查看“Linux内核-HDMI驱动移植”的源代码

==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。<br>

[[Image:51-1-1-1.png]]<br>

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。<br>

[[Image:51-1-1-2.png]]<br>

查看原理图确认I2C5、中断、复位管脚对应关系：

[[Image:51-1-1-3.png]]<br>

{|class="wikitable"
|-
! 原理图网络编号 !! 对应管脚 !! 管脚功能 !! 管脚功能码
|-
| I2C5_SCL 
| PA11 
| I2C5_SCL
| AF4
|-
| I2C5_SDA 
| PA12 
| I2C5_SDA
| AF4
|-
| HDMI_RST 
| PA13 
| GPIO
| 
|-
| HDMI_INT 
| PA14 
| INT
| 
|}

LCD接口管脚对应关系：

[[Image:51-1-1-4.png]]<br>

{|class="wikitable"
|-
! 原理图网络编号 !! 对应管脚 !! 管脚功能 !! 管脚功能码
|-
| LCD_R0 
| PI15 
| LCD_R0
| AF14
|-
| LCD_R1 
| PJ0
| LCD_R1
| AF14
|-
| LCD_R2 
| PJ1 
| LCD_R2
| AF14
|-
| LCD_R3 
| PJ2 
| LCD_R3
| AF14
|-
| LCD_R4
| PJ3
| LCD_R4
| AF14
|-
| LCD_R5 
| PJ4 
| LCD_R5
| AF14
|-
| LCD_R6 
| PJ5 
| LCD_R6
| AF14
|-
| LCD_R7 
| PJ6 
| LCD_R7
| AF14
|-
| LCD_G0 
| PJ8 
| LCD_G0
| AF14
|-
| LCD_G1 
| PJ7
| LCD_G1
| AF14
|-
| LCD_G2 
| PJ10 
| LCD_G2
| AF14
|-
| LCD_G3 
| PJ19 
| LCD_G3
| AF14
|-
| LCD_G4 
| PJ11 
| LCD_G4
| AF14
|-
| LCD_G5 
| PK0 
| LCD_G5
| AF14
|-
| LCD_G6 
| PK1 
| LCD_G6
| AF14
|-
| LCD_G7
| PK2 
| LCD_G7
| AF14
|-
| LCD_B0 
| PJ12 
| LCD_B0
| AF14
|-
| LCD_B1 
| PJ13 
| LCD_B1
| AF14
|-
| LCD_B2 
| PJ14 
| LCD_B2
| AF14
|-
| LCD_B3 
| PJ15 
| LCD_B3
| AF14
|-
| LCD_B4 
| PK3 
| LCD_B4
| AF14
|-
| LCD_B5 
| PK4 
| LCD_B5
| AF14
|-
| LCD_B6 
| PK5 
| LCD_B6
| AF14
|-
| LCD_B7 
| PK6 
| LCD_B7
| AF14
|-
| LCD_PCLK 
| PI14 
| LCD_PCLK
| AF14
|-
| LCD_DEN 
| PK7 
| LCD_DEN
| AF14
|-
| LCD_HSYNC 
| PI12 
| LCD_HSYNC
| AF14
|-
| LCD_VSYNC 
| PI13 
| LCD_VSYNC
| AF14
|}

*I2C5设备树节点<br>

参考文档：
 Documentation/devicetree/bindings/i2c/i2c-stm32.txt
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：
<pre><nowiki>
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";
};
</nowiki></pre>
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。<br>

参考stm32mp15xx-dkx.dtsi对于i2c设备节点的描述，修改i2c5内容如下：
<pre><nowiki>
&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";
};
</nowiki></pre>
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：
<pre><nowiki>
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 */
	};
};
</nowiki></pre>
*I2S2设备树节点<br>

参考文档：
 Documentation/devicetree/bindings/i2c/sound/st,stm32-i2s.txt
*LTDC设备树节点<br>

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。<br>

参考文档：
 Documentation/devicetree/bindings/display/st,stm32-ltdc.txt
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：
<pre><nowiki>
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";
};
</nowiki></pre>
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。<br>

参考stm32mp15xx-dkx.dtsi对于ltdc设备节点的描述，需增加内容如下：
<pre><nowiki>
&ltdc {
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&ltdc_pins_b>;
	pinctrl-1 = <&ltdc_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>;
		};
	};
};
</nowiki></pre>
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：<br>
<pre><nowiki>
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 */
	};
};
</nowiki></pre>
*SiI9022设备树节点<br>

参考文档：
 Documentation/devicetree/bindings/display/arm,hdlcd.txt
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：<br>
<pre><nowiki>
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 = <&ltdc_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>;
			};
		};
	};
};
</nowiki></pre>
*电源节点添加<br>

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。<br>

参考文档：
 Documentation/devicetree/bindings/regulator/fixed-regulator.yaml
需在设备树根节点下添加，内容如下：
<pre><nowiki>
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;
};
</nowiki></pre>
==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。

==实验平台==
华清远见开发环境，FS-MP1A平台；

==实验步骤==