linux_驱动_IIC_设备树配置详解

做驱动的要经常配置i2c,而配置i2c无非就是确定i2c器件挂在哪一个i2c总线上,以及i2c的具体地址.下面以高通8909平台为例子说一下

 

• 确定i2c机器挂在哪一个i2c总线上

1. 1. 从原理图得到SDA,SCL对应的gpio，我这个gpio为gpio6，gpio7
   2. 在msm8909-pinctrl.dtsi文件中找到该gpio对应的i2c总线，如下，可见其对应的i2c总线是i2c_1

      
             
             
             
             
      
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                         pmx_i2c_1 {
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                             i2c_1_active: i2c_1_active {
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                 mux {
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                     pins = 
                 
                 
                 
                 "gpio6", 
                 
                 
                 
                 "gpio7";
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
                          
                 
                 
                 
                 function = "blsp_i2c1";
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                 };
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                 config {
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                     pins = 
                 
                 
                 
                 "gpio6", 
                 
                 
                 
                 "gpio7";
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                     drive-strength = <
                 
                 
                 
                 2>; 
                 
                 
                 
                 /* 2 MA */
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                     bias-disable; 
                 
                 
                 
                 /* No PULL */
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                 };
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                             };
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                             i2c_1_sleep: i2c_1_sleep {
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                 mux {
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                     pins = 
                 
                 
                 
                 "gpio6", 
                 
                 
                 
                 "gpio7";
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
                          
                 
                 
                 
                 function = "blsp_i2c1";
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                 };
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                 config {
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                     pins = 
                 
                 
                 
                 "gpio6", 
                 
                 
                 
                 "gpio7";
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                     drive-strength = <
                 
                 
                 
                 2>; 
                 
                 
                 
                 /* 2 MA */
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                     bias-disable; 
                 
                 
                 
                 /* No PULL */
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                                 };
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                             };
                
                
                
                
               
               
               
               
              
              
              
              
      
               
               
               
               
      
                
                
                
                
      
               
               
               
               
               
               
               
               
      
                
                
                
                
      
                 
                 
                 
                         };
                
                
                
                
               
               
               
               
             
             
             
             
             
             
             
             
      

 

然后在msm8909.dtsi里面查找i2c_1,就可以得到其i2c地址为78b5000

 

	
    i2c_1: i2c@78b5000 { /* BLSP1 QUP1 */
        compatible = "qcom,i2c-msm-v2";
        #address-cells = <1>;
        #size-cells = <0>;
        reg-names = "qup_phys_addr";
        reg = <0x78b5000 0x1000>;
        interrupt-names = "qup_irq";
        interrupts = <0 95 0>;
        clocks = <&clock_gcc clk_gcc_blsp1_ahb_clk>,
             <&clock_gcc clk_gcc_blsp1_qup1_i2c_apps_clk>;
        clock-names = "iface_clk", "core_clk";
        qcom,clk-freq-out = <100000>;
        qcom,clk-freq-in  = <19200000>;
        pinctrl-names = "i2c_active", "i2c_sleep";
        pinctrl-0 = <&i2c_1_active>;
        pinctrl-1 = <&i2c_1_sleep>;
        qcom,noise-rjct-scl = <0>;
        qcom,noise-rjct-sda = <0>;
        dmas = <&dma_blsp1 4 64 0x20000020 0x20>,
            <&dma_blsp1 5  32 0x20000020 0x20>;
        dma-names = "tx", "rx";
        qcom,master-id = <86>;
    };


	
 
	
	
在msm8909-mtp.dtsi里i2c@78b5000加入其i2c器件的配置
	
 

	
    i2c@78b5000 { /* BLSP1 QUP1 */
        fm2018@60 {
            compatible = "fortemedia,fm2018";
            reg = <0x60>;
            fm2018,vdd-en = <&sn7325_1gpio 5 0x00>;//p1 58////sn7325,5
            fm2018,pwd-gpio = <&sn7325_gpio 3 0x00>;//p1 26//sn7325,3
            fm2018,rst-gpio = <&sn7325_gpio 2 0x00>;//sn7325,2
            fm2018,int-gpio = <&sn7325_gpio 4 0x4>;//sn7325,4
        };
    };


	
 
	

• i2c器件的具体地址

        这个一般是由器件datasheet提供，如我使用的这个期间的i2c地址是0x60，如果不清楚，可以打电话问FAE。