[tip:x86/vdso] clocksource: Provide clocksource_arch_init()

[tip-bot for Thomas Gleixner <tipbot@zytor.com>]

Commit-ID:  d67f34c19a679436dd2963b588015e119279e7a8
Gitweb:     https://git.kernel.org/tip/d67f34c19a679436dd2963b588015e119279e7a8
Author:     Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Mon, 17 Sep 2018 14:45:34 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 4 Oct 2018 23:00:24 +0200

clocksource: Provide clocksource_arch_init()

Architectures have extra archdata in the clocksource, e.g. for VDSO
support. There are no sanity checks or general initializations for this
available. Add support for that.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20180917130706.973042587@linutronix.de

---
 include/linux/clocksource.h | 5 +++++
 kernel/time/Kconfig         | 4 ++++
 kernel/time/clocksource.c   | 2 ++
 3 files changed, 11 insertions(+)

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 308918928767..6e6b86f9046d 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -241,6 +241,11 @@ static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz
 	__clocksource_update_freq_scale(cs, 1000, khz);
 }
 
+#ifdef CONFIG_ARCH_CLOCKSOURCE_INIT
+extern void clocksource_arch_init(struct clocksource *cs);
+#else
+static inline void clocksource_arch_init(struct clocksource *cs) { }
+#endif
 
 extern int timekeeping_notify(struct clocksource *clock);
 
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 78eabc41eaa6..58b981f4bb5d 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -12,6 +12,10 @@ config CLOCKSOURCE_WATCHDOG
 config ARCH_CLOCKSOURCE_DATA
 	bool
 
+# Architecture has extra clocksource init called from registration
+config ARCH_CLOCKSOURCE_INIT
+	bool
+
 # Clocksources require validation of the clocksource against the last
 # cycle update - x86/TSC misfeature
 config CLOCKSOURCE_VALIDATE_LAST_CYCLE
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 0e6e97a01942..ffe081623aec 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -937,6 +937,8 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
 {
 	unsigned long flags;
 
+	clocksource_arch_init(cs);
+
 	/* Initialize mult/shift and max_idle_ns */
 	__clocksource_update_freq_scale(cs, scale, freq);