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: e590474768 ("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>
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>
Since commit f626d6dfb7 ("gpio: of: Break out OF-only code"),
there are no more users of of_get_named_gpiod_flags() outside
gpiolib-of.c.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20190906084539.21838-2-geert+renesas@glider.be
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The recent refactoring to break out OF code to its own file
contained a bug letting the need_valid_mask
be overridden by the need of the device tree range check,
and if there were no ranges, but device tree was active
and the reserved GPIO used in another way, things likely
crash.
Cc: Mark Brown <broonie@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Fixes: f626d6dfb7 ("gpio: of: Break out OF-only code")
Reported-by: Mark Brown <broonie@kernel.org>
Suggested-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The core gpiolib should not contain any OF/device tree-only
code. Try to break out the main part of it and push it down
into the optional gpiolib-of.c part of the library.
Create a local gpiolib-of.h header and move stuff around a
bit to get a clean cut.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20190717071001.3858-1-linus.walleij@linaro.org
Saravana Kannan
Geert Uytterhoeven
Stephen Boyd
Linus Walleij