From 4f5efcb39b25a2a9c24c36c467e7f14ce6e818a5 Mon Sep 17 00:00:00 2001 From: John Klug Date: Fri, 10 May 2019 17:10:10 -0500 Subject: Device Tree Overlay Example --- README | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 README (limited to 'README') diff --git a/README b/README new file mode 100644 index 0000000..1a4debd --- /dev/null +++ b/README @@ -0,0 +1,25 @@ +This is the device tree overlay(s) and its make. + +The purpose of the overlay is to define the system +for the mts-io driver and/or mtac drivers. + +The correct overlay for the system is loaded at +runtime before loading the mts-io driver. A method +for doing this is the device tree configfs driver. + +See this for the format of an overlay: + +https://www.kernel.org/doc/Documentation/devicetree/overlay-notes.txt + +Note that as of 10 May 2019, no overlays have been +released. + +The biggest flaw in overlays, is the inablitiy to use +the phandle described in an alias in the boot +time device tree in an overlay, so it appears +to be impossible to reference nodes in the main +device tree in any shorthand method. For instance, it +is common to reference a "pio" in device tree to +use a PIO with GPIO. For example, it does not appear +to be possible to use &pioC in the overlay without +redefining it. -- cgit v1.2.3