Re: [PATCH 1/4] dt/bindings: Introduce the FSL QorIQ DPAA BMan
From: Scott Wood <hidden>
Date: 2014-10-28 18:19:33
Also in:
linuxppc-dev
On Wed, 2014-10-22 at 09:09 -0500, Emil Medve wrote:
quoted hunk
The Buffer Manager is part of the Data-Path Acceleration Architecture (DPAA). BMan supports hardware allocation and deallocation of buffers belonging to pools originally created by software with configurable depletion thresholds. This binding covers the CCSR space programming model Signed-off-by: Emil Medve <redacted> Change-Id: I3ec479bfb3c91951e96902f091f5d7d2adbef3b2 --- .../devicetree/bindings/powerpc/fsl/bman.txt | 98 ++++++++++++++++++++++ 1 file changed, 98 insertions(+) create mode 100644 Documentation/devicetree/bindings/powerpc/fsl/bman.txtdiff --git a/Documentation/devicetree/bindings/powerpc/fsl/bman.txt b/Documentation/devicetree/bindings/powerpc/fsl/bman.txt new file mode 100644 index 0000000..c30bdde --- /dev/null +++ b/Documentation/devicetree/bindings/powerpc/fsl/bman.txt@@ -0,0 +1,98 @@ +QorIQ DPAA Buffer Manager Device Tree Bindings + +Copyright (C) 2008 - 2014 Freescale Semiconductor Inc. + +CONTENTS + + - BMan Node + - BMan Private Memory Node + - Example + +NOTE: The bindings described in this document are preliminary and subject to + change + +BMan Node + +PROPERTIES + +- compatible + Usage: Required + Value type: <stringlist> + Definition: Must include "fsl,bman" + May include "fsl,<SoC>-bman" + +- reg + Usage: Required + Value type: <prop-encoded-array> + Definition: Registers region within the CCSR address space
Is there a version register in reg? It would be nice to point it out in the binding along with an example chip for each version, similar to Documentation/devicetree/bindings/powerpc/fsl/interlaken-lac.txt. This would make it clear that the compatible needs to be changed if the version register moves or no longer works the same way.
+BMan Private Memory Node + +BMan requires a contiguous range of physical memory used for the backing store +for BMan Free Buffer Proxy Records. This memory is reserved/allocated as a node +under the /reserved-memory node + +The BMan FBPR memory node must be named "bman-fbpr" + +PROPERTIES + +- compatible + Usage: required + Value type: <stringlist> + Definition: Must inclide "fsl,bman-fbpr" + +The following constraints are relevant to the FBPR private memory: + - The size must be 2^(size + 1), with size = 11..33. That is 4 KiB to + 16 GiB + - The alignment must be a muliptle of the memory size + +The size of the FBPR must be chosen by observing the hardware features configured +via the RCW and that are relevant to a specific board (e.g. number of MAC(s) +pinned-out, number of offline/host command FMan ports, etc.). The size configured +in the DT must reflect the hardware capabilities and not the specific needs of an +application
What about accelerators?
+If the memory reserved in the device tree proves to be larger then the needs of +the application a BMan driver may provide a method to release the extra memory +back to the OS
What if the memory reserved in the device tree proves to be smaller than
the needs of the application?
I think we should document this size as being a sane default for the
hardware, and add a way of describing that the size is tunable.
Below is the reserved-memory extension that I suggested to you
internally:
resizable (optional) - empty property
- Indicates that the size of the dynamic allocation is flexible. If
resizeable is present, the size property is optional. If both resizable
and size are present, the size property indicates a recommended default
size for this hardware.
pow2-aligned (optional) - empty property
- Only valid if resizable is present. Indicates that the size must
be a power of two, and the address must be aligned to its size. If both
pow2-aligned and alignment properties are present, pow2-aligned is used
if the region is resized, and the alignment property is used if the
region is not resized.
min-size (optional) - Only valid if resizable is present. Specifies a
minimum acceptable size.
max-size (optional) - Only valid if resizable is present. Specifies a
maximum acceptable size.
-Scott
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