S3C2440_LINUX_adc.rar_arm9 Linux adc_linux adc

#include <linux/kernel.h> #include <linux/module.h> #include <asm/uaccess.h> #include <linux/mm.h> #include <linux/ioport.h> #include <asm/io.h> #include <linux/ioport.h> #include <linux/fs.h> #define ADC_MAJOR 102 //定义主设备号 #define DEVICE_NAME "adc_dev" //定义设备名称 #define SUCCESS 0 #define adc_con (unsigned long)ioremap(0x58000000,4) #define adc_dat0 (volatile unsigned long)ioremap(0x5800000c,4) static int Device_Open = 0; int adc_init(void); void adc_cleanup(void); static int device_open(struct inode *,struct file *); static int device_release(struct inode *,struct file *); static ssize_t device_read(struct file *,char *,size_t,loff_t *); int init_module(void); void cleanup_module(void); struct file_operations adc_ops = // 该结构包含在<linux/fs.h>中 { //结构中的每个字段指向驱动程序中实现特定的函数 .owner = THIS_MODULE, .read = device_read, .open = device_open, .release = device_release, }; static int Major; int __init adc_init(void) //初始化 { Major = register_chrdev(ADC_MAJOR,DEVICE_NAME,&adc_ops); //注册操作，返回主设备值 if(Major <0) { printk("ADC init_module:failed with %d\n",Major); //主设备号小于0，则注册失败 return Major; } devfs_mk_cdev(MKDEV(ADC_MAJOR, 0), S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP, DEVICE_NAME); printk(DEVICE_NAME " initialized\n"); return 0; } static int device_open(struct inode * inode,struct file *file) //与应用程序中open函数对应的驱动函数 { if(Device_Open) { return -EBUSY; } Device_Open++; return SUCCESS; } static int device_release(struct inode * inode,struct file *file) { Device_Open --; return 0; } static ssize_t device_read(struct file *file, char * buffer, size_t length, loff_t * offset) { unsigned long buf; __raw_writel((1<<14)|(0x5<<6), adc_con); //设置ADCCON __raw_writel(__raw_readl(adc_con)|0x1, adc_con); //启动AD转换 while(__raw_readl(adc_con) &0x1); //启动转换后，等待启动位清零 while(!(__raw_readl(adc_con) & 0x8000)); //等待转换是否完毕 buf=__raw_readl(adc_dat0) & 0x3ff; //取出转换后得到的有效数据 *buffer=(unsigned char)buf; buffer++; *buffer=(unsigned char)(buf>>8); return 2; } void adc_cleanup() //卸载驱动时执行该函数 { int ret; ret = unregister_chrdev(Major,DEVICE_NAME); //注销驱动 if(ret < 0) //返回值小于0时注销失败 { printk("unregister_chrdev:error %d\n",ret); } } module_init(adc_init); module_exit(adc_cleanup); MODULE_LICENSE("GPL");