timekeeping: remove arch_gettimeoffset

With Arm EBSA110 gone, nothing uses it any more, so the corresponding
code and the Kconfig option can be removed.
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Documentation/features/time/modern-timekeeping/arch-support.txt

-#
-# Feature name:          modern-timekeeping
-#         Kconfig:       !ARCH_USES_GETTIMEOFFSET
-#         description:   arch does not use arch_gettimeoffset() anymore
-#
-    -----------------------
-    |         arch |status|
-    -----------------------
-    |       alpha: |  ok  |
-    |         arc: |  ok  |
-    |         arm: | TODO |
-    |       arm64: |  ok  |
-    |         c6x: |  ok  |
-    |        csky: |  ok  |
-    |       h8300: |  ok  |
-    |     hexagon: |  ok  |
-    |        ia64: |  ok  |
-    |        m68k: |  ok  |
-    |  microblaze: |  ok  |
-    |        mips: |  ok  |
-    |       nds32: |  ok  |
-    |       nios2: |  ok  |
-    |    openrisc: |  ok  |
-    |      parisc: |  ok  |
-    |     powerpc: |  ok  |
-    |       riscv: |  ok  |
-    |        s390: |  ok  |
-    |          sh: |  ok  |
-    |       sparc: |  ok  |
-    |          um: |  ok  |
-    |         x86: |  ok  |
-    |      xtensa: |  ok  |
-    -----------------------

drivers/Makefile

@@ -135,9 +135,7 @@ obj-$(CONFIG_INFINIBAND)	+= infiniband/
 obj-y				+= firmware/
 obj-$(CONFIG_CRYPTO)		+= crypto/
 obj-$(CONFIG_SUPERH)		+= sh/
-ifndef CONFIG_ARCH_USES_GETTIMEOFFSET
 obj-y				+= clocksource/
-endif
 obj-$(CONFIG_DCA)		+= dca/
 obj-$(CONFIG_HID)		+= hid/
 obj-$(CONFIG_PPC_PS3)		+= ps3/

drivers/clocksource/Kconfig

@@ -563,7 +563,7 @@ config CLKSRC_QCOM
 
 config CLKSRC_VERSATILE
 	bool "ARM Versatile (Express) reference platforms clock source" if COMPILE_TEST
-	depends on GENERIC_SCHED_CLOCK && !ARCH_USES_GETTIMEOFFSET
+	depends on GENERIC_SCHED_CLOCK
 	select TIMER_OF
 	default y if (ARCH_VEXPRESS || ARCH_VERSATILE) && ARM
 	help

include/linux/time.h

@@ -21,19 +21,6 @@ extern time64_t mktime64(const unsigned int year, const unsigned int mon,
 			const unsigned int day, const unsigned int hour,
 			const unsigned int min, const unsigned int sec);
 
-/* Some architectures do not supply their own clocksource.
- * This is mainly the case in architectures that get their
- * inter-tick times by reading the counter on their interval
- * timer. Since these timers wrap every tick, they're not really
- * useful as clocksources. Wrapping them to act like one is possible
- * but not very efficient. So we provide a callout these arches
- * can implement for use with the jiffies clocksource to provide
- * finer then tick granular time.
- */
-#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
-extern u32 (*arch_gettimeoffset)(void);
-#endif
-
 #ifdef CONFIG_POSIX_TIMERS
 extern void clear_itimer(void);
 #else

kernel/time/Kconfig

@@ -26,10 +26,6 @@ config CLOCKSOURCE_VALIDATE_LAST_CYCLE
 config GENERIC_TIME_VSYSCALL
 	bool
 
