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[RFC,v2,00/39] Kconfig: Introduce HAS_IOPORT config option

Message ID 20220429135108.2781579-1-schnelle@linux.ibm.com (mailing list archive)
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Series Kconfig: Introduce HAS_IOPORT config option | expand

Message

Niklas Schnelle April 29, 2022, 1:49 p.m. UTC 
Hello Kernel Hackers,

Some platforms such as s390 do not support PCI I/O spaces. On such platforms
I/O space accessors like inb()/outb() are stubs that can never actually work.
The way these stubs are implemented in asm-generic/io.h leads to compiler
warnings because any use will cause a NULL pointer access. In a previous patch
we tried handling this with a run-time warning on access. This approach however
was rejected by Linus[0] with the argument that this really should be
a compile-time check and, though a much more invasive change, we believe that
is indeed the right approach.

This patch series aims to do exactly that by introducing a HAS_IOPORT config
option akin to the existing HAS_IOMEM. When this is unset inb()/outb() and
friends may not be defined.

This series builts heavily on an original patch for demonstating the concept by
Arnd Bergmann[1] and is a stripped down version of a previous RFC[2]. The most
important change being that we dropped the LEGACY_PCI config option in favor of
using HAS_IOPORT regardless of whether the device is a legacy PCI device.
As this is a significant change to the overall series I did not carry over
previous R-bs.

This version is based on v5.18-rc4 and is also available on my kernel.org tree
in the has_ioport branch with the PGP signed tag has_ioport_rfc_v2:

https://git.kernel.org/pub/scm/linux/kernel/git/niks/linux.git

Thanks,
Niklas Schnelle

Changes from RFC v1:
- Completely dropped the LEGACY_PCI option and replaced its dependencies with
  HAS_IOPORT as appropriate
- In the usb subsystem patch I incorporated the feedback from v1 by Alan Stern:
  - Used a local macro to nop in*()/out*() in the helpers
  - Removed an unnecessary further restriction on CONFIG_USB_UHCI_HCD
- Added a few more subsystems including wireless, ptp, and, mISDN that I had
  previously missed due to a blanket !S390.
- Removed blanket !S390 dependencies where they are added due to the I/O port
  problem
- In the sound system SND_OPL3_LIB needed to use "depends on" instead of
  "select" because of its added HAS_IOPORT dependency
- In the drm subsystem the bochs driver gets #ifdefs instead of a blanket
  dependency because its MMIO capable device variant should work without
  HAS_IOPORT.

[0] https://lore.kernel.org/lkml/CAHk-=wg80je=K7madF4e7WrRNp37e3qh6y10Svhdc7O8SZ_-8g@mail.gmail.com/
[1] https://lore.kernel.org/lkml/CAK8P3a0MNbx-iuzW_-=0ab6-TTZzwV-PT_6gAC1Gp5PgYyHcrA@mail.gmail.com/
[2] https://yhbt.net/lore/all/20211227164317.4146918-1-schnelle@linux.ibm.com/

Niklas Schnelle (39):
  Kconfig: introduce HAS_IOPORT option and select it as necessary
  ACPI: add dependency on HAS_IOPORT
  ata: add HAS_IOPORT dependencies
  char: impi, tpm: depend on HAS_IOPORT
  comedi: add HAS_IOPORT dependencies
  counter: add HAS_IOPORT dependencies
  /dev/port: don't compile file operations without CONFIG_DEVPORT
  drm: handle HAS_IOPORT dependencies
  firmware: dmi-sysfs: handle HAS_IOPORT=n
  gpio: add HAS_IOPORT dependencies
  hwmon: add HAS_IOPORT dependencies
  i2c: add HAS_IOPORT dependencies
  iio: adc: Kconfig: add HAS_IOPORT dependencies
  Input: add HAS_IOPORT dependencies
  Input: gameport: add ISA and HAS_IOPORT dependencies
  leds: add HAS_IOPORT dependencies
  media: add HAS_IOPORT dependencies
  misc: add HAS_IOPORT dependencies
  mISDN: add HAS_IOPORT dependencies
  mpt fusion: add HAS_IOPORT dependencies
  net: add HAS_IOPORT dependencies
  parport: PC style parport depends on HAS_IOPORT
  PCI: make quirk using inw() depend on HAS_IOPORT
  PCI/sysfs: make I/O resource depend on HAS_IOPORT
  pcmcia: add HAS_IOPORT dependencies
  platform: add HAS_IOPORT dependencies
  pnp: add HAS_IOPORT dependencies
  power: add HAS_IOPORT dependencies
  rtc: add HAS_IOPORT dependencies
  scsi: add HAS_IOPORT dependencies
  sound: add HAS_IOPORT dependencies
  speakup: add HAS_IOPORT dependency for SPEAKUP_SERIALIO
  staging: add HAS_IOPORT dependencies
  tty: serial: add HAS_IOPORT dependencies
  usb: handle HAS_IOPORT dependencies
  video: handle HAS_IOPORT dependencies
  watchdog: add HAS_IOPORT dependencies
  wireless: add HAS_IOPORT dependencies
  asm-generic/io.h: drop inb() etc for HAS_IOPORT=n

