当管脚复用为GPIO子系统时候
&iomuxc { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_hog_1>; imx6ul-evk { pinctrl_hog_1: hoggrp-1 { fsl,pins = < MX6UL_PAD_UART1_RTS_B__GPIO1_IO19 0x17059 /* SD1 CD */ MX6UL_PAD_GPIO1_IO05__USDHC1_VSELECT 0x17059 /* SD1 VSELECT */ MX6UL_PAD_GPIO1_IO09__GPIO1_IO09 0x17059 /* SD1 RESET */ >; }; 以 MX6UL_PAD_UART1_RTS_B__GPIO1_IO19 0x17059 /* SD1 CD */为例子 在设备树上找到 &usdhc1 { pinctrl-names = "default", "state_100mhz", "state_200mhz"; pinctrl-0 = <&pinctrl_usdhc1>; pinctrl-1 = <&pinctrl_usdhc1_100mhz>; pinctrl-2 = <&pinctrl_usdhc1_200mhz>; cd-gpios = <&gpio1 19 GPIO_ACTIVE_LOW>; keep-power-in-suspend; enable-sdio-wakeup; vmmc-supply = <®_sd1_vmmc>; status = "okay"; }; pinctrl_usdhc1: usdhc1grp { fsl,pins = < MX6UL_PAD_SD1_CMD__USDHC1_CMD 0x17059 MX6UL_PAD_SD1_CLK__USDHC1_CLK 0x10071 MX6UL_PAD_SD1_DATA0__USDHC1_DATA0 0x17059 MX6UL_PAD_SD1_DATA1__USDHC1_DATA1 0x17059 MX6UL_PAD_SD1_DATA2__USDHC1_DATA2 0x17059 MX6UL_PAD_SD1_DATA3__USDHC1_DATA3 0x17059 >; cd-gpios = <&gpio1 19 GPIO_ACTIVE_LOW>; 定义了一个叫cd-gpios的属性 此处使用了GPIO1_IO09 gpio1: gpio@0209c000 { compatible = "fsl,imx6ul-gpio", "fsl,imx35-gpio"; reg = <0x0209c000 0x4000>; interrupts = <GIC_SPI 66 IRQ_TYPE_LEVEL_HIGH>, <GIC_SPI 67 IRQ_TYPE_LEVEL_HIGH>; gpio-controller; #gpio-cells = <2>; interrupt-controller; #interrupt-cells = <2>; }; 如何从设备树中获取要使用的GPIO信息 of函数 结点 编号请求 输入输出 set get 1. 首先 获取到GPIO所处的设备节点，比如of_find_node_by_path 2. 获取GPIO编号，of_get_named_gpio函数 ，返回值就是GPIO编号 3. 请求此编号 gpio_request函数 4. 设置GPIO输入输出 gpio_direction_input or output 5. 输入 gpio_get_value ,输出 gpio_set_value gpio驱动