第二十八章 linux-设备树二

第二十八章 linux-设备树二


文章目录

  • 第二十八章 linux-设备树二
  • 设备树是什么
  • 为什么需要设备树
  • 设备树技术如何工作
  • 设备树
    • dts文件在哪里
    • dts的格式简介
    • dts的节点格式
    • imx6ull-14x14-evk.dts
    • property
    • 常见预定义标准属性
  • gpio实例
  • 驱动中device来源


设备树是什么

  • device tree,设备树,是一种linux内核中采用的参数表示和传递技术
  • dts,device tree source,设备树源文件
  • dtc,device tree compiler,设备树编译/反编译/调试工具
  • dtb,device tree blob,二进制设备树镜像

为什么需要设备树

  • 典型需求就是内核设备驱动,我们以驱动为例分析,但是不止可以用于驱动场景
  • 驱动源码包括2大部分:策略(操作函数)和数据(硬件信息)
  • 早期解决方案:策略和数据都在kernel源码中硬编码
  • 坏处:kernel源码中充斥大量描述硬件信息的文件,污染内核

设备树技术如何工作

  • 驱动开发者编写/改写dts,适配硬件和自己的需求
  • make ulmage(make dtbs)时,kernet内部会先编译出dtc,然后用dtc将dts加工成dtb
  • uboot启动kernel时,将ulmage和dtb都准备好并告知ulmage在哪里找dtb
  • kernel启动初期调用内部函数解析dtb,得到硬件信息,并组装成数据结构,配合策略函数工作

设备树

dts文件在哪里

  • 早期版本的硬件信息.h文件多放在arch/arm/mach-xxx或者arch/arm/plat-xxx中
  • dts文件放在arch/arm/boot/dts目录中

dts的格式简介

  • 后缀名一般为dts和dts主,可以被include,甚至可以include那些c语言的头文件
  • dtsi主一般写soc共性部分,而dts—般写目标单板特性部分,所以一般dts包含并重写部分dtsi
  • 注释用/* */,注意#开头的不是注释
  • 分号是段落块之间的分隔符,{}和[]是段落块的封装符号,和c语言语言类似
  • /dts-v1/节点,表示dts的版本号,目前都是vl
  • /{}是根节点root node,理论上只应该有一个根节点,有说法dtc会合并所有root node为同一个
  • dts是树状的多节点组织,基本单元是node,除root外其他node都有parent,还可以有child

dts的节点格式

  • 格式定义
[label:] <node-name> [@<unit-address>]{
	[property]
	[child nodes]
	[child nodes]
	....
};
  • 格式解读
    []:表示该项可以省略,<>表示不可省略
    [label]:标签,为了方便访问节点,后面可以直接通过&label来访问该节。
    node-name:节点名称。根节点的名称必须是/
    [@unit-address]:地址,如cpu node就是0、1这种,reg node就是0X12010000这种

imx6ull-14x14-evk.dts

/*
 * Copyright (C) 2016 Freescale Semiconductor, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

/dts-v1/;

#include 
#include "imx6ull.dtsi"

/ {
	model = "Freescale i.MX6 ULL 14x14 EVK Board";
	compatible = "fsl,imx6ull-14x14-evk", "fsl,imx6ull";

	chosen {
		stdout-path = &uart1;
	};

	memory {
		reg = <0x80000000 0x20000000>;
	};

	reserved-memory {
		#address-cells = <1>;
		#size-cells = <1>;
		ranges;

		linux,cma {
			compatible = "shared-dma-pool";
			reusable;
			size = <0x14000000>;
			linux,cma-default;
		};
	};

	backlight {
		compatible = "pwm-backlight";
		pwms = <&pwm1 0 5000000>;
		brightness-levels = <0 4 8 16 32 64 128 255>;
		default-brightness-level = <6>;
		status = "okay";
	};

	pxp_v4l2 {
		compatible = "fsl,imx6ul-pxp-v4l2", "fsl,imx6sx-pxp-v4l2", "fsl,imx6sl-pxp-v4l2";
		status = "okay";
	};

	regulators {
		compatible = "simple-bus";
		#address-cells = <1>;
		#size-cells = <0>;

		reg_can_3v3: regulator@0 {
			compatible = "regulator-fixed";
			reg = <0>;
			regulator-name = "can-3v3";
			regulator-min-microvolt = <3300000>;
			regulator-max-microvolt = <3300000>;
			gpios = <&gpio_spi 3 GPIO_ACTIVE_LOW>;
		};

		reg_sd1_vmmc: regulator@1 {
			compatible = "regulator-fixed";
			regulator-name = "VSD_3V3";
			regulator-min-microvolt = <3300000>;
			regulator-max-microvolt = <3300000>;
			gpio = <&gpio1 9 GPIO_ACTIVE_HIGH>;
			enable-active-high;
		};

		reg_gpio_dvfs: regulator-gpio {
			compatible = "regulator-gpio";
			pinctrl-names = "default";
			pinctrl-0 = <&pinctrl_dvfs>;
			regulator-min-microvolt = <1300000>;
			regulator-max-microvolt = <1400000>;
			regulator-name = "gpio_dvfs";
			regulator-type = "voltage";
			gpios = <&gpio5 3 GPIO_ACTIVE_HIGH>;
			states = <1300000 0x1 1400000 0x0>;
		};
	};

	sound {
		compatible = "fsl,imx6ul-evk-wm8960",
			   "fsl,imx-audio-wm8960";
		model = "wm8960-audio";
		cpu-dai = <&sai2>;
		audio-codec = <&codec>;
		asrc-controller = <&asrc>;
		codec-master;
		gpr = <&gpr 4 0x100000 0x100000>;
		/*
                 * hp-det = <hp-det-pin hp-det-polarity>;
		 * hp-det-pin: JD1 JD2  or JD3
		 * hp-det-polarity = 0: hp detect high for headphone
		 * hp-det-polarity = 1: hp detect high for speaker
		 */
		hp-det = <3 0>;
		hp-det-gpios = <&gpio5 4 0>;
		mic-det-gpios = <&gpio5 4 0>;
		audio-routing =
			"Headphone Jack", "HP_L",
			"Headphone Jack", "HP_R",
			"Ext Spk", "SPK_LP",
			"Ext Spk", "SPK_LN",
			"Ext Spk", "SPK_RP",
			"Ext Spk", "SPK_RN",
			"LINPUT2", "Mic Jack",
			"LINPUT3", "Mic Jack",
			"RINPUT1", "Main MIC",
			"RINPUT2", "Main MIC",
			"Mic Jack", "MICB",
			"Main MIC", "MICB",
			"CPU-Playback", "ASRC-Playback",
			"Playback", "CPU-Playback",
			"ASRC-Capture", "CPU-Capture",
			"CPU-Capture", "Capture";
	};

