STM32MP157 Linux系统移植开发篇11：Linux HDMI驱动移植

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STMCU小助手发布时间：2022-9-30 18:21

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文章简介:	STM32MP157 Linux系统移植开发篇11：Linux HDMI驱动移植

1.1实验原理
STM32MP157A系列SoC中默认没有HDMI相关控制器，FS-MP1A使用SiI9022芯片将RGB信号转化为HDMI信号。STM32MP157A集成LTDC(LCD-TFT Display Controller)，提供一个24bit RGB并行接口用于连接到各种LCD和TFT面板。

SiI9022芯片通过I2C5总线与SoC进行交互，通过SoC的LCD_PCLK、LCD_VSYNC、LCD_HSYNC、LCD_DEN与RGB信号线来进行图像信号的传输，通过I2S2总线进行音频数据的传输。

查看原理图确认I2C5、中断、复位管脚对应关系：

LCD接口管脚对应关系：

1.I2C5设备树节点

内核中ST对STM32MP15x系列芯片的设备树资源了做了定义，可参见：

arch/arm/boot/dts/stm32mp151.dtsi

stm32mp151中i2c5定义如下：

i2c5: i2c@40015000 {
compatible = "st,stm32mp15-i2c";
reg = <0x40015000 0x400>;
interrupt-names = "event", "error";
interrupts-extended = <&exti 25 IRQ_TYPE_LEVEL_HIGH>,
<&intc GIC_SPI 108 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&rcc I2C5_K>;
resets = <&rcc I2C5_R>;
#address-cells = <1>;
#size-cells = <0>;
dmas = <&dmamux1 115 0x400 0x80000001>,
<&dmamux1 116 0x400 0x80000001>;
dma-names = "rx", "tx";
power-domains = <&pd_core>;
st,syscfg-fmp = <&syscfg 0x4 0x10>;
wakeup-source;
status = "disabled";
};

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上述代码只对i2c5做了基本的初始化，并没有针对不同的硬件设计做适配，所以需结合硬件补全设备树节点信息。

参考stm32mp15xx-dkx.dtsi对于i2c设备节点的描述，修改i2c5内容如下：

&i2c5 {
pinctrl-names = "default", "sleep";
pinctrl-0 = <&i2c5_pins_a>;
pinctrl-1 = <&i2c5_pins_sleep_a>;
i2c-scl-rising-time-ns = <100>;
i2c-scl-falling-time-ns = <7>;
clock-frequency = <100000>;
/* spare dmas for other usage */
/delete-property/dmas;
/delete-property/dma-names;
status = "okay";
};

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由于stm32mp15-pinctrl.dtsi中对于i2c5_pins_a和i2c5_pins_sleep_a的定义与板子实际使用管脚一致，所以无需修改，内容如下：

i2c5_pins_a: i2c5-0 {
pins {
pinmux = <STM32_PINMUX('A', 11, AF4)>, /* I2C5_SCL */
<STM32_PINMUX('A', 12, AF4)>; /* I2C5_SDA */
bias-disable;
drive-open-drain;
slew-rate = <0>;
};
};
i2c5_pins_sleep_a: i2c5-1 {
pins {
pinmux = <STM32_PINMUX('A', 11, ANALOG)>, /* I2C5_SCL */
<STM32_PINMUX('A', 12, ANALOG)>; /* I2C5_SDA */
};
};

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2.I2S2设备树节点

3.LTDC设备树节点
SiI9022实现HDMI输出需要RGB信号作为数据源，LTDC为STM32MP157的LCD显示控制器，可以输出24bit的并行数据，HDMI显示首先需要驱动LTDC。

内核中ST对STM32MP15x系列芯片的设备树资源了做了定义，可参见：

arch/arm/boot/dts/stm32mp151.dtsi

stm32mp151中ltdc定义如下：

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";
};

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上述代码只对ltdc做了基本的初始化，并没有针对不同的硬件设计做适配，所以需结合硬件补全设备树节点信息。

