diff mbox series

[3/3] timekeeping: remove arch_gettimeoffset

Message ID 20201008154601.1901004-4-arnd@arndb.de
State New
Headers show
Series ARM, timers: ebsa110 cleanup | expand

Commit Message

Arnd Bergmann Oct. 8, 2020, 3:46 p.m. UTC 
With Arm EBSA110 gone, nothing uses it any more, so the corresponding
code and the Kconfig option can be removed.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 .../time/modern-timekeeping/arch-support.txt  | 33 -------------------
 drivers/Makefile                              |  2 --
 drivers/clocksource/Kconfig                   |  2 +-
 include/linux/time.h                          | 13 --------
 kernel/time/Kconfig                           |  9 -----
 kernel/time/clocksource.c                     |  8 -----
 kernel/time/timekeeping.c                     | 25 +-------------
 kernel/trace/Kconfig                          |  2 --
 8 files changed, 2 insertions(+), 92 deletions(-)
 delete mode 100644 Documentation/features/time/modern-timekeeping/arch-support.txt

Comments

Thomas Gleixner Oct. 14, 2020, 12:41 a.m. UTC | #1 
On Thu, Oct 08 2020 at 17:46, Arnd Bergmann wrote:
> With Arm EBSA110 gone, nothing uses it any more, so the corresponding
> code and the Kconfig option can be removed.

Yay! It only took 11+ years to get rid of that.

Feel free to route it through your tree.

Acked-by: Thomas Gleixner <tglx@linutronix.de>
Linus Walleij Oct. 15, 2020, 7:53 a.m. UTC | #2 
On Thu, Oct 8, 2020 at 5:46 PM Arnd Bergmann <arnd@arndb.de> wrote:

> With Arm EBSA110 gone, nothing uses it any more, so the corresponding
> code and the Kconfig option can be removed.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Very nice cleanup.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

At some point we should do a retrospect about how hard it really is for
us to get rid of some really annoying core legacy codepaths and the best
strategy for doing so, even though this took 11+ years as Thomas
says it still looks like a solid path to move over to a generic framework,
only it requires enough gritty people (like you) to hang around and do the
work piece by piece.

Yours,
Linus Walleij
Russell King (Oracle) Oct. 15, 2020, 9:53 a.m. UTC | #3 
On Thu, Oct 15, 2020 at 09:53:29AM +0200, Linus Walleij wrote:
> On Thu, Oct 8, 2020 at 5:46 PM Arnd Bergmann <arnd@arndb.de> wrote:
> 
> > With Arm EBSA110 gone, nothing uses it any more, so the corresponding
> > code and the Kconfig option can be removed.
> >
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> 
> Very nice cleanup.
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> 
> At some point we should do a retrospect about how hard it really is for
> us to get rid of some really annoying core legacy codepaths and the best
> strategy for doing so, even though this took 11+ years as Thomas
> says it still looks like a solid path to move over to a generic framework,
> only it requires enough gritty people (like you) to hang around and do the
> work piece by piece.

Don't be misled. It was not a matter of "enough gritty people", it
was a matter that EBSA110 was blocking it.
Linus Walleij Oct. 15, 2020, 12:38 p.m. UTC | #4 
On Thu, Oct 15, 2020 at 11:53 AM Russell King - ARM Linux admin
<linux@armlinux.org.uk> wrote:

> Don't be misled. It was not a matter of "enough gritty people", it
> was a matter that EBSA110 was blocking it.

I remember that EBSA110 was quite different in that it had this
especially limited PIT timer, true that. At one point I even read
up on the details of it and then forgot them :/

Yours,
Linus Walleij
Russell King (Oracle) Oct. 18, 2020, 9:51 a.m. UTC | #5 
On Thu, Oct 15, 2020 at 02:38:07PM +0200, Linus Walleij wrote:
> On Thu, Oct 15, 2020 at 11:53 AM Russell King - ARM Linux admin
> <linux@armlinux.org.uk> wrote:
> 
> > Don't be misled. It was not a matter of "enough gritty people", it
> > was a matter that EBSA110 was blocking it.
> 
> I remember that EBSA110 was quite different in that it had this
> especially limited PIT timer, true that. At one point I even read
> up on the details of it and then forgot them :/

Yes, it was so basic that it required software to reprogram it on every
interrupt - it had no sensible periodic mode. The side effect of which
was that unless done carefully, your timekeeping varied all over the
place (so much that ntpd was not happy.) The final implementation made
ntpd really quite happy on the machine despite the timer's weirdness,
up until Linux stopped allowing interrupts to be nested. At that point,
it was back to utterly crap timekeeping.
diff mbox series

Patch

diff --git a/Documentation/features/time/modern-timekeeping/arch-support.txt b/Documentation/features/time/modern-timekeeping/arch-support.txt
deleted file mode 100644
index a84c3b9d9a94..000000000000
--- a/Documentation/features/time/modern-timekeeping/arch-support.txt
+++ /dev/null
@@ -1,33 +0,0 @@ 
-#
-# 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  |
-    -----------------------
diff --git a/drivers/Makefile b/drivers/Makefile
index c0cd1b9075e3..4ff1e4459512 100644
--- a/drivers/Makefile
+++ b/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/
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 68b087bff59c..764936bfcb2c 100644
--- a/drivers/clocksource/Kconfig
+++ b/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
diff --git a/include/linux/time.h b/include/linux/time.h
index b142cb5f5a53..16cf4522d6f3 100644
--- a/include/linux/time.h
+++ b/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
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index a09b1d61df6a..51d298ccbe05 100644
--- a/kernel/time/Kconfig
+++ b/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
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 02441ead3c3b..cce484a2cc7c 100644
--- a/kernel/time/clocksource.c
+++ b/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
  *
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4c47f388a83f..cf99a9a00716 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -352,13 +352,6 @@  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;
@@ -366,8 +359,7 @@  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)
@@ -707,16 +699,8 @@  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);
 }
 
@@ -2062,19 +2046,12 @@  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);
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index a4020c0b4508..b74099f990bf 100644
--- a/kernel/trace/Kconfig
+++ b/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