	spi4 {
		compatible = "spi-gpio";
		pinctrl-names = "default";
		pinctrl-0 = <&pinctrl_spi4>;
		pinctrl-assert-gpios = <&gpio5 8 GPIO_ACTIVE_LOW>;
		status = "okay";
		gpio-sck = <&gpio5 11 0>;
		gpio-mosi = <&gpio5 10 0>;
		cs-gpios = <&gpio5 7 0>;
		num-chipselects = <1>;
		#address-cells = <1>;
		#size-cells = <0>;

		gpio_spi: gpio_spi@0 {
			compatible = "fairchild,74hc595";
			gpio-controller;
			#gpio-cells = <2>;
			reg = <0>;
			registers-number = <1>;
			registers-default = /bits/ 8 <0x57>;
			spi-max-frequency = <100000>;
		};
	};

    alphaled {
             #address-cells = <1>;
             #size-celll = <1>;
             compatible = "atkalpha-led";
             status = "okay";
             reg =<  0X020C406C 0X04 /* CCM_CCGR1_BASE */
                     0X020E0068 0X04 /* SW_MUX_GPIO1_IO03_BASE */
                     0X020E02F4 0X04 /* SW_PAD_GPIO1_IO03_BASE */
                     0X0209C000 0X04 /* GPIO1_DR_BASE */
                     0X0209C004 0X04 >; /* GPIO1_GDIR_BASE */
         };

	gpioled {
		 #address-cells = <1>;
		 #size-cells = <1>;
		 compatible = "atkalpha-gpioled";
		 pinctrl-names = "default";
		 pinctrl-0 = <&pinctrl_led>;
		 led-gpio = <&gpio1 3 GPIO_ACTIVE_LOW>;
		 status = "okay";
	 };
};

&cpu0 {
	arm-supply = <&reg_arm>;
	soc-supply = <&reg_soc>;
	dc-supply = <&reg_gpio_dvfs>;
};

&clks {
	assigned-clocks = <&clks IMX6UL_CLK_PLL4_AUDIO_DIV>;
	assigned-clock-rates = <786432000>;
};

&csi {
	status = "okay";

	port {
		csi1_ep: endpoint {
			remote-endpoint = <&ov5640_ep>;
		};
	};
};

&fec1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_enet1>;
	phy-mode = "rmii";
	phy-handle = <&ethphy0>;
	status = "okay";
};

&fec2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_enet2>;
	phy-mode = "rmii";
	phy-handle = <&ethphy1>;
	status = "okay";

	mdio {
		#address-cells = <1>;
		#size-cells = <0>;

		ethphy0: ethernet-phy@2 {
			compatible = "ethernet-phy-ieee802.3-c22";
			reg = <2>;
		};

		ethphy1: ethernet-phy@1 {
			compatible = "ethernet-phy-ieee802.3-c22";
			reg = <1>;
		};
	};
};

&flexcan1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_flexcan1>;
	xceiver-supply = <&reg_can_3v3>;
	status = "okay";
};

&flexcan2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_flexcan2>;
	xceiver-supply = <&reg_can_3v3>;
	status = "okay";
};

&gpc {
	fsl,cpu_pupscr_sw2iso = <0x1>;
	fsl,cpu_pupscr_sw = <0x0>;
	fsl,cpu_pdnscr_iso2sw = <0x1>;
	fsl,cpu_pdnscr_iso = <0x1>;
	fsl,ldo-bypass = <0>; /* DCDC, ldo-enable */
};

&i2c1 {
	clock-frequency = <100000>;
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_i2c1>;
	status = "okay";

	mag3110@0e {
		compatible = "fsl,mag3110";
		reg = <0x0e>;
		position = <2>;
	};

	fxls8471@1e {
		compatible = "fsl,fxls8471";
		reg = <0x1e>;
		position = <0>;
		interrupt-parent = <&gpio5>;
		interrupts = <0 8>;
	};
};

&i2c2 {
	clock_frequency = <100000>;
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_i2c2>;
	status = "okay";

	codec: wm8960@1a {
		compatible = "wlf,wm8960";
		reg = <0x1a>;
		clocks = <&clks IMX6UL_CLK_SAI2>;
		clock-names = "mclk";
		wlf,shared-lrclk;
	};

	ov5640: ov5640@3c {
		compatible = "ovti,ov5640";
		reg = <0x3c>;
		pinctrl-names = "default";
		pinctrl-0 = <&pinctrl_csi1>;
		clocks = <&clks IMX6UL_CLK_CSI>;
		clock-names = "csi_mclk";
		pwn-gpios = <&gpio_spi 6 1>;
		rst-gpios = <&gpio_spi 5 0>;
		csi_id = <0>;
		mclk = <24000000>;
		mclk_source = <0>;
		status = "okay";
		port {
			ov5640_ep: endpoint {
				remote-endpoint = <&csi1_ep>;
			};
		};
	};
};

&iomuxc {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_hog_1>;
	imx6ul-evk {
		 pinctrl_led: ledgrp {
			 fsl,pins = <
				 MX6UL_PAD_GPIO1_IO03__GPIO1_IO03 0x10B0 /* LED0 */
			 >;
		 };
		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 */
			>;
		};

		pinctrl_csi1: csi1grp {
			fsl,pins = <
				MX6UL_PAD_CSI_MCLK__CSI_MCLK		0x1b088
				MX6UL_PAD_CSI_PIXCLK__CSI_PIXCLK	0x1b088
				MX6UL_PAD_CSI_VSYNC__CSI_VSYNC		0x1b088
				MX6UL_PAD_CSI_HSYNC__CSI_HSYNC		0x1b088
				MX6UL_PAD_CSI_DATA00__CSI_DATA02	0x1b088
				MX6UL_PAD_CSI_DATA01__CSI_DATA03	0x1b088
				MX6UL_PAD_CSI_DATA02__CSI_DATA04	0x1b088
				MX6UL_PAD_CSI_DATA03__CSI_DATA05	0x1b088
				MX6UL_PAD_CSI_DATA04__CSI_DATA06	0x1b088
				MX6UL_PAD_CSI_DATA05__CSI_DATA07	0x1b088
				MX6UL_PAD_CSI_DATA06__CSI_DATA08	0x1b088
				MX6UL_PAD_CSI_DATA07__CSI_DATA09	0x1b088
			>;
		};