参考stm32mp15xx-dkx.dtsi对于ltdc设备节点的描述，需增加内容如下：

<dc {
pinctrl-names = "default", "sleep";
pinctrl-0 = <<dc_pins_b>;
pinctrl-1 = <<dc_pins_sleep_b>;
status = "okay";
port {
#address-cells = <1>;
#size-cells = <0>;
ltdc_ep0_out: endpoint@0 {
reg = <0>;
/*图像输出通道，需对接显示设备*/
remote-endpoint = <&sii9022_in>;
};
};
};

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由于stm32mp15-pinctrl.dtsi中对于ltdc_pins_b和ltdc_pins_b的定于与板子实际使用管脚一致，所以无需修改，内容如下：

ltdc_pins_b: ltdc-b-0 {
pins {
pinmux = <STM32_PINMUX('I', 14, AF14)>, /* LCD_CLK */
<STM32_PINMUX('I', 12, AF14)>, /* LCD_HSYNC */
<STM32_PINMUX('I', 13, AF14)>, /* LCD_VSYNC */
<STM32_PINMUX('K', 7, AF14)>, /* LCD_DE */
<STM32_PINMUX('I', 15, AF14)>, /* LCD_R0 */
<STM32_PINMUX('J', 0, AF14)>, /* LCD_R1 */
<STM32_PINMUX('J', 1, AF14)>, /* LCD_R2 */
<STM32_PINMUX('J', 2, AF14)>, /* LCD_R3 */
<STM32_PINMUX('J', 3, AF14)>, /* LCD_R4 */
<STM32_PINMUX('J', 4, AF14)>, /* LCD_R5 */
<STM32_PINMUX('J', 5, AF14)>, /* LCD_R6 */
<STM32_PINMUX('J', 6, AF14)>, /* LCD_R7 */
<STM32_PINMUX('J', 7, AF14)>, /* LCD_G0 */
<STM32_PINMUX('J', 8, AF14)>, /* LCD_G1 */
<STM32_PINMUX('J', 9, AF14)>, /* LCD_G2 */
<STM32_PINMUX('J', 10, AF14)>, /* LCD_G3 */
<STM32_PINMUX('J', 11, AF14)>, /* LCD_G4 */
<STM32_PINMUX('K', 0, AF14)>, /* LCD_G5 */
<STM32_PINMUX('K', 1, AF14)>, /* LCD_G6 */
<STM32_PINMUX('K', 2, AF14)>, /* LCD_G7 */
<STM32_PINMUX('J', 12, AF14)>, /* LCD_B0 */
<STM32_PINMUX('J', 13, AF14)>, /* LCD_B1 */
<STM32_PINMUX('J', 14, AF14)>, /* LCD_B2 */
<STM32_PINMUX('J', 15, AF14)>, /* LCD_B3 */
<STM32_PINMUX('K', 3, AF14)>, /* LCD_B4 */
<STM32_PINMUX('K', 4, AF14)>, /* LCD_B5 */
<STM32_PINMUX('K', 5, AF14)>, /* LCD_B6 */
<STM32_PINMUX('K', 6, AF14)>; /* LCD_B7 */
bias-disable;
drive-push-pull;
slew-rate = <1>;
};
};
ltdc_pins_sleep_b: ltdc-b-1 {
pins {
pinmux = <STM32_PINMUX('I', 14, ANALOG)>, /* LCD_CLK */
<STM32_PINMUX('I', 12, ANALOG)>, /* LCD_HSYNC */
<STM32_PINMUX('I', 13, ANALOG)>, /* LCD_VSYNC */
<STM32_PINMUX('K', 7, ANALOG)>, /* LCD_DE */
<STM32_PINMUX('I', 15, ANALOG)>, /* LCD_R0 */
<STM32_PINMUX('J', 0, ANALOG)>, /* LCD_R1 */
<STM32_PINMUX('J', 1, ANALOG)>, /* LCD_R2 */
<STM32_PINMUX('J', 2, ANALOG)>, /* LCD_R3 */
<STM32_PINMUX('J', 3, ANALOG)>, /* LCD_R4 */
<STM32_PINMUX('J', 4, ANALOG)>, /* LCD_R5 */
<STM32_PINMUX('J', 5, ANALOG)>, /* LCD_R6 */
<STM32_PINMUX('J', 6, ANALOG)>, /* LCD_R7 */
<STM32_PINMUX('J', 7, ANALOG)>, /* LCD_G0 */
<STM32_PINMUX('J', 8, ANALOG)>, /* LCD_G1 */
<STM32_PINMUX('J', 9, ANALOG)>, /* LCD_G2 */
<STM32_PINMUX('J', 10, ANALOG)>, /* LCD_G3 */
<STM32_PINMUX('J', 11, ANALOG)>, /* LCD_G4 */
<STM32_PINMUX('K', 0, ANALOG)>, /* LCD_G5 */
<STM32_PINMUX('K', 1, ANALOG)>, /* LCD_G6 */
<STM32_PINMUX('K', 2, ANALOG)>, /* LCD_G7 */
<STM32_PINMUX('J', 12, ANALOG)>, /* LCD_B0 */
<STM32_PINMUX('J', 13, ANALOG)>, /* LCD_B1 */
<STM32_PINMUX('J', 14, ANALOG)>, /* LCD_B2 */
<STM32_PINMUX('J', 15, ANALOG)>, /* LCD_B3 */
<STM32_PINMUX('K', 3, ANALOG)>, /* LCD_B4 */
<STM32_PINMUX('K', 4, ANALOG)>, /* LCD_B5 */
<STM32_PINMUX('K', 5, ANALOG)>, /* LCD_B6 */
<STM32_PINMUX('K', 6, ANALOG)>; /* LCD_B7 */
};
};

