| Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 1 | # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) |
| 2 | %YAML 1.2 |
| 3 | --- |
| 4 | $id: http://devicetree.org/schemas/serial/nvidia,tegra20-hsuart.yaml# |
| 5 | $schema: http://devicetree.org/meta-schemas/core.yaml# |
| 6 | |
| 7 | title: NVIDIA Tegra20/Tegra30 high speed (DMA based) UART controller driver |
| 8 | |
| 9 | maintainers: |
| 10 | - Thierry Reding <thierry.reding@gmail.com> |
| 11 | - Jon Hunter <jonathanh@nvidia.com> |
| 12 | |
| 13 | properties: |
| 14 | compatible: |
| 15 | oneOf: |
| 16 | - enum: |
| 17 | - nvidia,tegra20-hsuart |
| 18 | - nvidia,tegra30-hsuart |
| 19 | - nvidia,tegra186-hsuart |
| 20 | - nvidia,tegra194-hsuart |
| 21 | - items: |
| 22 | - const: nvidia,tegra124-hsuart |
| 23 | - const: nvidia,tegra30-hsuart |
| 24 | |
| 25 | reg: |
| 26 | maxItems: 1 |
| 27 | |
| 28 | interrupts: |
| 29 | maxItems: 1 |
| 30 | |
| 31 | clocks: |
| 32 | items: |
| 33 | - description: module clock |
| 34 | |
| 35 | resets: |
| 36 | items: |
| 37 | - description: module reset |
| 38 | |
| 39 | reset-names: |
| 40 | items: |
| 41 | - const: serial |
| 42 | |
| 43 | dmas: |
| 44 | items: |
| 45 | - description: DMA channel used for reception |
| 46 | - description: DMA channel used for transmission |
| 47 | |
| 48 | dma-names: |
| 49 | items: |
| 50 | - const: rx |
| 51 | - const: tx |
| 52 | |
| 53 | nvidia,enable-modem-interrupt: |
| 54 | $ref: /schemas/types.yaml#/definitions/flag |
| 55 | description: Enable modem interrupts. Should be enable only if all 8 lines of UART controller |
| 56 | are pinmuxed. |
| 57 | |
| 58 | nvidia,adjust-baud-rates: |
| 59 | $ref: /schemas/types.yaml#/definitions/uint32-matrix |
| 60 | description: | |
| 61 | List of entries providing percentage of baud rate adjustment within a range. Each entry |
| 62 | contains a set of 3 values: range low/high and adjusted rate. When the baud rate set on the |
| 63 | controller falls within the range mentioned in this field, the baud rate will be adjusted by |
| 64 | percentage mentioned here. |
| 65 | |
| 66 | Example: <9600 115200 200> |
| 67 | |
| 68 | Increase baud rate by 2% when set baud rate falls within range 9600 to 115200. |
| 69 | |
| 70 | Standard UART devices are expected to have tolerance for baud rate error by -4 to +4 %. All |
| 71 | Tegra devices till Tegra210 had this support. However, Tegra186 chip has a known hardware |
| 72 | issue. UART RX baud rate tolerance level is 0% to +4% in 1-stop config. Otherwise, the |
| 73 | received data will have corruption/invalid framing errors. Parker errata suggests adjusting |
| 74 | baud rate to be higher than the deviations observed in TX. |
| 75 | |
| 76 | TX deviation of connected device can be captured over scope (or noted from its spec) for |
| 77 | valid range and Tegra baud rate has to be set above actual TX baud rate observed. To do this |
| 78 | we use nvidia,adjust-baud-rates. |
| 79 | |
| 80 | As an example, consider there is deviation observed in TX for baud rates as listed below. 0 |
| 81 | to 9600 has 1% deviation 9600 to 115200 2% deviation. This slight deviation is expcted and |
| 82 | Tegra UART is expected to handle it. Due to the issue stated above, baud rate on Tegra UART |
| 83 | should be set equal to or above deviation observed for avoiding frame errors. Property |
| 84 | should be set like this: |
| 85 | |
| 86 | nvidia,adjust-baud-rates = <0 9600 100>, |
| 87 | <9600 115200 200>; |
| 88 | items: |
| 89 | items: |
| 90 | - description: range lower bound |
| 91 | - description: range upper bound |
| 92 | - description: adjustment (in permyriad, i.e. 0.01%) |
| 93 | |
| 94 | required: |
| 95 | - compatible |
| 96 | - reg |
| 97 | - interrupts |
| 98 | - clocks |
| 99 | - resets |
| 100 | - reset-names |
| 101 | - dmas |
| 102 | - dma-names |
| 103 | |
| 104 | allOf: |
| 105 | - $ref: serial.yaml |
| 106 | |
| 107 | unevaluatedProperties: false |
| 108 | |
| 109 | examples: |
| 110 | - | |
| 111 | #include <dt-bindings/clock/tegra30-car.h> |
| 112 | #include <dt-bindings/interrupt-controller/arm-gic.h> |
| 113 | |
| 114 | serial@70006000 { |
| 115 | compatible = "nvidia,tegra30-hsuart"; |
| 116 | reg = <0x70006000 0x40>; |
| 117 | interrupts = <GIC_SPI 36 IRQ_TYPE_LEVEL_HIGH>; |
| 118 | nvidia,enable-modem-interrupt; |
| 119 | clocks = <&tegra_car TEGRA30_CLK_UARTA>; |
| 120 | resets = <&tegra_car 6>; |
| 121 | reset-names = "serial"; |
| 122 | dmas = <&apbdma 8>, <&apbdma 8>; |
| 123 | dma-names = "rx", "tx"; |
| 124 | nvidia,adjust-baud-rates = <1000000 4000000 136>; /* 1.36% shift */ |
| 125 | }; |