		pinctrl_enet1: enet1grp {
			fsl,pins = <
				MX6UL_PAD_ENET1_RX_EN__ENET1_RX_EN	0x1b0b0
				MX6UL_PAD_ENET1_RX_ER__ENET1_RX_ER	0x1b0b0
				MX6UL_PAD_ENET1_RX_DATA0__ENET1_RDATA00	0x1b0b0
				MX6UL_PAD_ENET1_RX_DATA1__ENET1_RDATA01	0x1b0b0
				MX6UL_PAD_ENET1_TX_EN__ENET1_TX_EN	0x1b0b0
				MX6UL_PAD_ENET1_TX_DATA0__ENET1_TDATA00	0x1b0b0
				MX6UL_PAD_ENET1_TX_DATA1__ENET1_TDATA01	0x1b0b0
				MX6UL_PAD_ENET1_TX_CLK__ENET1_REF_CLK1	0x4001b031
							>;
		};

		pinctrl_enet2: enet2grp {
			fsl,pins = <
				MX6UL_PAD_GPIO1_IO07__ENET2_MDC		0x1b0b0
				MX6UL_PAD_GPIO1_IO06__ENET2_MDIO	0x1b0b0
				MX6UL_PAD_ENET2_RX_EN__ENET2_RX_EN	0x1b0b0
				MX6UL_PAD_ENET2_RX_ER__ENET2_RX_ER	0x1b0b0
				MX6UL_PAD_ENET2_RX_DATA0__ENET2_RDATA00	0x1b0b0
				MX6UL_PAD_ENET2_RX_DATA1__ENET2_RDATA01	0x1b0b0
				MX6UL_PAD_ENET2_TX_EN__ENET2_TX_EN	0x1b0b0
				MX6UL_PAD_ENET2_TX_DATA0__ENET2_TDATA00	0x1b0b0
				MX6UL_PAD_ENET2_TX_DATA1__ENET2_TDATA01	0x1b0b0
				MX6UL_PAD_ENET2_TX_CLK__ENET2_REF_CLK2	0x4001b031
			>;
		};

		pinctrl_flexcan1: flexcan1grp{
			fsl,pins = <
				MX6UL_PAD_UART3_RTS_B__FLEXCAN1_RX	0x1b020
				MX6UL_PAD_UART3_CTS_B__FLEXCAN1_TX	0x1b020
			>;
		};

		pinctrl_flexcan2: flexcan2grp{
			fsl,pins = <
				MX6UL_PAD_UART2_RTS_B__FLEXCAN2_RX	0x1b020
				MX6UL_PAD_UART2_CTS_B__FLEXCAN2_TX	0x1b020
			>;
		};

		pinctrl_i2c1: i2c1grp {
			fsl,pins = <
				MX6UL_PAD_UART4_TX_DATA__I2C1_SCL 0x4001b8b0
				MX6UL_PAD_UART4_RX_DATA__I2C1_SDA 0x4001b8b0
			>;
		};

		pinctrl_i2c2: i2c2grp {
			fsl,pins = <
				MX6UL_PAD_UART5_TX_DATA__I2C2_SCL 0x4001b8b0
				MX6UL_PAD_UART5_RX_DATA__I2C2_SDA 0x4001b8b0
			>;
		};

		pinctrl_lcdif_dat: lcdifdatgrp {
			fsl,pins = <
				MX6UL_PAD_LCD_DATA00__LCDIF_DATA00  0x79
				MX6UL_PAD_LCD_DATA01__LCDIF_DATA01  0x79
				MX6UL_PAD_LCD_DATA02__LCDIF_DATA02  0x79
				MX6UL_PAD_LCD_DATA03__LCDIF_DATA03  0x79
				MX6UL_PAD_LCD_DATA04__LCDIF_DATA04  0x79
				MX6UL_PAD_LCD_DATA05__LCDIF_DATA05  0x79
				MX6UL_PAD_LCD_DATA06__LCDIF_DATA06  0x79
				MX6UL_PAD_LCD_DATA07__LCDIF_DATA07  0x79
				MX6UL_PAD_LCD_DATA08__LCDIF_DATA08  0x79
				MX6UL_PAD_LCD_DATA09__LCDIF_DATA09  0x79
				MX6UL_PAD_LCD_DATA10__LCDIF_DATA10  0x79
				MX6UL_PAD_LCD_DATA11__LCDIF_DATA11  0x79
				MX6UL_PAD_LCD_DATA12__LCDIF_DATA12  0x79
				MX6UL_PAD_LCD_DATA13__LCDIF_DATA13  0x79
				MX6UL_PAD_LCD_DATA14__LCDIF_DATA14  0x79
				MX6UL_PAD_LCD_DATA15__LCDIF_DATA15  0x79
				MX6UL_PAD_LCD_DATA16__LCDIF_DATA16  0x79
				MX6UL_PAD_LCD_DATA17__LCDIF_DATA17  0x79
				MX6UL_PAD_LCD_DATA18__LCDIF_DATA18  0x79
				MX6UL_PAD_LCD_DATA19__LCDIF_DATA19  0x79
				MX6UL_PAD_LCD_DATA20__LCDIF_DATA20  0x79
				MX6UL_PAD_LCD_DATA21__LCDIF_DATA21  0x79
				MX6UL_PAD_LCD_DATA22__LCDIF_DATA22  0x79
				MX6UL_PAD_LCD_DATA23__LCDIF_DATA23  0x79
			>;
		};

		pinctrl_lcdif_ctrl: lcdifctrlgrp {
			fsl,pins = <
				MX6UL_PAD_LCD_CLK__LCDIF_CLK	    0x79
				MX6UL_PAD_LCD_ENABLE__LCDIF_ENABLE  0x79
				MX6UL_PAD_LCD_HSYNC__LCDIF_HSYNC    0x79
				MX6UL_PAD_LCD_VSYNC__LCDIF_VSYNC    0x79
			>;
		};

		pinctrl_pwm1: pwm1grp {
			fsl,pins = <
				MX6UL_PAD_GPIO1_IO08__PWM1_OUT   0x110b0
			>;
		};

		pinctrl_qspi: qspigrp {
			fsl,pins = <
				MX6UL_PAD_NAND_WP_B__QSPI_A_SCLK      0x70a1
				MX6UL_PAD_NAND_READY_B__QSPI_A_DATA00 0x70a1
				MX6UL_PAD_NAND_CE0_B__QSPI_A_DATA01   0x70a1
				MX6UL_PAD_NAND_CE1_B__QSPI_A_DATA02   0x70a1
				MX6UL_PAD_NAND_CLE__QSPI_A_DATA03     0x70a1
				MX6UL_PAD_NAND_DQS__QSPI_A_SS0_B      0x70a1
			>;
		};