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3.SiI9022设备树节点
由于SiI9002只是I2C5总线上的一个外设，所以STM32MP157A的通用设备树文件中并没有相关的定义，结合arm,hdlcd.txt和stm32mp15xx-dkx.dtsi对于HDMI的描述，增加SiI9002的支持，需在I2C5节点下添加相关信息，添加内容为：

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>;
#sound-dai-cells = <0>;
status = "okay";
ports {
#address-cells = <1>;
#size-cells = <0>;
port@0 {
reg = <0>;
sii9022_in: endpoint {
/*视频输入端口，与LTDC输出端口对接*/
remote-endpoint = <<dc_ep0_out>;
};
};
port@3 {
reg = <3>;
sii9022_tx_endpoint: endpoint {
/*音频输入端口，与声卡输出端口对接*/
remote-endpoint = <&i2s2_endpoint>;
};
};
};
};

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4.电源节点添加
由于内核中很多驱动会根据电源的方位调整设备的工作方式，所以在设备树中需要传递相关电源电压参数，如sii9022驱动中需要两个电源分别是iovcc和cvcc12，但是在设备树中并没有这两个电源的定义，官方参考板DK1使用的是MPU作为电源管理，而FS-MP1A使用的分离元器件的形式，所以stm32mp15xx-dkx.dtsi中对于电源的定义就不实用了。参考内核中相关文档添加固定电源节点的形式添加iovcc和cvcc12即可，根据sii9022的需求，iovcc和cvcc12电压分别为3.3v和1.2v。

需在设备树根节点下添加，内容如下：

v3v3_hdmi: regulator-v3v3-hdmi {
compatible = "regulator-fixed";
regulator-name = "v3v3_hdmi ";
regulator-min-microvolt = <3300000>;
regulator-max-microvolt = <3300000>;
regulator-always-on;
regulator-boot-on;
};
v1v2_hdmi: regulator-v1v2-hdmi {
compatible = "regulator-fixed";
regulator-name = "v1v2_hdmi";
regulator-min-microvolt = <1200000>;
regulator-max-microvolt = <1200000>;
regulator-always-on;
regulator-boot-on;
};

