[v3,00/38] Kconfig: Introduce HAS_IOPORT config option

  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 be a NULL pointer access on these platforms. 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 is also the same approach originally planned by
Uwe Kleine-König as mentioned in commit ce816fa88cca ("Kconfig: rename
HAS_IOPORT to HAS_IOPORT_MAP").

This series builds heavily on an original patch for demonstating the concept by
Arnd Bergmann[1] and incoporates feedback of previous RFC versions [2] and [3].

This version is based on v6.3-rc1 and is also available on my kernel.org tree
in the has_ioport_v3 branch with the PGP signed tag has_ioport_v3_signed:

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

Thanks,
Niklas Schnelle

Changes from RFC v2:
- Rebased on v6.3-rc1
- Fixed a NULL pointer dereference in set_io_from_upio() due to accidentially
  expanded #ifdef CONFIG_SERIAL_8250_RT288X (kernel test robot)
- Dropped "ACPI: add dependency on HAS_IOPORT" (Bjorn Helgaas)
- Reworded commit message and moved ifdefs for "PCI/sysfs: Make I/O resource
  depend on HAS_IOPORT" (Bjorn Helgaas)
- Instead of complete removal inb() etc. are marked with __compiletime_error()
  when HAS_IOPORT is unset allowing for better error reporting (Ahmad Fatoum)
- Removed HAS_IOPORT dependency from PCMCIA as I/O port use is optional in at
  least PC Card. Instead added HAS_IOPORT on a per driver basis. (Bjorn
  Helgaas)
- Made uhci_has_pci_registers() constant 0 if HAS_IOPORT is not defined (Alan
  Stern)

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/
[3] https://lore.kernel.org/all/20220429135108.2781579-1-schnelle@linux.ibm.com/

Niklas Schnelle (38):
  Kconfig: introduce HAS_IOPORT option and select it as necessary
  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: ad7606: 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: handle 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: handle 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                            |   2 +
 arch/parisc/Kconfig                          |   2 +
 arch/powerpc/Kconfig                         |   2 +-
 arch/riscv/Kconfig                           |   1 +
 arch/sh/Kconfig                              |   1 +
 arch/sparc/Kconfig                           |   1 +
 arch/um/Kconfig                              |   1 +
 arch/x86/Kconfig                             |   2 +
 drivers/accessibility/speakup/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/pcmcia/Kconfig                  |   8 +-
 drivers/char/tpm/Kconfig                     |   1 +
 drivers/char/tpm/tpm_infineon.c              |  14 ++-
 drivers/char/tpm/tpm_tis_core.c              |  19 ++-
 drivers/comedi/Kconfig                       | 103 +++++++++------
 drivers/counter/Kconfig                      |   1 +
 drivers/eisa/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/3com/Kconfig            |   4 +-
 drivers/net/ethernet/8390/Kconfig            |   6 +-
 drivers/net/ethernet/amd/Kconfig             |   4 +-
 drivers/net/ethernet/fujitsu/Kconfig         |   2 +-
 drivers/net/ethernet/intel/Kconfig           |   2 +-
 drivers/net/ethernet/sis/Kconfig             |   4 +-
 drivers/net/ethernet/smsc/Kconfig            |   2 +-
 drivers/net/ethernet/ti/Kconfig              |   2 +-
 drivers/net/ethernet/via/Kconfig             |   1 +
 drivers/net/ethernet/xircom/Kconfig          |   2 +-
 drivers/net/fddi/Kconfig                     |   2 +-
 drivers/net/fddi/defxx.c                     |   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                      |   4 +
 drivers/pci/quirks.c                         |   2 +
 drivers/pcmcia/Kconfig                       |   5 +-
 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                         |  25 ++--
 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/pcmcia/Kconfig                  |   6 +-
 drivers/scsi/qla2xxx/Kconfig                 |   2 +-
 drivers/staging/sm750fb/Kconfig              |   2 +-
 drivers/staging/vt6655/Kconfig               |   2 +-
 drivers/tty/Kconfig                          |   2 +-
 drivers/tty/serial/8250/8250_early.c         |   4 +
 drivers/tty/serial/8250/8250_pci.c           |  14 +++
 drivers/tty/serial/8250/8250_port.c          |  44 +++++--
 drivers/tty/serial/8250/Kconfig              |   5 +-
 drivers/tty/serial/Kconfig                   |   2 +-
 drivers/usb/core/hcd-pci.c                   |   2 +
 drivers/usb/host/Kconfig                     |   4 +-
 drivers/usb/host/pci-quirks.c                | 125 ++++++++++---------
 drivers/usb/host/pci-quirks.h                |  31 +++--
 drivers/usb/host/uhci-hcd.c                  |   2 +-
 drivers/usb/host/uhci-hcd.h                  |  36 ++++--
 drivers/video/console/Kconfig                |   1 +
 drivers/video/fbdev/Kconfig                  |  25 ++--
 drivers/watchdog/Kconfig                     |   6 +-
 include/asm-generic/io.h                     |  60 +++++++++
 include/linux/gameport.h                     |   9 +-
 include/linux/parport.h                      |   2 +-
 include/video/vga.h                          |   8 ++
 lib/Kconfig                                  |   4 +
 lib/Kconfig.kgdb                             |   3 +-
 net/ax25/Kconfig                             |   2 +-
 sound/drivers/Kconfig                        |   3 +
 sound/isa/Kconfig                            |  31 ++++-
 sound/pci/Kconfig                            |  45 +++++--
 sound/pcmcia/Kconfig                         |   2 +
 114 files changed, 649 insertions(+), 281 deletions(-)


