[PATCH 1/4] rtc-lib: Add rtc_show_time(const char *prefix_msg)

[PATCH 1/4] rtc-lib: Add rtc_show_time(const char *prefix_msg)

[Mark Salyzyn]

Go directly to the rtc for persistent wall clock time and print.
Useful if REALTIME is required to be logged in a low level power
management function or when clock activities are suspended.  An
aid to permit user space alignment of kernel activities.

Feature activated by CONFIG_RTC_SHOW_TIME.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
---
 drivers/rtc/Kconfig   | 11 +++++++++++
 drivers/rtc/rtc-lib.c | 16 ++++++++++++++++
 include/linux/rtc.h   |  5 +++++
 3 files changed, 32 insertions(+)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 72419ac2c52a..7c308605bf42 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -5,6 +5,17 @@
 config RTC_LIB
 	bool
 
+config RTC_SHOW_TIME
+	bool "rtc_show_time instrumentation"
+	select RTC_LIB
+	help
+	  Activate rtc_show_time(const char *msg) wall clock time
+	  instrumentation.
+
+	  The instrumentation is used to help triage and synchronize
+	  kernel logs using CLOCK_MONOTONIC and user space activity
+	  logs utilizing CLOCK_REALTIME references.
+
 config RTC_MC146818_LIB
 	bool
 	select RTC_LIB
diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c
index 1ae7da5cfc60..676d6a83e843 100644
--- a/drivers/rtc/rtc-lib.c
+++ b/drivers/rtc/rtc-lib.c
@@ -94,6 +94,22 @@ void rtc_time64_to_tm(time64_t time, struct rtc_time *tm)
 }
 EXPORT_SYMBOL(rtc_time64_to_tm);
 
+#ifdef CONFIG_RTC_SHOW_TIME
+void rtc_show_time(const char *prefix_msg)
+{
+	struct timespec ts;
+	struct rtc_time tm;
+
+	getnstimeofday(&ts);
+	rtc_time_to_tm(ts.tv_sec, &tm);
+	pr_info("%s %d-%02d-%02d %02d:%02d:%02d.%09lu UTC\n",
+		prefix_msg ? prefix_msg : "Time:",
+		tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
+		tm.tm_hour, tm.tm_min, tm.tm_sec, ts.tv_nsec);
+}
+EXPORT_SYMBOL(rtc_show_time);
+#endif
+
 /*
  * Does the rtc_time represent a valid date/time?
  */
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 0a0f0d14a5fb..bf625e023799 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -22,6 +22,11 @@ extern int rtc_year_days(unsigned int day, unsigned int month, unsigned int year
 extern int rtc_valid_tm(struct rtc_time *tm);
 extern time64_t rtc_tm_to_time64(struct rtc_time *tm);
 extern void rtc_time64_to_tm(time64_t time, struct rtc_time *tm);
+#ifdef CONFIG_RTC_SHOW_TIME
+extern void rtc_show_time(const char *prefix_msg);
+#else
+#define rtc_show_time(prefix_msg)
+#endif
 ktime_t rtc_tm_to_ktime(struct rtc_time tm);
 struct rtc_time rtc_ktime_to_tm(ktime_t kt);
 
-- 
2.13.2.932.g7449e964c-goog

Re: [PATCH 1/4] rtc-lib: Add rtc_show_time(const char *prefix_msg)

[Joe Perches]

On Tue, 2017-07-18 at 10:25 -0700, Mark Salyzyn wrote:
> Go directly to the rtc for persistent wall clock time and print.
> Useful if REALTIME is required to be logged in a low level power
> management function or when clock activities are suspended.  An
> aid to permit user space alignment of kernel activities.
[]
> diff --git a/include/linux/rtc.h b/include/linux/rtc.h
[]
> @@ -22,6 +22,11 @@ extern int rtc_year_days(unsigned int day, unsigned int month, unsigned int year
>  extern int rtc_valid_tm(struct rtc_time *tm);
>  extern time64_t rtc_tm_to_time64(struct rtc_time *tm);
>  extern void rtc_time64_to_tm(time64_t time, struct rtc_time *tm);
> +#ifdef CONFIG_RTC_SHOW_TIME
> +extern void rtc_show_time(const char *prefix_msg);
> +#else
> +#define rtc_show_time(prefix_msg)

It's generally better to use a static inline to avoid
misuses in newly added code in the !CONFIG_RTC_SHOW_TIME
compile path when CONFIG_RTC_SHOW_TIME may not be compiled.

static inline void rtc_show_time(const char *prefix_msg)
{
}

Re: [PATCH 1/4] rtc-lib: Add rtc_show_time(const char *prefix_msg)

[Andy Shevchenko]

On Tue, Jul 18, 2017 at 8:25 PM, Mark Salyzyn <salyzyn@android.com> wrote:
> Go directly to the rtc for persistent wall clock time and print.
> Useful if REALTIME is required to be logged in a low level power
> management function or when clock activities are suspended.  An
> aid to permit user space alignment of kernel activities.
>
> Feature activated by CONFIG_RTC_SHOW_TIME.

What's wrong with procfs device nodes for that?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 1/4] rtc-lib: Add rtc_show_time(const char *prefix_msg)

[Andy Shevchenko]

On Tue, Jul 18, 2017 at 8:46 PM, Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Tue, Jul 18, 2017 at 8:25 PM, Mark Salyzyn <salyzyn@android.com> wrote:
>> Go directly to the rtc for persistent wall clock time and print.
>> Useful if REALTIME is required to be logged in a low level power
>> management function or when clock activities are suspended.  An
>> aid to permit user space alignment of kernel activities.
>>
>> Feature activated by CONFIG_RTC_SHOW_TIME.
>
> What's wrong with procfs device nodes for that?

