[RFC,1/7] soc: qcom: Add device tree binding for SMEM

Commit Message

Bjorn Andersson Sept. 30, 2014, 12:34 a.m. UTC

Add device tree binding documentation for the Qualcom Shared Memory
manager.

Signed-off-by: Bjorn Andersson <[e-mail]>
---

Exposed by this node is a set of items of different sizes. For many things a
standard of_xlate method of referencing the individual nodes would be
preferable, so a #something-cells would make sense. We do however also needs
access to these items without explicitly stating the references in devicetree
(e.g. SMD references 257 of these). I haven't found any good example of how to
implement this, so suggestions are welcome.

Note that the hwspinlock reference is not yet supported in the mainline, but
this will likely need a few iterations so I wanted to get this out.

 .../devicetree/bindings/soc/qcom/qcom,smem.txt     |   34 ++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt

Comments

Kumar Gala Sept. 30, 2014, 1:52 p.m. UTC | #1

On Sep 29, 2014, at 7:34 PM, Bjorn Andersson <[e-mail]> wrote:

> Add device tree binding documentation for the Qualcom Shared Memory
> manager.
> 
> Signed-off-by: Bjorn Andersson <[e-mail]>
> ---
> 
> Exposed by this node is a set of items of different sizes. For many things a
> standard of_xlate method of referencing the individual nodes would be
> preferable, so a #something-cells would make sense. We do however also needs
> access to these items without explicitly stating the references in devicetree
> (e.g. SMD references 257 of these). I haven't found any good example of how to
> implement this, so suggestions are welcome.
> 
> Note that the hwspinlock reference is not yet supported in the mainline, but
> this will likely need a few iterations so I wanted to get this out.
> 
> .../devicetree/bindings/soc/qcom/qcom,smem.txt     |   34 ++++++++++++++++++++
> 1 file changed, 34 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt
> 
> diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt b/Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt
> new file mode 100644
> index 0000000..ddd58c7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt
> @@ -0,0 +1,34 @@
> +Qualcomm Shared Memory binding
> +
> +This binding describes the Qualcomm Shared Memory, used to share data between
> +various subsystems and OSes in Qualcomm platforms.
> +
> +- compatible:
> +	Usage: required
> +	Value type: <stringlist>
> +	Definition: must be:
> +		    "qcom,smem"
> +
> +- reg:
> +	Usage: required
> +	Value type: <prop-encoded-array>
> +	Definition: base address and size pair for each area representing the
> +		    shared memory. The first pair will must represent the "main"
> +		    area, where the shared memory header and table-of-content
> +		    can be found.
> +
> +- hwspinlocks:
> +	Usage: required
> +	Value type: <prop-encoded-array>
> +	Definition: reference to a hwspinlock used to protect allocations from
> +		    the shared memory
> +
> += EXAMPLE
> +
> +        smem: smem@fa00000 {
> +                compatible = "qcom,smem";
> +                reg = <0x0fa00000 0x200000>,
> +                      <0xfc428000 0x4000>;
> +
> +                hwspinlocks = <&tcsr_mutex 3>;
> +        };
> -- 
> 1.7.9.5
> 
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Stephen Boyd Sept. 30, 2014, 7:03 p.m. UTC | #2

On 09/29/14 17:34, Bjorn Andersson wrote:
> +
> +- reg:
> +	Usage: required
> +	Value type: <prop-encoded-array>
> +	Definition: base address and size pair for each area representing the
> +		    shared memory. The first pair will must represent the "main"
> +		    area, where the shared memory header and table-of-content
> +		    can be found.
>
> +
> += EXAMPLE
> +
> +        smem: smem@fa00000 {
> +                compatible = "qcom,smem";
> +                reg = <0x0fa00000 0x200000>,
> +                      <0xfc428000 0x4000>;

Isn't this second entry rpm message ram? That isn't the same as smem.
Plus smem is part of ram (and rpm message ram is not) so we need to do
memory reservations or something.