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1.2实验目的
熟悉基于Linux操作系统下的HDMI设备驱动移植配置过程。

1.3实验平台
华清远见开发环境，FS-MP1A平台；

1.4实验步骤
1.导入交叉编译工具链
linux@ubuntu

source /opt/st/stm32mp1/3.1-openstlinux-5.4-dunfell-mp1-20-06-24/environment-setup-cortexa7t2hf-neon-vfpv4-ostl-linux-gnueabi

2.添加i2c5及sii9022内容
修改arch/arm/boot/dts/stm32mp15xx-fsmp1x.dtsi文件，在文件末尾添加如下内容：

&i2c5 {
pinctrl-names = "default", "sleep";
pinctrl-0 = <&i2c5_pins_a>;
pinctrl-1 = <&i2c5_pins_sleep_a>;
i2c-scl-rising-time-ns = <100>;
i2c-scl-falling-time-ns = <7>;
clock-frequency = <100000>;
/* spare dmas for other usage */
/delete-property/dmas;
/delete-property/dma-names;
status = "okay";
hdmi-transmitter@39 {
compatible = "sil,sii9022";
reg = <0x39>;
iovcc-supply = <&v3v3_hdmi>;
cvcc12-supply = <&v1v2_hdmi>;
reset-gpios = <&gpioa 13 GPIO_ACTIVE_LOW>;
interrupts = <14 IRQ_TYPE_EDGE_FALLING>;
interrupt-parent = <&gpioa>;
#sound-dai-cells = <0>;
status = "okay";
ports {
#address-cells = <1>;
#size-cells = <0>;
port@0 {
reg = <0>;
sii9022_in: endpoint {
remote-endpoint = <<dc_ep0_out>;
};
};
};
};
};

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3.添加ltdc内容
修改arch/arm/boot/dts/stm32mp15xx-fsmp1x.dtsi文件，在文件末尾添加如下内容：

<dc {
pinctrl-names = "default", "sleep";
pinctrl-0 = <<dc_pins_b>;
pinctrl-1 = <<dc_pins_sleep_b>;
status = "okay";
port {
#address-cells = <1>;
#size-cells = <0>;
ltdc_ep0_out: endpoint@0 {
reg = <0>;
remote-endpoint = <&sii9022_in>;
};
};
};

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4.添加电源内容
修改arch/arm/boot/dts/stm32mp15xx-fsmp1x.dtsi文件，在根节点末尾添加如下内容：

v3v3_hdmi: regulator-v3v3-hdmi {
compatible = "regulator-fixed";
regulator-name = "v3v3_hdmi ";
regulator-min-microvolt = <3300000>;
regulator-max-microvolt = <3300000>;
regulator-always-on;
regulator-boot-on;
};
v1v2_hdmi: regulator-v1v2-hdmi {
compatible = "regulator-fixed";
regulator-name = "v1v2_hdmi";
regulator-min-microvolt = <1200000>;
regulator-max-microvolt = <1200000>;
regulator-always-on;
regulator-boot-on;
};

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5.配置内核
由于内核源码默认配置以及支持sii902x，本节列出主要选项，如下：

linux@ubuntu

make menuconfig

Device Drivers --->

Graphics support --->

<*> Direct Rendering Manager (XFree86 4.1.0 and higher DRI support) --->

<*> DRM Support for STMicroelectronics SoC Series

Display Interface Bridges --->

<*> Silicon Image sii902x RGB/HDMI bridge

6.编译内核及设备树：
linux@ubuntu

make -j4 uImage dtbs LOADADDR=0xC2000040

7.重启测试
将编译好的设备树和内核镜像拷贝到/tftpboot目录下，通过tftp引导内核，设备连接HDMI显示器，重启设备后查看/sys/class/drm会多出HMID的信息，同时显示器会有显示。