linux-kernel - [PATCH v2 2/4] time: Print wall time at die and reboot

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Message-Id: <20170718212117.123296-1-salyzyn@android.com>
Date:   Tue, 18 Jul 2017 14:21:08 -0700
From:   Mark Salyzyn <salyzyn@...roid.com>
To:     linux-kernel@...r.kernel.org
Cc:     rjw@...ysocki.net, len.brown@...el.com, pavel@....cz,
        linux-pm@...r.kernel.org, a.zummo@...ertech.it,
        alexandre.belloni@...e-electrons.com, linux-rtc@...r.kernel.org,
        Mark Salyzyn <salyzyn@...roid.com>,
        Mark Salyzyn <salyzyn@...gle.com>,
        Thierry Strudel <tstrudel@...gle.com>
Subject: [PATCH v2 2/4] time: Print wall time at die and reboot

Permits power state and battery life diagnosis.

Feature activated by CONFIG_RTC_SHOW_TIME.

Signed-off-by: Mark Salyzyn <salyzyn@...roid.com>

v2:
- react to implementation move to kernel timekeeping from rtc_lib
- use late_initcall to ensure rtc_lib driver(s) are loaded
---
 kernel/time/rtc_show_time.c | 59 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/kernel/time/rtc_show_time.c b/kernel/time/rtc_show_time.c
index bbf4f92abf4f..d52e2a76cd00 100644
--- a/kernel/time/rtc_show_time.c
+++ b/kernel/time/rtc_show_time.c
@@ -6,6 +6,8 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/kdebug.h>
+#include <linux/reboot.h>
 #include <linux/rtc.h>
 
 void rtc_show_time(const char *prefix_msg)
@@ -21,3 +23,60 @@ void rtc_show_time(const char *prefix_msg)
 		tm.tm_hour, tm.tm_min, tm.tm_sec, ts.tv_nsec);
 }
 EXPORT_SYMBOL(rtc_show_time);
+
+static int rtc_show_time_die_notify(struct notifier_block *self,
+		unsigned long event, void *data)
+{
+	if (event != DIE_OOPS)
+		return NOTIFY_DONE;
+	rtc_show_time("Oops");
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block rtc_show_time_die_nb = {
+	.notifier_call = rtc_show_time_die_notify,
+	.priority = 0,
+};
+
+static int rtc_show_time_reboot_notify(struct notifier_block *self,
+		unsigned long event, void *data)
+{
+	const char *txt;
+
+	switch (event) {
+	case SYS_RESTART:
+		txt = "Restart";
+		break;
+	case SYS_HALT:
+		txt = "Halt";
+		break;
+	case SYS_POWER_OFF:
+		txt = "Power-Off";
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+	rtc_show_time(txt);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block rtc_show_time_reboot_nb = {
+	.notifier_call = rtc_show_time_reboot_notify,
+	.priority = 0,
+};
+
+static __init int init_rtc_show_time(void)
+{
+	int ret;
+
+	ret = register_die_notifier(&rtc_show_time_die_nb);
+	if (ret)
+		pr_warn("Failed to register rtc_show_time die notifier\n");
+	ret = register_reboot_notifier(&rtc_show_time_reboot_nb);
+	if (ret)
+		pr_warn("Failed to register rtc_show_time reboot notifier\n");
+
+	return ret;
+}
+/* rtc driver needs to be loaded before this is truly functional */
+late_initcall(init_rtc_show_time);
-- 
2.13.2.932.g7449e964c-goog