Re: [PATCH] gpio: shared: call gpio_chip::of_xlate() if set

[Jon Hunter <jonathanh@nvidia.com>]

On 16/03/2026 13:52, Bartosz Golaszewski wrote:
> OF-based GPIO controller drivers may provide a translation function that
> calculates the real chip offset from whatever devicetree sources
> provide. We need to take this into account in the shared GPIO management
> and call of_xlate() if it's provided and adjust the entry->offset we
> initially set when scanning the tree.
> 
> To that end: modify the shared GPIO API to take the GPIO chip as
> argument on setup (to avoid having to rcu_dereference() it from the GPIO
> device) and protect the access to entry->offset with the existing lock.
> 
> Fixes: a060b8c511ab ("gpiolib: implement low-level, shared GPIO support")
> Reported-by: Jon Hunter <jonathanh@nvidia.com>
> Closes: https://lore.kernel.org/all/921ba8ce-b18e-4a99-966d-c763d22081e2@nvidia.com/
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
> ---
>   drivers/gpio/gpiolib-shared.c | 27 ++++++++++++++++++++++++++-
>   drivers/gpio/gpiolib-shared.h |  4 ++--
>   drivers/gpio/gpiolib.c        |  2 +-
>   3 files changed, 29 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib-shared.c b/drivers/gpio/gpiolib-shared.c
> index 17a7128b6bd9bf6023deccee50b2453caebe3d9a..3a8db9bf456daaf021d3c691677a90fc6da15889 100644
> --- a/drivers/gpio/gpiolib-shared.c
> +++ b/drivers/gpio/gpiolib-shared.c
> @@ -506,8 +506,9 @@ static void gpio_shared_remove_adev(struct auxiliary_device *adev)
>   	auxiliary_device_uninit(adev);
>   }
>   
> -int gpio_device_setup_shared(struct gpio_device *gdev)
> +int gpiochip_setup_shared(struct gpio_chip *gc)
>   {
> +	struct gpio_device *gdev = gc->gpiodev;
>   	struct gpio_shared_entry *entry;
>   	struct gpio_shared_ref *ref;
>   	struct gpio_desc *desc;
> @@ -532,12 +533,34 @@ int gpio_device_setup_shared(struct gpio_device *gdev)
>   	 * exposing shared pins. Find them and create the proxy devices.
>   	 */
>   	list_for_each_entry(entry, &gpio_shared_list, list) {
> +		guard(mutex)(&entry->lock);
> +
>   		if (!device_match_fwnode(&gdev->dev, entry->fwnode))
>   			continue;
>   
>   		if (list_count_nodes(&entry->refs) <= 1)
>   			continue;
>   
> +#if IS_ENABLED(CONFIG_OF)
> +		if (is_of_node(entry->fwnode) && gc->of_xlate) {
> +			/*
> +			 * This is the earliest that we can tranlate the
> +			 * devicetree offset to the chip offset.
> +			 */
> +			struct of_phandle_args gpiospec = { };
> +
> +			gpiospec.np = to_of_node(entry->fwnode);
> +			gpiospec.args_count = 2;
> +			gpiospec.args[0] = entry->offset;
> +
> +			ret = gc->of_xlate(gc, &gpiospec, NULL);
> +			if (ret < 0)
> +				return ret;
> +
> +			entry->offset = ret;
> +		}
> +#endif /* CONFIG_OF */

Do we need something similar to this in the gpio_device_teardown_shared 
function?

Jon

-- 
nvpublic