arm Linux 驱动LED子系统 测试

Linux内核在3.0以上引入了设备树概念（具体哪个版本不清楚）在编译内核后需要将与之对应的dtb文件也下载人板子上才能使内核与硬件关联起来。

dtb文件是有dts文件编译后生成的：例如

/*
 * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

/*
 * AM335x Starter Kit
 * http://www.ti.com/tool/tmdssk3358
 */

/dts-v1/;

#include "am33xx.dtsi"
#include <dt-bindings/pwm/pwm.h>

/ {
    model = "TI AM335x EVM-SK";
    compatible = "ti,am335x-evmsk", "ti,am33xx";

    cpus {
        cpu@ {
            cpu0-supply = <&vdd1_reg>;
        };
    };

    memory {
        device_type = "memory";
        reg = <0x80000000 0x10000000>; /* 256 MB */
    };

    vbat: fixedregulator@ {
        compatible = "regulator-fixed";
        regulator-name = "vbat";
        regulator-min-microvolt = <>;
        regulator-max-microvolt = <>;
        regulator-boot-on;
    };

    lis3_reg: fixedregulator@ {
        compatible = "regulator-fixed";
        regulator-name = "lis3_reg";
        regulator-boot-on;
    };

    leds {
        pinctrl-names = "default";
        pinctrl- = <&user_leds_s0>;

        compatible = "gpio-leds";

        led@ {
            label = "zyrD1:green:usr0";
            gpios = <&gpio1  GPIO_ACTIVE_HIGH>;
            default-state = "off";
        };

        led@ {
            label = "zyrD2:green:usr1";
            gpios = <&gpio1  GPIO_ACTIVE_HIGH>;
            default-state = "off";
        };

        led@ {
            label = "zyrD4:green:mmc0";
            gpios = <&gpio1  GPIO_ACTIVE_HIGH>;
            linux,default-trigger = "mmc0";
            default-state = "off";
        };

        led@ {
            label = "zyrD3:green:heartbeat";
            gpios = <&gpio1  GPIO_ACTIVE_HIGH>;
            linux,default-trigger = "heartbeat";
            default-state = "off";
        };
    };

    gpio_buttons: gpio_buttons@ {
        compatible = "gpio-keys";
        #address-cells = <>;
        #size-cells = <>;

        switch@ {
            label = "button0";
            linux,code = <0x100>;
            gpios = <&gpio2  GPIO_ACTIVE_HIGH>;
        };

        switch@ {
            label = "button1";
            linux,code = <0x101>;
            gpios = <&gpio2  GPIO_ACTIVE_HIGH>;
        };

        switch@ {
            label = "button2";
            linux,code = <0x102>;
            gpios = <&gpio0  GPIO_ACTIVE_HIGH>;
            gpio-key,wakeup;
        };

        switch@ {
            label = "button3";
            linux,code = <0x103>;
            gpios = <&gpio2  GPIO_ACTIVE_HIGH>;
        };
    };

    backlight {
        compatible = "pwm-backlight";
        pwms = <&ecap2   PWM_POLARITY_INVERTED>;
        brightness-levels = <        >;
        default-brightness-level = <>;
    };

    sound {
        compatible = "ti,da830-evm-audio";
        ti,model = "AM335x-EVMSK";
        ti,audio-codec = <&tlv320aic3106>;
        ti,mcasp-controller = <&mcasp1>;
        ti,codec-clock-rate = <>;
        ti,audio-routing =
            "Headphone Jack",       "HPLOUT",
            "Headphone Jack",       "HPROUT";
    };
};

&am33xx_pinmux {
    pinctrl-names = "default";
    pinctrl- = <&gpio_keys_s0 &clkout2_pin>;

    user_leds_s0: user_leds_s0 {
        pinctrl-single,pins = <
            0x10 (PIN_OUTPUT_PULLDOWN | MUX_MODE7)    /* gpmc_ad4.gpio1_4 */
            0x14 (PIN_OUTPUT_PULLDOWN | MUX_MODE7)    /* gpmc_ad5.gpio1_5 */
            0x18 (PIN_OUTPUT_PULLDOWN | MUX_MODE7)    /* gpmc_ad6.gpio1_6 */
            0x1c (PIN_OUTPUT_PULLDOWN | MUX_MODE7)    /* gpmc_ad7.gpio1_7 */
        >;
    };

