LTDC device tree configuration
目录
Article purpose
本文介绍了如何在将外围设备分配给 Linux®时配置“ LTDC” [1] 操作系统。
使用设备树机制 [2]执行配置。
The Device tree提供了STM32“ LTDC Linux驱动程序”使用的LTDC [1]的硬件描述。
DT bindings documentation
LTDC由STM32 LTDC设备树绑定表示 [3].
DT configuration
该硬件描述是“STM32微处理器”设备树文件(扩展名为.dtsi)和“板子”设备树文件(扩展名为.dts)的组合。 有关设备树文件分割的说明,请参见Device tree。
STM32CubeMX可用于生成板卡设备树。 有关更多详细信息,请参考How to configure the DT using STM32CubeMX。
DT configuration (STM32 level)
LTDC设备树节点在stm32mp157c.dtsi [4]. 声明(如下所示)提供了硬件寄存器的基地址,时钟,中断和复位。
ltdc: display-controller@5a001000 { compatible = "st,stm32-ltdc"; reg = <0x5a001000 0x400>; interrupts = <GIC_SPI 88 IRQ_TYPE_LEVEL_HIGH>, <GIC_SPI 89 IRQ_TYPE_LEVEL_HIGH>; clocks = <&rcc LTDC_PX>; clock-names = "lcd"; resets = <&rcc LTDC_R>; status = "disabled"; };
该设备树部分与STM32微处理器有关。 它必须保持原样,而不能由最终用户修改。 |
DT configuration (board level)
与特定板卡相关的LTDC设备树可能具有以下节点,具体取决于板卡硬件:
- ltdc节点:包含输入/输出端口说明。
- panel或i2cx网桥rgb节点(取决于板硬件):包含LTDC Pinctrl和输入/输出端口说明
- panel_backlight节点(取决于板硬件):与面板节点有关
LTDC引脚的完整示例[5] 在stm32mp157-pinctrl.dtsi中提供 [6]
ltdc_pins_a: ltdc-a-0 { pins { pinmux = <STM32_PINMUX('G', 7, AF14)>, /* LCD_CLK */ <STM32_PINMUX('I', 10, AF14)>, /* LCD_HSYNC */ <STM32_PINMUX('I', 9, AF14)>, /* LCD_VSYNC */ <STM32_PINMUX('F', 10, AF14)>, /* LCD_DE */ <STM32_PINMUX('H', 2, AF14)>, /* LCD_R0 */ <STM32_PINMUX('H', 3, AF14)>, /* LCD_R1 */ <STM32_PINMUX('H', 8, AF14)>, /* LCD_R2 */ <STM32_PINMUX('H', 9, AF14)>, /* LCD_R3 */ <STM32_PINMUX('H', 10, AF14)>, /* LCD_R4 */ <STM32_PINMUX('C', 0, AF14)>, /* LCD_R5 */ <STM32_PINMUX('H', 12, AF14)>, /* LCD_R6 */ <STM32_PINMUX('E', 15, AF14)>, /* LCD_R7 */ <STM32_PINMUX('E', 5, AF14)>, /* LCD_G0 */ <STM32_PINMUX('E', 6, AF14)>, /* LCD_G1 */ <STM32_PINMUX('H', 13, AF14)>, /* LCD_G2 */ <STM32_PINMUX('H', 14, AF14)>, /* LCD_G3 */ <STM32_PINMUX('H', 15, AF14)>, /* LCD_G4 */ <STM32_PINMUX('I', 0, AF14)>, /* LCD_G5 */ <STM32_PINMUX('I', 1, AF14)>, /* LCD_G6 */ <STM32_PINMUX('I', 2, AF14)>, /* LCD_G7 */ <STM32_PINMUX('D', 9, AF14)>, /* LCD_B0 */ <STM32_PINMUX('G', 12, AF14)>, /* LCD_B1 */ <STM32_PINMUX('G', 10, AF14)>, /* LCD_B2 */ <STM32_PINMUX('D', 10, AF14)>, /* LCD_B3 */ <STM32_PINMUX('I', 4, AF14)>, /* LCD_B4 */ <STM32_PINMUX('A', 3, AF14)>, /* LCD_B5 */ <STM32_PINMUX('B', 8, AF14)>, /* LCD_B6 */ <STM32_PINMUX('D', 8, AF14)>; /* LCD_B7 */ bias-disable; drive-push-pull; slew-rate = <2>; }; }; ltdc_pins_sleep_a: ltdc-a-1 { pins { pinmux = <STM32_PINMUX('G', 7, ANALOG)>, /* LCD_CLK */ <STM32_PINMUX('I', 10, ANALOG)>, /* LCD_HSYNC */ <STM32_PINMUX('I', 9, ANALOG)>, /* LCD_VSYNC */ <STM32_PINMUX('F', 10, ANALOG)>, /* LCD_DE */ <STM32_PINMUX('H', 2, ANALOG)>, /* LCD_R0 */ <STM32_PINMUX('H', 3, ANALOG)>, /* LCD_R1 */ <STM32_PINMUX('H', 8, ANALOG)>, /* LCD_R2 */ <STM32_PINMUX('H', 9, ANALOG)>, /* LCD_R3 */ <STM32_PINMUX('H', 10, ANALOG)>, /* LCD_R4 */ <STM32_PINMUX('C', 0, ANALOG)>, /* LCD_R5 */ <STM32_PINMUX('H', 12, ANALOG)>, /* LCD_R6 */ <STM32_PINMUX('E', 15, ANALOG)>, /* LCD_R7 */ <STM32_PINMUX('E', 5, ANALOG)>, /* LCD_G0 */ <STM32_PINMUX('E', 6, ANALOG)>, /* LCD_G1 */ <STM32_PINMUX('H', 13, ANALOG)>, /* LCD_G2 */ <STM32_PINMUX('H', 14, ANALOG)>, /* LCD_G3 */ <STM32_PINMUX('H', 15, ANALOG)>, /* LCD_G4 */ <STM32_PINMUX('I', 0, ANALOG)>, /* LCD_G5 */ <STM32_PINMUX('I', 1, ANALOG)>, /* LCD_G6 */ <STM32_PINMUX('I', 2, ANALOG)>, /* LCD_G7 */ <STM32_PINMUX('D', 9, ANALOG)>, /* LCD_B0 */ <STM32_PINMUX('G', 12, ANALOG)>, /* LCD_B1 */ <STM32_PINMUX('G', 10, ANALOG)>, /* LCD_B2 */ <STM32_PINMUX('D', 10, ANALOG)>, /* LCD_B3 */ <STM32_PINMUX('I', 4, ANALOG)>, /* LCD_B4 */ <STM32_PINMUX('A', 3, ANALOG)>, /* LCD_B5 */ <STM32_PINMUX('B', 8, ANALOG)>, /* LCD_B6 */ <STM32_PINMUX('D', 8, ANALOG)>; /* LCD_B7 */ }; };
一个完整的例子 STM32MP157 Discovery board 设备树在stm32mp157a-dk1.dts中可用 [7].
<dc { status = "okay"; port { #address-cells = <1>; #size-cells = <0>; ltdc_ep0_out: endpoint@0 { reg = <0>; remote-endpoint = <&sii9022_in>; }; }; }; &i2c1 { ... hdmi-transmitter@39 { compatible = "sil,sii9022"; reg = <0x39>; iovcc-supply = <&v3v3_hdmi>; cvcc12-supply = <&v1v2_hdmi>; reset-gpios = <&gpioa 10 GPIO_ACTIVE_LOW>; interrupts = <1 IRQ_TYPE_EDGE_FALLING>; interrupt-parent = <&gpiog>; pinctrl-names = "default", "sleep"; pinctrl-0 = <<dc_pins_a>; pinctrl-1 = <<dc_pins_sleep_a>; status = "okay"; ports { #address-cells = <1>; #size-cells = <0>; port@0 { reg = <0>; sii9022_in: endpoint { remote-endpoint = <<dc_ep0_out>; }; }; port@1 { reg = <1>; sii9022_tx_endpoint: endpoint { remote-endpoint = <&i2s2_endpoint>; }; }; }; }; };
How to configure the DT using STM32CubeMX
STM32CubeMX 工具可用于配置STM32MPU设备并获取相应的 platform configuration device tree 文件。
STM32CubeMX可能不支持以上 DT bindings documentation段中描述的所有属性。 如果是这样,该工具会在生成的设备树中插入用户部分。 然后可以编辑这些部分以添加一些属性,并将它们一代一代地保留下来。 有关更多信息,请参见STM32CubeMX 用户手册。
References
Please refer to the following links for additional information:
- ↑ 1.01.1 LTDC internal peripheral
- ↑ Device tree
- ↑ Documentation/devicetree/bindings/display/st,stm32-ltdc.txt | |}} Linux kernel STM32 LTDC bindings (st,stm32-ltdc.txt)
- ↑ arch/arm/boot/dts/stm32mp157c.dtsi | |}} Linux kernel STM32MP157C device tree (stm32mp157c.dtsi)
- ↑ Pinctrl device tree configuration
- ↑ arch/arm/boot/dts/stm32mp157-pinctrl.dtsi | |}} Linux kernel STM32MP157 pinctrl device tree (stm32mp157-pinctrl.dtsi)
- ↑ arch/arm/boot/dts/stm32mp157a-dk1.dts | |}} Linux kernel STM32MP157 Discovery board device tree (stm32mp157a-dk1.dts)
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