		pinctrl_sai2: sai2grp {
			fsl,pins = <
				MX6UL_PAD_JTAG_TDI__SAI2_TX_BCLK	0x17088
				MX6UL_PAD_JTAG_TDO__SAI2_TX_SYNC	0x17088
				MX6UL_PAD_JTAG_TRST_B__SAI2_TX_DATA	0x11088
				MX6UL_PAD_JTAG_TCK__SAI2_RX_DATA	0x11088
				MX6UL_PAD_JTAG_TMS__SAI2_MCLK		0x17088
			>;
		};

		pinctrl_tsc: tscgrp {
			fsl,pins = <
				MX6UL_PAD_GPIO1_IO01__GPIO1_IO01	0xb0
				MX6UL_PAD_GPIO1_IO02__GPIO1_IO02	0xb0
				MX6UL_PAD_GPIO1_IO03__GPIO1_IO03	0xb0
				MX6UL_PAD_GPIO1_IO04__GPIO1_IO04	0xb0
			>;
		};

		pinctrl_uart1: uart1grp {
			fsl,pins = <
				MX6UL_PAD_UART1_TX_DATA__UART1_DCE_TX 0x1b0b1
				MX6UL_PAD_UART1_RX_DATA__UART1_DCE_RX 0x1b0b1
			>;
		};

		pinctrl_uart2: uart2grp {
			fsl,pins = <
				MX6UL_PAD_UART2_TX_DATA__UART2_DCE_TX	0x1b0b1
				MX6UL_PAD_UART2_RX_DATA__UART2_DCE_RX	0x1b0b1
				MX6UL_PAD_UART3_RX_DATA__UART2_DCE_RTS	0x1b0b1
				MX6UL_PAD_UART3_TX_DATA__UART2_DCE_CTS	0x1b0b1
			>;
		};

		pinctrl_uart2dte: uart2dtegrp {
			fsl,pins = <
				MX6UL_PAD_UART2_TX_DATA__UART2_DTE_RX	0x1b0b1
				MX6UL_PAD_UART2_RX_DATA__UART2_DTE_TX	0x1b0b1
				MX6UL_PAD_UART3_RX_DATA__UART2_DTE_CTS	0x1b0b1
				MX6UL_PAD_UART3_TX_DATA__UART2_DTE_RTS	0x1b0b1
			>;
		};

		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
			>;
		};

		pinctrl_usdhc1_100mhz: usdhc1grp100mhz {
			fsl,pins = <
				MX6UL_PAD_SD1_CMD__USDHC1_CMD     0x170b9
				MX6UL_PAD_SD1_CLK__USDHC1_CLK     0x100b9
				MX6UL_PAD_SD1_DATA0__USDHC1_DATA0 0x170b9
				MX6UL_PAD_SD1_DATA1__USDHC1_DATA1 0x170b9
				MX6UL_PAD_SD1_DATA2__USDHC1_DATA2 0x170b9
				MX6UL_PAD_SD1_DATA3__USDHC1_DATA3 0x170b9
			>;
		};

		pinctrl_usdhc1_200mhz: usdhc1grp200mhz {
			fsl,pins = <
				MX6UL_PAD_SD1_CMD__USDHC1_CMD     0x170f9
				MX6UL_PAD_SD1_CLK__USDHC1_CLK     0x100f9
				MX6UL_PAD_SD1_DATA0__USDHC1_DATA0 0x170f9
				MX6UL_PAD_SD1_DATA1__USDHC1_DATA1 0x170f9
				MX6UL_PAD_SD1_DATA2__USDHC1_DATA2 0x170f9
				MX6UL_PAD_SD1_DATA3__USDHC1_DATA3 0x170f9
			>;
		};

		pinctrl_usdhc2: usdhc2grp {
			fsl,pins = <
				MX6UL_PAD_NAND_RE_B__USDHC2_CLK     0x10069
				MX6UL_PAD_NAND_WE_B__USDHC2_CMD     0x17059
				MX6UL_PAD_NAND_DATA00__USDHC2_DATA0 0x17059
				MX6UL_PAD_NAND_DATA01__USDHC2_DATA1 0x17059
				MX6UL_PAD_NAND_DATA02__USDHC2_DATA2 0x17059
				MX6UL_PAD_NAND_DATA03__USDHC2_DATA3 0x17059
			>;
		};

		pinctrl_usdhc2_8bit: usdhc2grp_8bit {
			fsl,pins = <
				MX6UL_PAD_NAND_RE_B__USDHC2_CLK     0x10069
				MX6UL_PAD_NAND_WE_B__USDHC2_CMD     0x17059
				MX6UL_PAD_NAND_DATA00__USDHC2_DATA0 0x17059
				MX6UL_PAD_NAND_DATA01__USDHC2_DATA1 0x17059
				MX6UL_PAD_NAND_DATA02__USDHC2_DATA2 0x17059
				MX6UL_PAD_NAND_DATA03__USDHC2_DATA3 0x17059
				MX6UL_PAD_NAND_DATA04__USDHC2_DATA4 0x17059
				MX6UL_PAD_NAND_DATA05__USDHC2_DATA5 0x17059
				MX6UL_PAD_NAND_DATA06__USDHC2_DATA6 0x17059
				MX6UL_PAD_NAND_DATA07__USDHC2_DATA7 0x17059
			>;
		};

		pinctrl_usdhc2_8bit_100mhz: usdhc2grp_8bit_100mhz {
			fsl,pins = <
				MX6UL_PAD_NAND_RE_B__USDHC2_CLK     0x100b9
				MX6UL_PAD_NAND_WE_B__USDHC2_CMD     0x170b9
				MX6UL_PAD_NAND_DATA00__USDHC2_DATA0 0x170b9
				MX6UL_PAD_NAND_DATA01__USDHC2_DATA1 0x170b9
				MX6UL_PAD_NAND_DATA02__USDHC2_DATA2 0x170b9
				MX6UL_PAD_NAND_DATA03__USDHC2_DATA3 0x170b9
				MX6UL_PAD_NAND_DATA04__USDHC2_DATA4 0x170b9
				MX6UL_PAD_NAND_DATA05__USDHC2_DATA5 0x170b9
				MX6UL_PAD_NAND_DATA06__USDHC2_DATA6 0x170b9
				MX6UL_PAD_NAND_DATA07__USDHC2_DATA7 0x170b9
			>;
		};

