FDDI: defxx: Implement dynamic CSR I/O address space selection

Recent versions of the PCI Express specification have deprecated support
for I/O transactions and actually some PCIe host bridges, such as Power
Systems Host Bridge 4 (PHB4), do not implement them. Conversely a DEFEA
adapter can have its MMIO decoding disabled with ECU (EISA Configuration
Utility) and therefore not available for us with the resource allocation
infrastructure we implement.

However either I/O address space will always be available for use with
the DEFEA (EISA) and DEFPA (PCI) adapters and both have double address
decoding implemented in hardware for Control and Status Register access.
The two kinds of adapters can be present both at once in a single mixed
PCI/EISA system. For the DEFTA (TURBOchannel) variant there is no issue
as there has been no port I/O address space defined for that bus.

To make people's life easier and the driver more robust remove the
DEFXX_MMIO configuration option so as to rather than making the choice
for the I/O address space to use at build time for all the adapters
installed in the system let the driver choose the most suitable address
space dynamically on a case-by-case basis at run time. Make MMIO the
default and resort to port I/O should the default fail for some reason.

This way multiple adapters installed in one system can use different I/O
address spaces each, in particular in the presence of DEFEA adapters in
a pure-EISA or a mixed EISA/PCI system (it is expected that DEFPA boards
will use MMIO in normal circumstances).

The choice of the I/O address space to use continues being reported by
the driver on startup, e.g.:

eisa 00:05: EISA: slot 5: DEC3002 detected
defxx: v1.12 2021/03/10 Lawrence V. Stefani and others
00:05: DEFEA at I/O addr = 0x5000, IRQ = 10, Hardware addr = 00-00-f8-c8-b3-b6
00:05: registered as fddi0

and:

defxx: v1.12 2021/03/10 Lawrence V. Stefani and others
0031:02:04.0: DEFPA at MMIO addr = 0x620c080020000, IRQ = 57, Hardware addr = 00-60-6d-93-91-98
0031:02:04.0: registered as fddi0

and:

defxx: v1.12 2021/03/10 Lawrence V. Stefani and others
tc2: DEFTA at MMIO addr = 0x1f100000, IRQ = 21, Hardware addr = 08-00-2b-b0-8b-1e
tc2: registered as fddi0

so there is no need to add further information.

The change is supposed to cause a negligible performance hit as I/O
accessors will now have code executed conditionally at run time.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

FDDI: defxx: Make MMIO the configuration default except for EISA

Recent versions of the PCI Express specification have deprecated support
for I/O transactions and actually some PCIe host bridges, such as Power
Systems Host Bridge 4 (PHB4), do not implement them.

The default kernel configuration choice for the defxx driver is the use
of I/O ports rather than MMIO for PCI and EISA systems. It may have
made sense as a conservative backwards compatible choice back when MMIO
operation support was added to the driver as a part of TURBOchannel bus
support. However nowadays this configuration choice makes the driver
unusable with systems that do not implement I/O transactions for PCIe.

Make DEFXX_MMIO the configuration default then, except where configured
for EISA. This exception is because an EISA adapter can have its MMIO
decoding disabled with ECU (EISA Configuration Utility) and therefore
not available with the resource allocation infrastructure we implement,
while port I/O is always readily available as it uses slot-specific
addressing, directly mapped to the slot an option card has been placed
in and handled with our EISA bus support core. Conversely a kernel that
supports modern systems which may not have I/O transactions implemented
for PCIe will usually not be expected to handle legacy EISA systems.

The change of the default will make it easier for people, including but
not limited to distribution packagers, to make a working choice for the
driver.

Update the option description accordingly and while at it replace the
potentially ambiguous PIO acronym with IOP for "port I/O" vs "I/O ports"
according to our nomenclature used elsewhere.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Fixes: e89a2cfb7d7b ("[TC] defxx: TURBOchannel support")
Cc: stable@vger.kernel.org # v2.6.21+
Signed-off-by: David S. Miller <davem@davemloft.net>

docs: networking: move FDDI drivers to the hw driver section

Move docs for defza and skfp under device_drivers/fddi.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

treewide: replace '---help---' in Kconfig files with 'help'

Since commit 84af7a6194e4 ("checkpatch: kconfig: prefer 'help' over
'---help---'"), the number of '---help---' has been gradually
decreasing, but there are still more than 2400 instances.

This commit finishes the conversion. While I touched the lines,
I also fixed the indentation.

There are a variety of indentation styles found.

a) 4 spaces + '---help---'
b) 7 spaces + '---help---'
c) 8 spaces + '---help---'
d) 1 space + 1 tab + '---help---'
e) 1 tab + '---help---' (correct indentation)
f) 1 tab + 1 space + '---help---'
g) 1 tab + 2 spaces + '---help---'

In order to convert all of them to 1 tab + 'help', I ran the
following commend:

$ find . -name 'Kconfig*' | xargs sed -i 's/^[[:space:]]*---help---/\thelp/'

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

docs: networking: convert skfp.txt to ReST

- add SPDX header;
- use copyright symbol;
- add a document title;
- adjust titles and chapters, adding proper markups;
- comment out text-only TOC from html/pdf output;
- adjust identation, whitespaces and blank lines where needed;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

FDDI: defza: Add support for DEC FDDIcontroller 700 TURBOchannel adapter

Add support for the DEC FDDIcontroller 700 (DEFZA), Digital Equipment
Corporation's first-generation FDDI network interface adapter, made for
TURBOchannel and based on a discrete version of what eventually became
Motorola's widely used CAMEL chipset.

The CAMEL chipset is present for example in the DEC FDDIcontroller
TURBOchannel, EISA and PCI adapters (DEFTA/DEFEA/DEFPA) that we support
with the `defxx' driver, however the host bus interface logic and the
firmware API are different in the DEFZA and hence a separate driver is
required.

There isn't much to say about the driver except that it works, but there
is one peculiarity to mention. The adapter implements two Tx/Rx queue
pairs.

Of these one pair is the usual network Tx/Rx queue pair, in this case
used by the adapter to exchange frames with the ring, via the RMC (Ring
Memory Controller) chip. The Tx queue is handled directly by the RMC
chip and resides in onboard packet memory. The Rx queue is maintained
via DMA in host memory by adapter's firmware copying received data
stored by the RMC in onboard packet memory.

The other pair is used to communicate SMT frames with adapter's
firmware. Any SMT frame received from the RMC via the Rx queue must be
queued back by the driver to the SMT Rx queue for the firmware to
process. Similarly the firmware uses the SMT Tx queue to supply the
driver with SMT frames that must be queued back to the Tx queue for the
RMC to send to the ring.

This solution was chosen because the designers ran out of PCB space and
could not squeeze in more logic onto the board that would be required to
handle this SMT frame traffic without the need to involve the driver, as
with the later DEFTA/DEFEA/DEFPA adapters.

Finally the driver does some Frame Control byte decoding, so to avoid
magic numbers some macros are added to <linux/if_fddi.h>.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

fddi: Move the FDDI drivers

Move the FDDI drivers into drivers/net/fddi/ and make the
necessary Kconfig and Makefile changes.

CC: "Maciej W. Rozycki" <macro@linux-mips.org>
CC: Christoph Goos <cgoos@syskonnect.de>
CC: <linux@syskonnect.de>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>