    gpio_keys_s0: gpio_keys_s0 {
        pinctrl-single,pins = <
            0x94 (PIN_INPUT_PULLDOWN | MUX_MODE7)    /* gpmc_oen_ren.gpio2_3 */
            0x90 (PIN_INPUT_PULLDOWN | MUX_MODE7)    /* gpmc_advn_ale.gpio2_2 */
            0x70 (PIN_INPUT_PULLDOWN | MUX_MODE7)    /* gpmc_wait0.gpio0_30 */
            0x9c (PIN_INPUT_PULLDOWN | MUX_MODE7)    /* gpmc_ben0_cle.gpio2_5 */
        >;
    };

    i2c0_pins: pinmux_i2c0_pins {
        pinctrl-single,pins = <
            0x188 (PIN_INPUT_PULLUP | MUX_MODE0)    /* i2c0_sda.i2c0_sda */
            0x18c (PIN_INPUT_PULLUP | MUX_MODE0)    /* i2c0_scl.i2c0_scl */
        >;
    };

    uart0_pins: pinmux_uart0_pins {
        pinctrl-single,pins = <
            0x170 (PIN_INPUT_PULLUP | MUX_MODE0)    /* uart0_rxd.uart0_rxd */
            0x174 (PIN_OUTPUT_PULLDOWN | MUX_MODE0)        /* uart0_txd.uart0_txd */
        >;
    };

    clkout2_pin: pinmux_clkout2_pin {
        pinctrl-single,pins = <
            0x1b4 (PIN_OUTPUT_PULLDOWN | MUX_MODE3)        /* xdma_event_intr1.clkout2 */
        >;
    };

    ecap2_pins: backlight_pins {
        pinctrl-single,pins = <
            0x19c 0x4    /* mcasp0_ahclkr.ecap2_in_pwm2_out MODE4 */
        >;
    };

    cpsw_default: cpsw_default {
        pinctrl-single,pins = <
            /* Slave 1 */
            0x114 (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* mii1_txen.rgmii1_tctl */
            0x118 (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* mii1_rxdv.rgmii1_rctl */
            0x11c (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* mii1_txd3.rgmii1_td3 */
            0x120 (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* mii1_txd2.rgmii1_td2 */
            0x124 (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* mii1_txd1.rgmii1_td1 */
            0x128 (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* mii1_txd0.rgmii1_td0 */
            0x12c (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* mii1_txclk.rgmii1_tclk */
            0x130 (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* mii1_rxclk.rgmii1_rclk */
            0x134 (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* mii1_rxd3.rgmii1_rd3 */
            0x138 (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* mii1_rxd2.rgmii1_rd2 */
            0x13c (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* mii1_rxd1.rgmii1_rd1 */
            0x140 (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* mii1_rxd0.rgmii1_rd0 */

            /* Slave 2 */
            0x40 (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a0.rgmii2_tctl */
            0x44 (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a1.rgmii2_rctl */
            0x48 (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a2.rgmii2_td3 */
            0x4c (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a3.rgmii2_td2 */
            0x50 (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a4.rgmii2_td1 */
            0x54 (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a5.rgmii2_td0 */
            0x58 (PIN_OUTPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a6.rgmii2_tclk */
            0x5c (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a7.rgmii2_rclk */
            0x60 (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a8.rgmii2_rd3 */
            0x64 (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a9.rgmii2_rd2 */
            0x68 (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a10.rgmii2_rd1 */
            0x6c (PIN_INPUT_PULLDOWN | MUX_MODE2)    /* gpmc_a11.rgmii2_rd0 */
        >;
    };

    cpsw_sleep: cpsw_sleep {
        pinctrl-single,pins = <
            /* Slave 1 reset value */
            0x114 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x118 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x11c (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x120 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x124 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x128 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x12c (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x130 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x134 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x138 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x13c (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x140 (PIN_INPUT_PULLDOWN | MUX_MODE7)