		pinctrl_usdhc2_8bit_200mhz: usdhc2grp_8bit_200mhz {
			fsl,pins = <
				MX6UL_PAD_NAND_RE_B__USDHC2_CLK     0x100f9
				MX6UL_PAD_NAND_WE_B__USDHC2_CMD     0x170f9
				MX6UL_PAD_NAND_DATA00__USDHC2_DATA0 0x170f9
				MX6UL_PAD_NAND_DATA01__USDHC2_DATA1 0x170f9
				MX6UL_PAD_NAND_DATA02__USDHC2_DATA2 0x170f9
				MX6UL_PAD_NAND_DATA03__USDHC2_DATA3 0x170f9
				MX6UL_PAD_NAND_DATA04__USDHC2_DATA4 0x170f9
				MX6UL_PAD_NAND_DATA05__USDHC2_DATA5 0x170f9
				MX6UL_PAD_NAND_DATA06__USDHC2_DATA6 0x170f9
				MX6UL_PAD_NAND_DATA07__USDHC2_DATA7 0x170f9
			>;
		};

		pinctrl_wdog: wdoggrp {
			fsl,pins = <
				MX6UL_PAD_LCD_RESET__WDOG1_WDOG_ANY    0x30b0
			>;
		};
	};
};

&iomuxc_snvs {
	pinctrl-names = "default_snvs";
        pinctrl-0 = <&pinctrl_hog_2>;
        imx6ul-evk {
		pinctrl_hog_2: hoggrp-2 {
                        fsl,pins = <
                                MX6ULL_PAD_SNVS_TAMPER0__GPIO5_IO00      0x80000000
                        >;
                };

		pinctrl_dvfs: dvfsgrp {
                        fsl,pins = <
                                MX6ULL_PAD_SNVS_TAMPER3__GPIO5_IO03      0x79
                        >;
                };
		
		pinctrl_lcdif_reset: lcdifresetgrp {
                        fsl,pins = <
                                /* used for lcd reset */
                                MX6ULL_PAD_SNVS_TAMPER9__GPIO5_IO09  0x79
                        >;
                };

		pinctrl_spi4: spi4grp {
                        fsl,pins = <
                                MX6ULL_PAD_BOOT_MODE0__GPIO5_IO10        0x70a1
                                MX6ULL_PAD_BOOT_MODE1__GPIO5_IO11        0x70a1
                                MX6ULL_PAD_SNVS_TAMPER7__GPIO5_IO07      0x70a1
                                MX6ULL_PAD_SNVS_TAMPER8__GPIO5_IO08      0x80000000
                        >;
                };

                pinctrl_sai2_hp_det_b: sai2_hp_det_grp {
                        fsl,pins = <
                                MX6ULL_PAD_SNVS_TAMPER4__GPIO5_IO04   0x17059
                        >;
                };
        };
};


&lcdif {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_lcdif_dat
		     &pinctrl_lcdif_ctrl
		     &pinctrl_lcdif_reset>;
	display = <&display0>;
	status = "okay";

	display0: display {
		bits-per-pixel = <16>;
		bus-width = <24>;

		display-timings {
			native-mode = <&timing0>;
			timing0: timing0 {
			clock-frequency = <9200000>;
			hactive = <480>;
			vactive = <272>;
			hfront-porch = <8>;
			hback-porch = <4>;
			hsync-len = <41>;
			vback-porch = <2>;
			vfront-porch = <4>;
			vsync-len = <10>;

			hsync-active = <0>;
			vsync-active = <0>;
			de-active = <1>;
			pixelclk-active = <0>;
			};
		};
	};
};

&pwm1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_pwm1>;
	status = "okay";
};

&pxp {
	status = "okay";
};

&qspi {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_qspi>;
	status = "okay";
	ddrsmp=<0>;

	flash0: n25q256a@0 {
		#address-cells = <1>;
		#size-cells = <1>;
		compatible = "micron,n25q256a";
		spi-max-frequency = <29000000>;
		spi-nor,ddr-quad-read-dummy = <6>;
		reg = <0>;
	};
};

&sai2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_sai2
		     &pinctrl_sai2_hp_det_b>;

	assigned-clocks = <&clks IMX6UL_CLK_SAI2_SEL>,
			  <&clks IMX6UL_CLK_SAI2>;
	assigned-clock-parents = <&clks IMX6UL_CLK_PLL4_AUDIO_DIV>;
	assigned-clock-rates = <0>, <12288000>;

	status = "okay";
};

&tsc {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_tsc>;
	xnur-gpio = <&gpio1 3 GPIO_ACTIVE_LOW>;
	measure-delay-time = <0xffff>;
	pre-charge-time = <0xfff>;
	status = "okay";
};

&uart1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart1>;
	status = "okay";
};

&uart2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart2>;
	fsl,uart-has-rtscts;
	/* for DTE mode, add below change */
	/* fsl,dte-mode; */
	/* pinctrl-0 = <&pinctrl_uart2dte>; */
	status = "okay";
};

&usbotg1 {
	dr_mode = "otg";
	srp-disable;
	hnp-disable;
	adp-disable;
	status = "okay";
};

&usbotg2 {
	dr_mode = "host";
	disable-over-current;
	status = "okay";
};

&usbphy1 {
	tx-d-cal = <0x5>;
};

&usbphy2 {
	tx-d-cal = <0x5>;
};

&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 = <&reg_sd1_vmmc>;
	status = "okay";
};

&usdhc2 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_usdhc2>;
	non-removable;
	status = "okay";
};

&wdog1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_wdog>;
	fsl,wdog_b;
};

property

  • 每个property就是一个key value对,property-name就是key
  • 属性可以有值或者没有值
    [label:]prooerty-name=value;//有值
    [label:]property-name; //没有值
  • value的几种可能情况
    字符串 compatible=“arm,cortex-a7”;
    32位无符号整数 reg=<1 0x123456 100>
    16进制字节序列 reg=[00 11 22 33] //每个数据必须是2位,也可以附加上0x
    字符串列表 compatible=“fsl,imx6ull-gpmi-nand”,“fsl,imx6ull-gpmi-nand”;

