This device should use ready-gpios rather than ready-gpio. Fix it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

ACPI GPEs are used to signal interrupts from peripherals that are accessed
via ACPI. In U-Boot these are modelled as interrupts using a separate
interrupt controller. Configuration is via the device tree.

Add a simple driver for this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

At present driver model supports the IRQ uclass but there is no way to
request a particular interrupt for a driver.

Add a mechanism, similar to clock and reset, to read the interrupts
required by a device from the device tree and to request those interrupts.

U-Boot itself does not have interrupt-driven handlers, so just provide a
means to read and clear an interrupt. This can be useful to handle
peripherals which must use an interrupt to determine when data is
available, for example.

Bring over the basic binding file as well, from Linux v5.4. Note that the
older binding is not supported in U-Boot; the newer 'special form' must be
used.

Add a simple test of the new functionality.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>