CVS commit: src/sys

["Jason R Thorpe" <thorpej%netbsd.org@localhost>]

Module Name:    src
Committed By:   thorpej
Date:           Fri Feb  5 17:03:35 UTC 2021

Modified Files:
        src/sys/kern: subr_device.c
        src/sys/sys: device.h param.h

Log Message:
Introduce a generalized "device handle", designed to abstract the handles
used by platform description mechanisms like OpenFirmware, Device Tree,
and ACPI.  In addition to encapsulating the handle's opaque value, the
handle also contains a pointer to an "implementation", which can be used
to invoke methods on a device / device handle.

Device handles are designed to be passed around by-value.  It is expected
that any other memory objects they refer to will be durable.  They are an
aggregate type that consumes 2 pointers worth of storage space.

When device_t's are created, they initially have an invalid device handle.
It is currently the responsibility of platform-specific code to assign
device handles to device_t's.

When necessary, platform-specific code can override a handle's implementation
in a way that resembles sub-classing, such that specific methods can by
intercepted, but others simply passed through.  This also allows platforms
that do not otherwise have a platform description mechanism to provide
handle implementations in specific circumstances to describe the hardware
to platform-independent code.

A general device method calling infrastructure is provided.  Method names
that begin with "device-" are reserved for / defined by the autoconfiguration
subsystem.  Define the "device-enumerate-children" method.  Other subsystems
are free to define their own device method calls and bindings.

Welcome to NetBSD 9.99.80.


To generate a diff of this commit:
cvs rdiff -u -r1.5 -r1.6 src/sys/kern/subr_device.c
cvs rdiff -u -r1.165 -r1.166 src/sys/sys/device.h
cvs rdiff -u -r1.683 -r1.684 src/sys/sys/param.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.