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> I'm nearly out of complaints, two tiny cosmetic issues remaining: [...] > 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 [...] > @@ -813,12 +838,161 @@ static void __reset_control_put_internal(struct reset_control *rstc) > kref_put(&rstc->refcnt, __reset_control_release); > } > > +static int __reset_add_reset_gpio_lookup(int id, struct device_node *np, > + unsigned int gpio, > + unsigned int of_flags) > +{ > + unsigned int lookup_flags; > + const char *label_tmp; > + > + /* > + * Later we map GPIO flags between OF and Linux, however not all > + * constants from include/dt-bindings/gpio/gpio.h and > + * include/linux/gpio/machine.h match each other. > + */ > + if (of_flags > GPIO_ACTIVE_LOW) { > + pr_err("reset-gpio code does not support GPIO flags %u for GPIO %u\n", > + of_flags, gpio); Alignment to parenthesis is slightly off. > + return -EINVAL; > + } > + > + struct gpio_device *gdev __free(gpio_device_put) = gpio_device_find_by_fwnode(of_fwnode_handle(np)); Adding a local fwnode variable would make this fit in the 100 character limit again. regards Philipp
