Linux下AM335X的GPIO控制

本文章转自：
1. GPIO的char型驱动，这里主要就是点个灯，感受一下驱动的设计和硬件的控制驱动程序：

#include <linux/init.h>
#include <linux/module.h>
#include <linux/leds.h>
#include <linux/io.h>
#include <linux/semaphore.h>
#include <linux/kernel.h>
#include <linux/cdev.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <mach/gpio.h>
#include <plat/mux.h>
#include <linux/gpio.h>
/*******************************************/
#define NAME "leds"
#define GPIO_TO_PIN(bank, gpio)        (32 * (bank) + (gpio))
static int major =251;//定义主设备号
/*******************************************/
void led_on(void)
{
     gpio_set_value(GPIO_TO_PIN(1,22), 1);
}

void led_off(void)
{
     gpio_set_value(GPIO_TO_PIN(1,22), 0);
}

void led_init(void)
{
        int result;
         /* Allocating GPIOs and setting direction */
        result = gpio_request(GPIO_TO_PIN(1,22), "Leds");//usr1
        if (result != 0)
                printk("gpio_request(1_22) failed!\n");
        result = gpio_direction_output(GPIO_TO_PIN(1,22), 1);
        if (result != 0)
                printk("gpio_direction(1_22) failed!\n");
}

struct light_dev
{
    struct cdev cdev;
    unsigned char value;
};

struct light_dev *light_devp;

MODULE_AUTHOR("chenzhufly");
MODULE_LICENSE("Dual BSD/GPL");

// 打开和关闭函数
int light_open(struct inode *inode,struct file *filp)
{
    struct light_dev *dev;

    // 获得设备结构体指针
    dev = container_of(inode->i_cdev,struct light_dev,cdev);
    // 让设备结构体作为设备的私有信息
    filp->private_data = dev;

    return 0;
}

int light_release(struct inode *inode,struct file *filp)
{
    return 0;
}


// ioctl
int light_ioctl(struct file *filp,unsigned int cmd,
unsigned long arg)
{
    struct light_dev *dev = filp->private_data;

    switch(cmd)
    {
        case 0:
            dev->value = 0;
            led_off();
        break;

        case 1:
            dev->value = 1;
            led_on();
        break;

        default:

            return -ENOTTY;
        // break;
    }

    return 0;
}

struct file_operations light_fops =
{
    .owner = THIS_MODULE,
    .unlocked_ioctl = light_ioctl,
    .open  = light_open,
    .release = light_release,
};
// 模块加载函数
int light_init(void)
{
    int ret;
    led_init();
    printk(KERN_ALERT "led modules is install\n");
    ret=register_chrdev(major,NAME,&light_fops);
    if(ret<0)
    {
      printk("unable to register myled driver!\n");
      return ret;
     }
    return 0;

}

// 模块卸载函数
void light_cleanup(void)
{
    unregister_chrdev(major,NAME);
    printk("Goodbye,cruel world!\n");
}

module_init(light_init);
module_exit(light_cleanup);

应用程序：

#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/input.h>
#include <unistd.h>
#include <sys/ioctl.h>

int main(int argc, char * argv)
{
    int i, n, fd;

    fd = open("/dev/leds", O_RDWR);
        if (fd < 0)
        {
            printf("can't open /dev/leds!\n");
            exit(1);
        }

        while (1) {
            ioctl(fd, 1, 1);
            sleep(1);

            ioctl(fd, 0, 1);
            sleep(1);
        }

    close(fd);

    return 0;
}

Makefile文件：

ARCH=arm
CROSS_COMPILE=/home/chenzhufly/beaglebone/linux-devkit/bin/arm-arago-linux-gnueabi-
obj-m := leds.o
KDIR := /home/chenzhufly/beaglebone/board-support/linux-3.1.0-psp04.06.00.03.sdk
PWD := $(shell pwd)
default:
        make -C $(KDIR) M=$(PWD) ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE) modules
app: leds_test.c
        $(CROSS_COMPILE)gcc -o leds_test leds_test.c
clean:
        $(MAKE) -C $(KDIR) M=$(PWD) clean

leds.sh脚本

insmod leds.ko
mknod /dev/leds c 251 0
./leds_test

2. 使用echo命令，这个我在前面也说过

点亮usr1
root@beaglebone:~# echo 1 >
/sys/class/leds/beaglebone::usr1/brightness
关闭usr1
root@beaglebone:~# echo 0 > /sys/class/leds/beaglebone::usr1/brightness

3. 做个应用程序实现流水灯功能吧

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#define LED1 "/sys/class/leds/beaglebone::usr1/brightness"  // usr1 led
#define LED2 "/sys/class/leds/beaglebone::usr2/brightness"  // usr2 led
#define LED3 "/sys/class/leds/beaglebone::usr3/brightness"  // usr3 led

int main(void)
{
    int f_led1 = open(LED1, O_RDWR);
    int f_led2 = open(LED2, O_RDWR);
    int f_led3 = open(LED3, O_RDWR);

    unsigned char dat1, dat2, dat3;
    unsigned char i = 0;

    if (f_led1 < 0)
{
printf("error in open %s",LED1);
        return -1;
    }
    if (f_led2 < 0)
    {
           printf("error in open %s",LED2);
        return -1;
    }
    if (f_led3 < 0)
    {
           printf("error in open %s",LED3);
        return -1;
    }
    //add 10 times
    for(i=1; i<30; i++)
    {
    dat1 = ((i%3) == 1) ? '1' : '0';
    dat2 = ((i%3) == 2) ? '1' : '0';
    dat3 = ((i%3) == 0) ? '1' : '0';
    write(f_led1, &dat1, sizeof(dat1));
        write(f_led2, &dat2, sizeof(dat2));
        write(f_led3, &dat3, sizeof(dat3));
        usleep(300000);
    }
    // all  the  bright
    {
        dat1 = '1';
        dat2 = '1';
        dat3 = '1';
        write(f_led1, &dat1, sizeof(dat1));
        write(f_led2, &dat2, sizeof(dat2));
        write(f_led3, &dat3, sizeof(dat3));
    }
}