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  • linux 高精度定时器例子

    //author:DriverMonkey
    //phone:13410905075
    //mail:bookworepeng@Hotmail.com
    //qq:196568501
    
    
    #include <linux/kernel.h>  
    #include <linux/module.h>  
    #include <linux/cdev.h>  
    #include <linux/fs.h>  
    #include <linux/device.h>  
    #include <linux/syscalls.h>
    #include <linux/interrupt.h> 
    #include <linux/gpio.h>
    #include <linux/of_gpio.h>
    #include <linux/of_platform.h>
    #include <linux/uaccess.h>  
    #include <linux/string.h> 
    
    #include <mach/gpio.h>
    #include <mach/irqs.h>
    
    #define GPIO_TO_PIN(bank, gpio) (32 * (bank) + (gpio))
    
    #define US (1000)
    
    #define PPM_CHANEL 8
    #define FIX_LOW_TIME 100*US
    
    
    struct ppm_dev  
    {  
        struct cdev cdev;  
        dev_t devno;  
        struct class *ppm_class; 
    	int message_cdev_open;	
    }; 
    
    struct ppm_dev ppm_dev;  
    
    
    static long long ppm_values[(PPM_CHANEL + 1)*2] = 
    	   {FIX_LOW_TIME,1000*US,  	// 1
    	   FIX_LOW_TIME,1000*US,	// 2
    	   FIX_LOW_TIME,1000*US,	// 3
    	   FIX_LOW_TIME,1000*US,  	// 4
    	   FIX_LOW_TIME,1000*US,	// 5
    	   FIX_LOW_TIME,1000*US,	// 6
    	   FIX_LOW_TIME,1000*US,	// 7
    	   FIX_LOW_TIME,1000*US,	// 8
    	   FIX_LOW_TIME,5000*US, };	// 9
    
    ktime_t ktime;
    static struct hrtimer hr_timer;
    
    static enum hrtimer_restart hrtimer_callback(struct hrtimer *timer)
    {
    	static int index = 0;
    	static ktime_t ktime;
    	if(index == ((PPM_CHANEL + 1)*2))
    		index = 0;
    	ktime.tv64 = ppm_values[index];
    	hrtimer_forward(timer, timer->base->get_time(), ktime);
    	index++;
    	if(ktime.tv64 == FIX_LOW_TIME)
    		gpio_direction_output(GPIO_TO_PIN(0,27), 0);
    	else
    		gpio_direction_output(GPIO_TO_PIN(0,27), 1);
    
    	//printk("%d
    ",(int)ktime.tv64);
    	
    	return HRTIMER_RESTART;
    }
    
    
    static int ppm_open(struct inode *node, struct file *fd)  
    {  
    	int ret = 0;
    	
    	printk("ppm_open()++
    "); 
    	
    	ktime = ktime_set( 0, 200*1000);				   // 200us
    	hrtimer_init( &hr_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL );
    	hr_timer.function = &hrtimer_callback;
    	hrtimer_start( &hr_timer, ktime, HRTIMER_MODE_REL );
    
    
        printk("ppm_open()--
    ");  
      
        return ret;  
    }   
    
     ssize_t ppm_write(struct file *pfile, 
     					const char __user *buffer, 
     					size_t size, 
     					loff_t *pnull)
     
    {	
    
    	printk("ppm_write()++
    ");
    	
    	if(size != (PPM_CHANEL * sizeof(long long)))
    		return 0;
    
    	//copy_from_user(ppm_values, buffer, size);
    	
    	printk("ppm_write()--
    ");
    	
    	return size;
    }
    static int ppm_fasync(int fd, struct file *filp, int mode)
    {
    
    	printk("ppm_fasync()++
    ");
    	
    
    	printk("ppm_fasync()--
    ");
    	
    	return 0;
    }
    
    static int ppm_release(struct inode *node, struct file *fd)  
    {  
    	printk("ppm_release()++
    "); 
    
    	hrtimer_cancel(&hr_timer);	
        printk("ppm_release()--
    ");  
        return 0;  
    } 
    
    
    struct file_operations meassage_operatons =  
    {  
        .owner = THIS_MODULE,  
        .open = ppm_open,  
        
    	.write = ppm_write,
        .fasync = ppm_fasync,
        .release = ppm_release,  
    };  
      
    static int __init ppm_init(void)  
    {  
        struct ppm_dev * dev;  
    	int ret = 0;
      
    
        dev = &ppm_dev;  
    
        alloc_chrdev_region(&dev->devno, 0, 1, "out_ppm");  
    
        dev->ppm_class = class_create(THIS_MODULE, "ppm_class");  
        if(IS_ERR(dev->ppm_class)) {  
             printk(KERN_ERR"Err: failed in creating class./n");  
             goto fail1;   
         }  
        device_create(dev->ppm_class, NULL, dev->devno, NULL, "ppm");  
    
    	
    	//init irq
    	ret = gpio_request(GPIO_TO_PIN(0,27), "ppm_inter");
    	if(ret){
    		printk(KERN_ERR"gpio_request() failed !
    ");
    		goto fail1;
    	}
    	ret = gpio_direction_output(GPIO_TO_PIN(0,27), 1);
    	if(ret){
    		printk(KERN_ERR"gpio_direction_input() failed !
    ");
    		goto fail2;	
    	}
    	
        cdev_init(&dev->cdev, &meassage_operatons);  
        cdev_add(&dev->cdev, dev->devno, 1);  
    
    	
    	if(ret){
    		printk(KERN_ERR"request_irq() failed ! %d
    ", ret);
    		goto fail2;
    	}
    	
       printk("ppm_to_app_init(void)--
    ");      
        return 0;  
    
    fail2:	
    	gpio_free(GPIO_TO_PIN(0,27));	
    fail1:    
    	device_destroy(dev->ppm_class, dev->devno);  
        class_destroy(dev->ppm_class);   
        cdev_del(&dev->cdev);  
        unregister_chrdev_region(dev->devno, 1);  
    
    	return ret;
    }  
    static void __exit ppm_exit(void)  
    {  
        struct ppm_dev *dev = &ppm_dev;  
      
       // printk("ppm_to_app_exit(void)++
    "); 
       	gpio_free(GPIO_TO_PIN(0,27));
    
        device_destroy(dev->ppm_class, dev->devno);  
        class_destroy(dev->ppm_class);   
        cdev_del(&dev->cdev);  
        unregister_chrdev_region(dev->devno, 1);  
           
       // printk("ppm_to_app_exit(void)--
    ");  
    }  
    module_init(ppm_init);  
    module_exit(ppm_exit);  
      
    MODULE_LICENSE("GPL");  
    MODULE_AUTHOR("Driver Monkey");  
    MODULE_DESCRIPTION("Test ppm");  
    
    
    



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  • 原文地址:https://www.cnblogs.com/jiangu66/p/3214980.html
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