[RFC v4 00/25] Re-use nvram module

From	Finn Thain <fthain@telegraphics.com.au>
Newsgroups	linux.kernel
Subject	[RFC v4 00/25] Re-use nvram module
Date	2015-07-12 12:50 +0200
Message-ID	<pLmZz-7cl-3@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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The generic NVRAM module, drivers/char/generic_nvram, implements a
/dev/nvram misc device. It is used only by 32-bit PowerPC platforms and
isn't generic enough to be more widely used.

The RTC NVRAM module, drivers/char/nvram, also implements a /dev/nvram
misc device. It is used by x86, ARM and m68k.

The former module cannot be used on x86, ARM or m68k because it
cannot co-exist with the latter module, partly due to the Kconfig logic.

It is possible to modify the modules so that one kernel binary could
have either, neither or both. However, automatically loading the
appropriate module is then impossible; if both provide the
char-major-10-144 alias then the wrong module will end up being loaded.
Hence a multi-platform kernel binary needs a single generic nvram module
with alias char-major-10-144.

Therefore, drivers/char/nvram.c should be made more generic and the
arch-specific code therein should be moved to a more appropriate
place under arch/. Also, drivers/char/generic_nvram.c should be removed
to reduce code duplication.

In this patch series, Atari-specific code is moved from the nvram module
to arch/m68k/atari. More arch-specific code in the nvram module could
be moved, probably to arch/x86, but it is difficult to determine just
what code is relevant to ARM platforms and what code is x86-only.

In addressing code duplication, this patch series removes three
inconsistent /dev/nvram misc device implementations. One of these,
drivers/macintosh/nvram.c is entirely unused already. The other two,
drivers/char/generic_nvram.c and the misc device implementation in
arch/powerpc/kernel/nvram_64.c, are replaced by drivers/char/nvram.c.

A benefit of this work is better consistency -- between PPC32 and PPC64
as well as between PPC_PMAC and MAC. This new uniformity does have
implications for userspace, that is, some error codes for some ioctl calls
become consistent on all PowerPC platforms.

The drivers/char/nvram module becomes sufficiently generic to be useful
to other platforms and architectures, besides those with "CMOS" RTC. At the
end of this patch series the module is adopted by the m68k Mac port, which
already has PRAM access functions but lacks the /dev/nvram misc device.

This patch series has been compile-tested for arm, m68k, powerpc and x86.
The nvram and thinkpad_acpi modules were regression tested on a ThinkPad T43.
The /dev/nvram functionality was also regression tested on a G3 PowerMac.
The nvram module was also tested on a PowerBook 520 and Quadra 650.
Note that my testing doesn't cover PPC64 or Atari.

Changes since v1:
- Minor changes to patches 7, 15 and 20 as described in commit logs.
- Revised patches 21 and 24 to address comments from Geert.

Changes since v2:
- Dropped patch 1, "macintosh/nvram: Remove as unused", because it has
since been merged.
- Inserted a new patch, "m68k/mac: Use macros for RTC accesses not
magic numbers".
- Revised patches 21 and 23 to address comments from Geert.

Changes since v3:
- Split the patch, "m68k/atari: Move Atari-specific code out of
drivers/char/nvram.c", as suggested by Geert.
- Revised patches 11 and 25 to address comments from Geert.
- Minor change to patch 21 as described in commit log.

