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| 1 | +# SPDX-License-Identifier: GPL-2.0 |
| 2 | +%YAML 1.2 |
| 3 | +--- |
| 4 | +$id: http://devicetree.org/schemas/display/simple-framebuffer.yaml# |
| 5 | +$schema: http://devicetree.org/meta-schemas/core.yaml# |
| 6 | + |
| 7 | +title: Simple Framebuffer Device Tree Bindings |
| 8 | + |
| 9 | +maintainers: |
| 10 | + - Bartlomiej Zolnierkiewicz <[email protected]> |
| 11 | + - Hans de Goede <[email protected]> |
| 12 | + |
| 13 | +description: |+ |
| 14 | + A simple frame-buffer describes a frame-buffer setup by firmware or |
| 15 | + the bootloader, with the assumption that the display hardware has |
| 16 | + already been set up to scan out from the memory pointed to by the |
| 17 | + reg property. |
| 18 | +
|
| 19 | + Since simplefb nodes represent runtime information they must be |
| 20 | + sub-nodes of the chosen node (*). Simplefb nodes must be named |
| 21 | + framebuffer@<address>. |
| 22 | +
|
| 23 | + If the devicetree contains nodes for the display hardware used by a |
| 24 | + simplefb, then the simplefb node must contain a property called |
| 25 | + display, which contains a phandle pointing to the primary display |
| 26 | + hw node, so that the OS knows which simplefb to disable when handing |
| 27 | + over control to a driver for the real hardware. The bindings for the |
| 28 | + hw nodes must specify which node is considered the primary node. |
| 29 | +
|
| 30 | + It is advised to add display# aliases to help the OS determine how |
| 31 | + to number things. If display# aliases are used, then if the simplefb |
| 32 | + node contains a display property then the /aliases/display# path |
| 33 | + must point to the display hw node the display property points to, |
| 34 | + otherwise it must point directly to the simplefb node. |
| 35 | +
|
| 36 | + If a simplefb node represents the preferred console for user |
| 37 | + interaction, then the chosen node stdout-path property should point |
| 38 | + to it, or to the primary display hw node, as with display# |
| 39 | + aliases. If display aliases are used then it should be set to the |
| 40 | + alias instead. |
| 41 | +
|
| 42 | + It is advised that devicetree files contain pre-filled, disabled |
| 43 | + framebuffer nodes, so that the firmware only needs to update the |
| 44 | + mode information and enable them. This way if e.g. later on support |
| 45 | + for more display clocks get added, the simplefb nodes will already |
| 46 | + contain this info and the firmware does not need to be updated. |
| 47 | +
|
| 48 | + If pre-filled framebuffer nodes are used, the firmware may need |
| 49 | + extra information to find the right node. In that case an extra |
| 50 | + platform specific compatible and platform specific properties should |
| 51 | + be used and documented. |
| 52 | +
|
| 53 | +properties: |
| 54 | + compatible: |
| 55 | + items: |
| 56 | + - enum: |
| 57 | + - allwinner,simple-framebuffer |
| 58 | + - amlogic,simple-framebuffer |
| 59 | + - const: simple-framebuffer |
| 60 | + |
| 61 | + reg: |
| 62 | + description: Location and size of the framebuffer memory |
| 63 | + |
| 64 | + clocks: |
