ - __asm__ __volatile__( -" b,pt %%xcc, 1f\n" -" cmp %0, 0\n" -" .align 32\n" -"1:\n" -" bne,pt %%xcc, 1b\n" -" subcc %0, 1, %0\n" - : "=&r" (loops) - : "0" (loops) - : "cc"); -} - -static __inline__ void __udelay(unsigned long usecs, unsigned long lps) -{ - usecs *= 0x00000000000010c6UL; /* 2**32 / 1000000 */ - - __asm__ __volatile__( -" mulx %1, %2, %0\n" -" srlx %0, 32, %0\n" - : "=r" (usecs) - : "r" (usecs), "r" (lps)); - - __delay(usecs * HZ); -} - -extern __inline__ void __ndelay(unsigned long usecs, unsigned long lps) -{ - usecs *= 0x0000000000000005UL; /* 2**32 / 10000 */ - - __asm__ __volatile__( -" mulx %1, %2, %0\n" -" srlx %0, 32, %0\n" - : "=r" (usecs) - : "r" (usecs), "r" (lps)); - - __delay(usecs * HZ); -} - -#define __udelay_val cpu_data(smp_processor_id()).udelay_val - -#define udelay(usecs) __udelay((usecs),__udelay_val) -#define ndelay(usecs) __ndelay((usecs),__udelay_val) +extern void __bad_udelay(void); +extern void __bad_ndelay(void); + +extern void __udelay(unsigned long usecs); +extern void __ndelay(unsigned long nsecs); +extern void __const_udelay(unsigned long usecs); +extern void __delay(unsigned long loops); + +#define udelay(n) (__builtin_constant_p(n) ? \ + ((n) > 20000 ? __bad_udelay() : __const_udelay((n) * 0x10c7ul)) : \ + __udelay(n)) + +#define ndelay(n) (__builtin_constant_p(n) ? \ + ((n) > 20000 ? __bad_ndelay() : __const_udelay((n) * 5ul)) : \ + __ndelay(n)) #endif /* !__ASSEMBLY__ */ -- 2.53.0