gpiolib: Bind gpio_device to a driver to enable fw_devlink=on by default

There are multiple instances of GPIO device tree nodes of the form:

foo {
compatible = "acme,foo";
...

gpio0: gpio0@xxxx

gpiolib: Bind gpio_device to a driver to enable fw_devlink=on by default

There are multiple instances of GPIO device tree nodes of the form:

foo {
compatible = "acme,foo";
...

gpio0: gpio0@xxxxxxxx {
compatible = "acme,bar";
...
gpio-controller;
};

gpio1: gpio1@xxxxxxxx {
compatible = "acme,bar";
...
gpio-controller;
};

...
}

bazz {
my-gpios = <&gpio0 ...>;
}

Case 1: The driver for "foo" populates struct device for these gpio*
nodes and then probes them using a driver that binds with "acme,bar".
This driver for "acme,bar" then registers the gpio* nodes with gpiolib.
This lines up with how DT nodes with the "compatible" property are
typically converted to struct devices and then registered with driver
core to probe them. This also allows the gpio* devices to hook into all
the driver core capabilities like runtime PM, probe deferral,
suspend/resume ordering, device links, etc.

Case 2: The driver for "foo" doesn't populate struct devices for these
gpio* nodes before registering them with gpiolib. Instead it just loops
through its child nodes and directly registers the gpio* nodes with
gpiolib.

Drivers that follow case 2 cause problems with fw_devlink=on. This is
because fw_devlink will prevent bazz from probing until there's a struct
device that has gpio0 as its fwnode (because bazz lists gpio0 as a GPIO
supplier). Once the struct device is available, fw_devlink will create a
device link with gpio0 device as the supplier and bazz device as the
consumer. After this point, since the gpio0 device will never bind to a
driver, the device link will prevent bazz device from ever probing.

Finding and refactoring all the instances of drivers that follow case 2
will cause a lot of code churn and it is not something that can be done
in one shot. In some instances it might not even be possible to refactor
them cleanly. Examples of such instances are [1] [2].

This patch works around this problem and avoids all the code churn by
simply setting the fwnode of the gpio_device and creating a stub driver
to bind to the gpio_device. This allows all the consumers to continue
probing when the driver follows case 2.

[1] - https://lore.kernel.org/lkml/20201014191235.7f71fcb4@xhacker.debian/
[2] - https://lore.kernel.org/lkml/e28e1f38d87c12a3c714a6573beba6e1@kernel.org/

Fixes: e590474768f1 ("driver core: Set fw_devlink=on by default")
Cc: Marc Zyngier <maz@kernel.org>
Cc: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Cc: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210122193600.1415639-1-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Merge branch 'master' into for-next

Sync with Linus' branch in order to be able to apply fixups
of more recent patches.

Merge branch 'next' into for-linus

Prepare input updates for 5.9 merge window.

Merge branch 'elan-i2c' into next

Bring in update to Elan touchpad driver to support newer touchpads with
higher resolution.

Merge branches 'for-5.7/upstream-fixes', 'for-5.8/apple', 'for-5.8/asus', 'for-5.8/core', 'for-5.8/intel-ish', 'for-5.8/logitech', 'for-5.8/mcp2221' and 'for-5.8/multitouch' into for-linus

Merge branch 'for-5.8' into for-linus

Merge branch 'timers/drivers/timer-ti' into timers/drivers/next

Merge branch 'kvm-amd-fixes' into HEAD

Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu

Pull RCU updates from Paul McKenney:

1. Miscellaneous fixes.
2. kfree_rcu() updates.

Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu

Pull RCU updates from Paul McKenney:

1. Miscellaneous fixes.
2. kfree_rcu() updates.
3. Remove scheduler locking restriction
4. RCU-tasks update, including addition of RCU Tasks Trace for
BPF use and RCU Tasks Rude. (This branch is on top of #3 due
to overlap of changed code.)
5. RCU CPU stall warning updates.
6. Torture-test updates.

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Merge tag 'efi-next' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi into efi/core

Pull EFI changes for v5.8 from Ard Biesheuvel:

"- preliminary changes for RISC-V
- add support for setti

Merge tag 'efi-next' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi into efi/core

Pull EFI changes for v5.8 from Ard Biesheuvel:

"- preliminary changes for RISC-V
- add support for setting the resolution on the EFI framebuffer
- simplify kernel image loading for arm64
- Move .bss into .data via the linker script instead of relying on symbol
annotations.
- Get rid of __pure getters to access global variables
- Clean up the config table matching arrays"

Signed-off-by: Ingo Molnar <mingo@kernel.org>

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Merge branch 'topic/nhlt' into for-next

Merge NHLT init cleanup.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

Merge tag 'tegra-for-5.7-asoc' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux into asoc-5.7

ASoC: tegra: Fixes for v5.7-rc3

This contains a couple of fixes that are needed to properly

Merge tag 'tegra-for-5.7-asoc' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux into asoc-5.7

ASoC: tegra: Fixes for v5.7-rc3

This contains a couple of fixes that are needed to properly reconfigure
the audio clocks on older Tegra devices.

