linux-kernel - [RFC PATCH v3 00/14] m68k: Drop arch_gettimeoffset and adopt clocksource API

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Date:   Sat, 24 Nov 2018 14:09:03 +1100
From:   Finn Thain <fthain@...egraphics.com.au>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Andreas Schwab <schwab@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        Stephen N Chivers <schivers@....com.au>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kars de Jong <jongk@...ux-m68k.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Michael Schmitz <schmitzmic@...il.com>,
        John Stultz <john.stultz@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH v3 00/14] m68k: Drop arch_gettimeoffset and adopt clocksource API

This series removes "select ARCH_USES_GETTIMEOFFSET" from arch/m68k
and converts users of arch_gettimeoffset to the clocksource API.
Various bugs are fixed along the way.

Those platforms which do not actually implement arch_gettimeoffset
(apollo, q40, sun3, sun3x) use the "jiffies" clocksource by default.

The difficulty with these patches is the use of the timer interrupt to
update the counter for the clock source. The timer interrupt handler races
with clocksource read method, and both of those functions race with the
timer hardware.

Hence, more testing and code review would be appreciated.

Changed since v2:
 - Reinstated patch "m68k: hp300: Convert to clocksource API", and added
a new patch "m68k: hp300: Handle timer counter overflow" to address 
monotonicity issues.
 - Omitted a minor cleanup patch which may be merged independently.
 - Various other changes summarized in the relevant patches.

Changed since v1:
 - Dropped patches 1/13 and 2/13. These were a failed attempt to fix
5cfc8ee0bb51 and 4ad4c76b7afb. By adopting the clocksource API we can fix
this issue in mainline. By backporting this series we can fix it for -stable
(for m68k at least).
 - Dropped patch "m68k: hp300: Convert to clocksource API" and added
patch "m68k: hp300: Remove hp300_gettimeoffset".
 - Added a new patch to address an old m68k bug pointed out by Thomas
Gleixner. The bug can arise when a timer interrupt handler gets interrupted.
 - Added new patches to address old mvme16x and mvme147 bugs pointed out
by Thomas Gleixner. The bug could cause the clock to jump backwards.
 - Various other changes summarized in the relevant patches.


Finn Thain (14):
  m68k: Call timer_interrupt() with interrupts disabled
  m68k: mac: Fix VIA timer counter accesses
  m68k: apollo, q40, sun3, sun3x: Remove arch_gettimeoffset
    implementations
  m68k: Drop ARCH_USES_GETTIMEOFFSET
  m68k: amiga: Convert to clocksource API
  m68k: atari: Convert to clocksource API
  m68k: bvme6000: Convert to clocksource API
  m68k: hp300: Convert to clocksource API
  m68k: hp300: Handle timer counter overflow
  m68k: mac: Convert to clocksource API
  m68k: mvme147: Convert to clocksource API
  m68k: mvme147: Handle timer counter overflow
  m68k: mvme16x: Convert to clocksource API
  m68k: mvme16x: Handle timer counter overflow

 arch/m68k/Kconfig                 |   1 -
 arch/m68k/amiga/cia.c             |   9 ++
 arch/m68k/amiga/config.c          |  67 +++++++++-----
 arch/m68k/apollo/config.c         |   7 --
 arch/m68k/atari/ataints.c         |   4 +-
 arch/m68k/atari/config.c          |   2 -
 arch/m68k/atari/time.c            |  70 +++++++++++----
 arch/m68k/bvme6000/config.c       |  76 ++++++++++------
 arch/m68k/hp300/config.c          |   1 -
 arch/m68k/hp300/time.c            |  73 +++++++++++----
 arch/m68k/hp300/time.h            |   1 -
 arch/m68k/include/asm/mvme147hw.h |   2 +-
 arch/m68k/mac/config.c            |   3 -
 arch/m68k/mac/via.c               | 145 ++++++++++++++++++++----------
 arch/m68k/mvme147/config.c        |  73 ++++++++++-----
 arch/m68k/mvme16x/config.c        |  97 ++++++++++++++------
 arch/m68k/q40/config.c            |   9 --
 arch/m68k/q40/q40ints.c           |  19 ++--
 arch/m68k/sun3/config.c           |   2 -
 arch/m68k/sun3/intersil.c         |   7 --
 arch/m68k/sun3/sun3ints.c         |   3 +
 arch/m68k/sun3x/config.c          |   1 -
 arch/m68k/sun3x/time.c            |  21 +++--
 arch/m68k/sun3x/time.h            |   1 -
 24 files changed, 449 insertions(+), 245 deletions(-)

-- 
2.18.1