查看Raspberry的源代码

== DTB ==

Raspberry 3 model B (BCM2837 主控），linux kernel 4.4/4.15 始终使用 '''bcm2710-rpi-3-b.dtb''' 作为主 dtb，另一个 bcm2837-rpi-3-b.dtb 用不上

<source lang=bash>
$ ls arch/arm/boot/dts/broadcom/*rpi-3-b.dtb
arch/arm/boot/dts/broadcom/bcm2710-rpi-3-b.dtb  arch/arm/boot/dts/broadcom/bcm2837-rpi-3-b.dtb

$ scp arch/arm/boot/dts/overlays/sx12xx-spi0.dtbo root@192.168.1.98:/boot/overlays/
</source>

'''Overlay:''' 置于 /boot/overlays/ 目录下，/boot/config.txt 中增加：

<source lang=bash>
#dtoverlay=spi0-1cs
dtoverlay=sx12xx-spi0
</source>

<source lang=cpp>
/dts-v1/;
/plugin/;

#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/interrupt-controller/irq.h>

/ {
    compatible = "brcm,bcm2835";
    /* disable spi-dev for spi0.0 */
    fragment@0 {
        target = <&spi0>;
        __overlay__ {
            status = "okay";
        };
    };

    fragment@1 {
        target = <&spidev0>;
        __overlay__ {
            status = "disabled";
        };
    };

    /* interrupt pin */
    fragment@2 {
        target = <&gpio>;
        __overlay__ {
            radio0_pins: radio0_pins {
                brcm,pins = <4>;        /* gpio4 as interrupt */
                brcm,function = <0>;    /* input */
                brcm,pull = <1>;        /* pull-down */
            };
        };
    };

    /* the spi config of the can-controller itself binding everything together */
    fragment@4 {
        target = <&spi0>;
        __overlay__ {
            /* needed to avoid dtc warning */
            #address-cells = <1>;
            #size-cells = <0>;

            status = "okay";

            radio0: sx127x@0 {
                reg = <0>;      /* CS0 */
                compatible = "semtech,sx12xx";
                pinctrl-names = "default";
                pinctrl-0 = <&radio0_pins>;

                spi-max-frequency = <5000000>;

                reset-gpios = <&gpio 17 GPIO_ACTIVE_LOW>;   /* GPIO 17, 1: GPIO_ACTIVE_LOW */

                interrupt-parent = <&gpio>;
                //interrupts = <25 IRQ_TYPE_EDGE_RISING>;   /* gpio 25 */
                interrupts = <4 IRQ_TYPE_EDGE_RISING>;      /* gpio 4 */
                status = "okay";
            };
        };
    };
    __overrides__ {
        spimaxfrequency = <&radio0>,"spi-max-frequency:0";
    };
};
</source>

使用 GPIO4 作为中断输入，要把 LED_GPIO 关掉：

<source lang=bash>
# CONFIG_LEDS_GPIO=y
# CONFIG_LEDS_TRIGGERS=y
# CONFIG_LEDS_TRIGGER_TIMER=y
# CONFIG_LEDS_TRIGGER_ONESHOT=y
# CONFIG_LEDS_TRIGGER_HEARTBEAT=y
# CONFIG_LEDS_TRIGGER_BACKLIGHT=y
# CONFIG_LEDS_TRIGGER_CPU=y
# CONFIG_LEDS_TRIGGER_GPIO=y
# CONFIG_LEDS_TRIGGER_DEFAULT_ON=y
# CONFIG_LEDS_TRIGGER_TRANSIENT=m
# CONFIG_LEDS_TRIGGER_CAMERA=m
# CONFIG_LEDS_TRIGGER_INPUT=y
</source>

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