常见预定义标准属性

  • compatible,节点数据将来去匹配内核策略部分的兼容性设置
    案例1:compatible=“manufacturer,model”
    案例2:compatible=“fsl,imx6ul-evk-wm8960”,“fsl,imx-audio-wm8960”
    案例3:16dv300的串口uart
    注意1:根节点的compatible属性是确认内核是否适配该dtb的,作用类似于老版本的machine id,而设备节点的compatible属性是为了匹配Linux内核中的驱动程序,作用类似于以前的.name
    注意2:compatible如果有多个,前面的更精准,后面的越来越泛化,所以优先匹配前面
  • model,描述设备模块信息,比如名字、详细版本号
    案例1:model=“wm8960-audio-VI.0”
    案例2:model=“Hisilicon H13516DV300 DEMO Board”

gpio实例

  1. gpio驱动确定
    (1)看dts中gpio节点的compatible属性,在内核中搜索
    (2)在编译过的内核中看drivers/gpio目录,找那些有.o的对应的.c文件
    (3)查drivers/gpio/Makefile,以及.config中的CONFIG项目对应
    (4)总结:还是要先懂linux的基本驱动框架知识,否则逻辑再强也没法分析
  2. gpio驱动框架组成
    (1)gpio-pl061,c中是H13516DV300对应的GPIO驱动,准确说是驱动中自己写的那部分
    (2)gpiolib.c等其他几个是gpiolib,linux gpio框架部分
    (3)gpiolib-of.c是gpiolib对接设备树的部分
  3. gpio驱动分析
    (1)关键点1:device_initcalI(p1061_gpi0_init)
    (2)关键点2:driver和device分离,然后在bus上match与probe
    (3)关键点3:上层实现具体平台封装,框架层实现通用封装
gpio_chip1:gpio_chip@120d1000{
	compatible="arm,p1061","arm,primecell"
	reg=<0X120d10000X1000>interrupts=<0174>clocks=<&clock H13516DV300_SYSAPB_CLK>;
	clock-names="apb_pclk"·
	#gpio-cells=<2>;
	status="disabled";
};

驱动中device来源

/driver/of/platform.c

/*
 *    Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corp.
 *			 <[email protected]>
 *    and		 Arnd Bergmann, IBM Corp.
 *    Merged from powerpc/kernel/of_platform.c and
 *    sparc{,64}/kernel/of_device.c by Stephen Rothwell
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

const struct of_device_id of_default_bus_match_table[] = {
	{ .compatible = "simple-bus", },
	{ .compatible = "simple-mfd", },
#ifdef CONFIG_ARM_AMBA
	{ .compatible = "arm,amba-bus", },
#endif /* CONFIG_ARM_AMBA */
	{} /* Empty terminated list */
};

static int of_dev_node_match(struct device *dev, void *data)
{
	return dev->of_node == data;
}

/**
 * of_find_device_by_node - Find the platform_device associated with a node
 * @np: Pointer to device tree node
 *
 * Returns platform_device pointer, or NULL if not found
 */
struct platform_device *of_find_device_by_node(struct device_node *np)
{
	struct device *dev;

	dev = bus_find_device(&platform_bus_type, NULL, np, of_dev_node_match);
	return dev ? to_platform_device(dev) : NULL;
}
EXPORT_SYMBOL(of_find_device_by_node);

#ifdef CONFIG_OF_ADDRESS
/*
 * The following routines scan a subtree and registers a device for
 * each applicable node.
 *
 * Note: sparc doesn't use these routines because it has a different
 * mechanism for creating devices from device tree nodes.
 */

/**
 * of_device_make_bus_id - Use the device node data to assign a unique name
 * @dev: pointer to device structure that is linked to a device tree node
 *
 * This routine will first try using the translated bus address to
 * derive a unique name. If it cannot, then it will prepend names from
 * parent nodes until a unique name can be derived.
 */
void of_device_make_bus_id(struct device *dev)
{
	struct device_node *node = dev->of_node;
	const __be32 *reg;
	u64 addr;

	/* Construct the name, using parent nodes if necessary to ensure uniqueness */
	while (node->parent) {
		/*
		 * If the address can be translated, then that is as much
		 * uniqueness as we need. Make it the first component and return
		 */
		reg = of_get_property(node, "reg", NULL);
		if (reg && (addr = of_translate_address(node, reg)) != OF_BAD_ADDR) {
			dev_set_name(dev, dev_name(dev) ? "%llx.%s:%s" : "%llx.%s",
				     (unsigned long long)addr, node->name,
				     dev_name(dev));
			return;
		}

		/* format arguments only used if dev_name() resolves to NULL */
		dev_set_name(dev, dev_name(dev) ? "%s:%s" : "%s",
			     strrchr(node->full_name, '/') + 1, dev_name(dev));
		node = node->parent;
	}
}

/**
 * of_device_alloc - Allocate and initialize an of_device
 * @np: device node to assign to device
 * @bus_id: Name to assign to the device.  May be null to use default name.
 * @parent: Parent device.
 */
struct platform_device *of_device_alloc(struct device_node *np,
				  const char *bus_id,
				  struct device *parent)
{
	struct platform_device *dev;
	int rc, i, num_reg = 0, num_irq;
	struct resource *res, temp_res;

	dev = platform_device_alloc("", -1);
	if (!dev)
		return NULL;

	/* count the io and irq resources */
	while (of_address_to_resource(np, num_reg, &temp_res) == 0)
		num_reg++;
	num_irq = of_irq_count(np);

	/* Populate the resource table */
	if (num_irq || num_reg) {
		res = kzalloc(sizeof(*res) * (num_irq + num_reg), GFP_KERNEL);
		if (!res) {
			platform_device_put(dev);
			return NULL;
		}

		dev->num_resources = num_reg + num_irq;
		dev->resource = res;
		for (i = 0; i < num_reg; i++, res++) {
			rc = of_address_to_resource(np, i, res);
			WARN_ON(rc);
		}
		if (of_irq_to_resource_table(np, res, num_irq) != num_irq)
			pr_debug("not all legacy IRQ resources mapped for %s\n",
				 np->name);
	}

	dev->dev.of_node = of_node_get(np);
	dev->dev.parent = parent ? : &platform_bus;

	if (bus_id)
		dev_set_name(&dev->dev, "%s", bus_id);
	else
		of_device_make_bus_id(&dev->dev);

	return dev;
}
EXPORT_SYMBOL(of_device_alloc);

static void of_dma_deconfigure(struct device *dev)
{
	arch_teardown_dma_ops(dev);
}

