现在我们来进行最简单的设备程序的编写LED的驱动.
首先进入根文件目录
# mkdir driver
# cd driver/
# mkdir led
# cd led
# vim leds.c
#include
#include
#include
#include
#include
#include
#include
#include #define NAME "four led test"
static int major =231;//定义主设备号
static unsigned long led_table [] = //定义不同的led控制引脚
{
AT91_PIN_PA15,
AT91_PIN_PA16,
AT91_PIN_PA30,
AT91_PIN_PA31,
};
static int myled_driver_open(struct inode *inode,struct file *file)
{
unsigned m =iminor(inode);
if(m>63) return -EINVAL;
printk("led test driver opened! ");
return nonseekable_open(inode,file);
}
static int myled_driver_release(struct inode *inode,struct file *file)
{
printk("my test driver released! ");
return 0;
}
static int myled_driver_ioctl(struct inode *inode,struct file *file,unsigned int cmd,unsigned long arg)
{
unsigned int regled1;
regled1=gpio_get_value(led_table[arg]);
printk("led1 reg is : %d",regled1);
at91_set_gpio_output(led_table[arg],1);
switch(cmd)//控制led_table[arg]的亮灭
{
case 0x00:at91_set_gpio_value(led_table[arg],0);
break;
case 0x01:gpio_set_value(led_table[arg],1);
break;
default:
break;
}
return 1;
}
static struct file_operations myled_driver_fops =
{
.owner =THIS_MODULE,
.ioctl =myled_driver_ioctl,
.open =myled_driver_open,
.release =myled_driver_release,
};
static int __init myled_driver_init(void) //执行insmod的时候调用次函数
{
int ret;
gpio_set_value(led_table[0],0);
gpio_set_value(led_table[1],0);
gpio_set_value(led_table[2],0);
gpio_set_value(led_table[3],0);
printk(KERN_ALERT "led modules is install ");
ret=register_chrdev(major,NAME,&myled_driver_fops);
if(ret<0)
{
printk("unable to register myled driver! ");
return ret;
}
return 0;
}
static void __exit myled_driver_exit(void) //执行rmmod的时候调用次函数
{
unregister_chrdev(major,NAME);
printk("Goodbye,cruel world! ");
}
module_init(myled_driver_init);
module_exit(myled_driver_exit);
MODULE_AUTHOR("microcreat");
MODULE_DESCRIPTION("this is test modules used to test at91sam9261 led");
MODULE_LICENSE("Dual BSD/GPL");
然后写一个Makefile文件
# Makefile2.6
ifneq ($(KERNELRELEASE),)
#kbuild syntax. dependency relationship of files and target modules are listed here.
obj-m +=leds.o
#obj-m :=gpio_driver.o
else
PWD :=$(shell pwd)
KEVER ?=$(shell uname -r)
KDIR :=/workdir/at91sam9261/kernel/linux-2.6.24
default:
#$(MAKE) -C $(KDIR) M=$(PWD)
make -C $(KDIR) M=$(PWD) modules
clean:
rm -rf .*.cmd *.o *.mod.c *.ko .tmp_versions *.order *symvers
endif
然后进行make
# ls
leds.c Makefile
# make
make -C /workdir/at91sam9261/kernel/linux-2.6.24 M=/workdir/at91sam9261/filesyetem/rootfs/driver/led modules
make[1]: Entering directory `/workdir/at91sam9261/kernel/linux-2.6.24'
CC [M] /workdir/at91sam9261/filesyetem/rootfs/driver/led/leds.o
Building modules, stage 2.
MODPOST 1 modules
CC /workdir/at91sam9261/filesyetem/rootfs/driver/led/leds.mod.o
LD [M] /workdir/at91sam9261/filesyetem/rootfs/driver/led/leds.ko
make[1]: Leaving directory `/workdir/at91sam9261/kernel/linux-2.6.24'
# ls
leds.c leds.ko leds.mod.c leds.mod.o leds.o Makefile Module.symvers
然后建立一个led的测试文件:
# mkdir ledtest
# cd ledtest
# vim ledtest.c
#include
#include
#include
#include
int main(void)
{
int fd;
fd=open("/dev/leds",0);
if(fd<0)
{
printf("Can't open /dev/leds\n");
goto end1;
}
while(1)
{
ioctl(fd,0,0);
sleep(1);
ioctl(fd,1,0);
sleep(1);
}
close(fd);
end1:
return 0;
}
保存退出
# arm-none-linux-gnueabi-gcc -static ledtest.c -o ledtest
# ls
ledtest ledtest.c
这样生成的led的测试文件.
然后将新的文件系统制作成为cramfs下载到板子上去,当板子进入界面后进行下面的操作.
[root@microcreat /]$ls
app dev home mnt sbin usr
bin driver lib proc sys var
boot etc linuxrc root tmp
[root@microcreat /]$cd /driver/led/
[root@microcreat led]$ls
Makefile leds.c leds.mod.c leds.o
Module.symvers leds.ko leds.mod.o
[root@microcreat led]$insmod leds.ko
led modules is install
可以看到动态加载成功!
[root@microcreat led]$mknod /dev/leds c 231 0
建立设备节点
这样就到ledtest目录下运行led测试程序.
[root@microcreat led]$cd /app/ledtest/
[root@microcreat ledtest]$ls
ledtest ledtest.c
[root@microcreat ledtest]$./ledtest
led test driver opened! led1 reg is : 1led1 reg is : 0led1 reg is : 1led1 reg is : 0led1 reg is : 1led1 reg is : 0led1 reg is : 1led1 reg is : 0led1 reg is : 1
可以看到对应的LED闪烁,这样就点亮了led灯了！
