[PATCH] dm: button: support remapping phone keys

[Quentin Schulz]

Hi Caleb,

On 7/14/24 9:49 PM, Caleb Connolly wrote:
> We don't have audio support in U-Boot, but we do have boot menus. Add an
> option to re-map the volume and power buttons to up/down/enter so that
> in situations where these are the only available buttons (such as on
> mobile phones) it's still possible to navigate menus built in U-Boot or
> an external EFI app like GRUB or systemd-boot.
> 

Are those event codes properly defined in the DT already?

e.g. 
https://elixir.bootlin.com/linux/latest/source/arch/arm64/boot/dts/rockchip/px30-ringneck-haikou.dts#L31

If so, what prevents us from simply patching the U-Boot DT to change 
that code? No additional code required anywhere, no need to maintain a 
list of mapping, etc...

If that isn't possible, .........

> Signed-off-by: Caleb Connolly <caleb.connolly at linaro.org>
> ---
> Cc: u-boot-qcom at groups.io
> ---
>   drivers/button/Kconfig         | 11 +++++++++++
>   drivers/button/button-uclass.c | 22 +++++++++++++++++++++-
>   2 files changed, 32 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/button/Kconfig b/drivers/button/Kconfig
> index 3918b05ae03e..6cae16fcc8bf 100644
> --- a/drivers/button/Kconfig
> +++ b/drivers/button/Kconfig
> @@ -8,8 +8,19 @@ config BUTTON
>   	  U-Boot provides a uclass API to implement this feature. Button drivers
>   	  can provide access to board-specific buttons. Use of the device tree
>   	  for configuration is encouraged.
>   
> +config BUTTON_REMAP_PHONE_KEYS
> +	bool "Remap phone keys for navigation"
> +	depends on BUTTON
> +	help
> +	  Enable remapping of phone keys to navigation keys. This is useful for
> +	  devices with phone keys that are not used in U-Boot. The phone keys
> +	  are remapped to the following navigation keys:
> +	  - Volume up: Up
> +	  - Volume down: Down
> +	  - Power: Enter
> +
>   config BUTTON_ADC
>   	bool "Button adc"
>   	depends on BUTTON
>   	depends on ADC
> diff --git a/drivers/button/button-uclass.c b/drivers/button/button-uclass.c
> index cda243389df3..729983d58701 100644
> --- a/drivers/button/button-uclass.c
> +++ b/drivers/button/button-uclass.c
> @@ -9,8 +9,9 @@
>   
>   #include <button.h>
>   #include <dm.h>
>   #include <dm/uclass-internal.h>
> +#include <dt-bindings/input/linux-event-codes.h>
>   
>   int button_get_by_label(const char *label, struct udevice **devp)
>   {
>   	struct udevice *dev;
> @@ -36,16 +37,35 @@ enum button_state_t button_get_state(struct udevice *dev)
>   
>   	return ops->get_state(dev);
>   }
>   
> +static int button_remap_phone_keys(int code)
> +{
> +	switch (code) {
> +	case KEY_VOLUMEUP:
> +		return KEY_UP;
> +	case KEY_VOLUMEDOWN:
> +		return KEY_DOWN;
> +	case KEY_POWER:
> +		return KEY_ENTER;
> +	default:
> +		return code;
> +	}
> +}
> +

....... I suggest to make this a weak function that can be overridden by 
boards (should it maybe be only defined in boards C file?) so that it's 
easy for people to come up with their own mapping without having to deal 
with two people/the maintainer disagreeing with what should be the one 
and true mapping for that key.

Cheers,
Quentin