Re: [PATCH 05/21] x86/platform: select legacy gpiolib interfaces where used

[Hans de Goede]

Hi Arnd, Andy,

On 9-Aug-25 9:44 PM, Arnd Bergmann wrote:
> On Sat, Aug 9, 2025, at 12:00, Andy Shevchenko wrote:
>> On Fri, Aug 08, 2025 at 05:17:49PM +0200, Arnd Bergmann wrote:
>>> From: Arnd Bergmann <arnd@xxxxxxxx>
>>>
>>> A few old machines have not been converted away from the old-style
>>> gpiolib interfaces. Make these select the new CONFIG_GPIOLIB_LEGACY
>>> symbol so the code still works where it is needed but can be left
>>> out otherwise.
>>
>>> --- a/drivers/platform/x86/x86-android-tablets/Kconfig
>>> +++ b/drivers/platform/x86/x86-android-tablets/Kconfig
>>> @@ -8,6 +8,7 @@ config X86_ANDROID_TABLETS
>>>  	depends on I2C && SPI && SERIAL_DEV_BUS
>>>  	depends on GPIOLIB && PMIC_OPREGION
>>>  	depends on ACPI && EFI && PCI
>>> +	select GPIOLIB_LEGACY
>>>  	select NEW_LEDS
>>>  	select LEDS_CLASS
>>>  	select POWER_SUPPLY
>>
>> Hmm... This is a surprising change. But I leave it to Hans.

Yes I was surprised by this myself since I explicitly removed
all legacy GPIO use from the x86-android-tablets code a while
ago (or so I thought).

> I think the only function that still needs it is
> x86_android_tablet_probe() doing
> 
> static struct gpio_keys_button *buttons;
> 
>                 for (i = 0; i < dev_info->gpio_button_count; i++) {
>                         ret = x86_android_tablet_get_gpiod(dev_info->gpio_button[i].chip,
>                                                            dev_info->gpio_button[i].pin,
>                                                            dev_info->gpio_button[i].button.desc,
>                                                            false, GPIOD_IN, &gpiod);
> 
>                         buttons[i] = dev_info->gpio_button[i].button;
>                         buttons[i].gpio = desc_to_gpio(gpiod);
>                         /* Release GPIO descriptor so that gpio-keys can request it */
>                         devm_gpiod_put(&x86_android_tablet_device->dev, gpiod);
>                 }
> 
> So the driver itself uses gpio descriptors, but it passes
> some of them into another driver by number. There is probably
> an easy workaround that I did not see.

Ah I see, so this is basically in the same boat as
drivers/input/misc/soc_button_array.c which also first
gets a gpio_desc and then calls desc_to_gpio() to store
the GPIO number in struct gpio_keys_button which is passed
as platform_data to drivers/input/keyboard/gpio_keys.c

The gpio_keys driver then converts things back
into a gpio_desc in gpio_keys_setup_key()
using devm_gpio_request_one() + gpio_to_desc()

So it looks like we need to add a gpiod member to
struct gpio_keys_button (include/linux/gpio_keys.h)
and modify gpio_keys.c to prefer that over using
button->gpio, something like the attached patch
basically.

I won't have time to work on this until September,
so if someone wants to take the attached patch and run
with it go for it.

Note the x86-android-tablets / soc_button_array code
will become responsible for requesting / releasing
the gpiod when using the new gpio_keys_button.gpiod
member.

For the x86-android-tablets code this is easy, just drop
these 2 lines:

                        /* Release GPIO descriptor so that gpio-keys can request it */
                        devm_gpiod_put(&x86_android_tablet_device->dev, gpiod);

And for soc_button_array.c it is _probably_ just a matter
of switching to devm_gpiod_get_index() and drop the
gpiod_put().

I have hardware to test both the x86-android-tablets
code as well as the soc_button_array code. I might be
able to do a quick test on August 22nd or 29th.

Regards,

Hans


p.s.

It looks like this will also help with:

drivers/platform/x86/meraki-mx100.c
drivers/platform/x86/pcengines-apuv2.c
drivers/platform/x86/barco-p50-gpio.c

I do not have hardware to test these, but if the changes
work for x86-android-tablets + soc_button_array then
hopefully they will be fine here too.
From 6fe4bd731db59bb01cc0ce3cbd2412434ea053c6 Mon Sep 17 00:00:00 2001
From: Hans de Goede <hansg@xxxxxxxxxx>
Date: Sun, 10 Aug 2025 16:58:01 +0200
Subject: [PATCH] Input: gpio-keys - Allow directly passing a gpio_desc instead
 of a GPIO number

Using GPIO numbers is deprecated. Allow code passing GPIO-keys info through
platform-data (struct gpio_keys_button) to directly pass a gpio_desc
instead of a GPIO number.

Note requesting / releasing the gpio_desc will be the responsibility
of the code passing in the platform-data.

Signed-off-by: Hans de Goede <hansg@xxxxxxxxxx>
---
 drivers/input/keyboard/gpio_keys.c | 2 ++
 include/linux/gpio_keys.h          | 5 ++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
index f9db86da0818..323247f63a7e 100644
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/drivers/input/keyboard/gpio_keys.c
@@ -528,6 +528,8 @@ static int gpio_keys_setup_key(struct platform_device *pdev,
 			 */
 			bdata->gpiod = NULL;
 		}
+	} else if (button->gpiod) {
+		bdata->gpiod = button->gpiod;
 	} else if (gpio_is_valid(button->gpio)) {
 		/*
 		 * Legacy GPIO number, so request the GPIO here and
diff --git a/include/linux/gpio_keys.h b/include/linux/gpio_keys.h
index 80fa930b04c6..7c32c3a0695f 100644
--- a/include/linux/gpio_keys.h
+++ b/include/linux/gpio_keys.h
@@ -5,11 +5,13 @@
 #include <linux/types.h>
 
 struct device;
+struct gpio_desc;
 
 /**
  * struct gpio_keys_button - configuration parameters
  * @code:		input event code (KEY_*, SW_*)
- * @gpio:		%-1 if this key does not support gpio
+ * @gpio:		%-1 if this key does not support gpio (deprecated use gpiod)
+ * @gpiod:		gpio_desc for the GPIO, NULL if this key does not support gpio
  * @active_low:		%true indicates that button is considered
  *			depressed when gpio is low
  * @desc:		label that will be attached to button's gpio
@@ -26,6 +28,7 @@ struct device;
 struct gpio_keys_button {
 	unsigned int code;
 	int gpio;
+	struct gpio_desc *gpiod;
 	int active_low;
 	const char *desc;
 	unsigned int type;
-- 
2.49.0