[RFC 0/6] pcmcia: separate 16-bit support from cardbus

[Arnd Bergmann]

From: Arnd Bergmann <arnd at arndb.de>

Based on some recent discussions [1][2][3], I experimented wtih what
drivers/pcmcia would look like if we completely removed 16-bit support,
which was one of the options that Dominik suggested for winding down
pcmcia maintenance.

The remaining cardbus/yenta support is essentially a PCI hotplug driver
with a slightly unusual sysfs interface, and it would still support all
32-bit cardbus hosts and cards, but no longer work with the even older
16-bit cards that require the pcmcia_driver infrastructure.

I don't expect this to be a problem normal laptop support, as the last
PC models that predate Cardbus support (e.g. 1997 ThinkPad 380ED) are
all limited to i586MMX CPUs and 80MB of RAM. This is barely enough to
boot Tiny Core Linux but not a regular distro.

Support for device drivers is somewhat less clear. Losing support for
16-bit cards in cardbus sockets is obviously a limiting factor for
anyone who still has those cards, but there is also a good chance that
the only reason to keep the cards around is for using them in pre-cardbus
machines that cannot be upgrade to 32-bit devices.

Completely removing the 16-bit PCMCIA support would however break some
20+ year old embedded machines that rely on CompactFlash cards as their
mass-storage device (extension), this notably includes early PocketPC
models and the reference implementations for OMAP1, StrongARM1100,
Alchemy and PA-Semi. All of these are still maintained, though most
of the PocketPC machines got removed in the 6.3 merge window and the
PA-Semi Electra board is the only one that was introduced after
2003.

The approach that I take in this series is to split drivers/pcmcia
into two mutually incompatible parts: the Cardbus support contains
all the code that is relevant for post-1997 laptops and gets moved
to drivers/pci/hotplug, while the drivers/pcmcia/ subsystem is
retained for both the older laptops and the embedded systems but no
longer works with the yenta socket host driver. The BCM63xx
PCMCIA/Cardbus host driver appears to be unused and conflicts with
this series, so it is removed in the process.

My series does not touch any of the pcmcia_driver instances, but
if there is consensus about splitting out the cardbus support,
a lot of them can probably get removed as a follow-up.

[1] https://lore.kernel.org/all/Y07d7rMvd5++85BJ@owl.dominikbrodowski.net/
[2] https://lore.kernel.org/all/c5b39544-a4fb-4796-a046-0b9be9853787@app.fastmail.com/
[3] https://lore.kernel.org/all/20230222092302.6348-1-jirislaby@kernel.org/

Cc: Bjorn Helgaas <bhelgaas at google.com>
Cc: Dominik Brodowski <linux at dominikbrodowski.net>
Cc: Florian Fainelli <f.fainelli at gmail.com>
Cc: H Hartley Sweeten <hsweeten at visionengravers.com>
Cc: Ian Abbott <abbotti at mev.co.uk>
Cc: Jakub Kicinski <kuba at kernel.org>
Cc: Kevin Cernekee <cernekee at gmail.com>
Cc: Lukas Wunner <lukas at wunner.de>
Cc: Manuel Lauss <manuel.lauss at gmail.com>
Cc: Oliver Hartkopp <socketcan at hartkopp.net>
Cc: Olof Johansson <olof at lixom.net>
Cc: Robert Jarzmik <robert.jarzmik at free.fr>
Cc: YOKOTA Hiroshi <yokota at netlab.is.tsukuba.ac.jp>
Cc: bcm-kernel-feedback-list at broadcom.com
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-can at vger.kernel.org
Cc: linux-mips at vger.kernel.org
Cc: linux-pci at vger.kernel.org
Cc: linux-wireless at vger.kernel.org
Cc: netdev at vger.kernel.org

Arnd Bergmann (6):
  pccard: remove bcm63xx socket driver
  pccard: split cardbus support from pcmcia
  yenta_socket: copy pccard core code into driver
  yenta_socket: remove dead code
  pccard: drop remnants of cardbus support
  pci: hotplug: move cardbus code from drivers/pcmcia

 arch/mips/bcm63xx/Makefile                    |    2 +-
 arch/mips/bcm63xx/boards/board_bcm963xx.c     |   14 -
 arch/mips/bcm63xx/dev-pcmcia.c                |  144 -
 arch/mips/configs/bcm63xx_defconfig           |    1 -
 .../asm/mach-bcm63xx/bcm63xx_dev_pcmcia.h     |   14 -
 arch/mips/pci/ops-bcm63xx.c                   |  294 --
 arch/mips/pci/pci-bcm63xx.c                   |   44 -
 drivers/Makefile                              |    2 +-
 drivers/pci/hotplug/Kconfig                   |   56 +
 drivers/pci/hotplug/Makefile                  |    1 +
 drivers/pci/hotplug/yenta_socket.c            | 4056 +++++++++++++++++
 drivers/pcmcia/Kconfig                        |   63 +-
 drivers/pcmcia/Makefile                       |   13 +-
 drivers/pcmcia/bcm63xx_pcmcia.c               |  538 ---
 drivers/pcmcia/bcm63xx_pcmcia.h               |   61 -
 drivers/pcmcia/cardbus.c                      |  124 -
 drivers/pcmcia/cistpl.c                       |   10 +-
 drivers/pcmcia/cs.c                           |  103 +-
 drivers/pcmcia/cs_internal.h                  |   10 +-
 drivers/pcmcia/ds.c                           |   14 +-
 drivers/pcmcia/i82092.c                       |    2 +-
 drivers/pcmcia/i82365.c                       |    2 +-
 drivers/pcmcia/o2micro.h                      |  183 -
 drivers/pcmcia/pd6729.c                       |    3 +-
 drivers/pcmcia/ricoh.h                        |  169 -
 drivers/pcmcia/socket_sysfs.c                 |    2 -
 drivers/pcmcia/ti113x.h                       |  978 ----
 drivers/pcmcia/topic.h                        |  168 -
 drivers/pcmcia/yenta_socket.c                 | 1455 ------
 drivers/pcmcia/yenta_socket.h                 |  136 -
 {drivers => include}/pcmcia/i82365.h          |    0
 include/pcmcia/ss.h                           |   21 -
 32 files changed, 4147 insertions(+), 4536 deletions(-)
 delete mode 100644 arch/mips/bcm63xx/dev-pcmcia.c
 delete mode 100644 arch/mips/include/asm/mach-bcm63xx/bcm63xx_dev_pcmcia.h
 create mode 100644 drivers/pci/hotplug/yenta_socket.c
 delete mode 100644 drivers/pcmcia/bcm63xx_pcmcia.c
 delete mode 100644 drivers/pcmcia/bcm63xx_pcmcia.h
 delete mode 100644 drivers/pcmcia/cardbus.c
 delete mode 100644 drivers/pcmcia/o2micro.h
 delete mode 100644 drivers/pcmcia/ti113x.h
 delete mode 100644 drivers/pcmcia/topic.h
 delete mode 100644 drivers/pcmcia/yenta_socket.c
 delete mode 100644 drivers/pcmcia/yenta_socket.h
 rename {drivers => include}/pcmcia/i82365.h (100%)

-- 
2.39.2