From 023f333a99cee9b5cd3268ff87298eb01a31f78e Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Mon, 17 Dec 2012 14:30:53 -0700 Subject: NTP: Add a CONFIG_RTC_SYSTOHC configuration The purpose of this option is to allow ARM/etc systems that rely on the class RTC subsystem to have the same kind of automatic NTP based synchronization that we have on PC platforms. Today ARM does not implement update_persistent_clock and makes extensive use of the class RTC system. When enabled CONFIG_RTC_SYSTOHC will provide a generic rtc_update_persistent_clock that stores the current time in the RTC and is intended complement the existing CONFIG_RTC_HCTOSYS option that loads the RTC at boot. Like with RTC_HCTOSYS the platform's update_persistent_clock is used first, if it works. Platforms with mixed class RTC and non-RTC drivers need to return ENODEV when class RTC should be used. Such an update for PPC is included in this patch. Long term, implementations of update_persistent_clock should migrate to proper class RTC drivers and use CONFIG_RTC_SYSTOHC instead. Tested on ARM kirkwood and PPC405 Signed-off-by: Jason Gunthorpe Signed-off-by: John Stultz --- arch/powerpc/kernel/time.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index ce4cb772dc78..bc844a857e05 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -667,7 +667,7 @@ int update_persistent_clock(struct timespec now) struct rtc_time tm; if (!ppc_md.set_rtc_time) - return 0; + return -ENODEV; to_tm(now.tv_sec + 1 + timezone_offset, &tm); tm.tm_year -= 1900; -- cgit v1.2.3 From 2353b47bffe4e6ab39042f470c55d41bb3ff3846 Mon Sep 17 00:00:00 2001 From: Bernd Faust Date: Wed, 5 Dec 2012 15:16:49 +0100 Subject: Round the calculated scale factor in set_cyc2ns_scale() During some experiments with an external clock (in a FPGA), we saw that the TSC clock drifted approx. 2.5ms per second. This drift was caused by the current way of calculating the scale. In our case cpu_khz had a value of 3292725. This resulted in a scale value of 310. But when doing the calculation by hand it shows that the actual value is 310.9886188491, so a value of 311 would be more precise. With this change the value is rounded. Signed-off-by: Bernd Faust Signed-off-by: John Stultz --- arch/x86/kernel/tsc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index cfa5d4f7ca56..8ed085733773 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -617,7 +617,8 @@ static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu) ns_now = __cycles_2_ns(tsc_now); if (cpu_khz) { - *scale = (NSEC_PER_MSEC << CYC2NS_SCALE_FACTOR)/cpu_khz; + *scale = ((NSEC_PER_MSEC << CYC2NS_SCALE_FACTOR) + + cpu_khz / 2) / cpu_khz; *offset = ns_now - mult_frac(tsc_now, *scale, (1UL << CYC2NS_SCALE_FACTOR)); } -- cgit v1.2.3 From e90c83f757fffdacec8b3c5eee5617dcc038338f Mon Sep 17 00:00:00 2001 From: John Stultz Date: Tue, 15 Jan 2013 19:45:19 +0000 Subject: x86: Select HAS_PERSISTENT_CLOCK on x86 Select HAS_PERSISTENT_CLOCK on x86 to simplify RTC options and allow the compiler to remove unused code. Signed-off-by: John Stultz --- arch/x86/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'arch') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 46c3bff3ced2..a4135b5e562e 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -108,6 +108,7 @@ config X86 select GENERIC_STRNLEN_USER select HAVE_RCU_USER_QS if X86_64 select HAVE_IRQ_TIME_ACCOUNTING + select HAS_PERSISTENT_CLOCK select GENERIC_KERNEL_THREAD select GENERIC_KERNEL_EXECVE select MODULES_USE_ELF_REL if X86_32 -- cgit v1.2.3 From 6f16eebe1ff82176339a0439c98ebec9768b0ee2 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Fri, 25 Jan 2013 17:08:12 -0800 Subject: timekeeping: Switch HAS_PERSISTENT_CLOCK to ALWAYS_USE_PERSISTENT_CLOCK Jason pointed out the HAS_PERSISTENT_CLOCK name isn't quite accurate for the config, as some systems may have the persistent_clock in some cases, but not always. So change the config name to the more clear ALWAYS_USE_PERSISTENT_CLOCK. Signed-off-by: John Stultz --- arch/x86/Kconfig | 2 +- drivers/rtc/Kconfig | 4 ++-- include/linux/time.h | 2 +- kernel/time/Kconfig | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) (limited to 'arch') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index a4135b5e562e..335da90560e4 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -108,7 +108,7 @@ config X86 select GENERIC_STRNLEN_USER select HAVE_RCU_USER_QS if X86_64 select HAVE_IRQ_TIME_ACCOUNTING - select HAS_PERSISTENT_CLOCK + select ALWAYS_USE_PERSISTENT_CLOCK select GENERIC_KERNEL_THREAD select GENERIC_KERNEL_EXECVE select MODULES_USE_ELF_REL if X86_32 diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig index 05761de7929b..da60de01f732 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -20,7 +20,7 @@ if RTC_CLASS config RTC_HCTOSYS bool "Set system time from RTC on startup and resume" default y - depends on !HAS_PERSISTENT_CLOCK + depends on !ALWAYS_USE_PERSISTENT_CLOCK help If you say yes here, the system time (wall clock) will be set using the value read from a specified RTC device. This is useful to avoid @@ -29,7 +29,7 @@ config RTC_HCTOSYS config RTC_SYSTOHC bool "Set the RTC time based on NTP synchronization" default y - depends on !HAS_PERSISTENT_CLOCK + depends on !ALWAYS_USE_PERSISTENT_CLOCK help If you say yes here, the system time (wall clock) will be stored in the RTC specified by RTC_HCTOSYS_DEVICE approximately every 11 diff --git a/include/linux/time.h b/include/linux/time.h index 369b6e3b87d8..476e1d7b2c37 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -117,7 +117,7 @@ static inline bool timespec_valid_strict(const struct timespec *ts) extern bool persistent_clock_exist; -#ifdef CONFIG_HAS_PERSISTENT_CLOCK +#ifdef ALWAYS_USE_PERSISTENT_CLOCK #define has_persistent_clock() true #else static inline bool has_persistent_clock(void) diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index f7e45b9b142b..0dddb9d09d0b 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -13,7 +13,7 @@ config ARCH_CLOCKSOURCE_DATA bool # Platforms has a persistent clock -config HAS_PERSISTENT_CLOCK +config ALWAYS_USE_PERSISTENT_CLOCK bool default n -- cgit v1.2.3