Every 11 minutes ntp attempts to update the x86 rtc with the current
system time. Currently, the x86 code only updates the rtc if the system
time is within +/-15 minutes of the current value of the rtc. Other
architectures do a full synchronization and there is no reason that x86
should be software limited to a 30 minute window.
This patch changes the behavior of the kernel to do a full synchronization
(year, month, day, hour, minute, and second) of the rtc when ntp requests
a synchronization between the system time and the rtc.
I've used the RTC library functions in this patchset as they do all the
required bounds checking.
Signed-off-by: Prarit Bhargava <pra...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: John Stultz <john.stu...@linaro.org>
Cc: x...@kernel.org
Cc: Matt Fleming <matt.flem...@intel.com>
Cc: David Vrabel <david.vra...@citrix.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Andi Kleen <a...@linux.intel.com>
Cc: linux-...@vger.kernel.org
---
arch/x86/kernel/rtc.c | 69 ++++++++-----------------------------------
arch/x86/platform/efi/efi.c | 24 ++++++++++-----
arch/x86/platform/mrst/vrtc.c | 41 ++++++++++++++-----------
3 files changed, 52 insertions(+), 82 deletions(-)
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 801602b..44e6c3a 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -13,6 +13,7 @@
#include <asm/x86_init.h>
#include <asm/time.h>
#include <asm/mrst.h>
+#include <asm/rtc.h>
#ifdef CONFIG_X86_32
/*
@@ -36,70 +37,24 @@ EXPORT_SYMBOL(rtc_lock);
* nowtime is written into the registers of the CMOS clock, it will
* jump to the next second precisely 500 ms later. Check the Motorola
* MC146818A or Dallas DS12887 data sheet for details.
- *
- * BUG: This routine does not handle hour overflow properly; it just
- * sets the minutes. Usually you'll only notice that after reboot!
*/
int mach_set_rtc_mmss(unsigned long nowtime)
{
- int real_seconds, real_minutes, cmos_minutes;
- unsigned char save_control, save_freq_select;
- unsigned long flags;
+ struct rtc_time tm;
int retval = 0;
- spin_lock_irqsave(&rtc_lock, flags);
-
- /* tell the clock it's being set */
- save_control = CMOS_READ(RTC_CONTROL);
- CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
-
- /* stop and reset prescaler */
- save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
- CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
-
- cmos_minutes = CMOS_READ(RTC_MINUTES);
- if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
- cmos_minutes = bcd2bin(cmos_minutes);
-
- /*
- * since we're only adjusting minutes and seconds,
- * don't interfere with hour overflow. This avoids
- * messing with unknown time zones but requires your
- * RTC not to be off by more than 15 minutes
- */
- real_seconds = nowtime % 60;
- real_minutes = nowtime / 60;
- /* correct for half hour time zone */
- if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
- real_minutes += 30;
- real_minutes %= 60;
-
- if (abs(real_minutes - cmos_minutes) < 30) {
- if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
- real_seconds = bin2bcd(real_seconds);
- real_minutes = bin2bcd(real_minutes);
- }
- CMOS_WRITE(real_seconds, RTC_SECONDS);
- CMOS_WRITE(real_minutes, RTC_MINUTES);
+ rtc_time_to_tm(nowtime, &tm);
+ if (!rtc_valid_tm(&tm)) {
+ retval = set_rtc_time(&tm);
+ if (retval)
+ printk(KERN_ERR "%s: RTC write failed with error %d\n",
+ __FUNCTION__, retval);
} else {
- printk_once(KERN_NOTICE
- "set_rtc_mmss: can't update from %d to %d\n",
- cmos_minutes, real_minutes);