            /* Slave 2 reset value*/
            0x40 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x44 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x48 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x4c (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x50 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x54 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x58 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x5c (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x60 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x64 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x68 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x6c (PIN_INPUT_PULLDOWN | MUX_MODE7)
        >;
    };

    davinci_mdio_default: davinci_mdio_default {
        pinctrl-single,pins = <
            /* MDIO */
            0x148 (PIN_INPUT_PULLUP | SLEWCTRL_FAST | MUX_MODE0)    /* mdio_data.mdio_data */
            0x14c (PIN_OUTPUT_PULLUP | MUX_MODE0)            /* mdio_clk.mdio_clk */
        >;
    };

    davinci_mdio_sleep: davinci_mdio_sleep {
        pinctrl-single,pins = <
            /* MDIO reset value */
            0x148 (PIN_INPUT_PULLDOWN | MUX_MODE7)
            0x14c (PIN_INPUT_PULLDOWN | MUX_MODE7)
        >;
    };

    mmc1_pins: pinmux_mmc1_pins {
        pinctrl-single,pins = <
            0x160 (PIN_INPUT | MUX_MODE7) /* spi0_cs1.gpio0_6 */
        >;
    };

    mcasp1_pins: mcasp1_pins {
        pinctrl-single,pins = <
            0x10c (PIN_INPUT_PULLDOWN | MUX_MODE4) /* mii1_crs.mcasp1_aclkx */
            0x110 (PIN_INPUT_PULLDOWN | MUX_MODE4) /* mii1_rxerr.mcasp1_fsx */
            0x108 (PIN_OUTPUT_PULLDOWN | MUX_MODE4) /* mii1_col.mcasp1_axr2 */
            0x144 (PIN_INPUT_PULLDOWN | MUX_MODE4) /* rmii1_ref_clk.mcasp1_axr3 */
        >;
    };
};

&uart0 {
    pinctrl-names = "default";
    pinctrl- = <&uart0_pins>;

    status = "okay";
};

&i2c0 {
    pinctrl-names = "default";
    pinctrl- = <&i2c0_pins>;

    status = "okay";
    clock-frequency = <>;

    tps: tps@2d {
        reg = <0x2d>;
    };

    lis331dlh: lis331dlh@ {
        compatible = "st,lis331dlh", "st,lis3lv02d";
        reg = <0x18>;
        Vdd-supply = <&lis3_reg>;
        Vdd_IO-supply = <&lis3_reg>;

        st,click-single-x;
        st,click-single-y;
        st,click-single-z;
        st,click-thresh-x = <>;
        st,click-thresh-y = <>;
        st,click-thresh-z = <>;
        st,irq1-click;
        st,irq2-click;
        st,wakeup-x-lo;
        st,wakeup-x-hi;
        st,wakeup-y-lo;
        st,wakeup-y-hi;
        st,wakeup-z-lo;
        st,wakeup-z-hi;
        st,min-limit-x = <>;
        st,min-limit-y = <>;
        st,min-limit-z = <>;
        st,max-limit-x = <>;
        st,max-limit-y = <>;
        st,max-limit-z = <>;
    };

    tlv320aic3106: tlv320aic3106@1b {
        compatible = "ti,tlv320aic3106";
        reg = <0x1b>;
        status = "okay";

        /* Regulators */
        AVDD-supply = <&vaux2_reg>;
        IOVDD-supply = <&vaux2_reg>;
        DRVDD-supply = <&vaux2_reg>;
        DVDD-supply = <&vbat>;
    };
};

&usb {
    status = "okay";

    control@44e10620 {
        status = "okay";
    };

    usb-phy@ {
        status = "okay";
    };

    usb@ {
        status = "okay";
    };
};

&epwmss2 {
    status = "okay";

    ecap2: ecap@ {
        status = "okay";
        pinctrl-names = "default";
        pinctrl- = <&ecap2_pins>;
    };
};

#include "tps65910.dtsi"

&tps {
    vcc1-supply = <&vbat>;
    vcc2-supply = <&vbat>;
    vcc3-supply = <&vbat>;
    vcc4-supply = <&vbat>;
    vcc5-supply = <&vbat>;
    vcc6-supply = <&vbat>;
    vcc7-supply = <&vbat>;
    vccio-supply = <&vbat>;

    regulators {
        vrtc_reg: regulator@ {
            regulator-always-on;
        };

        vio_reg: regulator@ {
            regulator-always-on;
        };

        vdd1_reg: regulator@ {
            /* VDD_MPU voltage limits 0.95V - 1.26V with +/-4% tolerance */
            regulator-name = "vdd_mpu";
            regulator-min-microvolt = <>;
            regulator-max-microvolt = <>;
            regulator-boot-on;
            regulator-always-on;
        };

