On 23/01/2024 16:06, Philipp Zabel wrote: > 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. Ack > >> + 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. Ack Best regards, Krzysztof
