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作者：chenzhufly QQ：36886052 ( 转载请注明出处)
一路走来，熟悉硬件系统，搭建软件开发环境，编译Linux系统等等，现在也该到对硬件做一些事情了，这是我这几天的研究心得，与君共享。
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：
复制内容到剪贴板代码:#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：
复制内容到剪贴板代码:#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：
复制内容到剪贴板代码: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
复制内容到剪贴板代码: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
复制内容到剪贴板代码: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
复制内容到剪贴板代码:#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));
}
}
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