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0058_DebugHAT_Poweroff.md

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0058_DebugHAT_Poweroff.md

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DebugHAT Poweroff

这里的Poweroff不是是触发系统断电的按键功能，而是这个引脚默认低电平，如果系统关机，那么会给出高电平，告诉外围电路系统断电了。

参考文档

注意

  • overlay文件中的__overrides__字段内容不会附加到系统__overrides__中去；
  • dtoverlay加参数执行的命令，其参数只会覆盖overlay文件中的__overrides__；
  • dtparam修改的是系统__overrides__；

测试方法

  • shutdown -P；
  • 采用GPIO9观察LED等状态；

dts测试

  • /boot/config.txt 
    dtdebug=1
  • sudo dtc -I fs -O dtb -o base.dtb /proc/device-tree 1>/dev/null 2>&1
  • fdtdump base.dtb > base.dts
  • 应用gpio-poweroff
    • sudo dtoverlay -v gpio-poweroff 
      run_cmd: which dtoverlay-pre >/dev/null 2>&1 && dtoverlay-pre
DTOVERLAY[debug]: delete_node(/__symbols__)
DTOVERLAY[debug]: Wrote 1106 bytes to '/tmp/.dtoverlays/0_gpio-shutdown.dtbo'
DTOVERLAY[debug]: Wrote 1106 bytes to '/sys/kernel/config/device-tree/overlays/0_gpio-shutdown/dtbo'
run_cmd: which dtoverlay-post >/dev/null 2>&1 && dtoverlay-post
    • sudo dtoverlay -v gpio-poweroff gpiopin=26 
      run_cmd: which dtoverlay-pre >/dev/null 2>&1 && dtoverlay-pre
* dtoverlay_add: gpiopin 26
DTOVERLAY[debug]: Found override gpiopin
DTOVERLAY[debug]:   override gpiopin: cell target gpios @ offset 4 (size 4)
DTOVERLAY[debug]:   override gpiopin: cell target brcm,pins @ offset 0 (size 4)
DTOVERLAY[debug]: delete_node(/__symbols__)
DTOVERLAY[debug]: Wrote 874 bytes to '/tmp/.dtoverlays/0_gpio-poweroff.dtbo'
DTOVERLAY[debug]: Wrote 885 bytes to '/sys/kernel/config/device-tree/overlays/0_gpio-poweroff/dtbo'
run_cmd: which dtoverlay-post >/dev/null 2>&1 && dtoverlay-post
  • 如果需要删除刚刚应用的overlay：sudo rmdir /sys/kernel/config/device-tree/overlays/*
  • /sys/kernel/debug/gpio 
    gpiochip0: GPIOs 0-53, parent: platform/fe200000.gpio, pinctrl-bcm2835:
 gpio-26  (                    |power_ctrl          ) out lo
 gpio-42  (                    |led0                ) out lo

gpiochip2: GPIOs 100-101, brcmvirt-gpio, can sleep:

gpiochip1: GPIOs 504-511, parent: platform/soc:firmware:gpio, raspberrypi-exp-gpio, can sleep:
 gpio-504 (BT_ON               )
 gpio-505 (WL_ON               )
 gpio-506 (PWR_LED_OFF         |led1                ) out lo
 gpio-507 (GLOBAL_RESET        )
 gpio-508 (VDD_SD_IO_SEL       |vdd-sd-io           ) out hi
 gpio-509 (CAM_GPIO            )
 gpio-510 (                    )
 gpio-511 (                    )

gpio-poweroff-overlay.dts

  • GPIO number for CAM_GPIO0
  • arm/boot/dts/overlays/gpio-shutdown-overlay.dts
  • arm/boot/dts/overlays/gpio-poweroff-overlay.dts 
    // Definitions for gpio-poweroff module
/dts-v1/;
/plugin/;

/ {
        compatible = "brcm,bcm2835";

        fragment@0 {
                target-path = "/";
                __overlay__ {
                        power_ctrl: power_ctrl {
                                compatible = "gpio-poweroff";
                                gpios = <&gpio 26 0>;
                                force;
                        };
                };
        };

        fragment@1 {
                target = <&gpio>;
                __overlay__ {
                        power_ctrl_pins: power_ctrl_pins {
                                brcm,pins = <26>;
                                brcm,function = <1>; // out
                        };
                };
        };

        __overrides__ {
                gpiopin =       <&power_ctrl>,"gpios:4",
                                <&power_ctrl_pins>,"brcm,pins:0";
                active_low =    <&power_ctrl>,"gpios:8";
                input =         <&power_ctrl>,"input?";
                export =        <&power_ctrl>,"export?";
        };
};
  • fdtdump /boot/overlays/gpio-poweroff.dtbo 
    **** fdtdump is a low-level debugging tool, not meant for general use.
**** If you want to decompile a dtb, you probably want
****     dtc -I dtb -O dts <filename>

/dts-v1/;
// magic:               0xd00dfeed
// totalsize:           0x3e2 (994)
// off_dt_struct:       0x38
// off_dt_strings:      0x358
// off_mem_rsvmap:      0x28
// version:             17
// last_comp_version:   16
// boot_cpuid_phys:     0x0
// size_dt_strings:     0x8a
// size_dt_struct:      0x320

/ {
    compatible = "brcm,bcm2835";
    fragment@0 {
        target-path = "/";
        __overlay__ {
            power_ctrl {
                compatible = "gpio-poweroff";
                gpios = <0xffffffff 0x0000001a 0x00000000>;
                force;
                phandle = <0x00000001>;
            };
        };
    };
    fragment@1 {
        target = <0xffffffff>;
        __overlay__ {
            power_ctrl_pins {
                brcm,pins = <0x0000001a>;
                brcm,function = <0x00000001>;
                phandle = <0x00000002>;
            };
        };
    };
    __overrides__ {
        gpiopin = <0x00000001 0x6770696f 0x733a3400 0x00000002 0x6272636d 0x2c70696e 0x733a3000>;
        active_low = <0x00000001 0x6770696f 0x733a3800>;
        input = [00 00 00 01 69 6e 70 75 74 3f 00];
        export = <0x00000001 0x6578706f 0x72743f00>;
    };
    __symbols__ {
        power_ctrl = "/fragment@0/__overlay__/power_ctrl";
        power_ctrl_pins = "/fragment@1/__overlay__/power_ctrl_pins";
    };
    __fixups__ {
        gpio = "/fragment@0/__overlay__/power_ctrl:gpios:0", "/fragment@1:target:0";
    };
    __local_fixups__ {
        __overrides__ {
            gpiopin = <0x00000000 0x0000000c>;
            active_low = <0x00000000>;
            input = <0x00000000>;
            export = <0x00000000>;
        };
    };
};

Driver

  • drivers/power/reset/gpio-poweroff.c 
    [...省略]
static void gpio_poweroff_do_poweroff(void)
{
        BUG_ON(!reset_gpio);

        /* drive it active, also inactive->active edge */
        gpiod_direction_output(reset_gpio, 1);
        mdelay(100);
        /* drive inactive, also active->inactive edge */
        gpiod_set_value_cansleep(reset_gpio, 0);
        mdelay(100);

        /* drive it active, also inactive->active edge */
        gpiod_set_value_cansleep(reset_gpio, 1);

        /* give it some time */
        mdelay(timeout);

        WARN_ON(1);
}
[...省略]