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|
# SPDX-License-Identifier: GPL-2.0
%YAML 1.2
---
$id: http://devicetree.org/schemas/display/simple-framebuffer.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: Simple Framebuffer Device Tree Bindings
maintainers:
- Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
- Hans de Goede <hdegoede@redhat.com>
description: |+
A simple frame-buffer describes a frame-buffer setup by firmware or
the bootloader, with the assumption that the display hardware has
already been set up to scan out from the memory pointed to by the
reg property.
Since simplefb nodes represent runtime information they must be
sub-nodes of the chosen node (*). Simplefb nodes must be named
framebuffer@<address>.
If the devicetree contains nodes for the display hardware used by a
simplefb, then the simplefb node must contain a property called
display, which contains a phandle pointing to the primary display
hw node, so that the OS knows which simplefb to disable when handing
over control to a driver for the real hardware. The bindings for the
hw nodes must specify which node is considered the primary node.
It is advised to add display# aliases to help the OS determine how
to number things. If display# aliases are used, then if the simplefb
node contains a display property then the /aliases/display# path
must point to the display hw node the display property points to,
otherwise it must point directly to the simplefb node.
If a simplefb node represents the preferred console for user
interaction, then the chosen node stdout-path property should point
to it, or to the primary display hw node, as with display#
aliases. If display aliases are used then it should be set to the
alias instead.
It is advised that devicetree files contain pre-filled, disabled
framebuffer nodes, so that the firmware only needs to update the
mode information and enable them. This way if e.g. later on support
for more display clocks get added, the simplefb nodes will already
contain this info and the firmware does not need to be updated.
If pre-filled framebuffer nodes are used, the firmware may need
extra information to find the right node. In that case an extra
platform specific compatible and platform specific properties should
be used and documented.
properties:
compatible:
items:
- enum:
- allwinner,simple-framebuffer
- amlogic,simple-framebuffer
- const: simple-framebuffer
reg:
description: Location and size of the framebuffer memory
clocks:
description: List of clocks used by the framebuffer.
power-domains:
description: List of power domains used by the framebuffer.
width:
$ref: /schemas/types.yaml#/definitions/uint32
description: Width of the framebuffer in pixels
height:
$ref: /schemas/types.yaml#/definitions/uint32
description: Height of the framebuffer in pixels
stride:
$ref: /schemas/types.yaml#/definitions/uint32
description: Number of bytes of a line in the framebuffer
format:
description: >
Format of the framebuffer:
* `a8b8g8r8` - 32-bit pixels, d[31:24]=a, d[23:16]=b, d[15:8]=g, d[7:0]=r
* `r5g6b5` - 16-bit pixels, d[15:11]=r, d[10:5]=g, d[4:0]=b
enum:
- a8b8g8r8
- r5g6b5
display:
$ref: /schemas/types.yaml#/definitions/phandle
description: Primary display hardware node
allwinner,pipeline:
description: Pipeline used by the framebuffer on Allwinner SoCs
enum:
- de_be0-lcd0
- de_be0-lcd0-hdmi
- de_be0-lcd0-tve0
- de_be1-lcd0
- de_be1-lcd1-hdmi
- de_fe0-de_be0-lcd0
- de_fe0-de_be0-lcd0-hdmi
- de_fe0-de_be0-lcd0-tve0
- mixer0-lcd0
- mixer0-lcd0-hdmi
- mixer1-lcd1-hdmi
- mixer1-lcd1-tve
amlogic,pipeline:
description: Pipeline used by the framebuffer on Amlogic SoCs
enum:
- vpu-cvbs
- vpu-hdmi
patternProperties:
"^[a-zA-Z0-9-]+-supply$":
$ref: /schemas/types.yaml#/definitions/phandle
description:
Regulators used by the framebuffer. These should be named
according to the names in the device design.
required:
# The binding requires also reg, width, height, stride and format,
# but usually they will be filled by the bootloader.
- compatible
allOf:
- if:
properties:
compatible:
contains:
const: allwinner,simple-framebuffer
then:
required:
- allwinner,pipeline
- if:
properties:
compatible:
contains:
const: amlogic,simple-framebuffer
then:
required:
- amlogic,pipeline
additionalProperties: false
examples:
- |
aliases {
display0 = &lcdc0;
};
chosen {
#address-cells = <1>;
#size-cells = <1>;
stdout-path = "display0";
framebuffer0: framebuffer@1d385000 {
compatible = "allwinner,simple-framebuffer", "simple-framebuffer";
allwinner,pipeline = "de_be0-lcd0";
reg = <0x1d385000 3840000>;
width = <1600>;
height = <1200>;
stride = <3200>;
format = "r5g6b5";
clocks = <&ahb_gates 36>, <&ahb_gates 43>, <&ahb_gates 44>;
lcd-supply = <®_dc1sw>;
display = <&lcdc0>;
};
};
soc@1c00000 {
lcdc0: lcdc@1c0c000 {
compatible = "allwinner,sun4i-a10-lcdc";
};
};
...
|
