Re: [PATCH v4 2/2] platform/x86: x86-android-tablets: enable fwnode matching of GPIO chips

[Rafael J. Wysocki]

On Thu, Apr 30, 2026 at 9:34 AM Bartosz Golaszewski
<bartosz.golaszewski@xxxxxxxxxxxxxxxx> wrote:
>
> In order to allow GPIOLIB to match cherryview and baytrail GPIO
> controllers by their firmware nodes instead of their names, we need to
> attach the - currently "dangling" - existing software nodes to their
> target devices dynamically.
>
> The driver uses platform_create_bundle() and expects all required
> providers to be present before it itself is probed. We know the name of
> the device we're waiting for so look them up and assign the appropriate
> software node as the secondary firmware node of the underlying ACPI node.
>
> Scheduling fine-grained devres actions allows for proper teardown and
> unsetting of the secondary firmware nodes.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>

I may have missed something subtle, but overall it looks reasonable to me, so

Reviewed-by: Rafael J. Wysocki (Intel) <rafael@xxxxxxxxxx>

> ---
>  drivers/platform/x86/x86-android-tablets/core.c | 78 ++++++++++++++++++++++++-
>  1 file changed, 75 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/platform/x86/x86-android-tablets/core.c b/drivers/platform/x86/x86-android-tablets/core.c
> index 021009e9085bec3db9c4daa1f6235600210a6099..8fd0cffe351577182f31c90c104b616cec78c481 100644
> --- a/drivers/platform/x86/x86-android-tablets/core.c
> +++ b/drivers/platform/x86/x86-android-tablets/core.c
> @@ -13,6 +13,7 @@
>  #include <linux/acpi.h>
>  #include <linux/device.h>
>  #include <linux/dmi.h>
> +#include <linux/fwnode.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/gpio/machine.h>
>  #include <linux/irq.h>
> @@ -360,6 +361,76 @@ static const struct software_node *cherryview_gpiochip_node_group[] = {
>         NULL
>  };
>
> +static void auto_secondary_unset(void *data)
> +{
> +       struct fwnode_handle *fwnode = data;
> +
> +       fwnode->secondary = NULL;
> +}
> +
> +static int acpi_set_secondary_fwnode(struct device *parent, struct device *dev,
> +                                    const struct software_node *const swnode)
> +{
> +       struct acpi_device *device = to_acpi_device(dev);
> +       struct fwnode_handle *fwnode;
> +       int ret;
> +
> +       fwnode = software_node_fwnode(swnode);
> +       if (WARN_ON(!fwnode))
> +               return -ENOENT;
> +
> +       fwnode->secondary = ERR_PTR(-ENODEV);
> +       device->fwnode.secondary = fwnode;
> +
> +       ret = devm_add_action_or_reset(parent, auto_secondary_unset, &device->fwnode);
> +       if (ret)
> +               dev_err(parent, "Failed to schedule the unset action for secondary fwnode\n");
> +
> +       return ret;
> +}
> +
> +static void auto_secondary_unregister_node_group(void *data)
> +{
> +       const struct software_node **nodes = data;
> +
> +       software_node_unregister_node_group(nodes);
> +}
> +
> +static int auto_secondary_fwnode_init(struct device *parent)
> +{
> +       const struct software_node *const *swnode;
> +       int ret;
> +
> +       if (!gpiochip_node_group)
> +               return 0;
> +
> +       ret = software_node_register_node_group(gpiochip_node_group);
> +       if (ret)
> +               return ret;
> +
> +       ret = devm_add_action_or_reset(parent,
> +                                      auto_secondary_unregister_node_group,
> +                                      gpiochip_node_group);
> +       if (ret)
> +               return ret;
> +
> +       for (swnode = gpiochip_node_group; *swnode; swnode++) {
> +               struct device *dev __free(put_device) =
> +                               acpi_bus_find_device_by_name((*swnode)->name);
> +               if (!dev) {
> +                       dev_err(parent, "Failed to find the required GPIO controller: %s\n",
> +                               (*swnode)->name);
> +                       return -ENODEV;
> +               }
> +
> +               ret = acpi_set_secondary_fwnode(parent, dev, *swnode);
> +               if (ret)
> +                       return ret;
> +       }
> +
> +       return 0;
> +}
> +
>  static void x86_android_tablet_remove(struct platform_device *pdev)
>  {
>         int i;
> @@ -391,7 +462,6 @@ static void x86_android_tablet_remove(struct platform_device *pdev)
>
>         software_node_unregister_node_group(gpio_button_swnodes);
>         software_node_unregister_node_group(swnode_group);
> -       software_node_unregister_node_group(gpiochip_node_group);
>  }
>
>  static __init int x86_android_tablet_probe(struct platform_device *pdev)
> @@ -427,9 +497,11 @@ static __init int x86_android_tablet_probe(struct platform_device *pdev)
>                 break;
>         }
>
> -       ret = software_node_register_node_group(gpiochip_node_group);
> -       if (ret)
> +       ret = auto_secondary_fwnode_init(&pdev->dev);
> +       if (ret) {
> +               x86_android_tablet_remove(pdev);
>                 return ret;
> +       }
>
>         ret = software_node_register_node_group(dev_info->swnode_group);
>         if (ret) {
>
> --