Some devices implement ACPI driver as a way to manage devices enumerated by the ACPI. This might be confusing as a preferred way to implement a driver for devices not connected to any bus is a platform driver, as stated in the documentation. Clarify relationships between ACPI device, platform device and ACPI entries. Suggested-by: Elena Reshetova <elena.reshetova@xxxxxxxxx> Signed-off-by: Michal Wilczynski <michal.wilczynski@xxxxxxxxx> --- Documentation/firmware-guide/acpi/enumeration.rst | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/Documentation/firmware-guide/acpi/enumeration.rst b/Documentation/firmware-guide/acpi/enumeration.rst index 56d9913a3370..f56cc79a9e83 100644 --- a/Documentation/firmware-guide/acpi/enumeration.rst +++ b/Documentation/firmware-guide/acpi/enumeration.rst @@ -64,6 +64,19 @@ If the driver needs to perform more complex initialization like getting and configuring GPIOs it can get its ACPI handle and extract this information from ACPI tables. +ACPI bus +==================== + +Historically some devices not connected to any bus were represented as ACPI +devices, and had to implement ACPI driver. This is not a preferred way for new +drivers. As explained above devices not connected to any bus should implement +platform driver. ACPI device would be created during enumeration nonetheless, +and would be accessible through ACPI_COMPANION() macro, and the ACPI handle would +be accessible through ACPI_HANDLE() macro. ACPI device is meant to describe +information related to ACPI entry e.g. handle of the ACPI entry. Think - +ACPI device interfaces with the FW, and the platform device with the rest of +the system. + DMA support =========== -- 2.41.0
