From 4214832392cb94f5ccd8f3bf460fcf11427f039b Mon Sep 17 00:00:00 2001
From: Tao Huang <huangtao@rock-chips.com>
Date: Fri, 12 Nov 2021 11:05:18 +0800
Subject: [PATCH] printk: Introduce CONFIG_PRINTK_TIME_FROM_ARM_ARCH_TIMER

Some examples for console output:

Starting kernel ...

[    1.956071][    T0] Booting Linux on physical CPU 0x0000000000 [0x412fd050]

Change-Id: I0ab5914349ad3e0028954c831c5e79d46fe2d420
Signed-off-by: Tao Huang <huangtao@rock-chips.com>
---
 kernel/printk/printk.c | 20 +++++++++++++++++++-
 lib/Kconfig.debug      |  4 ++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index de278ccc3940..6db82cd7fdaf 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -63,6 +63,24 @@
 #include "braille.h"
 #include "internal.h"
 
+#ifdef CONFIG_PRINTK_TIME_FROM_ARM_ARCH_TIMER
+#include <clocksource/arm_arch_timer.h>
+static u64 get_local_clock(void)
+{
+	u64 ns;
+
+	ns = arch_timer_read_counter() * 1000;
+	do_div(ns, 24);
+
+	return ns;
+}
+#else
+static inline u64 get_local_clock(void)
+{
+	return local_clock();
+}
+#endif
+
 int console_printk[4] = {
 	CONSOLE_LOGLEVEL_DEFAULT,	/* console_loglevel */
 	MESSAGE_LOGLEVEL_DEFAULT,	/* default_message_loglevel */
@@ -528,7 +546,7 @@ static int log_store(u32 caller_id, int facility, int level,
 	if (ts_nsec > 0)
 		r.info->ts_nsec = ts_nsec;
 	else
-		r.info->ts_nsec = local_clock();
+		r.info->ts_nsec = get_local_clock();
 	r.info->caller_id = caller_id;
 	if (dev_info)
 		memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info));
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 3f4a695edd0d..19d31d3f859e 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -18,6 +18,10 @@ config PRINTK_TIME
 	  The behavior is also controlled by the kernel command line
 	  parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
 
+config PRINTK_TIME_FROM_ARM_ARCH_TIMER
+	bool "Timing from ARM architected timer"
+	depends on PRINTK_TIME && ARM_ARCH_TIMER && NO_GKI
+
 config PRINTK_CALLER
 	bool "Show caller information on printks"
 	depends on PRINTK