Re: [RFC 1/8] dt-bindings: mfd: Add Altera Arria10 System Resource Chip bindings

Thor Thayer
2016-04-15T16:57:40Z

Hi Lee

On 03/30/2016 06:35 AM, Lee Jones wrote:

On Tue, 29 Mar 2016, ttha...@opensource.altera.com wrote:

From: Thor Thayer <ttha...@opensource.altera.com>
To: linux-hwmon@vger.kernel.org

The Altera Arria10 Devkit System Resource chip is a Multi-Function
Device, it has two subdevices:
- GPIO
- HWMON

This patch adds documentation for the Altera A10-SR DT bindings.

Signed-off-by: Thor Thayer <ttha...@opensource.altera.com>
---
.../devicetree/bindings/mfd/altera-a10sr.txt | 35 ++++++++++++++++++++
1 file changed, 35 insertions(+)
create mode 100644 Documentation/devicetree/bindings/mfd/altera-a10sr.txt

diff --git a/Documentation/devicetree/bindings/mfd/altera-a10sr.txt
b/Documentation/devicetree/bindings/mfd/altera-a10sr.txt
new file mode 100644
index 0000000..564c761
--- /dev/null
+++ b/Documentation/devicetree/bindings/mfd/altera-a10sr.txt
@@ -0,0 +1,35 @@
+* Altera Arria10 Development Kit System Resource Chip
+
+Required parent device properties:
+- compatible : "altr,altr_a10sr"
+- spi-max-frequency : Maximum SPI frequency.
+- reg : the SPI Chip Select address for the Arria10 System Resource chip

DT bindings are much easier to read in the following format:

- compatible : "altr,altr_a10sr"
- spi-max-frequency : Maximum SPI frequency.
- reg : the SPI Chip Select address for the Arria10 System
Resource chip

... also, sentences start with an uppercase char.

+The A10SR consists of this varied group of sub-devices:
+
+Device Description
+------ ----------
+altr_a10sr_gpio GPIO Controller
+altr_a10sr_hwmon Hardware Monitor
+
+The LEDs are implemented entirely in the device tree using
+the gpio-led framework.

This is a Linuxisum and should not live in DT bindings.

+Example:
+
+ a10-sr: a10-sr@0 {

Nodes should be named after their device 'type'.

Does this device really start a address 0?

I see in the documentation on device trees there are a number of
categories I can use. GPIO is easy because it is one of the categories
but I'm not sure about the new device I'm adding since the a10sr is a
new device.

I believe I should only call out the name and address on the SPI bus like:

a10sr@0 {

+ compatible = "altr,altr-a10sr";
+ reg = <0>;
+ spi-max-frequency = <100000>;
+
+ a10sr_gpio: a10sr_gpio {

Device type only please.

and this would be a10sr_gpio: gpio-controller {

Does that seem correct?

+ compatible = "altr,a10sr-gpio";
+ gpio-controller;
+ #gpio-cells = <2>;
+ ngpios = <16>;
+ };
+
+ a10sr_hwmon: a10sr_hwmon {

Device type only please.

I need to revisit where this will live (hwmon does not seem to be the
correct place) so it will change but I can follow the format above if it
is correct.

Thanks for reviewing.

+ compatible = "altr,a10sr-hwmon";
+ };
+ };

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