RE: How to use an ACPI declared GPIO in a userspace ...

Flavio Suligoi
2020-09-30T15:39:19Z

Hi Andy,

> I guess you simply didn't get. The "gpio-line-names" property of GPIO
> *controller* (provider!) and you are trying to do something with the
> *consumer*
> if I got it right.
>
> And of course GPIO line, which has name, has no difference in use from
> another
> w/o name assigned. You will need to request it by *consumer* either in
> kernel
> or in user space.
>
> To be more precise we have to look at your DSDT.
>
> --
> With Best Regards,
> Andy Shevchenko
>

My SSDT table is:

DefinitionBlock ("gpio_button.aml", "SSDT", 5, "ASEMsp", "GPIO_BTN", 1)
{
External (_SB_.GPO1, DeviceObj)

Scope (\_SB.GPO1)
{
Device (BTNS)
{
Name (_HID, "PRP0001")
Name (_DDN, "GPIO buttons device")

Name (_CRS, ResourceTemplate ()
{
GpioIo (
Exclusive, // Not shared
PullNone, // No need for pulls
0, // Debounce timeout
0, // Drive strength
IoRestrictionInputOnly, // Only used as input
"\\_SB.GPO1", // GPIO controller
0, ResourceConsumer, , ) // Must be 0
{
1, // GPIO number
}
})

Name (_DSD, Package () {
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
Package () {
Package () {
"gpio-line-names",
Package () {
"USER_PUSH_BUTTON",
}
},
}
})
}
}
}

And the kernel messages, after loading the table, are:

ACPI: Host-directed Dynamic ACPI Table Load:
ACPI: SSDT 0xFFFF908274285200 0000E8 (v05 ASEMsp GPIO_BTN 00000001 INTL 20200717)
ACPI: \_SB_.GPO1.BTNS: PRP0001 requires 'compatible' property

So I need a "consumer", but I don't want to export the GPIO using its number...
If you have any suggestion ...

Thanks!

Flavi