 arch/alpha/Kconfig                           |   1 +
 arch/arm/Kconfig                             |   1 +
 arch/arm64/Kconfig                           |   1 +
 arch/ia64/Kconfig                            |   1 +
 arch/m68k/Kconfig                            |   1 +
 arch/microblaze/Kconfig                      |   1 +
 arch/mips/Kconfig                            |   1 +
 arch/parisc/Kconfig                          |   1 +
 arch/powerpc/Kconfig                         |   1 +
 arch/riscv/Kconfig                           |   1 +
 arch/sh/Kconfig                              |   1 +
 arch/sparc/Kconfig                           |   1 +
 arch/x86/Kconfig                             |   1 +
 drivers/accessibility/speakup/Kconfig        |   1 +
 drivers/acpi/Kconfig                         |   1 +
 drivers/ata/Kconfig                          |   1 +
 drivers/bus/Kconfig                          |   2 +-
 drivers/char/Kconfig                         |   3 +-
 drivers/char/ipmi/Makefile                   |  11 +-
 drivers/char/ipmi/ipmi_si_intf.c             |   3 +-
 drivers/char/ipmi/ipmi_si_pci.c              |   3 +
 drivers/char/mem.c                           |   6 +-
 drivers/char/tpm/Kconfig                     |   1 +
 drivers/char/tpm/tpm_infineon.c              |  14 +-
 drivers/char/tpm/tpm_tis_core.c              |  19 ++-
 drivers/comedi/Kconfig                       |  33 ++++-
 drivers/counter/Kconfig                      |   1 +
 drivers/firmware/dmi-sysfs.c                 |   4 +
 drivers/gpio/Kconfig                         |   2 +-
 drivers/gpu/drm/qxl/Kconfig                  |   1 +
 drivers/gpu/drm/tiny/bochs.c                 |  19 +++
 drivers/gpu/drm/tiny/cirrus.c                |   2 +
 drivers/hwmon/Kconfig                        |  21 ++-
 drivers/i2c/busses/Kconfig                   |  31 +++--
 drivers/iio/adc/Kconfig                      |   2 +-
 drivers/input/gameport/Kconfig               |   4 +-
 drivers/input/serio/Kconfig                  |   2 +
 drivers/input/touchscreen/Kconfig            |   1 +
 drivers/isdn/Kconfig                         |   1 -
 drivers/isdn/hardware/mISDN/Kconfig          |  12 +-
 drivers/leds/Kconfig                         |   2 +-
 drivers/media/pci/dm1105/Kconfig             |   2 +-
 drivers/media/radio/Kconfig                  |  14 +-
 drivers/media/rc/Kconfig                     |   6 +
 drivers/message/fusion/Kconfig               |   2 +-
 drivers/misc/altera-stapl/Makefile           |   3 +-
 drivers/misc/altera-stapl/altera.c           |   6 +-
 drivers/net/Kconfig                          |   2 +-
 drivers/net/arcnet/Kconfig                   |   2 +-
 drivers/net/can/cc770/Kconfig                |   1 +
 drivers/net/can/sja1000/Kconfig              |   1 +
 drivers/net/ethernet/8390/Kconfig            |   2 +-
 drivers/net/ethernet/amd/Kconfig             |   2 +-
 drivers/net/ethernet/intel/Kconfig           |   2 +-
 drivers/net/ethernet/sis/Kconfig             |   4 +-
 drivers/net/ethernet/ti/Kconfig              |   2 +-
 drivers/net/ethernet/via/Kconfig             |   1 +
 drivers/net/fddi/Kconfig                     |   2 +-
 drivers/net/hamradio/Kconfig                 |   6 +-
 drivers/net/wan/Kconfig                      |   2 +-
 drivers/net/wireless/atmel/Kconfig           |   2 +-
 drivers/net/wireless/intersil/hostap/Kconfig |   2 +-
 drivers/parport/Kconfig                      |   4 +-
 drivers/pci/pci-sysfs.c                      |  16 +++
 drivers/pci/quirks.c                         |   2 +
 drivers/pcmcia/Kconfig                       |   2 +-
 drivers/platform/chrome/Kconfig              |   1 +
 drivers/platform/chrome/wilco_ec/Kconfig     |   1 +
 drivers/pnp/isapnp/Kconfig                   |   2 +-
 drivers/power/reset/Kconfig                  |   1 +
 drivers/rtc/Kconfig                          |   4 +-
 drivers/scsi/Kconfig                         |  19 +--
 drivers/scsi/aic7xxx/Kconfig.aic79xx         |   2 +-
 drivers/scsi/aic7xxx/Kconfig.aic7xxx         |   2 +-
 drivers/scsi/aic94xx/Kconfig                 |   2 +-
 drivers/scsi/megaraid/Kconfig.megaraid       |   6 +-
 drivers/scsi/mvsas/Kconfig                   |   2 +-
 drivers/scsi/qla2xxx/Kconfig                 |   2 +-
 drivers/staging/sm750fb/Kconfig              |   2 +-
 drivers/staging/vt6655/Kconfig               |   2 +-
 drivers/tty/Kconfig                          |   2 +-
 drivers/tty/serial/8250/Kconfig              |   2 +-
 drivers/tty/serial/Kconfig                   |   2 +-
 drivers/usb/core/hcd-pci.c                   |   2 +
 drivers/usb/host/Kconfig                     |   4 +-
 drivers/usb/host/pci-quirks.c                | 128 ++++++++++---------
 drivers/usb/host/pci-quirks.h                |  31 +++--
 drivers/usb/host/uhci-hcd.c                  |   2 +-
 drivers/usb/host/uhci-hcd.h                  |  33 +++--
 drivers/video/fbdev/Kconfig                  |  25 ++--
 drivers/watchdog/Kconfig                     |   6 +-
 include/asm-generic/io.h                     |   5 +
 include/linux/gameport.h                     |   9 +-
 include/linux/parport.h                      |   2 +-
 include/video/vga.h                          |   8 ++
 lib/Kconfig                                  |   4 +
 lib/Kconfig.kgdb                             |   1 +
 net/ax25/Kconfig                             |   2 +-
 sound/drivers/Kconfig                        |   5 +
 sound/isa/Kconfig                            |  44 +++----
 sound/pci/Kconfig                            |  64 +++++++---
 101 files changed, 489 insertions(+), 246 deletions(-)

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>