bus: Add ACPI locator support

[imp]

Summary

Add support for printing ACPI paths. This is a bit of a degenerate case
for this interface since it's always just the device handle if the
device has one. But it is illustrtive of how to do this for a few nodes
in the tree.

Sponsored by: Netflix

[imp]

rebase + ping

[jhb]

sys/dev/acpica/acpi.c

935

You could take advantage of all of the ACPI-aware buses supporting the ACPI handle ivar to make this a shared function across the various ACPI-aware buses. Something like:

int
acpi_get_device_path(device_t bus, device_t child, const char *locator, struct sbuf *sb)
{
     if (strcmp(locator, BUS_LOCATOR_ACPI) == 0) {
         ACPI_HANDLE *handle = acpi_get_handle(child);

         if (handle != NULL)
              sbuf_printf(sb, "%s", acpi_name(handle);
         return (0);
    }

    return (bus_generic_get_device_path(bus, child, locator, sb));
}

I think all of the buses you patch here could then just reuse that directly (some of them might later have to still grow a driver-specific method for UEFI, but that could at least call this shared routine after handling UEFI).

sys/sys/bus.h

742

Maybe sort these somehow, e.g. alphabetically? Probably make the first commit that adds UEFI follow whatever convention you decide to follow?

[jhb]

Should this review also update the devctl manpage?

[imp]

sys/sys/bus.h

742

sure.

[imp]

In D32748#741302, @jhb wrote:

Should this review also update the devctl manpage?

I thought I'd already updated it elsewhere. Or maybe I should ask 'which devctl man page?'

[imp]

update, per review comments, rebase, likely randomly break something subtle