/**
 * of_platform_device_create_pdata - Alloc, initialize and register an of_device
 * @np: pointer to node to create device for
 * @bus_id: name to assign device
 * @platform_data: pointer to populate platform_data pointer with
 * @parent: Linux device model parent device.
 *
 * Returns pointer to created platform device, or NULL if a device was not
 * registered.  Unavailable devices will not get registered.
 */
static struct platform_device *of_platform_device_create_pdata(
					struct device_node *np,
					const char *bus_id,
					void *platform_data,
					struct device *parent)
{
	struct platform_device *dev;

	if (!of_device_is_available(np) ||
	    of_node_test_and_set_flag(np, OF_POPULATED))
		return NULL;

	dev = of_device_alloc(np, bus_id, parent);
	if (!dev)
		goto err_clear_flag;

	dev->dev.bus = &platform_bus_type;
	dev->dev.platform_data = platform_data;
	of_dma_configure(&dev->dev, dev->dev.of_node);

	if (of_device_add(dev) != 0) {
		of_dma_deconfigure(&dev->dev);
		platform_device_put(dev);
		goto err_clear_flag;
	}

	return dev;

err_clear_flag:
	of_node_clear_flag(np, OF_POPULATED);
	return NULL;
}

/**
 * of_platform_device_create - Alloc, initialize and register an of_device
 * @np: pointer to node to create device for
 * @bus_id: name to assign device
 * @parent: Linux device model parent device.
 *
 * Returns pointer to created platform device, or NULL if a device was not
 * registered.  Unavailable devices will not get registered.
 */
struct platform_device *of_platform_device_create(struct device_node *np,
					    const char *bus_id,
					    struct device *parent)
{
	return of_platform_device_create_pdata(np, bus_id, NULL, parent);
}
EXPORT_SYMBOL(of_platform_device_create);

#ifdef CONFIG_ARM_AMBA
static struct amba_device *of_amba_device_create(struct device_node *node,
						 const char *bus_id,
						 void *platform_data,
						 struct device *parent)
{
	struct amba_device *dev;
	const void *prop;
	int i, ret;

	pr_debug("Creating amba device %s\n", node->full_name);

	if (!of_device_is_available(node) ||
	    of_node_test_and_set_flag(node, OF_POPULATED))
		return NULL;

	dev = amba_device_alloc(NULL, 0, 0);
	if (!dev) {
		pr_err("%s(): amba_device_alloc() failed for %s\n",
		       __func__, node->full_name);
		goto err_clear_flag;
	}

	/* setup generic device info */
	dev->dev.of_node = of_node_get(node);
	dev->dev.parent = parent ? : &platform_bus;
	dev->dev.platform_data = platform_data;
	if (bus_id)
		dev_set_name(&dev->dev, "%s", bus_id);
	else
		of_device_make_bus_id(&dev->dev);
	of_dma_configure(&dev->dev, dev->dev.of_node);

	/* Allow the HW Peripheral ID to be overridden */
	prop = of_get_property(node, "arm,primecell-periphid", NULL);
	if (prop)
		dev->periphid = of_read_ulong(prop, 1);

	/* Decode the IRQs and address ranges */
	for (i = 0; i < AMBA_NR_IRQS; i++)
		dev->irq[i] = irq_of_parse_and_map(node, i);

	ret = of_address_to_resource(node, 0, &dev->res);
	if (ret) {
		pr_err("%s(): of_address_to_resource() failed (%d) for %s\n",
		       __func__, ret, node->full_name);
		goto err_free;
	}

	ret = amba_device_add(dev, &iomem_resource);
	if (ret) {
		pr_err("%s(): amba_device_add() failed (%d) for %s\n",
		       __func__, ret, node->full_name);
		goto err_free;
	}

	return dev;

err_free:
	amba_device_put(dev);
err_clear_flag:
	of_node_clear_flag(node, OF_POPULATED);
	return NULL;
}
#else /* CONFIG_ARM_AMBA */
static struct amba_device *of_amba_device_create(struct device_node *node,
						 const char *bus_id,
						 void *platform_data,
						 struct device *parent)
{
	return NULL;
}
#endif /* CONFIG_ARM_AMBA */

/**
 * of_devname_lookup() - Given a device node, lookup the preferred Linux name
 */
static const struct of_dev_auxdata *of_dev_lookup(const struct of_dev_auxdata *lookup,
				 struct device_node *np)
{
	struct resource res;

	if (!lookup)
		return NULL;

	for(; lookup->compatible != NULL; lookup++) {
		if (!of_device_is_compatible(np, lookup->compatible))
			continue;
		if (!of_address_to_resource(np, 0, &res))
			if (res.start != lookup->phys_addr)
				continue;
		pr_debug("%s: devname=%s\n", np->full_name, lookup->name);
		return lookup;
	}

	return NULL;
}

/**
 * of_platform_bus_create() - Create a device for a node and its children.
 * @bus: device node of the bus to instantiate
 * @matches: match table for bus nodes
 * @lookup: auxdata table for matching id and platform_data with device nodes
 * @parent: parent for new device, or NULL for top level.
 * @strict: require compatible property
 *
 * Creates a platform_device for the provided device_node, and optionally
 * recursively create devices for all the child nodes.
 */
static int of_platform_bus_create(struct device_node *bus,
				  const struct of_device_id *matches,
				  const struct of_dev_auxdata *lookup,
				  struct device *parent, bool strict)
{
	const struct of_dev_auxdata *auxdata;
	struct device_node *child;
	struct platform_device *dev;
	const char *bus_id = NULL;
	void *platform_data = NULL;
	int rc = 0;

	/* Make sure it has a compatible property */
	if (strict && (!of_get_property(bus, "compatible", NULL))) {
		pr_debug("%s() - skipping %s, no compatible prop\n",
			 __func__, bus->full_name);
		return 0;
	}

	auxdata = of_dev_lookup(lookup, bus);
	if (auxdata) {
		bus_id = auxdata->name;
		platform_data = auxdata->platform_data;
	}

	if (of_device_is_compatible(bus, "arm,primecell")) {
		/*
		 * Don't return an error here to keep compatibility with older
		 * device tree files.
		 */
		of_amba_device_create(bus, bus_id, platform_data, parent);
		return 0;
	}

	dev = of_platform_device_create_pdata(bus, bus_id, platform_data, parent);
	if (!dev || !of_match_node(matches, bus))
		return 0;

	for_each_child_of_node(bus, child) {
		pr_debug("   create child: %s\n", child->full_name);
		rc = of_platform_bus_create(child, matches, lookup, &dev->dev, strict);
		if (rc) {
			of_node_put(child);
			break;
		}
	}
	of_node_set_flag(bus, OF_POPULATED_BUS);
	return rc;
}

