PCI/VGA: Select VGA devices earlier

Select VGA devices in vga_arb_device_init() and pci_notify() instead of in
vga_arbiter_add_pci_device().

This is a trivial optimization for adding devices. It's a bigger
optimization for the removal case because pci_notify() won't call
vga_arbiter_del_pci_device() for non-VGA devices, so it won't have to
search the vga_list for them.

https://lore.kernel.org/r/20230830111532.444535-3-sui.jingfeng@linux.dev
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
[bhelgaas: commit log, split from functional change]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Use pci_is_vga() to identify VGA devices

Use pci_is_vga() to identify VGA devices, so the arbiter will handle old
PCI_CLASS_NOT_DEFINED_VGA (0x0001) devices as well as the
PCI_CLASS_DISPLAY_VGA (0x0300) devices it previously handled.

Link: https://lore.kernel.org/r/20230830111532.444535-3-sui.jingfeng@linux.dev
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
[bhelgaas: commit log, split functional change from optimization]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>

arch: Remove Itanium (IA-64) architecture

The Itanium architecture is obsolete, and an informal survey [0] reveals
that any residual use of Itanium hardware in production is mostly HP-UX
or OpenVMS based. The use of Linux on Itanium appears to be limited to
enthusiasts that occasionally boot a fresh Linux kernel to see whether
things are still working as intended, and perhaps to churn out some
distro packages that are rarely used in practice.

None of the original companies behind Itanium still produce or support
any hardware or software for the architecture, and it is listed as
'Orphaned' in the MAINTAINERS file, as apparently, none of the engineers
that contributed on behalf of those companies (nor anyone else, for that
matter) have been willing to support or maintain the architecture
upstream or even be responsible for applying the odd fix. The Intel
firmware team removed all IA-64 support from the Tianocore/EDK2
reference implementation of EFI in 2018. (Itanium is the original
architecture for which EFI was developed, and the way Linux supports it
deviates significantly from other architectures.) Some distros, such as
Debian and Gentoo, still maintain [unofficial] ia64 ports, but many have
dropped support years ago.

While the argument is being made [1] that there is a 'for the common
good' angle to being able to build and run existing projects such as the
Grid Community Toolkit [2] on Itanium for interoperability testing, the
fact remains that none of those projects are known to be deployed on
Linux/ia64, and very few people actually have access to such a system in
the first place. Even if there were ways imaginable in which Linux/ia64
could be put to good use today, what matters is whether anyone is
actually doing that, and this does not appear to be the case.

There are no emulators widely available, and so boot testing Itanium is
generally infeasible for ordinary contributors. GCC still supports IA-64
but its compile farm [3] no longer has any IA-64 machines. GLIBC would
like to get rid of IA-64 [4] too because it would permit some overdue
code cleanups. In summary, the benefits to the ecosystem of having IA-64
be part of it are mostly theoretical, whereas the maintenance overhead
of keeping it supported is real.

So let's rip off the band aid, and remove the IA-64 arch code entirely.
This follows the timeline proposed by the Debian/ia64 maintainer [5],
which removes support in a controlled manner, leaving IA-64 in a known
good state in the most recent LTS release. Other projects will follow
once the kernel support is removed.

[0] https://lore.kernel.org/all/CAMj1kXFCMh_578jniKpUtx_j8ByHnt=s7S+yQ+vGbKt9ud7+kQ@mail.gmail.com/
[1] https://lore.kernel.org/all/0075883c-7c51-00f5-2c2d-5119c1820410@web.de/
[2] https://gridcf.org/gct-docs/latest/index.html
[3] https://cfarm.tetaneutral.net/machines/list/
[4] https://lore.kernel.org/all/87bkiilpc4.fsf@mid.deneb.enyo.de/
[5] https://lore.kernel.org/all/ff58a3e76e5102c94bb5946d99187b358def688a.camel@physik.fu-berlin.de/

Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

PCI/VGA: Fix typos

Fix typos, rewrap to fill 78 columns, convert to conventional multi-line
style.

[bhelgaas: squash and add more fixes]
Link: https://lore.kernel.org/r/20230808223412.1743176-7-sui.jingfeng@linux.dev
Link: https://lore.kernel.org/r/20230808223412.1743176-9-sui.jingfeng@linux.dev
Link: https://lore.kernel.org/r/20230808223412.1743176-10-sui.jingfeng@linux.dev
Link: https://lore.kernel.org/r/20230808223412.1743176-11-sui.jingfeng@linux.dev
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Simplify vga_client_register()

Reorganize vga_client_register() to avoid the goto and the need to save the
return value. Update the kernel-doc to reflect -ENODEV on failure. No
functional change intended.

[bhelgaas: drop "ret" variable, commit log]
Link: https://lore.kernel.org/r/20230808223412.1743176-8-sui.jingfeng@linux.dev
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Simplify vga_arbiter_notify_clients()

In vga_arbiter_notify_clients(), "new_state" was computed during every loop
iteration even though it doesn't depend on anything that changes during the
loop. Move the computation outside the loop.