-# Old style timekeeping
-config ARCH_USES_GETTIMEOFFSET
-	bool
-
 # The generic clock events infrastructure
 config GENERIC_CLOCKEVENTS
 	bool
@@ -72,7 +68,6 @@ config TICK_ONESHOT
 
 config NO_HZ_COMMON
 	bool
-	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
 	select TICK_ONESHOT
 
 choice
@@ -87,7 +82,6 @@ config HZ_PERIODIC
 
 config NO_HZ_IDLE
 	bool "Idle dynticks system (tickless idle)"
-	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
 	select NO_HZ_COMMON
 	help
 	  This option enables a tickless idle system: timer interrupts
@@ -99,7 +93,6 @@ config NO_HZ_IDLE
 config NO_HZ_FULL
 	bool "Full dynticks system (tickless)"
 	# NO_HZ_COMMON dependency
-	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
 	# We need at least one periodic CPU for timekeeping
 	depends on SMP
 	depends on HAVE_CONTEXT_TRACKING
@@ -158,7 +151,6 @@ config CONTEXT_TRACKING_FORCE
 
 config NO_HZ
 	bool "Old Idle dynticks config"
-	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
 	help
 	  This is the old config entry that enables dynticks idle.
 	  We keep it around for a little while to enforce backward
@@ -166,7 +158,6 @@ config NO_HZ
 
 config HIGH_RES_TIMERS
 	bool "High Resolution Timer Support"
-	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
 	select TICK_ONESHOT
 	help
 	  This option enables high resolution timer support. If your

kernel/time/clocksource.c

@@ -705,8 +705,6 @@ static inline void clocksource_update_max_deferment(struct clocksource *cs)
 						&cs->max_cycles);
 }
 
-#ifndef CONFIG_ARCH_USES_GETTIMEOFFSET
-
 static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur)
 {
 	struct clocksource *cs;
@@ -798,12 +796,6 @@ static void clocksource_select_fallback(void)
 	__clocksource_select(true);
 }
 
-#else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */
-static inline void clocksource_select(void) { }
-static inline void clocksource_select_fallback(void) { }
-
-#endif
-
 /*
  * clocksource_done_booting - Called near the end of core bootup
  *

kernel/time/timekeeping.c

@@ -369,13 +369,6 @@ static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
 
 /* Timekeeper helper functions. */
 
-#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
-static u32 default_arch_gettimeoffset(void) { return 0; }
-u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset;
-#else
-static inline u32 arch_gettimeoffset(void) { return 0; }
-#endif
-
 static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta)
 {
 	u64 nsec;
@@ -383,8 +376,7 @@ static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 de
 	nsec = delta * tkr->mult + tkr->xtime_nsec;
 	nsec >>= tkr->shift;
 
-	/* If arch requires, add in get_arch_timeoffset() */
-	return nsec + arch_gettimeoffset();
+	return nsec;
 }
 
 static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
@@ -778,16 +770,8 @@ static void timekeeping_forward_now(struct timekeeper *tk)
 	tk->tkr_raw.cycle_last  = cycle_now;
 
 	tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
-
-	/* If arch requires, add in get_arch_timeoffset() */
-	tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
-
-
 	tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
 
-	/* If arch requires, add in get_arch_timeoffset() */
-	tk->tkr_raw.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_raw.shift;
-
 	tk_normalize_xtime(tk);
 }
 
@@ -2133,19 +2117,12 @@ static void timekeeping_advance(enum timekeeping_adv_mode mode)
 	if (unlikely(timekeeping_suspended))
 		goto out;
 
-#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
-	offset = real_tk->cycle_interval;
-
-	if (mode != TK_ADV_TICK)
-		goto out;
-#else
 	offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
 				   tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
 
 	/* Check if there's really nothing to do */
 	if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
 		goto out;
-#endif
 
 	/* Do some additional sanity checking */
 	timekeeping_check_update(tk, offset);

kernel/trace/Kconfig

@@ -253,7 +253,6 @@ config IRQSOFF_TRACER
 	bool "Interrupts-off Latency Tracer"
 	default n
 	depends on TRACE_IRQFLAGS_SUPPORT
-	depends on !ARCH_USES_GETTIMEOFFSET
 	select TRACE_IRQFLAGS
 	select GENERIC_TRACER
 	select TRACER_MAX_TRACE
@@ -277,7 +276,6 @@ config IRQSOFF_TRACER
 config PREEMPT_TRACER
 	bool "Preemption-off Latency Tracer"
 	default n
-	depends on !ARCH_USES_GETTIMEOFFSET
 	depends on PREEMPTION
 	select GENERIC_TRACER
 	select TRACER_MAX_TRACE