linux平台 DHT11驱动程序

#include <linux/init.h> #include <linux/module.h> #include <linux/delay.h> #include <linux/kernel.h> #include <linux/moduleparam.h> #include <linux/init.h> #include <linux/types.h> #include <linux/fs.h> #include <mach/regs-gpio.h> #include <mach/hardware.h> #include <linux/cdev.h> #include <asm/uaccess.h> #include <linux/errno.h> #include <linux/gpio.h> #include <linux/device.h> /* 相关引脚定义,方便以后移植 */ #define DQ S3C2410_GPB(1) #define CFG_IN S3C2410_GPIO_INPUT #define CFG_OUT S3C2410_GPIO_OUTPUT #define TIME_OUT_DEALY 100 // dht11主次设备号（动态分配） static int dht11_major = 0; static int dht11_minor = 0; static int dht11_nr_devs = 1; unsigned short temperature,humidity; unsigned char checknum; static volatile unsigned char values[6]={0,0,0,0,0,0}; // 定义设备类型 static struct dht11_device { struct cdev cdev; }; struct dht11_device *dht11_devp; /*设备结构体指针 */ static struct class *dht11_class; static struct class_device *dht11_class_dev; /* 函数声明 */ static int dht11_open(struct inode *inode, struct file *filp); static int dht11_init(void); static ssize_t dht11_read(struct file *filp, char __user * buf, size_t count, loff_t * f_pos); void dht11_setup_cdev(struct dht11_device *dev, int index); static void set_pin_high(void) { s3c2410_gpio_cfgpin(DQ,CFG_OUT); s3c2410_gpio_setpin(DQ, 1); } static void set_pin_low(void) { s3c2410_gpio_cfgpin(DQ,CFG_OUT); s3c2410_gpio_setpin(DQ, 0); } static int set_pin_delay_get(unsigned int time) { s3c2410_gpio_cfgpin(DQ,CFG_IN); udelay(time); if(s3c2410_gpio_getpin(DQ)) return 1; else return 0; } static int set_pin_get(void) { if(s3c2410_gpio_getpin(DQ)) return 1; else return 0; } static int dht11_open(struct inode *inode, struct file *filp) { int flag = 0; flag = dht11_init(); if (flag & 0x01) { printk(KERN_WARNING "open dht11 failed\n"); return -1; } printk(KERN_NOTICE "open dht11 successful\n"); return 0; } static int dht11_init(void) { int retval = 0; set_pin_high(); return retval; } static int read_word_data(void) { int i; int counter=0; int timerout_counter=0; int timerout_flag=0; int ret=0; start: set_pin_low(); // mdelay(20); //18ms set_pin_high(); // if(set_pin_delay_get(50)) // { printk(KERN_INFO"can not detect the low ack!"); counter++; if(counter>5) { ret=-1; goto stop; } goto start; } counter=0; timerout_counter=0; while((!set_pin_get())&&(timerout_counter++<TIME_OUT_DEALY))udelay(5);// if(timerout_counter>=TIME_OUT_DEALY) { timerout_flag=1; goto out_err; } timerout_counter=0; while((set_pin_get())&&(timerout_counter++<TIME_OUT_DEALY))udelay(5);// // if(timerout_counter>=TIME_OUT_DEALY) { timerout_flag=1; goto out_err; } for(i=0;i<16;i++) { humidity <<=1; //<< must at the head,or the value will be the double to real value. timerout_counter=0; while((!set_pin_get())&&(timerout_counter++<TIME_OUT_DEALY))udelay(5);// // if(timerout_counter>=TIME_OUT_DEALY) { timerout_flag=1; goto out_err; } if(set_pin_delay_get(45)) //40us { humidity |=1; timerout_counter=0; while((set_pin_get())&&(timerout_counter++<TIME_OUT_DEALY))udelay(5);// // if(timerout_counter>=TIME_OUT_DEALY) { timerout_flag=1; goto