S3C2440驱动篇之ADC驱动分析

                           bool '/dev/kmem virtual device support'

                           default y

                           help

                           Say Y here if you want to support the /dev/kmem device. The

                                    /dev/kmem device is rarely used, but can be used for certain

                                   kind of kernel debugging operations.

                                   When in doubt, say 'N'.

                config S3C2440_ADC

                            bool 'ADC driver for S3C2440 development boards'

                           default y

                           help

                                    this is ADC driver for S3C2440 development boards

                                    Notes: the touch-screen-driver required this option

       4.添加好ADC驱动后，在内核源代码目录执行：make menuconfig

            Device Drivers --->

                      Character devides --->

                                [*]ADC driver for S3C2440 development boards

           # make zImage编译出带ADC驱动的内核

        动态编译：

         编辑一个Makefile如下：

1. ifneq ($(KERNELRELEASE),)    

2.     obj-m:=s3c2440_adc.o    

3. else    

4.     KERNELDIR:=/home/liao/image/linux-2.6.32.2    

5.     PWD:=$(shell pwd)    

6.     all:    

7.     make -C $(KERNELDIR) M=$(PWD) modules ARCH=arm CROSS_COMPILE=arm-linux-    

8.     clean:    

9.     rm -rf *.ko *.o *.mod.c *.mod.o *.symvers    

10. endif  

         # make 生成s3c2440_adc.ko驱动文件，将此文件拷贝至开发板

         # insmod s3c2440_adc.ko   ADC驱动采用misc设备，自动生成设备文件/dev/adc

三．测试

编写应用测试程序，编译、下载至开发板，运行，扭动AD电位器，观察ADC转换值变化，代码如下：

1. #include    

2. #include    

3. #include    

4.   

5. int main(int argc, char **argv)  

6. {  

7.     int fd;  

8.     fd = open('/dev/adc', 0);  

9.     if(fd < 0)  

10.     {  

11.         printf('Open ADC Device Faild!n');  

12.         exit(1);  

13.     }  

14.   

15.     while(1)  

16.     {  

17.         int ret;  

18.         int data;  

19.           

20.         ret = read(fd, &data, sizeof(data));  

21.         if(ret != sizeof(data))  

22.         {  

23.             continue;  

24.         }  

25.         else  

26.         {  

27.             printf('Read ADC value is: %dn', data);  

28.         }  

29.     }  

30.   

31.     close(fd);  

32.     return 0;  

33. }