[PATCH v7 05/11] dt-bindings: pwm: add microchip corepwm binding

conor.dooley
2022-02-14T13:56:40Z

From: Conor Dooley <conor.dooley@microchip.com>

Add device tree bindings for the Microchip fpga fabric based "core" PWM
controller.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
---
.../bindings/pwm/microchip,corepwm.yaml | 81 +++++++++++++++++++
1 file changed, 81 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pwm/microchip,corepwm.yaml

diff --git a/Documentation/devicetree/bindings/pwm/microchip,corepwm.yaml b/Documentation/devicetree/bindings/pwm/microchip,corepwm.yaml
new file mode 100644
index 000000000000..a7fae1772a81
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/microchip,corepwm.yaml
@@ -0,0 +1,81 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/microchip,corepwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip IP corePWM controller bindings
+
+maintainers:
+ - Conor Dooley <conor.dooley@microchip.com>
+
+description: |
+ corePWM is an 16 channel pulse width modulator FPGA IP
+
+ https://www.microsemi.com/existing-parts/parts/152118
+
+allOf:
+ - $ref: pwm.yaml#
+
+properties:
+ compatible:
+ items:
+ - const: microchip,corepwm-rtl-v4
+
+ reg:
+ maxItems: 1
+
+ clocks:
+ maxItems: 1
+
+ "#pwm-cells":
+ const: 2
+
+ microchip,sync-update-mask:
+ description: |
+ Depending on how the IP is instantiated, there are two modes of operation.
+ In synchronous mode, all channels are updated at the beginning of the PWM period,
+ and in asynchronous mode updates happen as the control registers are written.
+ A 16 bit wide "SHADOW_REG_EN" parameter of the IP core controls whether synchronous
+ mode is possible for each channel, and is set by the bitstream programmed to the
+ FPGA. If the IP core is instantiated with SHADOW_REG_ENx=1, both registers that
+ control the duty cycle for channel x have a second "shadow"/buffer reg synthesised.
+ At runtime a bit wide register exposed to APB can be used to toggle on/off
+ synchronised mode for all channels it has been synthesised for.
+ Each bit of "microchip,sync-update-mask" corresponds to a PWM channel & represents
+ whether synchronous mode is possible for the PWM channel.
+
+ $ref: /schemas/types.yaml#/definitions/uint32
+ default: 0
+
+ microchip,dac-mode-mask:
+ description: |
+ Optional, per-channel Low Ripple DAC mode is possible on this IP core. It creates
+ a minimum period pulse train whose High/Low average is that of the chosen duty
+ cycle. This "DAC" will have far better bandwidth and ripple performance than the
+ standard PWM algorithm can achieve. A 16 bit DAC_MODE module parameter of the IP
+ core, set at instantiation and by the bitstream programmed to the FPGA, determines
+ whether a given channel operates in regular PWM or DAC mode.
+ Each bit corresponds to a PWM channel & represents whether DAC mode is enabled
+ for that channel.
+
+ $ref: /schemas/types.yaml#/definitions/uint32
+ default: 0
+
+required:
+ - compatible
+ - reg
+ - clocks
+
+additionalProperties: false
+
+examples:
+ - |
+ pwm@41000000 {
+ compatible = "microchip,corepwm-rtl-v4";
+ microchip,sync-update-mask = /bits/ 32 <0>;
+ clocks = <&clkcfg 30>;
+ reg = <0x41000000 0xF0>;
+ #pwm-cells = <2>;
+ };
--
2.35.1