[bhelgaas: drop renames that obscure the purpose, commit log]
Link: https://lore.kernel.org/r/20230808223412.1743176-6-sui.jingfeng@linux.dev
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Correct vga_update_device_decodes() parameter type

Previously vga_update_device_decodes() took "int new_decodes", but the
callers pass "unsigned int new_decodes". Correct the
vga_update_device_decodes() parameter type to "unsigned int" to match.

In vga_arbiter_notify_clients(), the return from vgadev->set_decode() is
"unsigned int" but was stored as "uint32_t new_decodes". Correct the
new_decodes type to "unsigned int".

[bhelgaas: use correct type for ->set_decode() return, commit log]
Link: https://lore.kernel.org/r/20230808223412.1743176-5-sui.jingfeng@linux.dev
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Correct vga_str_to_iostate() io_state parameter type

Previously vga_str_to_iostate() took "int *io_state", but vga_arb_write()
is the only caller and it passes "unsigned int *". Make the
vga_str_to_iostate() parameter type "unsigned int *" to match.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/20230808223412.1743176-2-sui.jingfeng@linux.dev
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

PCI: Introduce pci_dev_for_each_resource()

Instead of open-coding it everywhere introduce a tiny helper that can be
used to iterate over each resource of a PCI device, and convert the most
obvious users into it.

While at it drop doubled empty line before pdev_sort_resources().

No functional changes intended.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230330162434.35055-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Krzysztof Wilczyński <kw@linux.com>

PCI/VGA: Replace full MIT license text with SPDX identifier

Per Documentation/process/license-rules.rst, the SPDX MIT identifier is
equivalent to including the entire MIT license text from
LICENSES/preferred/MIT.

Replace the MIT license text with the equivalent SPDX identifier.

Link: https://lore.kernel.org/r/20220224224753.297579-12-helgaas@kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Use unsigned format string to print lock counts

In struct vga_device, io_lock_cnt and mem_lock_cnt are unsigned, but we
previously printed them with "%d", the signed decimal format. Print them
with the unsigned format "%u" instead.

Link: https://lore.kernel.org/r/20220224224753.297579-11-helgaas@kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Log bridge control messages when adding devices

Previously vga_arb_device_init() iterated through all VGA devices and
indicated whether legacy VGA routing to each could be controlled by an
upstream bridge.

But we determine that information in vga_arbiter_add_pci_device(), which we
call for every device, so we can log it there without iterating through the
VGA devices again.

Note that we call vga_arbiter_check_bridge_sharing() before adding the
device to vga_list, so we have to handle the very first device separately.

Link: https://lore.kernel.org/r/20220224224753.297579-10-helgaas@kernel.org
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Remove empty vga_arb_device_card_gone()

vga_arb_device_card_gone() has always been empty. Remove it.

Link: https://lore.kernel.org/r/20220224224753.297579-9-helgaas@kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Move disabled VGA device detection to ADD_DEVICE path

a37c0f48950b ("vgaarb: Select a default VGA device even if there's no
legacy VGA") extended the vga_arb_device_init() subsys_initcall so that if
there are no other eligible devices, it could select a disabled VGA device
as the default.

Move this detection from vga_arb_select_default_device() to
vga_arbiter_add_pci_device() so every device, even those hot-added or
enumerated after vga_arb_device_init() is eligible for selection as the
default VGA device.

[bhelgaas: commit log, restructure]
Link: https://lore.kernel.org/r/20211015061512.2941859-5-chenhuacai@loongson.cn
Link: https://lore.kernel.org/r/20220224224753.297579-8-helgaas@kernel.org
Signed-off-by: Huacai Chen <chenhuacai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Daniel Axtens <dja@axtens.net>
Cc: Zhou Wang <wangzhou1@hisilicon.com>

PCI/VGA: Move non-legacy VGA detection to ADD_DEVICE path

a37c0f48950b ("vgaarb: Select a default VGA device even if there's no
legacy VGA") extended the vga_arb_device_init() subsys_initcall so it could
select a non-legacy VGA device as the default.

That failed to consider that PCI devices may be enumerated after
vga_arb_device_init(), e.g., hot-added devices or non-ACPI systems that do
PCI enumeration in pcibios_init(). Devices found then could never be
selected as the default.

One system where this is a problem is the MIPS-based Loongson where an
ASpeed AST2500 VGA device is behind a bridge that doesn't implement the VGA
Enable bit, so legacy resources are not routed to the VGA device. [1]

Fix this by moving the non-legacy VGA device selection from
vga_arb_select_default_device() to vga_arbiter_add_pci_device(), which is
called after every PCI device is enumerated, either by the
vga_arb_device_init() subsys_initcall or as an ADD_DEVICE notifier.

