linux-kernel - [PATCH 01/13] timekeeping: add CONFIG_LEGACY_TIMER

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Date:   Thu,  8 Oct 2020 17:46:39 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     linux-kernel@...r.kernel.org
Cc:     Arnd Bergmann <arnd@...db.de>,
        Russell King <linux@...linux.org.uk>,
        Tony Luck <tony.luck@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Greg Ungerer <gerg@...ux-m68k.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Finn Thain <fthain@...egraphics.com.au>,
        Philip Blundell <philb@....org>,
        Joshua Thompson <funaho@...ai.org>,
        Sam Creasey <sammy@...my.net>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Helge Deller <deller@....de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        John Stultz <john.stultz@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-ia64@...r.kernel.org, linux-parisc@...r.kernel.org,
        linux-m68k@...ts.linux-m68k.org,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 01/13] timekeeping: add CONFIG_LEGACY_TIMER_TICK

All platforms that currently do not use generic clockevents roughly call
the same set of functions in their timer interrupts: xtime_update(),
update_process_times() and profile_tick(), sometimes in a different
sequence.

Add a helper function that performs all three of them, to make the
callers more uniform and simplify the interface.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 include/linux/timekeeping.h |  1 +
 kernel/time/Kconfig         |  7 +++++++
 kernel/time/Makefile        |  1 +
 kernel/time/tick-legacy.c   | 19 +++++++++++++++++++
 4 files changed, 28 insertions(+)
 create mode 100644 kernel/time/tick-legacy.c

diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 7f7e4a3f4394..3670cb1670ff 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -12,6 +12,7 @@ extern int timekeeping_suspended;
 /* Architecture timer tick functions: */
 extern void update_process_times(int user);
 extern void xtime_update(unsigned long ticks);
+extern void legacy_timer_tick(unsigned long ticks);
 
 /*
  * Get and set timeofday
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index a09b1d61df6a..f2b0cfeade47 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -61,6 +61,13 @@ config POSIX_CPU_TIMERS_TASK_WORK
 	bool
 	default y if POSIX_TIMERS && HAVE_POSIX_CPU_TIMERS_TASK_WORK
 
+config LEGACY_TIMER_TICK
+	bool
+	help
+	  The legacy timer tick helper is used by platforms that
+	  lack support for the generic clockevent framework.
+	  New platforms should use generic clockevents instead.
+
 if GENERIC_CLOCKEVENTS
 menu "Timers subsystem"
 
diff --git a/kernel/time/Makefile b/kernel/time/Makefile
index c8f00168afe8..1fb1c1ef6a19 100644
--- a/kernel/time/Makefile
+++ b/kernel/time/Makefile
@@ -16,6 +16,7 @@ ifeq ($(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST),y)
 endif
 obj-$(CONFIG_GENERIC_SCHED_CLOCK)		+= sched_clock.o
 obj-$(CONFIG_TICK_ONESHOT)			+= tick-oneshot.o tick-sched.o
+obj-$(CONFIG_LEGACY_TIMER_TICK)			+= tick-legacy.o
 obj-$(CONFIG_HAVE_GENERIC_VDSO)			+= vsyscall.o
 obj-$(CONFIG_DEBUG_FS)				+= timekeeping_debug.o
 obj-$(CONFIG_TEST_UDELAY)			+= test_udelay.o
diff --git a/kernel/time/tick-legacy.c b/kernel/time/tick-legacy.c
new file mode 100644
index 000000000000..73c5a0af4743
--- /dev/null
+++ b/kernel/time/tick-legacy.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Timer tick function for architectures that lack generic clockevents,
+ * consolidated here from m68k/ia64/parisc/arm.
+ */
+
+#include <linux/irq.h>
+#include <linux/profile.h>
+#include <linux/timekeeper_internal.h>
+
+#include "tick-internal.h"
+
+void legacy_timer_tick(unsigned long ticks)
+{
+	if (ticks)
+		xtime_update(ticks);
+	update_process_times(user_mode(get_irq_regs()));
+	profile_tick(CPU_PROFILING);
+}
-- 
2.27.0