linux-kernel - [PATCH v6 06/12] dt-bindings: pwm: add microchip corepwm binding

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Date:   Mon, 7 Feb 2022 16:26:32 +0000
From:   <conor.dooley@...rochip.com>
To:     <linus.walleij@...aro.org>, <brgl@...ev.pl>, <robh+dt@...nel.org>,
        <jassisinghbrar@...il.com>, <thierry.reding@...il.com>,
        <u.kleine-koenig@...gutronix.de>, <lee.jones@...aro.org>,
        <a.zummo@...ertech.it>, <alexandre.belloni@...tlin.com>,
        <paul.walmsley@...ive.com>, <palmer@...belt.com>,
        <aou@...s.berkeley.edu>, <geert@...ux-m68k.org>,
        <krzysztof.kozlowski@...onical.com>, <linux-gpio@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-i2c@...r.kernel.org>, <linux-pwm@...r.kernel.org>,
        <linux-rtc@...r.kernel.org>, <linux-riscv@...ts.infradead.org>
CC:     <bin.meng@...driver.com>, <heiko@...ech.de>,
        <lewis.hanly@...rochip.com>, <conor.dooley@...rochip.com>,
        <daire.mcnamara@...rochip.com>, <ivan.griffin@...rochip.com>,
        <atishp@...osinc.com>, Rob Herring <robh@...nel.org>,
        Palmer Dabbelt <palmer@...osinc.com>
Subject: [PATCH v6 06/12] dt-bindings: pwm: add microchip corepwm binding

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

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

Reviewed-by: Rob Herring <robh@...nel.org>
Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
Acked-by: Palmer Dabbelt <palmer@...osinc.com>
---
 .../bindings/pwm/microchip,corepwm.yaml       | 79 +++++++++++++++++++
 1 file changed, 79 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..30ec70ac5c44
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/microchip,corepwm.yaml
@@ -0,0 +1,79 @@
+# 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@...rochip.com>
+
+description: |
+  corePWM is an 16 channel pulse width modulator FPGA IP
+
+  https://www.microsemi.com/existing-parts/parts/152118
+
+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
+  - "#pwm-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    pwm@...00000 {
+      compatible = "microchip,corepwm-rtl-v4";
+      microchip,sync-update-mask = /bits/ 32 <0>;
+      clocks = <&clkcfg 30>;
+      reg = <0x41000000 0xF0>;
+      #pwm-cells = <2>;
+    };
-- 
2.35.1