做驅動的要經常配置i2c,而配置i2c無非就是確定i2c器件掛在哪一個i2c總線上,以及i2c的具體地址.下面以高通8909平臺為例子說一下

• 確定i2c機器掛在哪一個i2c總線上

1. 1. 從原理圖得到SDA,SCL對應的gpio，我這個gpio為gpio6，gpio7
   2. 在msm8909-pinctrl.dtsi檔案中找到該gpio對應的i2c匯流排，如下，可見其對應的i2c匯流排是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 */
                      };
                  };
              };
       
      

   3. 然後在msm8909.dtsi裡面查詢i2c_1,就可以得到其i2c地址為78b5000

          i2c_1: [email protected] { /* 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>;
          };
       
      

   4. 在msm8909-mtp.dtsi裡[email protected]加入其i2c器件的配置

          [email protected] { /* BLSP1 QUP1 */
              [email protected] {
                  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器件的具體地址

        這個一般是由器件datasheet提供，如我使用的這個期間的i2c地址是0x60，如果不清楚，可以打電話問FAE。