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Subject[RFC v2 00/39] Kconfig: Introduce HAS_IOPORT config option
Date
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>
--
2.32.0

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