| 65 | + description: List of clocks used by the framebuffer. |
| 66 | + |
| 67 | + power-domains: |
| 68 | + description: List of power domains used by the framebuffer. |
| 69 | + |
| 70 | + width: |
| 71 | + $ref: /schemas/types.yaml#/definitions/uint32 |
| 72 | + description: Width of the framebuffer in pixels |
| 73 | + |
| 74 | + height: |
| 75 | + $ref: /schemas/types.yaml#/definitions/uint32 |
| 76 | + description: Height of the framebuffer in pixels |
| 77 | + |
| 78 | + stride: |
| 79 | + $ref: /schemas/types.yaml#/definitions/uint32 |
| 80 | + description: Number of bytes of a line in the framebuffer |
| 81 | + |
| 82 | + format: |
| 83 | + description: > |
| 84 | + Format of the framebuffer: |
| 85 | + * `a8b8g8r8` - 32-bit pixels, d[31:24]=a, d[23:16]=b, d[15:8]=g, d[7:0]=r |
| 86 | + * `r5g6b5` - 16-bit pixels, d[15:11]=r, d[10:5]=g, d[4:0]=b |
| 87 | + enum: |
| 88 | + - a8b8g8r8 |
| 89 | + - r5g6b5 |
| 90 | + |
| 91 | + display: |
| 92 | + $ref: /schemas/types.yaml#/definitions/phandle |
| 93 | + description: Primary display hardware node |
| 94 | + |
| 95 | + allwinner,pipeline: |
| 96 | + description: Pipeline used by the framebuffer on Allwinner SoCs |
| 97 | + enum: |
| 98 | + - de_be0-lcd0 |
| 99 | + - de_be0-lcd0-hdmi |
| 100 | + - de_be0-lcd0-tve0 |
| 101 | + - de_be1-lcd0 |
| 102 | + - de_be1-lcd1-hdmi |
| 103 | + - de_fe0-de_be0-lcd0 |
| 104 | + - de_fe0-de_be0-lcd0-hdmi |
| 105 | + - de_fe0-de_be0-lcd0-tve0 |
| 106 | + - mixer0-lcd0 |
| 107 | + - mixer0-lcd0-hdmi |
| 108 | + - mixer1-lcd1-hdmi |
| 109 | + - mixer1-lcd1-tve |
| 110 | + |
| 111 | + amlogic,pipeline: |
| 112 | + description: Pipeline used by the framebuffer on Amlogic SoCs |
| 113 | + enum: |
| 114 | + - vpu-cvbs |
| 115 | + - vpu-hdmi |
| 116 | + |
| 117 | +patternProperties: |
| 118 | + "^[a-zA-Z0-9-]+-supply$": |
| 119 | + $ref: /schemas/types.yaml#/definitions/phandle |
| 120 | + description: |
| 121 | + Regulators used by the framebuffer. These should be named |
| 122 | + according to the names in the device design. |
| 123 | + |
| 124 | +required: |
| 125 | + # The binding requires also reg, width, height, stride and format, |
| 126 | + # but usually they will be filled by the bootloader. |
| 127 | + - compatible |
| 128 | + |
| 129 | +additionalProperties: false |
| 130 | + |
| 131 | +examples: |
| 132 | + - | |
| 133 | + aliases { |
| 134 | + display0 = &lcdc0; |
| 135 | + }; |
| 136 | +
|
| 137 | + chosen { |
| 138 | + #address-cells = <1>; |
| 139 | + #size-cells = <1>; |
| 140 | + stdout-path = "display0"; |
| 141 | + framebuffer0: framebuffer@1d385000 { |
| 142 | + compatible = "simple-framebuffer"; |
| 143 | + reg = <0x1d385000 3840000>; |
| 144 | + width = <1600>; |
| 145 | + height = <1200>; |
| 146 | + stride = <3200>; |
| 147 | + format = "r5g6b5"; |
| 148 | + clocks = <&ahb_gates 36>, <&ahb_gates 43>, <&ahb_gates 44>; |
| 149 | + lcd-supply = <®_dc1sw>; |
| 150 | + display = <&lcdc0>; |
| 151 | + }; |
| 152 | + }; |
| 153 | +
|
| 154 | + soc@1c00000 { |
| 155 | + lcdc0: lcdc@1c0c000 { |
| 156 | + compatible = "allwinner,sun4i-a10-lcdc"; |
| 157 | + }; |
| 158 | + }; |
| 159 | +
|
| 160 | +... |
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