GPIO set/get value can be operated by accessing PIO space and the PIO
register definition for GPIO is in gpio_dm.h, frontend driver or ACPI
control methods can operate GPIO based on it.
GPIO mediator also defines ACPI control methods to support GPIO
operations, GPIO consumers can invoke PIO_GPIO_SET_VALUE/PIO_GPIO_GET_VALUE
in their own DSDT to set/get one GPIO value via ACPI control method.
v2: 1) Fix code style.
2) Use virtio configuration space callbacks to implement GPIO PIO operations
that replace pci_gpio_read/pci_gpio_write with virtio_cfgread/virtio_cfgwrite.
3) Return 0xFFFFFFFF as invalid result of PIO reading instead 0.
Tracked-On: #2512
Signed-off-by: Yuan Liu <yuan1.liu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
4a6bc369ad