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\n",(int)ktime.tv64);

	return HRTIMER_RESTART;
}

static int ppm_open(struct inode *node, struct file *fd)
{
	int ret = 0;

	printk("ppm_open()++\n"); 

	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()--\n");  

    return ret;
}   

 ssize_t ppm_write(struct file *pfile,
 					const char __user *buffer,
 					size_t size,
 					loff_t *pnull)

{	

	printk("ppm_write()++\n");

	if(size != (PPM_CHANEL * sizeof(long long)))
		return 0;

	//copy_from_user(ppm_values, buffer, size);

	printk("ppm_write()--\n");

	return size;
}
static int ppm_fasync(int fd, struct file *filp, int mode)
{

	printk("ppm_fasync()++\n");

	printk("ppm_fasync()--\n");

	return 0;
}

static int ppm_release(struct inode *node, struct file *fd)
{
	printk("ppm_release()++\n"); 

	hrtimer_cancel(&hr_timer);
    printk("ppm_release()--\n");
    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 !\n");
		goto fail1;
	}
	ret = gpio_direction_output(GPIO_TO_PIN(0,27), 1);
	if(ret){
		printk(KERN_ERR"gpio_direction_input() failed !\n");
		goto fail2;
	}

    cdev_init(&dev->cdev, &meassage_operatons);
    cdev_add(&dev->cdev, dev->devno, 1);  

	if(ret){
		printk(KERN_ERR"request_irq() failed ! %d\n", ret);
		goto fail2;
	}

   printk("ppm_to_app_init(void)--\n");
    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)++\n");
   	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)--\n");
}
module_init(ppm_init);
module_exit(ppm_exit);  

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Driver Monkey");
MODULE_DESCRIPTION("Test ppm");