[PATCH v6 6/9] dt-bindings: counter: Document stm32 quadrature encoder

On Fri, 18 May 2018 11:28:15 -0500
Rob Herring [off-list ref] wrote:

On Thu, May 17, 2018 at 08:59:40PM +0200, Benjamin Gaignard wrote:

quoted

2018-05-17 18:23 GMT+02:00 Rob Herring [off-list ref]:  

quoted

On Wed, May 16, 2018 at 12:51 PM, William Breathitt Gray
[off-list ref] wrote:  

quoted

From: Benjamin Gaignard <redacted>  

v6? Where's v1-v5?
 

quoted

Add bindings for STM32 Timer quadrature encoder.
It is a sub-node of STM32 Timer which implement the
counter part of the hardware.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Benjamin Gaignard <redacted>
Signed-off-by: William Breathitt Gray <redacted>
---
 .../bindings/counter/stm32-timer-cnt.txt      | 26 +++++++++++++++++++
 .../devicetree/bindings/mfd/stm32-timers.txt  |  7 +++++
 2 files changed, 33 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/counter/stm32-timer-cnt.txt

diff --git a/Documentation/devicetree/bindings/counter/stm32-timer-cnt.txt b/Documentation/devicetree/bindings/counter/stm32-timer-cnt.txt
new file mode 100644
index 000000000000..377728128bef
--- /dev/null
+++ b/Documentation/devicetree/bindings/counter/stm32-timer-cnt.txt

@@ -0,0 +1,26 @@
+STMicroelectronics STM32 Timer quadrature encoder
+
+STM32 Timer provides quadrature encoder counter mode to detect  

'mode' does not sound like a sub-block of the timers block.  

quadrature encoding is one of the counting modes of this hardware
block which is enable to count on other signals/triggers  

You don't need a child node and compatible to set a mode.

A pile of extra hardware becomes relevant and you only want
to be in this state if you have appropriate external device
wired up.  In this case there is admittedly not a lot here
but some devices will look a bit more like a touchscreen controller.

They are often build on top of an ADC module, but have a load
of touch screen only signals and electrical elements that
warrant being represented as a separate node in the DT.

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+angular position and direction of rotary elements,
+from IN1 and IN2 input signals.
+
+Must be a sub-node of an STM32 Timer device tree node.
+See ../mfd/stm32-timers.txt for details about the parent node.
+
+Required properties:
+- compatible:          Must be "st,stm32-timer-counter".
+- pinctrl-names:       Set to "default".
+- pinctrl-0:           List of phandles pointing to pin configuration nodes,
+                       to set IN1/IN2 pins in mode of operation for Low-Power
+                       Timer input on external pin.
+
+Example:
+       timers at 40010000  {
+               compatible = "st,stm32-timers";
+               ...
+               counter {
+                       compatible = "st,stm32-timer-counter";  

Is there only 1? How is the counter addressed?  

Yes there is only one counter per hardware block.
Counter is addressed like the two others sub-nodes and the details
about parent mode are describe in stm32-timers.txt
Should I add them here too ? so example will be like that:  

No, you should drop the child node and add pinctrl to the parent.

Any other functions this block has that you plan on adding? Please make 
bindings as complete as possible, not what you currently have drivers 
for.

quoted

timers at 40010000  {
  #address-cells = <1>;
  #size-cells = <0>;
  compatible = "st,stm32-timers";
  reg = <0x40010000 0x400>;
  clocks = <&rcc 0 160>;
  clock-names = "int";
  counter {
    compatible = "st,stm32-timer-counter";
    pinctrl-names = "default";
    pinctrl-0 = <&tim1_in_pins>;
    };
 };

Benjamin  

quoted

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