从Linux用户空间连接到i2c触摸屏(在设备树中)

Question

我试着和笔记本电脑的设备树上列出的触屏/触控板对话。触摸屏在/dev/中根本没有出现，就像我的USB鼠标一样。我使用的是一个ASUS C201 Chromebook (代号威龙速)，运行Debian 9，主流内核，而且按所有的说法，触摸屏应该能工作，但我甚至看不到它的/dev/。我想弄清楚Debian是否看到了。

以下是此计算机设备树的相关部分：

            trackpad {

                    trackpad-int {
                            rockchip,pins = <0x7 0x3 0x0 0x6a>;
                            linux,phandle = <0x31>;
                            phandle = <0x31>;
                    };
            };

下面是cat /sys/kernel/debug/gpio的输出：

gpiochip0: GPIOs 0-23, parent: platform/pinctrl, gpio0:
 gpio-5   (                    |Power               ) in  hi    
 gpio-6   (                    |Lid                 ) in  hi    
 gpio-8   (                    |gpio-charger        ) in  lo    
 gpio-11  (                    |vcc5_host1          ) out hi    
 gpio-12  (                    |vcc5_host2          ) out hi    
 gpio-13  (                    |?                   ) out lo    

gpiochip1: GPIOs 24-55, parent: platform/pinctrl, gpio1:

gpiochip2: GPIOs 56-87, parent: platform/pinctrl, gpio2:
 gpio-65  (                    |reset               ) in  lo    
 gpio-68  (                    |backlight_regulator ) out hi    
 gpio-69  (                    |vcc18_lcd           ) out hi    

gpiochip3: GPIOs 88-119, parent: platform/pinctrl, gpio3:

gpiochip4: GPIOs 120-151, parent: platform/pinctrl, gpio4:
 gpio-148 (                    |reset               ) in  lo    

gpiochip5: GPIOs 152-183, parent: platform/pinctrl, gpio5:
 gpio-171 (                    |vcc50_hdmi          ) out hi    

gpiochip6: GPIOs 184-215, parent: platform/pinctrl, gpio6:

gpiochip7: GPIOs 216-247, parent: platform/pinctrl, gpio7:
 gpio-218 (                    |enable              ) out hi    
 gpio-221 (                    |cd                  ) in  hi    
 gpio-230 (                    |panel_regulator     ) out hi    
 gpio-237 (                    |vcc_5v              ) out hi    

gpiochip8: GPIOs 248-263, parent: platform/pinctrl, gpio8:

这些GPIOs中的一个是dtb中列出的触摸屏吗？

Answer 1

rk3288-veyron-chromebook.dtsi中的完整声明是

&i2c4 {
    trackpad@15 {
        compatible = "elan,ekth3000";
        reg = <0x15>;
        interrupt-parent = <&gpio7>;
        interrupts = <RK_PA3 IRQ_TYPE_EDGE_FALLING>;
        pinctrl-names = "default";
        pinctrl-0 = <&trackpad_int>;
        vcc-supply = <&vcc33_io>;
        wakeup-source;
    };
};

查看包含的文件rk3288-veyron.dtsi，有

&i2c4 {
    status = "okay";

    clock-frequency = <400000>;
    i2c-scl-falling-time-ns = <50>;         /* 11ns measured */
    i2c-scl-rising-time-ns = <300>;         /* 225ns measured */
};

在rk3288.dtsi更远

i2c4: i2c@ff160000 {
        compatible = "rockchip,rk3288-i2c";
        reg = <0x0 0xff160000 0x0 0x1000>;
        interrupts = <GIC_SPI 64 IRQ_TYPE_LEVEL_HIGH>;
        #address-cells = <1>;
        #size-cells = <0>;
        clock-names = "i2c";
        clocks = <&cru PCLK_I2C4>;
        pinctrl-names = "default";
        pinctrl-0 = <&i2c4_xfer>;
        status = "disabled";
};

因此，这看起来非常像I2C接口不是GPIO接口，而是在rockchip中使用了专用的寄存器范围。

你试过在I2C resp中寻找/sys/bus总线吗？/sys/class？