base-commit: eeac8ede17557680855031c6f305ece2378af326
  

On Tue, 2023-03-14 at 13:11 +0100, Niklas Schnelle wrote:
> --- a/arch/um/Kconfig
> +++ b/arch/um/Kconfig
> @@ -56,6 +56,7 @@ config NO_IOPORT_MAP
>  
>  config ISA
>  	bool
> +	depends on HAS_IOPORT
> 

config ISA here is already unselectable, and nothing ever does "select
ISA" (only in some other architectures), so is there much point in this?

I'm not even sure why this exists at all.

But anyway, adding a dependency to a always-false symbol doesn't make it
less always-false :-)

Acked-by: Johannes Berg <johannes@sipsolutions.net> # for ARCH=um


Certainly will be nice to get rid of this cruft for architectures that
don't have it.

johannes
  

On Tue, Mar 14, 2023 at 1:13 PM Niklas Schnelle <schnelle@linux.ibm.com> wrote:
> We introduce a new HAS_IOPORT Kconfig option to indicate support for I/O
> Port access. In a future patch HAS_IOPORT=n will disable compilation of
> the I/O accessor functions inb()/outb() and friends on architectures
> which can not meaningfully support legacy I/O spaces such as s390. Also
> add dependencies on HAS_IOPORT for the ISA and HAVE_EISA config options
> as these busses always go along with HAS_IOPORT.
>
> The "depends on" relations on HAS_IOPORT in drivers as well as ifdefs
> for HAS_IOPORT specific sections will be added in subsequent patches on
> a per subsystem basis.
>
> Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>

>  arch/m68k/Kconfig       | 1 +

Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

Gr{oetje,eeting}s,

                        Geert
  

On Tue, Mar 14, 2023, at 13:11, Niklas Schnelle wrote:
> 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 be a NULL pointer access on these platforms. 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 is also the same approach originally planned by
> Uwe Kleine-König as mentioned in commit ce816fa88cca ("Kconfig: rename
> HAS_IOPORT to HAS_IOPORT_MAP").
>
> This series builds heavily on an original patch for demonstating the concept by
> Arnd Bergmann[1] and incoporates feedback of previous RFC versions [2] and [3].
>
> This version is based on v6.3-rc1 and is also available on my kernel.org tree
> in the has_ioport_v3 branch with the PGP signed tag has_ioport_v3_signed:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/niks/linux.git

Thanks a lot for the rebase, hopefully we can finally get this merged.
I'll go through all patches and note everything I spot that should
be improved. I'd like to make sure that at least the first patch
can get merged quickly so we can continue on the rest.

Since this is all related to asm-generic/io.h and cross-architecture
work, I can pick up anything that has nobody else maintaining it
through the asm-generic tree.

   Arnd