Linux 驱动开发 - 编写 PCF8591(ADC) 芯片驱动

#include <linux/init.h>#include <linux/module.h>#include <linux/platform_device.h>#include <linux/i2c.h>#include <linux/interrupt.h>  /*注册中断相关*/#include <linux/irq.h>       /*中断边沿类型定义*/#include <linux/gpio.h>     /*中断IO口定义*/#include <linux/workqueue.h>  /*工作队列相关*/#include <linux/mutex.h>      /*互斥信号量头文件*/#include <linux/delay.h>#include <linux/miscdevice.h> /*杂项设备相关结构体*/#include <linux/fs.h>         /*文件操作集合头文件*/#include <linux/uaccess.h>    /*使用copy_to_user和copy_from_user*/
#define AIN0 0x40#define AIN1 0x41#define AIN2 0x42#define AIN3 0x43
static struct i2c_client *PCF8591_client; /*IIC设备总线*/
/*读取PCF8591  ADC数据*/unsigned char PCF8591_ReadADC(unsigned char ch){  return i2c_smbus_read_byte_data(PCF8591_client,ch); }

static int PCF8591_open(struct inode *my_inode, struct file *my_file){  return 0;}
static ssize_t PCF8591_read(struct file *my_file, char __user *buf, size_t my_len, loff_t * my_loff){  unsigned char data=PCF8591_ReadADC(AIN0);  copy_to_user(buf,&data,1);    data=PCF8591_ReadADC(AIN1);  printk("1:%d\r\n",data);  data=PCF8591_ReadADC(AIN2);  printk("2:%d\r\n",data);  data=PCF8591_ReadADC(AIN3);  printk("3:%d\r\n",data);  return 0;}

static  ssize_t PCF8591_write(struct file *my_file, const char __user *buf, size_t my_len, loff_t *my_loff){  //DAC输出  i2c_smbus_write_byte_data(PCF8591_client,0x40,100);  return 0;}

static int  PCF8591_release(struct inode *my_inode, struct file *my_file){  return 0;}

/*定义一个文件操作集合结构体*/static struct file_operations ops_PCF8591={   .owner = THIS_MODULE,   .read=PCF8591_read,       /*读函数-被应用层read函数调用*/   .write=PCF8591_write,     /*写函数-被应用层write函数调用*/   .open=PCF8591_open,       /*打开函数-被应用层open函数调用*/   .release=PCF8591_release, /*释放函数*/};
/*定义一个杂项设备结构体*/static struct miscdevice misce_PCF8591={  .minor =MISC_DYNAMIC_MINOR, /*自动分配次设备号*/  .name = "Tiny4412_PCF8591",        /*名称  在dev/目录下边可以找到*/  .fops = &ops_PCF8591,       /*文件操作集合*/};
static int i2c_probe(struct i2c_client *client, const struct i2c_device_id *device_id)//匹配成功时调用{  PCF8591_client=client;  printk("<1>""驱动端IIC匹配的地址=0x%x\n",client->addr);    /* 检测适配器是否支持smbus字节读写函数 */    if(i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))   {    printk("适配器支持smbus字节读写函数\n");  }    /*注册*/  misc_register(&misce_PCF8591);  return 0;}

static int i2c_remove(struct i2c_client *client){  misc_deregister(&misce_PCF8591);/*注销*/  printk("i2c_驱动端卸载成功!!!\n");  return 0;}
/*IIC驱动端*/static const struct i2c_device_id i2c_id[] ={  {"Tiny4412_PCF8591",0},//设备端的名字为"my_PCF8591",后面的表示需要私有数据  {}};
struct i2c_driver i2c_drv ={  .driver=  {    .name = "PCF8591",       .owner = THIS_MODULE,  },    .probe = i2c_probe,  .remove = i2c_remove,  .id_table = i2c_id,};

static int __init i2c_drv_init(void){  i2c_add_driver(&i2c_drv);//向iic总线注册一个驱动  return 0;}
static void __exit i2c_drv_exit(void)//平台设备端的出口函数{  i2c_del_driver(&i2c_drv);}
module_init(i2c_drv_init);module_exit(i2c_drv_exit);MODULE_LICENSE("GPL");

#include <linux/init.h>#include <linux/module.h>#include <linux/platform_device.h>#include <linux/i2c.h>
/*获取总线*/struct i2c_adapter *i2c_adap;  //获取到的总线存放在这个结构体static struct i2c_client *i2cClient = NULL;
//PCF8591固定地址 b1001//PCF8591硬件地址 b000//组合:b1001000 = 0x48//注意:IIC标准地址是7位static unsigned short const i2c_addr_list[] = {   0x48, I2C_CLIENT_END};//地址队列

static int __init i2c_dev_init(void){  struct i2c_board_info i2c_info;//设备描述结构体，里面存放着欲设备的名字还有地址  i2c_adap = i2c_get_adapter(0); //获取0号总线  if(i2c_adap==NULL)  {    printk("PCF8591--II总线0 获取失败!!\n");  }    memset(&i2c_info,0,sizeof(struct i2c_board_info));//把设备描述结构体清空结构体清空  strlcpy(i2c_info.type,"Tiny4412_PCF8591",I2C_NAME_SIZE);//把设备的名字赋值给i2c_info    i2cClient = i2c_new_probed_device(i2c_adap,&i2c_info,i2c_addr_list,NULL);  if(i2cClient==NULL)  {    printk("PCF8591 0x%x:地址不可用!!\n",i2c_addr_list[0]);  }  i2c_put_adapter(i2c_adap);  printk("PCF8591_dev_init初始化成功!!\n");  return 0;}

static void __exit i2c_dev_exit(void)//平台设备端的出口函数{  /*注销设备*/  i2c_unregister_device(i2cClient);  i2c_release_client(i2cClient);  printk("PCF8591_dev_exit ok!!\n");}
module_init(i2c_dev_init);module_exit(i2c_dev_exit);MODULE_LICENSE("GPL");

#include <stdio.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>

/*PCF8591 应用层测试代码*/int main(int argc,char **argv){  unsigned char data=0;    int fp;  float tmp; //  tmp=5.34v   0.34  int a;  int b;    fp=open("/dev/Tiny4412_PCF8591",O_RDWR);  if(fp<0)      /*判断文件是否打开成功*/  {    printf("PCF8591 driver open error!\n");    return -1;  }  while(1)  {    read(fp,&data,1);    write(fp,&data,1);    printf("ADC1=%d\n",data);    tmp=(float)data*(5.0/255); //电压= 采集的数字量*(参考电压/分辨率);    a=tmp;  //a=5  tmp=5.3    b=(int)((tmp-a)*1000);    //b=0.34    printf("ADC1=%d.%dV\r\n",(int)a,(int)b);      sleep(1);  }  close(fp);  return 0;}