ACPI / driver core: Store an ACPI device pointer in struct acpi_dev_node
Modify struct acpi_dev_node to contain a pointer to struct acpi_device associated with the given device object (that is, its ACPI companion device) instead of an ACPI handle corresponding to it. Introduce two new macros for manipulating that pointer in a CONFIG_ACPI-safe way, ACPI_COMPANION() and ACPI_COMPANION_SET(), and rework the ACPI_HANDLE() macro to take the above changes into account. Drop the ACPI_HANDLE_SET() macro entirely and rework its users to use ACPI_COMPANION_SET() instead. For some of them who used to pass the result of acpi_get_child() directly to ACPI_HANDLE_SET() introduce a helper routine acpi_preset_companion() doing an equivalent thing. The main motivation for doing this is that there are things represented by struct acpi_device objects that don't have valid ACPI handles (so called fixed ACPI hardware features, such as power and sleep buttons) and we would like to create platform device objects for them and "glue" them to their ACPI companions in the usual way (which currently is impossible due to the lack of valid ACPI handles). However, there are more reasons why it may be useful. First, struct acpi_device pointers allow of much better type checking than void pointers which are ACPI handles, so it should be more difficult to write buggy code using modified struct acpi_dev_node and the new macros. Second, the change should help to reduce (over time) the number of places in which the result of ACPI_HANDLE() is passed to acpi_bus_get_device() in order to obtain a pointer to the struct acpi_device associated with the given "physical" device, because now that pointer is returned by ACPI_COMPANION() directly. Finally, the change should make it easier to write generic code that will build both for CONFIG_ACPI set and unset without adding explicit compiler directives to it. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com> # on Haswell Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Aaron Lu <aaron.lu@intel.com> # for ATA and SDIO part
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