---
 arch/m68k/Kconfig                          |    3 
 arch/m68k/Kconfig.machine                  |    2 
 arch/m68k/atari/Makefile                   |    2 
 arch/m68k/atari/nvram.c                    |  291 +++++++++++
 arch/m68k/include/asm/atarihw.h            |    6 
 arch/m68k/include/asm/macintosh.h          |    4 
 arch/m68k/kernel/setup_mm.c                |  100 +++
 arch/m68k/mac/misc.c                       |  207 +++++---
 arch/powerpc/Kconfig                       |    5 
 arch/powerpc/include/asm/nvram.h           |    9 
 arch/powerpc/kernel/nvram_64.c             |  203 +------
 arch/powerpc/kernel/setup_32.c             |   27 -
 arch/powerpc/platforms/chrp/Makefile       |    2 
 arch/powerpc/platforms/chrp/nvram.c        |   14 
 arch/powerpc/platforms/chrp/setup.c        |    2 
 arch/powerpc/platforms/powermac/Makefile   |    5 
 arch/powerpc/platforms/powermac/nvram.c    |    9 
 arch/powerpc/platforms/powermac/setup.c    |    3 
 arch/powerpc/platforms/pseries/nvram.c     |    2 
 drivers/char/Kconfig                       |   13 
 drivers/char/Makefile                      |    6 
 drivers/char/generic_nvram.c               |  174 ------
 drivers/char/nvram.c                       |  742 ++++++++++++-----------------
 drivers/platform/x86/thinkpad_acpi.c       |   20 
 drivers/scsi/Kconfig                       |    6 
 drivers/scsi/atari_scsi.c                  |   16 
 drivers/video/fbdev/controlfb.c            |    4 
 drivers/video/fbdev/imsttfb.c              |    7 
 drivers/video/fbdev/matrox/matroxfb_base.c |    4 
 drivers/video/fbdev/platinumfb.c           |    4 
 drivers/video/fbdev/valkyriefb.c           |    4 
 include/linux/nvram.h                      |   23 
 include/uapi/linux/pmu.h                   |    2 
 33 files changed, 986 insertions(+), 935 deletions(-)




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[RFC v4 00/25] Re-use nvram module Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 11/25] m68k/atari: Implement arch_nvram_ops methods and enable CONFIG_HAVE_ARCH_NVRAM_OPS Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 16/25] powerpc: Implement nvram sync ioctl Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 15/25] powerpc: Implement arch_nvram_ops.get_size() and remove old nvram_* exports Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 24/25] m68k/mac: Fix PRAM accessors Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 18/25] nvram: Drop nvram_* symbol exports and prototypes Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 14/25] powerpc: Add missing ppc_md.nvram_size for CHRP and PowerMac  Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 19/25] powerpc: Remove CONFIG_GENERIC_NVRAM and adopt CONFIG_HAVE_ARCH_NVRAM_OPS Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 09/25] char/nvram: Implement NVRAM read/write methods Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 13/25] powerpc: Cleanup nvram includes Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 10/25] char/nvram: Use generic fixed_size_llseek() Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 08/25] char/nvram: Allow the set_checksum and initialize ioctls to be omitted Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 01/25] scsi/atari_scsi: Dont select CONFIG_NVRAM Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 12/25] char/nvram: Add "devname:nvram" module alias Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 03/25] m68k/atari: Move Atari-specific code out of drivers/char/nvram.c Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
    Re: [RFC v4 03/25] m68k/atari: Move Atari-specific code out of  drivers/char/nvram.c Finn Thain <fthain@telegraphics.com.au> - 2015-07-14 10:20 +0200
      Re: [RFC v4 03/25] m68k/atari: Move Atari-specific code out of drivers/char/nvram.c Geert Uytterhoeven <geert@linux-m68k.org> - 2015-07-14 10:30 +0200
        Re: [RFC v4 03/25] m68k/atari: Move Atari-specific code out of drivers/char/nvram.c Andreas Schwab <schwab@linux-m68k.org> - 2015-07-14 10:40 +0200
  [RFC v4 21/25] powerpc: Adopt nvram module for PPC64 Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 25/25] m68k: Dispatch nvram_ops calls to Atari or Mac functions Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 23/25] m68k/mac: Use macros for RTC accesses not magic numbers Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 22/25] m68k/mac: Adopt naming and calling conventions for PRAM routines Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  [RFC v4 04/25] m68k/atari: Replace nvram_{read,write}_byte with arch_nvram_ops Finn Thain <fthain@telegraphics.com.au> - 2015-07-12 12:50 +0200
  Re: [RFC v4 00/25] Re-use nvram module Geert Uytterhoeven <geert@linux-m68k.org> - 2015-07-13 10:00 +0200

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