Re: [PATCH V2 2/3] dt-bindings: gpio: zynqmp: Add binding documentation for modepin

On 8/13/21 9:01 PM, Rob Herring wrote:

On Thu, Aug 05, 2021 at 11:12:18PM +0530, Piyush Mehta wrote:

quoted

This patch adds DT binding document for zynqmp modepin GPIO controller.
Modepin GPIO controller has four GPIO pins which can be configurable
as input or output.

Modepin driver is a bridge between the peripheral driver and GPIO pins.
It has set and get APIs for accessing GPIO pins, based on the device-tree
entry of reset-gpio property in the peripheral driver, every pin can be
configured as input/output and trigger GPIO pin.

For more information please refer zynqMp TRM link:
Link: https://www.xilinx.com/support/documentation/user_guides/ug1085-zynq-ultrascale-trm.pdf
Chapter 2: Signals, Interfaces, and Pins
Table 2-2: Clock, Reset, and Configuration Pins - PS_MODE

Signed-off-by: Piyush Mehta <redacted>
---
Changes in v2:
- Addressed review comments: Update commit message

https://lore.kernel.org/linux-arm-kernel/20210615080553.2021061-2-piyush.mehta@xilinx.com/T/#mbd1fbda813e33b19397b350bde75747c92a0d7e1 (local)
https://lore.kernel.org/linux-arm-kernel/20210615080553.2021061-2-piyush.mehta@xilinx.com/T/#me82b1444ab3776162cdb0077dfc9256365c7e736 (local)
---
 .../bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml    | 41 ++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml

diff --git a/Documentation/devicetree/bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml b/Documentation/devicetree/bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml
new file mode 100644
index 0000000..39d78f8
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml

@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/gpio/xlnx,zynqmp-gpio-modepin.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: ZynqMP Mode Pin GPIO controller
+
+description:
+  PS_MODE is 4-bits boot mode pins sampled on POR deassertion. Mode Pin
+  GPIO controller with configurable from numbers of pins (from 0 to 3 per
+  PS_MODE). Every pin can be configured as input/output.
+
+maintainers:
+  - Piyush Mehta <piyush.mehta@xilinx.com>
+
+properties:
+  compatible:
+    const: xlnx,zynqmp-gpio-modepin
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+
+required:
+  - compatible
+  - gpio-controller
+  - "#gpio-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    modepin_gpio: gpio {
+        compatible = "xlnx,zynqmp-gpio-modepin";
+        gpio-controller;
+        #gpio-cells = <2>;

No way to interact with this h/w?

As it is part of the firmware interface, it must be a child node in the 
firmware node schema.

Actually it is there. Only example is not showing this properly.
https://github.com/Xilinx/u-boot-xlnx/blob/master/arch/arm/dts/zynqmp.dtsi#L250

Piyush: Can you please do it as we have done with pinctrl.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/pinctrl/xlnx,zynqmp-pinctrl.yaml?h=v5.14-rc6#n301

like this

zynqmp_firmware: zynqmp-firmware {
    modepin_gpio: gpio {
        compatible = "xlnx,zynqmp-gpio-modepin";
        gpio-controller;
        #gpio-cells = <2>;
    };
};

That dt labels can be also removed because they are not needed in example.

Thanks,
Michal

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