out_err; } } else //40us humidity |=0; } for(i=0;i<16;i++) { temperature <<=1; timerout_counter=0; while((!set_pin_get())&&(timerout_counter++<TIME_OUT_DEALY))udelay(5);// if(timerout_counter>=TIME_OUT_DEALY) { timerout_flag=1; goto out_err; } if(set_pin_delay_get(45)) //40us { temperature|=1; timerout_counter=0; while((set_pin_get())&&(timerout_counter++<TIME_OUT_DEALY))udelay(5);// if(timerout_counter>=TIME_OUT_DEALY) { timerout_flag=1; goto out_err; } } else //40us temperature |=0; } for(i=0;i<8;i++) { checknum <<=1; timerout_counter=0; while((!set_pin_get())&&(timerout_counter++<TIME_OUT_DEALY))udelay(5);// if(timerout_counter>=TIME_OUT_DEALY) { timerout_flag=1; goto out_err; } if(set_pin_delay_get(40)) // { checknum |=1; timerout_counter=0; while((set_pin_get())&&(timerout_counter++<TIME_OUT_DEALY))udelay(5);// if(timerout_counter>=TIME_OUT_DEALY) { timerout_flag=1; goto out_err; } } else // checknum |=0; } set_pin_high(); stop: return ret; out_err: if (timerout_flag==1) ret=-2; return ret; } static ssize_t dht11_read(struct file *filp, char __user * buf, size_t count, loff_t * f_pos) { int ret = 0; unsigned char temp; // struct dht11_dev *dev = filp->private_data; /**/ ret=read_word_data(); // if(ret>=0) { values[0]=(temperature & 0xff00)>>8; values[1]=temperature & 0x00ff; values[2]=(humidity & 0xff00)>>8; values[3]=humidity & 0x00ff; temp=values[0]+values[1]+values[2]+values[3]; //printk(KERN_WARNING "temp=%d",temp); //printk(KERN_WARNING "checknum=%d",values[4]); if(temp!=checknum) {//crc ret=-3; goto out; } } else { goto out; } /*printk is for test,hide it when test finished */ // printk(KERN_INFO"vaule is %hd %hd\n",temperature,humidity); //printk(KERN_WARNING "vaule is %d %d %d %d %d\n",values[0],values[1],values[2],values[3],checknum); if (copy_to_user(buf, (void*)values, count)) //if values[] is int,only can read values[0],donnot know why. { ret = - EFAULT; } else { // printk(KERN_INFO "read %d bytes(s) from %ld\n", count, p); ret=count; } out: return ret; } static struct file_operations dht11_dev_fops = { .owner = THIS_MODULE, .open = dht11_open, .read = dht11_read, }; void dht11_setup_cdev(struct dht11_device *dev, int index) { int err, devno = MKDEV(dht11_major, dht11_minor + index); cdev_init(&dev->cdev, &dht11_dev_fops); dev->cdev.owner = THIS_MODULE; err = cdev_add(&(dev->cdev), devno, 1); if (err) { printk(KERN_NOTICE "ERROR %d add dht11\n", err); } } static int __init dht11_dev_init(void) { int result; dev_t dev = 0; dev = MKDEV(dht11_major, dht11_minor); if (dht11_major) { result = register_chrdev_region(dev, dht11_nr_devs, "dht11"); } else { result = alloc_chrdev_region(&dev, dht11_minor, dht11_nr_devs, "dht11"); dht11_major = MAJOR(dev); } if (result < 0) { printk(KERN_WARNING "dht11: failed to get major\n"); return result; } /* 为新设备分配内存和初始化 */ dht11_devp = kmalloc(sizeof(struct dht11_device), GFP_KERNEL); if (!dht11_devp) { /*申请失败 */ result = -ENOMEM; goto fail_malloc; } memset(dht11_devp, 0, sizeof(struct dht11_device)); dht11_setup_cdev(dht