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

[Lee Jones <lee.jones@linaro.org>]

On Fri, 15 Apr 2016, Thor Thayer wrote:
> 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>
> >>
> >>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.

It's always difficult with MFDs as they are by their very nature, more
than one device.  But how about 'resource-manager'?

> I believe I should only call out the name and address on the SPI bus like:
> 
> a10sr@0 {

Correct.

> >>+           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?

Also correct.  No address though?

> >>+                   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";
> >>+           };
> >>+   };
> >

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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