On Wed, 2014-10-22 at 09:09 -0500, Emil Medve wrote:
> 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 <Emilian.Medve@xxxxxxxxxxxxx>
> Change-Id: I3ec479bfb3c91951e96902f091f5d7d2adbef3b2
> ---
> .../devicetree/bindings/powerpc/fsl/bman.txt | 98 ++++++++++++++++++++++
> 1 file changed, 98 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/powerpc/fsl/bman.txt
>
> diff --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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