ok6410 linux的第一个驱动LED驱动
//驱动程序代码
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#include
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#include
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#include
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#include
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#include
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#include
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#include
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#include
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#include
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#define DEVICE_NAME "OK6410_LED"
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static long OK6410_LED_ioctl(
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struct file *file,
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unsigned int cmd,
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unsigned long arg);
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static ssize_t OK6410_LED_write(
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struct file *file,
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const char __user *buff,
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size_t size,
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loff_t *loff);
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static ssize_t OK6410_LED_read(
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struct file *file,
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char __user *buff,
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size_t size,
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loff_t *loff);
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static struct file_operations dev_fops = {
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.owner = THIS_MODULE,
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.unlocked_ioctl = OK6410_LED_ioctl,
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.read = OK6410_LED_read,
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.write = OK6410_LED_write
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};
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static struct miscdevice misc = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = DEVICE_NAME,
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.fops = &dev_fops,
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};
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struct semaphore led_sem;
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static int __init OK6410_LED_init(void)
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{
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int ret;
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unsigned int reg;
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reg = readl(S3C64XX_GPMCON);
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reg &= (~0xffff);
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reg |= 0x1111;
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writel(reg,S3C64XX_GPMCON);
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reg = readl(S3C64XX_GPMDAT);
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reg |= 0xf;
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writel(reg,S3C64XX_GPMDAT);
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ret = misc_register(&misc);
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if(ret < 0)
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{
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printk(KERN_ALERT DEVICE_NAME " can't initialized LED!\n");
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return ret;
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}
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init_MUTEX(&led_sem);
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printk(KERN_ALERT DEVICE_NAME " initialized\n");
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return 0;
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}
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static long OK6410_LED_ioctl(
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struct file *file,
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unsigned int cmd,
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unsigned long arg)
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{
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return 0;
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}
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static ssize_t OK6410_LED_write(
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struct file *file,
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const char __user *buff,
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size_t size,
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loff_t *loff)
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{
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unsigned int reg;
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if(down_interruptible(&led_sem))
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return -ERESTARTSYS;
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reg = readl(S3C64XX_GPMDAT);
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reg &= (~0xf);
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reg |= buff[0] & 0xf;
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writel(reg,S3C64XX_GPMDAT);
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up(&led_sem);
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return 0;
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}
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static ssize_t OK6410_LED_read(
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struct file *file,
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char __user *buff,
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size_t size,
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loff_t *loff)
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{
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unsigned int reg;
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if(down_interruptible(&led_sem))
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return -ERESTARTSYS;
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reg = readl(S3C64XX_GPMDAT);
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buff[0] = reg | 0xfffffff0;
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up(&led_sem);
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return 0;
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}
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static void __exit OK6410_LED_exit(void)
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{
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unsigned int reg;
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reg = readl(S3C64XX_GPMCON);
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reg &= (~0xffff);
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writel(reg,S3C64XX_GPMCON);
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misc_deregister(&misc);
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}
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module_init(OK6410_LED_init);
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module_exit(OK6410_LED_exit);
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MODULE_AUTHOR("cp1300@139.com");
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MODULE_DESCRIPTION("OK6410(S3C6410) LED Driver");
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MODULE_LICENSE("GPL");
//测试代码
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#include
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#include
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#include
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#include
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#include
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#include
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int main(void)
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{
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int fd;
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int retval;
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unsigned char led;
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printf("LED test...\n");
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fd = open("/dev/OK6410_LED",O_RDWR);
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if(fd == -1)
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{
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printf("open led error!\n");
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exit(-1);
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}
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else
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{
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printf("open led ok!\n");
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}
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while(1)
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{
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for(retval = 0;retval < 4;retval ++)
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{
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led = 1 << retval;
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led = ~led;
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write(fd,&led,sizeof((unsigned char)1));
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usleep(1000 * 100);
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}
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for(retval = 2;retval > 0;retval --)
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{
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led = 1 << retval;
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led = ~led;
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write(fd,&led,sizeof((unsigned char)1));
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usleep(1000 * 100);
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}
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}
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close(fd);
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exit(0);
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}
本驱动程序使用的是混杂设备驱动模型,主设备号为10,使用次设备号来区分不同的设备,使用宏MISC_DYNAMIC_MINOR可以自动分配次设备号。
makefile代码如下:
ifneq ($(KERNELRELEASE),)
obj-m:=led_drive.o
else
KERNELDIR:=/opt/kernel/linux-3.0.1
PWD:=$(shell pwd)
default:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:
rm -rf *.o *.mod.c *.mod.o *~ module* Module*
endif
KERNELDIR为内核路径,led_drive.o中的led_drive来自于源码文件名led_drive.c
执行make编译完成后会在模块源码目录下生成led_drive.ko
在开发板创建目录/lib/modules/3.0.1/,3.0.1为内核版本,可以通过cat /proc/version查看。将led_drive.ko拷贝至/lib/modules/3.0.1/,执行insmod led_drive.ko,会在/dev/目录下生成设备文件OK6410_LED。执行ls -l OK6410_LED 可以看到其主设备号为10,自动分配的次设备号为54。执行应用程序led_drive_test,可观察到led出现流水灯效果。
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