Camera学习-驱动篇

wangxiaoxuan217

已于 2023-08-15 09:27:33 修改

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分类专栏： Camera学习笔记文章标签：学习

于 2023-08-14 11:29:46 首次发布

本文链接：https://blog.youkuaiyun.com/weixin_37540091/article/details/132272505

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1 篇文章

订阅专栏

一、设备驱动篇

1.1 设备树

文件路径：kernel-5.10/arch/arm64/boot/dts/rockchip/rk3588.dtsi

设备树配置：

&i2c1 {
	status = "okay";
	pinctrl-0 = <&i2c1m2_xfer>;//i2c pin
	i2c-scl-rising-time-ns = <600>;
	i2c-scl-falling-time-ns = <20>;

	imx577_dphy: imx577@1a {
		compatible = "sony,imx577";
		reg = <0x1a>;
		clocks = <&cru CLK_MIPI_CAMARAOUT_M4>;
		clock-names = "xvclk";
		pinctrl-names = "default";
		pinctrl-0 = <&mipim0_camera4_clk>;   
        <&mipidphy1_reset>;
		power-domains = <&power RK**_PD_VI>;
		poweren-gpios = <&gpio1 RK**_ACTIVE_HIGH>;
		rockchip,camera-module-index = <1>;
		rockchip,camera-module-facing = "front";
		rockchip,camera-module-name = "***";
		rockchip,camera-module-lens-name = "default";
		port {
			imx577_out1: endpoint {
				remote-endpoint = <&mipi_in_ucamdphy3>;
				data-lanes = <1 2 3 4>;
			};
		};
	};
};

1.1.1 标签解读

1、pinctrl-0:

Rockchip pinctrl驱动包括Pinctrl驱动( drivers/pinctrl/pinctrl-rockchip.c ) 和 GPIO驱动( drivers/gpio/gpio-rockchip.c )。Pinctrl驱动是主要驱动,提供IO的方法集,包括PINMUX、PINCONF 和 GPIO。GPIO驱动是完成 gpiochip 的功能,包括 GPIO 和 IRQ,通常在 dts 配置中可以看到某个模块中对 pin 引脚的配置，如下所示

pinctrl-0 = <&i2c1m2_xfer>;//i2c pin

注：通常模块调用pinctrl-names pinctrl-0配置默认的IOMUX或者IOCONFIG,但不是所有的节点都可以加这两个属性,如果模块被driver_probe_device调用,它就可以加这两个属性。调试方法: drivers/base/dd.c 的 pinctrl_bind_pins 函数,在这里加打印看调用关系。模块引用pinctrl是通过 pinctrl-names 和 pinctrl-0 连接模块和pinctrl驱动。uart2m1_xfer 是一个pinctrl group;模块可以同时引用多组group，举例 rk3588 pdm1:

{
	pdm1: pdm@fe4c0000 {
		compatible = "rockchip,rk3588-pdm";
		reg = <0x0 0xfe4c0000 0x0 0x1000>;
		clocks = <&cru MCLK_PDM1>, <&cru HCLK_PDM1>;
		clock-names = "pdm_clk", "pdm_hclk";
		assigned-clocks = <&cru MCLK_PDM1>;
		assigned-clock-parents = <&cru PLL_AUPLL>;
		dmas = <&dmac1 4>;
		dma-names = "rx";
		power-domains = <&power RK3588_PD_AUDIO>;
		pinctrl-names = "default";
		pinctrl-0 = <&pdm1m0_clk
		&pdm1m0_clk1
		&pdm1m0_sdi0
		&pdm1m0_sdi1
		&pdm1m0_sdi2
		&pdm1m0_sdi3>;
		/* 等同于如下写法 */
		/*
		*
		pinctrl-0 = <&pdm1m0_clk>,
		* <&pdm1m0_clk1>,
		* <&pdm1m0_sdi0>,
		* <&pdm1m0_sdi1>,
		* <&pdm1m0_sdi2>,
		* <&pdm1m0_sdi3>;
		*/
		#sound-dai-cells = <0>;
		status = "disabled";
	};
};

pinctrl-names 可以支持多个实例,pinctrl 默认的有4种实例(state)。在Documentation/driver-api/pinctl.rst 文档中有相应的描述:


###include/linux/pinctrl/pinctrl-state.h

#define PINCTRL_STATE_DEFAULT "default"
#define PINCTRL_STATE_INIT "init"
#define PINCTRL_STATE_IDLE "idle"
#define PINCTRL_STATE_SLEEP "sleep"

“init” 在driver probe期间生效,probe done之后可能会切换回 “default”(如果probe中切换到其他state,就不会切换回 “init”)。pinctrl-names 是可以自定义的,有driver去匹配解析，如下

{
	pwm4: pwm@febd0000 {
		compatible = "rockchip,rk3588-pwm", "rockchip,rk3328-pwm";
		reg = <0x0 0xfebd0000 0x0 0x10>;
		#pwm-cells = <3>;
		pinctrl-names = "active";
		pinctrl-0 = <&pwm4m0_pins>;
		clocks = <&cru CLK_PWM1>, <&cru PCLK_PWM1>;
		clock-names = "pwm", "pclk";
		status = "disabled";
	};
};

2、i2c-scl-rising-time-ns&i2c-scl-falling-time-ns

i2c-rk3x.c 驱动的配置都在 DTS，参考文件Documentation/devicetree/bindings/i2c/i2c-rk3x.txt。

重点说明其中配置项，i2c-scl-rising-time-ns，i2c-scl-falling-time-ns：

clock-frequency：默认frequency 为100k 可不配置，其它 I2C 频率需要配置，最大可配置频率由 i2c-scl- rising-time-ns 决定；例如配置400k，clock-frequency=<400000>。
i2c-scl-rising-time-ns：SCL 上升沿时间由硬件决定，改变上拉电阻可调节该时间，需通过示波器量测，参考上图；例如测得 SCL 上升沿 365ns，i2c-scl-rising-time-ns=<365>。(默认可以不配置，但必须保证当前的上升沿时间不能超过所配置频率下的 I2C 标准所定义的最大上升沿时间)
i2c-scl-falling-time-ns: SCL 下降沿时间, 一般不变, 等同于 i2c-sda-falling-time-ns