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Merge branch 'fixes-v5.7' into fixes

Merge tag 'kvm-s390-master-5.7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into kvm-master

KVM: s390: Fix for 5.7 and maintainer update

- Silence false positive lockdep warnin

Merge tag 'kvm-s390-master-5.7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into kvm-master

KVM: s390: Fix for 5.7 and maintainer update

- Silence false positive lockdep warning
- add Claudio as reviewer

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Merge drm/drm-next into drm-misc-next

Backmerging required to pull topic/phy-compliance.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Merge drm/drm-next into drm-intel-next-queued

Backmerging in order to pull "topic/phy-compliance".

Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Merge v5.7-rc1 into drm-misc-fixes

Start the new drm-misc-fixes cycle.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Merge tag 'v5.7-rc1' into locking/kcsan, to resolve conflicts and refresh

Resolve these conflicts:

arch/x86/Kconfig
arch/x86/kernel/Makefile

Do a minor "evil merge" to move the KCSAN entry up a

Merge tag 'v5.7-rc1' into locking/kcsan, to resolve conflicts and refresh

Resolve these conflicts:

arch/x86/Kconfig
arch/x86/kernel/Makefile

Do a minor "evil merge" to move the KCSAN entry up a bit by a few lines
in the Kconfig to reduce the probability of future conflicts.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

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Merge tag 'gpio-v5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

Pull GPIO updates from Linus Walleij:
"This is the bulk of GPIO development for the v5.7 kernel cycle.

Merge tag 'gpio-v5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

Pull GPIO updates from Linus Walleij:
"This is the bulk of GPIO development for the v5.7 kernel cycle.

Core and userspace API:

- The userspace API KFIFOs have been imoproved with locks that do not
block interrupts. This makes us better at getting events to
userspace without blocking or disturbing new events arriving in the
same time. This was reviewed by the KFIFO maintainer Stefani. This
is a generic improvement which paves the road for similar
improvements in other subsystems.

- We provide a new ioctl() for monitoring changes in the line
information, such as when multiple clients are taking lines and
giving them back, possibly reconfiguring them in the process: we
can now monitor that and not get stuck with stale static
information.

- An example tool 'gpio-watch' is provided to showcase this
functionality.

- Timestamps for events are switched to ktime_get_ns() which is
monotonic. We previously had a 'realtime' stamp which could move
forward and *backward* in time, which probably would just cause
silent bugs and weird behaviour. In the long run we see two
relevant timestamps: ktime_get_ns() or the timestamp sometimes
provided by the GPIO hardware itself, if that exists.

- Device Tree overlay support for GPIO hogs. On systems that load
overlays, these overlays can now contain hogs, and will then be
respected.

- Handle pin control interaction with nonexisting pin ranges in the
GPIO library core instead of in the individual drivers.

New drivers:

- New driver for the Mellanox BlueField 2 GPIO controller.

Driver improvements:

- Introduce the BGPIOF_NO_SET_ON_INPUT flag to the generic MMIO GPIO
library and use this flag in the MT7621 driver.

- Texas Instruments OMAP CPU power management improvements, such as
blocking of idle on pending GPIO interrupts"

* tag 'gpio-v5.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (59 commits)
Revert "gpio: eic-sprd: Use devm_platform_ioremap_resource()"
pinctrl: Unconditionally assign .request()/.free()
gpio: Unconditionally assign .request()/.free()
gpio: export of_pinctrl_get to modules
pinctrl: Define of_pinctrl_get() dummy for !PINCTRL
gpio: Rename variable in core APIs
gpio: Avoid using pin ranges with !PINCTRL
gpiolib: Remove unused gpio_chip parameter from gpio_set_bias()
gpiolib: Pass gpio_desc to gpio_set_config()
gpiolib: Introduce gpiod_set_config()
tools: gpio: Fix out-of-tree build regression
gpio: gpiolib: fix a doc warning
gpio: tegra186: Add Tegra194 pin ranges for GG.0 and GG.1
gpio: tegra186: Add support for pin ranges
gpio: Support GPIO controllers without pin-ranges
ARM: integrator: impd1: Use GPIO_LOOKUP() helper macro
gpio: brcmstb: support gpio-line-names property
tools: gpio: Fix typo in gpio-utils
tools: gpio-hammer: Apply scripts/Lindent and retain good changes
gpiolib: gpio_name_to_desc: factor out !name check
...

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gpio: of: Add DT overlay support for GPIO hogs

As GPIO hogs are configured at GPIO controller initialization time,
adding/removing GPIO hogs in DT overlays does not work.

Add support for GPIO hogs

gpio: of: Add DT overlay support for GPIO hogs

As GPIO hogs are configured at GPIO controller initialization time,
adding/removing GPIO hogs in DT overlays does not work.

Add support for GPIO hogs described in DT overlays by registering an OF
reconfiguration notifier, to handle the addition and removal of GPIO hog
subnodes to/from a GPIO controller device node.

Note that when a GPIO hog device node is being removed, its "gpios"
properties is no longer available, so we have to keep track of which
node a hog belongs to, which is done by adding a pointer to the hog's
device node to struct gpio_desc.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200220130149.26283-3-geert+renesas@glider.be
Reviewed-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

show more ...

Merge branch 'next' into for-linus

Prepare input updates for 5.5 merge window.

Merge tag 'v5.4-rc8' into WIP.x86/mm, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>

Merge branch 'linus' into x86/hyperv

Pick up upstream fixes to avoid conflicts.

Merge tag 'v5.4-rc5' into next

Sync up with mainline.

Merge tag 'v5.4-rc3' into spi-5.4

Linux 5.4-rc3