Re: [PATCH RFC V2 1/2] Documentation: add Device tree bindings for QCA7000

Hello.

On 07/02/2014 11:01 AM, Stefan Wahren wrote:

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This patch adds the Device tree bindings for the
Ethernet over SPI protocol driver of the Qualcomm
QCA7000 HomePlug GreenPHY.

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Signed-off-by: Stefan Wahren <redacted>
---
   .../devicetree/bindings/net/qca-qca7000-spi.txt    |   47
++++++++++++++++++++
   1 file changed, 47 insertions(+)
   create mode 100644
Documentation/devicetree/bindings/net/qca-qca7000-spi.txt

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diff --git
a/Documentation/devicetree/bindings/net/qca-qca7000-spi.txt
b/Documentation/devicetree/bindings/net/qca-qca7000-spi.txt
new file mode 100644
index 0000000..66ff588

--- /dev/null
+++ b/Documentation/devicetree/bindings/net/qca-qca7000-spi.txt

@@ -0,0 +1,47 @@
+* Qualcomm QCA7000 (Ethernet over SPI protocol)
+
+Note: The QCA7000 is useable as a SPI device. In this case it must

be defined
+as a child of a SPI master in the device tree.
+
+Required properties:
+- compatible : Should be "qca,qca7000"
+- reg : Should specify the SPI chip select
+- interrupt-parent : Should specify the pHandle of the source interrupt

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    This property is not really required, it could be inherited from an
upper-level node.

should i move this property to the optional properties or drop it from
the properties?

    Make it optional, please.

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+- interrupts : The first cell should specify the index of the source
interrupt
+  and the second cell should specify the trigger type as rising edge
+- spi-cpha : Must be set
+- spi-cpol: Must be set
+
+Optional properties:
+- spi-max-frequency : Maximum frequency of the SPI bus the chip can
operate at.
+  Numbers smaller than 1000000 or greater than 16000000 are invalid.
Missing
+  the property will set the SPI frequency to 8000000 Hertz.
+- local-mac-address: 6 bytes, mac address

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    s/mac/MAC/.

I assume that the replacement should apply only to the property
description not to the property name.

    Yes, of course.

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+- qca,legacy-mode : Set the SPI data transfer of the QCA7000 to
legacy mode.
+  In this mode the SPI master must toggle the chip select between
each data
+  word. In burst mode these gaps aren't necessary, which is faster.
+  This setting depends on how the QCA7000 is setup via GPIO pin
strapping.
+  If the property is missing the driver defaults to burst mode.
+
+Example:
+
+/* Freescale i.MX28 SPI master*/
+ssp2: ssp@80014000 {

    The node name should probably be "spi" here.

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+    #address-cells = <1>;
+    #size-cells = <0>;
+    compatible = "fsl,imx28-spi";
+    pinctrl-names = "default";
+    pinctrl-0 = <&spi2_pins_a>;
+    status = "okay";
+
+    qca7000@0 {

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    According to the ePAPR standard [1]:

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The name of a node should be somewhat generic, reflecting the function
of the device and not its precise programming model. If appropriate,
the name should be one of the following choices:
[...]
  - ethernet;

I have doubts about that. I agree that the current node name doesn't fit
to ePAPR. The function of a QCA7000 isn't really a ethernet device. Yes,
this linux driver implementation handle the QCA7000 as a ethernet
device. But the QCA7000 a powerline device according to Homeplug GreenPHY.

How about using powerline as node name?

    I don't know the differences between Ethernet and PowerLine but looks like 
they are minimal as you're implementing an Ethernet driver. So I'm still for 
"ethernet".

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+        compatible = "qca,qca7000";
+        interrupt-parent = <&gpio3>;      /* GPIO Bank 3 */
+        interrupts = <25 0x1>;            /* Index: 25, rising edge */
+        reg = <0x0>;
+        spi-cpha;                         /* SPI mode: CPHA=1 */
+        spi-cpol;                         /* SPI mode: CPOL=1 */
+        spi-max-frequency = <8000000>;    /* freq: 8 MHz */
+        local-mac-address = [ A0 B0 C0 D0 E0 F0 ];
+    };
+};

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[1]
http://www.power.org/resources/downloads/Power_ePAPR_APPROVED_v1.0.pdf

BR Stefan Wahren

WBR, Sergei