        vdd2_reg: regulator@ {
            /* VDD_CORE voltage limits 0.95V - 1.1V with +/-4% tolerance */
            regulator-name = "vdd_core";
            regulator-min-microvolt = <>;
            regulator-max-microvolt = <>;
            regulator-boot-on;
            regulator-always-on;
        };

        vdd3_reg: regulator@ {
            regulator-always-on;
        };

        vdig1_reg: regulator@ {
            regulator-always-on;
        };

        vdig2_reg: regulator@ {
            regulator-always-on;
        };

        vpll_reg: regulator@ {
            regulator-always-on;
        };

        vdac_reg: regulator@ {
            regulator-always-on;
        };

        vaux1_reg: regulator@ {
            regulator-always-on;
        };

        vaux2_reg: regulator@ {
            regulator-always-on;
        };

        vaux33_reg: regulator@ {
            regulator-always-on;
        };

        vmmc_reg: regulator@ {
            regulator-min-microvolt = <>;
            regulator-max-microvolt = <>;
            regulator-always-on;
        };
    };
};

&mac {
    pinctrl-names = "default", "sleep";
    pinctrl- = <&cpsw_default>;
    pinctrl- = <&cpsw_sleep>;
};

&davinci_mdio {
    pinctrl-names = "default", "sleep";
    pinctrl- = <&davinci_mdio_default>;
    pinctrl- = <&davinci_mdio_sleep>;
};

&cpsw_emac0 {
    phy_id = <&davinci_mdio>, <>;
    phy-mode = "rgmii-txid";
};

&cpsw_emac1 {
    phy_id = <&davinci_mdio>, <>;
    phy-mode = "rgmii-txid";
};

&mmc1 {
    status = "okay";
    vmmc-supply = <&vmmc_reg>;
    bus-width = <>;
    pinctrl-names = "default";
    pinctrl- = <&mmc1_pins>;
    cd-gpios = <&gpio0  GPIO_ACTIVE_HIGH>;
};

&sham {
    status = "okay";
};

&aes {
    status = "okay";
};

&gpio0 {
    ti,no-reset-on-init;
};

&mcasp1 {
        pinctrl-names = "default";
        pinctrl- = <&mcasp1_pins>;

        status = "okay";

        op-mode = <>;          /* MCASP_IIS_MODE */
        tdm-slots = <>;
        /* 4 serializers */
        serial-dir = <  /* 0: INACTIVE, 1: TX, 2: RX */

        >;
        tx-num-evt = <>;
        rx-num-evt = <>;
};

&tscadc {
    status = "okay";
    tsc {
        ti,wires = <>;
        ti,x-plate-resistance = <>;
        ti,coordinate-readouts = <>;
        ti,wire-config = <0x00 0x11 0x22 0x33>;
    };
};

红色部分为LED子系统调用硬件配置。dtb文件和Linux内核是怎么关联的呢？主要是通过这个参数：compatible = "gpio-leds";

在leds-gpio.c中有相同的参数传递，具体是怎么操作的，没有详细的去了解。

    return priv;

err:
    for (count = priv->num_leds - ; count >= ; count--)
        delete_gpio_led(&priv->leds[count]);
    return ERR_PTR(-ENODEV);
}

static const struct of_device_id of_gpio_leds_match[] = {
    { .compatible = "gpio-leds", },
    {},
};
#else /* CONFIG_OF_GPIO */
static struct gpio_leds_priv *gpio_leds_create_of(struct platform_device *pdev)
{
    return ERR_PTR(-ENODEV);
}
#endif /* CONFIG_OF_GPIO */

static int gpio_led_probe(struct platform_device *pdev)
{
    struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);
    struct gpio_leds_priv *priv;
    int i, ret = ;

进入内核xxxx/drivers/leds/将led-class.c、led-core.c、leds.h、leds-gpio.c文件拷出来以模块的方法编译出leds-gpio.ko加载入模块中

编译模块的Makfile：

ifneq ($(KERNELRELEASE),)
obj-m := leds-gpio.o
else
KDIR :=/home/zyr/Source_code/linux-3.14./
all:
    make -C $(KDIR) M=$(PWD) modules ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j8
clean:
    rm -f *.ko *.o *.mod.o *.mod.c *.symvers *.order
endif