Ah, it's internal API, ok.

Then would it be possible to use %pt [1] or alike?

[1]: https://www.spinics.net/lists/kernel/msg2528401.html

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 1/4] rtc-lib: Add rtc_show_time(const char *prefix_msg)

[Alexandre Belloni]

Hi,

On 18/07/2017 at 10:25:23 -0700, Mark Salyzyn wrote:
> Go directly to the rtc for persistent wall clock time and print.
> Useful if REALTIME is required to be logged in a low level power
> management function or when clock activities are suspended.  An
> aid to permit user space alignment of kernel activities.
> 
> Feature activated by CONFIG_RTC_SHOW_TIME.
> 
> Signed-off-by: Mark Salyzyn <salyzyn@android.com>
> ---
>  drivers/rtc/Kconfig   | 11 +++++++++++
>  drivers/rtc/rtc-lib.c | 16 ++++++++++++++++
>  include/linux/rtc.h   |  5 +++++
>  3 files changed, 32 insertions(+)
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 72419ac2c52a..7c308605bf42 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -5,6 +5,17 @@
>  config RTC_LIB
>  	bool
>  
> +config RTC_SHOW_TIME
> +	bool "rtc_show_time instrumentation"
> +	select RTC_LIB
> +	help
> +	  Activate rtc_show_time(const char *msg) wall clock time
> +	  instrumentation.
> +
> +	  The instrumentation is used to help triage and synchronize
> +	  kernel logs using CLOCK_MONOTONIC and user space activity
> +	  logs utilizing CLOCK_REALTIME references.
> +
>  config RTC_MC146818_LIB
>  	bool
>  	select RTC_LIB
> diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c
> index 1ae7da5cfc60..676d6a83e843 100644
> --- a/drivers/rtc/rtc-lib.c
> +++ b/drivers/rtc/rtc-lib.c
> @@ -94,6 +94,22 @@ void rtc_time64_to_tm(time64_t time, struct rtc_time *tm)
>  }
>  EXPORT_SYMBOL(rtc_time64_to_tm);
>  
> +#ifdef CONFIG_RTC_SHOW_TIME
> +void rtc_show_time(const char *prefix_msg)
> +{
> +	struct timespec ts;
> +	struct rtc_time tm;
> +
> +	getnstimeofday(&ts);
> +	rtc_time_to_tm(ts.tv_sec, &tm);

Apart from using rtc_time_to_tm (and you should probably use
rtc_time64_to_tm), none of this is actually related to the RTC
subsystem. I feel like you should find another place to put that, maybe
timekeeping_debug.c?

> +	pr_info("%s %d-%02d-%02d %02d:%02d:%02d.%09lu UTC\n",
> +		prefix_msg ? prefix_msg : "Time:",
> +		tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
> +		tm.tm_hour, tm.tm_min, tm.tm_sec, ts.tv_nsec);
> +}
> +EXPORT_SYMBOL(rtc_show_time);
> +#endif
> +
>  /*
>   * Does the rtc_time represent a valid date/time?
>   */
> diff --git a/include/linux/rtc.h b/include/linux/rtc.h
> index 0a0f0d14a5fb..bf625e023799 100644
> --- a/include/linux/rtc.h
> +++ b/include/linux/rtc.h
> @@ -22,6 +22,11 @@ extern int rtc_year_days(unsigned int day, unsigned int month, unsigned int year
>  extern int rtc_valid_tm(struct rtc_time *tm);
>  extern time64_t rtc_tm_to_time64(struct rtc_time *tm);
>  extern void rtc_time64_to_tm(time64_t time, struct rtc_time *tm);
> +#ifdef CONFIG_RTC_SHOW_TIME
> +extern void rtc_show_time(const char *prefix_msg);
> +#else
> +#define rtc_show_time(prefix_msg)
> +#endif
>  ktime_t rtc_tm_to_ktime(struct rtc_time tm);
>  struct rtc_time rtc_ktime_to_tm(ktime_t kt);
>  
> -- 
> 2.13.2.932.g7449e964c-goog
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

Re: [PATCH 1/4] rtc-lib: Add rtc_show_time(const char *prefix_msg)

[Mark Salyzyn]

On 07/18/2017 10:52 AM, Alexandre Belloni wrote:
> Hi,
>
> On 18/07/2017 at 10:25:23 -0700, Mark Salyzyn wrote:
>> . . .
> Apart from using rtc_time_to_tm (and you should probably use
> rtc_time64_to_tm), none of this is actually related to the RTC
> subsystem. I feel like you should find another place to put that, maybe
> timekeeping_debug.c?
Makes a lot of sense!

-- Mark

Re: [PATCH 1/4] rtc-lib: Add rtc_show_time(const char *prefix_msg)

[Mark Salyzyn]

On 07/18/2017 01:00 PM, Mark Salyzyn wrote:
> On 07/18/2017 10:52 AM, Alexandre Belloni wrote:
>> Hi,
>>
>> On 18/07/2017 at 10:25:23 -0700, Mark Salyzyn wrote:
>>> . . .
>> Apart from using rtc_time_to_tm (and you should probably use
>> rtc_time64_to_tm), none of this is actually related to the RTC
>> subsystem. I feel like you should find another place to put that, maybe
>> timekeeping_debug.c?
> Makes a lot of sense!
>
> -- Mark

Ooops, timekeeping_debug.c is currently only to support a debugfs node. 
Perhaps a _new_ file in that hierarchy like kernel/time/rtc_show_time.c.

-- Mark