• Rafael J. Wysocki's avatar
    ACPI / driver core: Store an ACPI device pointer in struct acpi_dev_node · 7b199811
    Rafael J. Wysocki authored
    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: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com> # on Haswell
    Reviewed-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
    Reviewed-by: Aaron Lu <aaron.lu@intel.com> # for ATA and SDIO part
    7b199811
libata-acpi.c 25.7 KB