编写led子系统的测试：

1、点亮熄灭LED

[root@zyr-am335x ]#cd /sys/class
[root@zyr-am335x class]#ls
bdi           hwmon         mem           regulator     tty
block         i2c-adapter   misc          rtc           ubi
dma           i2c-dev       mmc_host      scsi_device   udc
extcon        input         mtd           scsi_disk     usbmon
firmware      lcd           net           scsi_host     vc
gpio          leds          phy           spi_master    vtconsole
graphics      mdio_bus      power_supply  thermal       watchdog
[root@zyr-am335x class]#cd leds
[root@zyr-am335x leds]#ls
zyrD1:green:usr0       zyrD3:green:heartbeat
zyrD2:green:usr1       zyrD4:green:mmc0
[root@zyr-am335x leds]#cd zyrD1\:green\:usr0/
[root@zyr-am335x zyrD1:green:usr0]#echo  > brightness
[root@zyr-am335x zyrD1:green:usr0]#echo  > brightness
[root@zyr-am335x zyrD1:green:usr0]#

2、也可以编写测试程序LED_zixitong.c

/********************************************************************
*       copyright (C) 2014 all rights reserved
*            @file: 子系统_led.c
*         @Created: 2017-6-27 14:00nd
*          @Author: Yinrui Zhu
*     @Description: test user leds
*     @Modify Date: 2017-6-27 14:00
*********************************************************************/

#include <stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/ioctl.h>
#include<sys/stat.h>
#include<sys/select.h>
#include<sys/time.h>
#include<fcntl.h>
#include<errno.h>
#include<linux/input.h>

int main(int argc, char *argv[])
{
    int ledn;
    char *tmp;
    int keys_fd;
    //char timer=6;

    tmp = (unsigned char*)malloc();

    while()
    {
        sprintf(tmp, "echo 1 > /sys/class/leds/zyrD1:green:usr0/brightness");
        printf("status led4%d on \n", ledn);
        system(tmp);
        usleep(*);
        sprintf(tmp, "echo 0 > /sys/class/leds/zyrD1:green:usr0/brightness");
        printf("status led4%d on \n", ledn);
        system(tmp);
        usleep(*);

        sprintf(tmp, "echo 1 > /sys/class/leds/zyrD2:green:usr1/brightness");
        printf("status led3%d on \n", ledn);
        system(tmp);
        usleep(*);
        sprintf(tmp, "echo 0 > /sys/class/leds/zyrD2:green:usr1/brightness");
        printf("status led3%d on \n", ledn);
        system(tmp);
        usleep(*);

        sprintf(tmp, "echo 1 > /sys/class/leds/zyrD3:green:heartbeat/brightness");
        printf("status led1%d on \n", ledn);
        system(tmp);
        usleep(*);
        sprintf(tmp, "echo 0 > /sys/class/leds/zyrD3:green:heartbeat/brightness");
        printf("status led1%d on \n", ledn);
        system(tmp);
        usleep(*);

        //sprintf(tmp, "echo 1 > /sys/class/leds/evmsk:green:usr0/brightness");
        printf("status led2%d on \n", ledn);
        system("echo 1 > /sys/class/leds/zyrD4:green:mmc0/brightness");
        usleep(*);
        //sprintf(tmp, "echo 0 > /sys/class/leds/evmsk:green:usr0/brightness");
        printf("status led2%d on \n", ledn);
        system("echo 0 > /sys/class/leds/zyrD4:green:mmc0/brightness");
        usleep(*);

    }

}

测试文件的Makefile；

#----------------------------
CC    = arm-linux-gnueabihf-gcc
CFLAGS    =
main : LED_zixitong.c
    $(CC) $(CFLAGS) LED_zixitong.c -o LED_zixitong

将生成可执行文件LED_zixitong copy到挂载配置好的nfs目录中执行既可以依次点亮4个LED了。

[root@zyr-am335x zyrD1:green:usr0]#cd
[root@zyr-am335x ]#cd /mnt/
[root@zyr-am335x mnt]#ls
LED_zixitong   led_test       leds-gpio.ko   zleds-gpio.ko  zyr-hello.ko
[root@zyr-am335x mnt]#./LED_zixitong
status led40 on
status led40 on
status led30 on
status led30 on
status led10 on