RE: [PATCH v4 09/23] cxl: Add helper function to retrieve ACPI handle of CXL root device

[Dan Williams <dan.j.williams@intel.com>]

Dave Jiang wrote:
> Provide a helper to find the ACPI0017 device in order to issue the _DSM.
> The helper will take the 'struct device' from a cxl_port and iterate until
> the root device is reached. The ACPI handle will be returned from the root
> device.

Following on from the last patch this should all be self contained to
drivers/cxl/acpi.c with something like:

struct cxl_root {
	struct cxl_port port;
	cxl_qos_class_fn qos_class;
};

...and then the caller does:

port = find_cxl_root(...);
root = container_of(port, typeof(*root), port);
class = root->qos_class(port, ...);

Yes, it means finally creating a formal 'struct cxl_root' type, but I
expect it will not be the last root method that gets added.