On Di, 2024-01-23 at 15:13 +0100, Krzysztof Kozlowski wrote: > Devices sharing a reset GPIO could use the reset framework for > coordinated handling of that shared GPIO line. We have several cases of > such needs, at least for Devicetree-based platforms. > > If Devicetree-based device requests a reset line, while "resets" > Devicetree property is missing but there is a "reset-gpios" one, > instantiate a new "reset-gpio" platform device which will handle such > reset line. This allows seamless handling of such shared reset-gpios > without need of changing Devicetree binding [1]. > > To avoid creating multiple "reset-gpio" platform devices, store the > Devicetree "reset-gpios" GPIO specifiers used for new devices on a > linked list. Later such Devicetree GPIO specifier (phandle to GPIO > controller, GPIO number and GPIO flags) is used to check if reset > controller for given GPIO was already registered. > > If two devices have conflicting "reset-gpios" property, e.g. with > different ACTIVE_xxx flags, this would allow to spawn two separate > "reset-gpio" devices, where the second would fail probing on busy GPIO > request. > > Link: https://lore.kernel.org/all/YXi5CUCEi7YmNxXM@xxxxxxxxxxxxxxxxxx/ [1] > Cc: Bartosz Golaszewski <brgl@xxxxxxxx> > Cc: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx> > Cc: Sean Anderson <sean.anderson@xxxxxxxx> > Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> > > --- > > Depends on previous of change. > --- > drivers/reset/core.c | 213 +++++++++++++++++++++++++++++-- > include/linux/reset-controller.h | 4 + > 2 files changed, 204 insertions(+), 13 deletions(-) > > diff --git a/drivers/reset/core.c b/drivers/reset/core.c > index 4d5a78d3c085..6e81b8d35055 100644 > --- a/drivers/reset/core.c > +++ b/drivers/reset/core.c > @@ -10,9 +10,13 @@ Oh, and #include <linux/cleanup.h> > #include <linux/export.h> > #include <linux/kernel.h> > #include <linux/kref.h> > +#include <linux/gpio/driver.h> > +#include <linux/gpio/machine.h> > +#include <linux/idr.h> > #include <linux/module.h> > #include <linux/of.h> > #include <linux/acpi.h> > +#include <linux/platform_device.h> > #include <linux/reset.h> > #include <linux/reset-controller.h> > #include <linux/slab.h> regards Philipp