/**
 * of_platform_bus_probe() - Probe the device-tree for platform buses
 * @root: parent of the first level to probe or NULL for the root of the tree
 * @matches: match table for bus nodes
 * @parent: parent to hook devices from, NULL for toplevel
 *
 * Note that children of the provided root are not instantiated as devices
 * unless the specified root itself matches the bus list and is not NULL.
 */
int of_platform_bus_probe(struct device_node *root,
			  const struct of_device_id *matches,
			  struct device *parent)
{
	struct device_node *child;
	int rc = 0;

	root = root ? of_node_get(root) : of_find_node_by_path("/");
	if (!root)
		return -EINVAL;

	pr_debug("of_platform_bus_probe()\n");
	pr_debug(" starting at: %s\n", root->full_name);

	/* Do a self check of bus type, if there's a match, create children */
	if (of_match_node(matches, root)) {
		rc = of_platform_bus_create(root, matches, NULL, parent, false);
	} else for_each_child_of_node(root, child) {
		if (!of_match_node(matches, child))
			continue;
		rc = of_platform_bus_create(child, matches, NULL, parent, false);
		if (rc)
			break;
	}

	of_node_put(root);
	return rc;
}
EXPORT_SYMBOL(of_platform_bus_probe);

/**
 * of_platform_populate() - Populate platform_devices from device tree data
 * @root: parent of the first level to probe or NULL for the root of the tree
 * @matches: match table, NULL to use the default
 * @lookup: auxdata table for matching id and platform_data with device nodes
 * @parent: parent to hook devices from, NULL for toplevel
 *
 * Similar to of_platform_bus_probe(), this function walks the device tree
 * and creates devices from nodes.  It differs in that it follows the modern
 * convention of requiring all device nodes to have a 'compatible' property,
 * and it is suitable for creating devices which are children of the root
 * node (of_platform_bus_probe will only create children of the root which
 * are selected by the @matches argument).
 *
 * New board support should be using this function instead of
 * of_platform_bus_probe().
 *
 * Returns 0 on success, < 0 on failure.
 */
int of_platform_populate(struct device_node *root,
			const struct of_device_id *matches,
			const struct of_dev_auxdata *lookup,
			struct device *parent)
{
	struct device_node *child;
	int rc = 0;

	root = root ? of_node_get(root) : of_find_node_by_path("/");
	if (!root)
		return -EINVAL;

	for_each_child_of_node(root, child) {
		rc = of_platform_bus_create(child, matches, lookup, parent, true);
		if (rc)
			break;
	}
	of_node_set_flag(root, OF_POPULATED_BUS);

	of_node_put(root);
	return rc;
}
EXPORT_SYMBOL_GPL(of_platform_populate);

static int of_platform_device_destroy(struct device *dev, void *data)
{
	/* Do not touch devices not populated from the device tree */
	if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED))
		return 0;

	/* Recurse for any nodes that were treated as busses */
	if (of_node_check_flag(dev->of_node, OF_POPULATED_BUS))
		device_for_each_child(dev, NULL, of_platform_device_destroy);

	if (dev->bus == &platform_bus_type)
		platform_device_unregister(to_platform_device(dev));
#ifdef CONFIG_ARM_AMBA
	else if (dev->bus == &amba_bustype)
		amba_device_unregister(to_amba_device(dev));
#endif

	of_dma_deconfigure(dev);
	of_node_clear_flag(dev->of_node, OF_POPULATED);
	of_node_clear_flag(dev->of_node, OF_POPULATED_BUS);
	return 0;
}

/**
 * of_platform_depopulate() - Remove devices populated from device tree
 * @parent: device which children will be removed
 *
 * Complementary to of_platform_populate(), this function removes children
 * of the given device (and, recurrently, their children) that have been
 * created from their respective device tree nodes (and only those,
 * leaving others - eg. manually created - unharmed).
 *
 * Returns 0 when all children devices have been removed or
 * -EBUSY when some children remained.
 */
void of_platform_depopulate(struct device *parent)
{
	if (parent->of_node && of_node_check_flag(parent->of_node, OF_POPULATED_BUS)) {
		device_for_each_child(parent, NULL, of_platform_device_destroy);
		of_node_clear_flag(parent->of_node, OF_POPULATED_BUS);
	}
}
EXPORT_SYMBOL_GPL(of_platform_depopulate);

#ifdef CONFIG_OF_DYNAMIC
static int of_platform_notify(struct notifier_block *nb,
				unsigned long action, void *arg)
{
	struct of_reconfig_data *rd = arg;
	struct platform_device *pdev_parent, *pdev;
	bool children_left;

	switch (of_reconfig_get_state_change(action, rd)) {
	case OF_RECONFIG_CHANGE_ADD:
		/* verify that the parent is a bus */
		if (!of_node_check_flag(rd->dn->parent, OF_POPULATED_BUS))
			return NOTIFY_OK;	/* not for us */

		/* already populated? (driver using of_populate manually) */
		if (of_node_check_flag(rd->dn, OF_POPULATED))
			return NOTIFY_OK;

		/* pdev_parent may be NULL when no bus platform device */
		pdev_parent = of_find_device_by_node(rd->dn->parent);
		pdev = of_platform_device_create(rd->dn, NULL,
				pdev_parent ? &pdev_parent->dev : NULL);
		of_dev_put(pdev_parent);

		if (pdev == NULL) {
			pr_err("%s: failed to create for '%s'\n",
					__func__, rd->dn->full_name);
			/* of_platform_device_create tosses the error code */
			return notifier_from_errno(-EINVAL);
		}
		break;

	case OF_RECONFIG_CHANGE_REMOVE:

		/* already depopulated? */
		if (!of_node_check_flag(rd->dn, OF_POPULATED))
			return NOTIFY_OK;

		/* find our device by node */
		pdev = of_find_device_by_node(rd->dn);
		if (pdev == NULL)
			return NOTIFY_OK;	/* no? not meant for us */

		/* unregister takes one ref away */
		of_platform_device_destroy(&pdev->dev, &children_left);

		/* and put the reference of the find */
		of_dev_put(pdev);
		break;
	}

	return NOTIFY_OK;
}

static struct notifier_block platform_of_notifier = {
	.notifier_call = of_platform_notify,
};

void of_platform_register_reconfig_notifier(void)
{
	WARN_ON(of_reconfig_notifier_register(&platform_of_notifier));
}
#endif /* CONFIG_OF_DYNAMIC */

#endif /* CONFIG_OF_ADDRESS */

你可能感兴趣的:(linux驱动,linux,驱动开发,c语言,arm开发,系统架构)