[PATCH v2 13/39] acpi: Add a binding for ACPI settings in the device tree
Andy Shevchenko
andriy.shevchenko at linux.intel.com
Tue Mar 10 15:50:34 CET 2020
On Sun, Mar 08, 2020 at 09:44:37PM -0600, Simon Glass wrote:
> Devices need to report various identifiers in the ACPI tables. Rather than
> hard-coding these in drivers it is typically better to put them in the
> device tree.
>
> Add a binding file to describe this.
...
> +Device bindings are described by their own individual binding files.
> +
> +U-Boot provides for some optional properties which are documented here. See
> +also hid-over-i2c.txt which describes HID devices.
> +
> + - acpi,has-power-resource : (boolean) true if this device has a power resource.
> + This causes a PRIC (ACPI PowerResource) to be written containing the
What is PRIC?
> + properties provided by this binding, to describe how to handle powering the
> + device up and down using GPIOs
> + - acpi,compatible : compatible string to report
Hmm... I didn't get this. Is it ACPI _CID?
> + - acpi,desc : Contains the string to use as the _DDN (DOS (Disk Operating
> + System) Device Name)
> + - acpi,hid : Contains the string to use as the HID (Hardware ID)
> + identifier _HID
HID can be dropped to avoid confusion with below.
> + - hid-descr-addr : HID register offset (for Human Interface Devices)
> + - acpi,probed : Tells U-Boot to add 'linux,probed' to the ACPI tables so that
> + Linux will not re-init the device
Why? How do we know that Linux will work correctly? Again, we must not depend
on the OS behaviour.
> + - acpi,uid : _UID value for device
> +
> +
> +Example
> +-------
> +
> +synaptics_touchpad: synaptics-touchpad at 2c {
> + compatible = "hid-over-i2c";
> + reg = <0x2c>;
> + acpi,hid = "PNP0C50";
> + acpi,desc = "Synaptics Touchpad";
> + interrupts-extended = <&acpi_gpe GPIO_18_IRQ
> + IRQ_TYPE_EDGE_FALLING>;
> + acpi,probed;
> + hid-descr-addr = <0x20>;
> +};
--
With Best Regards,
Andy Shevchenko
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