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Diffstat (limited to 'Documentation/devicetree/bindings/serial/nvidia,tegra20-hsuart.yaml')
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diff --git a/Documentation/devicetree/bindings/serial/nvidia,tegra20-hsuart.yaml b/Documentation/devicetree/bindings/serial/nvidia,tegra20-hsuart.yaml new file mode 100644 index 000000000000..a5d67563cd53 --- /dev/null +++ b/Documentation/devicetree/bindings/serial/nvidia,tegra20-hsuart.yaml @@ -0,0 +1,125 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/serial/nvidia,tegra20-hsuart.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: NVIDIA Tegra20/Tegra30 high speed (DMA based) UART controller driver + +maintainers: + - Thierry Reding <thierry.reding@gmail.com> + - Jon Hunter <jonathanh@nvidia.com> + +properties: + compatible: + oneOf: + - enum: + - nvidia,tegra20-hsuart + - nvidia,tegra30-hsuart + - nvidia,tegra186-hsuart + - nvidia,tegra194-hsuart + - items: + - const: nvidia,tegra124-hsuart + - const: nvidia,tegra30-hsuart + + reg: + maxItems: 1 + + interrupts: + maxItems: 1 + + clocks: + items: + - description: module clock + + resets: + items: + - description: module reset + + reset-names: + items: + - const: serial + + dmas: + items: + - description: DMA channel used for reception + - description: DMA channel used for transmission + + dma-names: + items: + - const: rx + - const: tx + + nvidia,enable-modem-interrupt: + $ref: /schemas/types.yaml#/definitions/flag + description: Enable modem interrupts. Should be enable only if all 8 lines of UART controller + are pinmuxed. + + nvidia,adjust-baud-rates: + $ref: /schemas/types.yaml#/definitions/uint32-matrix + description: | + List of entries providing percentage of baud rate adjustment within a range. Each entry + contains a set of 3 values: range low/high and adjusted rate. When the baud rate set on the + controller falls within the range mentioned in this field, the baud rate will be adjusted by + percentage mentioned here. + + Example: <9600 115200 200> + + Increase baud rate by 2% when set baud rate falls within range 9600 to 115200. + + Standard UART devices are expected to have tolerance for baud rate error by -4 to +4 %. All + Tegra devices till Tegra210 had this support. However, Tegra186 chip has a known hardware + issue. UART RX baud rate tolerance level is 0% to +4% in 1-stop config. Otherwise, the + received data will have corruption/invalid framing errors. Parker errata suggests adjusting + baud rate to be higher than the deviations observed in TX. + + TX deviation of connected device can be captured over scope (or noted from its spec) for + valid range and Tegra baud rate has to be set above actual TX baud rate observed. To do this + we use nvidia,adjust-baud-rates. + + As an example, consider there is deviation observed in TX for baud rates as listed below. 0 + to 9600 has 1% deviation 9600 to 115200 2% deviation. This slight deviation is expcted and + Tegra UART is expected to handle it. Due to the issue stated above, baud rate on Tegra UART + should be set equal to or above deviation observed for avoiding frame errors. Property + should be set like this: + + nvidia,adjust-baud-rates = <0 9600 100>, + <9600 115200 200>; + items: + items: + - description: range lower bound + - description: range upper bound + - description: adjustment (in permyriad, i.e. 0.01%) + +required: + - compatible + - reg + - interrupts + - clocks + - resets + - reset-names + - dmas + - dma-names + +allOf: + - $ref: serial.yaml + +unevaluatedProperties: false + +examples: + - | + #include <dt-bindings/clock/tegra30-car.h> + #include <dt-bindings/interrupt-controller/arm-gic.h> + + serial@70006000 { + compatible = "nvidia,tegra30-hsuart"; + reg = <0x70006000 0x40>; + interrupts = <GIC_SPI 36 IRQ_TYPE_LEVEL_HIGH>; + nvidia,enable-modem-interrupt; + clocks = <&tegra_car TEGRA30_CLK_UARTA>; + resets = <&tegra_car 6>; + reset-names = "serial"; + dmas = <&apbdma 8>, <&apbdma 8>; + dma-names = "rx", "tx"; + nvidia,adjust-baud-rates = <1000000 4000000 136>; /* 1.36% shift */ + }; |