acpi_device: Add support for writing ACPI GPIO descriptors
Add definitions to describe GPIOs in generated ACPI objects and a
method to write a GpioIo() or GpioInt() descriptor to the SSDT.
ACPI GPIOs have many possible configuration options and a structure
is created to describe it accurately in ACPI terms. There are many
shared descriptor fields between GpioIo() and GpioInt() so the same
function can write both types.
GpioInt shares many properties with ACPI Interrupts and the same types
are re-used here where possible. One addition is that GpioInt can be
configured to trigger on both low and high edge transitions.
One descriptor can describe multiple GPIO pins (limited to 8 in this
implementation) that all share configuration and controller and are
used by the same device scope.
Accurately referring to the GPIO controller that this pin is connected
to requires the SoC/board to implement a function handler for
acpi_gpio_path(), or for the caller to provide this directly as a
string in the acpi_gpio->reference variable.
This will get used by device drivers to describe their resources in
the SSDT. Here is a sample for a Maxim 98357A I2S codec which has a
GPIO for power and channel selection called "sdmode".
chip.h:
struct drivers_generic_max98357a_config {
struct acpi_gpio sdmode_gpio;
};
max98357a.c:
void acpi_fill_ssdt_generator(struct device *dev) {
struct drivers_generic_max98357a_config *config = dev->chip_info;
...
acpi_device_write_gpio(&config->sdmode_gpio);
...
}
devicetree.cb:
device pci 1f.3 on
chip drivers/generic/max98357a
register "sdmode_gpio" = "ACPI_GPIO_OUTPUT(GPP_C5)"
device generic 0 on end
end
end
SSDT.dsl:
GpioIo (Exclusive, PullDefault, 0, 0, IoRestrictionOutputOnly,
"\\_SB.PCI0.GPIO", 0, ResourceConsumer, ,) { 53 }
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Change-Id: Ibf5bab9c4bf6f21252373fb013e78f872550b167
Reviewed-on: https://review.coreboot.org/14934
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
2 files changed