Bjorn Andersson Sept. 30, 2014, 8 p.m. UTC | #3

On Tue 30 Sep 12:03 PDT 2014, Stephen Boyd wrote:

> On 09/29/14 17:34, Bjorn Andersson wrote:
> > +
> > +- reg:
> > +	Usage: required
> > +	Value type: <prop-encoded-array>
> > +	Definition: base address and size pair for each area representing the
> > +		    shared memory. The first pair will must represent the "main"
> > +		    area, where the shared memory header and table-of-content
> > +		    can be found.
> >
> > +
> > += EXAMPLE
> > +
> > +        smem: smem@fa00000 {
> > +                compatible = "qcom,smem";
> > +                reg = <0x0fa00000 0x200000>,
> > +                      <0xfc428000 0x4000>;
> 
> Isn't this second entry rpm message ram? That isn't the same as smem.
> Plus smem is part of ram (and rpm message ram is not) so we need to do
> memory reservations or something.
> 

Correct they are different, but smem covers both of those and allocations are
only supposed to be done in the first of these.

And I forgot to mention that I have the following in my dt:

/ {
        reserved-memory {
                #address-cells = <1>;
                #size-cells = <1>;
                ranges;

                smem@fa00000 {
                        #memory-region-cells = <0>;
                        reg = <0x0fa00000 0x200000>;
                        no-map;
                };
        };
};

Regards,
Bjorn

Suman Anna Sept. 30, 2014, 9:55 p.m. UTC | #4

Hi Bjorn,

On 09/29/2014 07:34 PM, Bjorn Andersson wrote:
> Add device tree binding documentation for the Qualcom Shared Memory
> manager.
> 
> Signed-off-by: Bjorn Andersson <[e-mail]>
> ---
> 
> Exposed by this node is a set of items of different sizes. For many things a
> standard of_xlate method of referencing the individual nodes would be
> preferable, so a #something-cells would make sense. We do however also needs
> access to these items without explicitly stating the references in devicetree
> (e.g. SMD references 257 of these). I haven't found any good example of how to
> implement this, so suggestions are welcome.
> 
> Note that the hwspinlock reference is not yet supported in the mainline, but
> this will likely need a few iterations so I wanted to get this out.
> 
>  .../devicetree/bindings/soc/qcom/qcom,smem.txt     |   34 ++++++++++++++++++++
>  1 file changed, 34 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt
> 
> diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt b/Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt
> new file mode 100644
> index 0000000..ddd58c7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt
> @@ -0,0 +1,34 @@
> +Qualcomm Shared Memory binding
> +
> +This binding describes the Qualcomm Shared Memory, used to share data between
> +various subsystems and OSes in Qualcomm platforms.
> +
> +- compatible:
> +	Usage: required
> +	Value type: <stringlist>
> +	Definition: must be:
> +		    "qcom,smem"
> +
> +- reg:
> +	Usage: required
> +	Value type: <prop-encoded-array>
> +	Definition: base address and size pair for each area representing the
> +		    shared memory. The first pair will must represent the "main"
> +		    area, where the shared memory header and table-of-content
> +		    can be found.
> +
> +- hwspinlocks:

The property name to use should be "hwlocks" and not "hwspinlocks". This
is what the hwspinlock driver core expects from client users.

regards
Suman

> +	Usage: required
> +	Value type: <prop-encoded-array>
> +	Definition: reference to a hwspinlock used to protect allocations from
> +		    the shared memory
> +
> += EXAMPLE
> +
> +        smem: smem@fa00000 {
> +                compatible = "qcom,smem";
> +                reg = <0x0fa00000 0x200000>,
> +                      <0xfc428000 0x4000>;
> +
> +                hwspinlocks = <&tcsr_mutex 3>;


> +        };
>

Patch

diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt b/Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt
new file mode 100644
index 0000000..ddd58c7
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/qcom/qcom,smem.txt
@@ -0,0 +1,34 @@ 
+Qualcomm Shared Memory binding
+
+This binding describes the Qualcomm Shared Memory, used to share data between
+various subsystems and OSes in Qualcomm platforms.
+
+- compatible:
+	Usage: required
+	Value type: <stringlist>
+	Definition: must be:
+		    "qcom,smem"
+
+- reg:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: base address and size pair for each area representing the
+		    shared memory. The first pair will must represent the "main"
+		    area, where the shared memory header and table-of-content
+		    can be found.
+
+- hwspinlocks:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: reference to a hwspinlock used to protect allocations from
+		    the shared memory
+
+= EXAMPLE
+
+        smem: smem@fa00000 {
+                compatible = "qcom,smem";
+                reg = <0x0fa00000 0x200000>,
+                      <0xfc428000 0x4000>;
+
+                hwspinlocks = <&tcsr_mutex 3>;
+        };