- retval = -1;
+ printk(KERN_ERR
+ "%s: Invalid RTC value: write of %lx to RTC failed\n",
+ __FUNCTION__, nowtime);
+ retval = -EINVAL;
}
-
- /* The following flags have to be released exactly in this order,
- * otherwise the DS12887 (popular MC146818A clone with integrated
- * battery and quartz) will not reset the oscillator and will not
- * update precisely 500 ms later. You won't find this mentioned in
- * the Dallas Semiconductor data sheets, but who believes data
- * sheets anyway ... -- Markus Kuhn
- */
- CMOS_WRITE(save_control, RTC_CONTROL);
- CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
-
- spin_unlock_irqrestore(&rtc_lock, flags);
-
return retval;
}
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 77cf009..6ca930e 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -48,6 +48,7 @@
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/x86_init.h>
+#include <asm/rtc.h>
#define EFI_DEBUG 1
@@ -262,10 +263,10 @@ static efi_status_t __init phys_efi_get_time(efi_time_t
*tm,
int efi_set_rtc_mmss(unsigned long nowtime)
{
- int real_seconds, real_minutes;
efi_status_t status;
efi_time_t eft;
efi_time_cap_t cap;
+ struct rtc_time tm;
status = efi.get_time(&eft, &cap);
if (status != EFI_SUCCESS) {
@@ -273,13 +274,20 @@ int efi_set_rtc_mmss(unsigned long nowtime)
return -1;
}
- real_seconds = nowtime % 60;
- real_minutes = nowtime / 60;
- if (((abs(real_minutes - eft.minute) + 15)/30) & 1)
- real_minutes += 30;
- real_minutes %= 60;
- eft.minute = real_minutes;
- eft.second = real_seconds;
+ rtc_time_to_tm(nowtime, &tm);
+ if (!rtc_valid_tm(&tm)) {
+ eft.year = tm.tm_year + 1900;
+ eft.month = tm.tm_mon + 1;
+ eft.day = tm.tm_mday;
+ eft.minute = tm.tm_min;
+ eft.second = tm.tm_sec;
+ eft.nanosecond = 0;
+ } else {
+ printk(KERN_ERR
+ "%s: Invalid EFI RTC value: write of %lx to EFI RTC
failed\n",
+ __FUNCTION__, nowtime);
+ return -1;
+ }
status = efi.set_time(&eft);
if (status != EFI_SUCCESS) {
diff --git a/arch/x86/platform/mrst/vrtc.c b/arch/x86/platform/mrst/vrtc.c
index 225bd0f..205b3d0 100644
--- a/arch/x86/platform/mrst/vrtc.c
+++ b/arch/x86/platform/mrst/vrtc.c
@@ -85,26 +85,33 @@ unsigned long vrtc_get_time(void)
return mktime(year, mon, mday, hour, min, sec);
}
-/* Only care about the minutes and seconds */
int vrtc_set_mmss(unsigned long nowtime)
{
- int real_sec, real_min;
unsigned long flags;
- int vrtc_min;
-
- spin_lock_irqsave(&rtc_lock, flags);
- vrtc_min = vrtc_cmos_read(RTC_MINUTES);
-
- real_sec = nowtime % 60;
- real_min = nowtime / 60;
- if (((abs(real_min - vrtc_min) + 15)/30) & 1)
- real_min += 30;
- real_min %= 60;
-
- vrtc_cmos_write(real_sec, RTC_SECONDS);
- vrtc_cmos_write(real_min, RTC_MINUTES);
- spin_unlock_irqrestore(&rtc_lock, flags);
-
+ struct rtc_time tm;
+ int year;
+
+ rtc_time_to_tm(nowtime, &tm);
+ if (!rtc_valid_tm(&tm) && tm.year >= 72) {
+ /*
+ * tm.year is the number of years since 1900, and the
+ * vrtc need the years since 1972.
+ */
+ year = tm.year - 72;
+ spin_lock_irqsave(&rtc_lock, flags);
+ vrtc_cmos_write(year, RTC_YEAR);
+ vrtc_cmos_write(tm.mon, RTC_MONTH);
+ vrtc_cmos_write(tm.mday, RTC_DAY_OF_MONTH);
+ vrtc_cmos_write(tm.hour, RTC_HOURS);
+ vrtc_cmos_write(tm.min, RTC_MINUTES);
+ vrtc_cmos_write(tm.sec, RTC_SECONDS);
+ spin_unlock_irqrestore(&rtc_lock, flags);
+ } else {
+ printk(KERN_ERR
+ "%s: Invalid vRTC value: write of %lx to vRTC failed\n",
+ __FUNCTION__, nowtime);
+ retval = -EINVAL;
+ }
return 0;
}
--
1.8.1.2
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