[1] https://lore.kernel.org/r/20210514080025.1828197-6-chenhuacai@loongson.cn

[bhelgaas: commit log, restructure]
Link: https://lore.kernel.org/r/20211015061512.2941859-5-chenhuacai@loongson.cn
Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn
Link: https://lore.kernel.org/r/20220224224753.297579-7-helgaas@kernel.org
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Daniel Axtens <dja@axtens.net>
Cc: Zhou Wang <wangzhou1@hisilicon.com>

PCI/VGA: Move firmware default device detection to ADD_DEVICE path

Previously we selected the firmware default device, i.e., one that owns the
boot framebuffer, as the default device in vga_arb_select_default_device().
This was only done in the vga_arb_device_init() subsys_initcall, so devices
enumerated later, e.g., by pcibios_init(), were not eligible.

Fix this by moving the firmware default device selection from
vga_arb_select_default_device() to vga_arbiter_add_pci_device(), which is
called after every PCI device is enumerated, either by the
vga_arb_device_init() subsys_initcall or as an ADD_DEVICE notifier.

Note that if vga_arb_select_default_device() previously found a device
owning the boot framebuffer, it unconditionally set it to be the default
VGA device, and no subsequent device could replace it.

[bhelgaas: commit log, restructure slightly]
Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn
Link: https://lore.kernel.org/r/20220224224753.297579-6-helgaas@kernel.org
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Bruno Prémont <bonbons@linux-vserver.org>

PCI/VGA: Factor out default VGA device selection

Default VGA device selection fails when PCI devices are enumerated after
the vga_arb_device_init() subsys_initcall.

vga_arbiter_add_pci_device() selects the first fully enabled device to
which legacy VGA resources are routed as the default VGA device. This is
an ADD_DEVICE notifier, so it runs after every PCI device is enumerated.

vga_arb_select_default_device() may select framebuffer devices, partially
enabled GPUs, or non-legacy devices that don't have legacy VGA resources
routed to them as the default VGA device. But this only happens once, from
the vga_arb_device_init() subsys_initcall, so it doesn't consider devices
enumerated after that:

acpi_init
acpi_scan_init
acpi_pci_root_init # PCI device enumeration (ACPI systems)

vga_arb_device_init
for_each_pci_device
vga_arbiter_add_pci_device # ADD_DEVICE notifier
if (VGA-owner)
vga_set_default_device <-- set default VGA
vga_arb_select_default_device # only called ONCE
for_each_vga_device
if (framebuffer)
vga_set_default_device <-- set default VGA to framebuffer
if (!vga_default_device())
if (non-legacy, integrated GPU, etc)
vga_set_default_device <-- set default VGA
if (!vga_default_device())
vga_set_default_device <-- set default VGA

pcibios_init
pcibios_scanbus # PCI device enumeration (non-ACPI systems)
...
vga_arbiter_add_pci_device # ADD_DEVICE notification
if (VGA-owner)
vga_set_default_device <-- set default VGA

Note that on non-ACPI systems, vga_arb_select_default_device() runs before
pcibios_init(), so it sees no VGA devices and can never set a framebuffer
device, a non-legacy integrated GPU, etc., as the default device.

Factor out the default VGA device selection to vga_is_boot_device(), called
from vga_arbiter_add_pci_device().

Then we can migrate the default device selection from
vga_arb_select_default_device() to the vga_arbiter_add_pci_device() path.

[bhelgaas: commit log, split to separate patch]
Link: https://lore.kernel.org/r/20211015061512.2941859-4-chenhuacai@loongson.cn
Link: https://lore.kernel.org/r/20220224224753.297579-5-helgaas@kernel.org
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Factor out vga_select_framebuffer_device()

On x86 and ia64, if a VGA device BARs include a framebuffer reported by
platform firmware, we select the device as the default VGA device. Factor
this code to a separate function. No functional change intended.

Link: https://lore.kernel.org/r/20220224224753.297579-4-helgaas@kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Bruno Prémont <bonbons@linux-vserver.org>

PCI/VGA: Move vga_arb_integrated_gpu() earlier in file

Move vga_arb_integrated_gpu() earlier in file to prepare for future patch.
No functional change intended.

[bhelgaas: pull #ifdefs inside function]
Link: https://lore.kernel.org/r/20211015061512.2941859-3-chenhuacai@loongson.cn
Link: https://lore.kernel.org/r/20220224224753.297579-3-helgaas@kernel.org
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/VGA: Move vgaarb to drivers/pci

The VGA arbiter is really PCI-specific and doesn't depend on any GPU
things. Move it to the PCI subsystem.

Note that misc_init() must be called before vga_arb_device_init(). These
are both subsys_initcalls, so this ordering depends on the link order,
which is determined by drivers/Makefile:

obj-y += pci/
obj-y += char/ <-- misc_init()
obj-y += gpu/ <-- vga_arb_device_init() (before this commit)

The drivers/pci/ subsys_initcalls are called *before* misc_init(), so
convert vga_arb_device_init() to subsys_initcall_sync(), which is called
after *all* subsys_initcalls.

Link: https://lore.kernel.org/r/20220224224753.297579-2-helgaas@kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>