3-2信号量驱动实例

原创 于 2013-07-05 12:07:39 发布 · 658 阅读 · 0 ·
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文章标签：

#sem

本文详细介绍了如何在Linux内核中实现一个无信号量和带信号量的设备驱动，并通过测试程序验证其功能。通过对比两个实例，展示了信号量在驱动程序中的作用以及如何在用户空间和内核空间之间进行数据传输。 
 实例一：没有信号量的程序


1、 
nosem\driver\ nosem.c驱动源代码


#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/init.h>
#include <linux/serio.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/miscdevice.h>
#include <linux/gpio.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <mach/regs-clock.h>
#include <plat/regs-timer.h>
	 
#include <mach/regs-gpio.h>
#include <linux/cdev.h>

static int test_major = 0;

MODULE_AUTHOR("Hanson He");
MODULE_LICENSE("Dual BSD/GPL");

#define GLOBALMEM_SIZE	0x1000	/*全局内存最大4K字节*/
unsigned char mem[GLOBALMEM_SIZE]; /*全局内存*/


/*
 * Open the device; in fact, there's nothing to do here.
 */
int test_open (struct inode *inode, struct file *filp)
{
	return 0;
}

ssize_t test_read(struct file *file, char __user *buff, size_t count, loff_t *offp)
{
	return 0;
}

ssize_t test_write(struct file *file, const char __user *buff, size_t count, loff_t *offp)
{
	int i;

	unsigned long p =  *offp;
	int ret = 0;

	/*分析和获取有效的写长度*/
	if (p >= GLOBALMEM_SIZE)
		return count ?  - ENXIO: 0;
	if (count > GLOBALMEM_SIZE - p)
		count = GLOBALMEM_SIZE - p;

	/*用户空间->内核空间*/
	  if (copy_from_user(mem + p, buff, count))
	    ret =  - EFAULT;
	  else
	  {
	    *offp += count;
	    ret = count;

	    //printk(KERN_INFO "written %d bytes(s) from %d\n", count, p);
	  }
  
	for(i=0;i<count;i++)
	{
		printk("%d",mem[i]);
		msleep(100); //delay 1ms
 	}
	printk("\n");
	return 0;
}

static int test_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
	return 0;

}

static int test_release(struct inode *node, struct file *file)
{
	return 0;
}

/*
 * Set up the cdev structure for a device.
 */
static void test_setup_cdev(struct cdev *dev, int minor,
		struct file_operations *fops)
{
	int err, devno = MKDEV(test_major, minor);
    
	cdev_init(dev, fops);
	dev->owner = THIS_MODULE;
	dev->ops = fops;
	err = cdev_add (dev, devno, 1);
	/* Fail gracefully if need be */
	if (err)
		printk (KERN_NOTICE "Error %d adding test%d", err, minor);
}


/*
 * Our various sub-devices.
 */
/* Device 0 uses remap_pfn_range */
static struct file_operations test_remap_ops = {
	.owner   = THIS_MODULE,
	.open    = test_open,
	.release = test_release,
	.read    = test_read,
	.write   = test_write,
	.ioctl   = test_ioctl,	
};

/*
 * There's no need for us to maintain any
 * special housekeeping info, so we just deal with raw cdevs.
 */
static struct cdev TestDevs;

/*
 * Module housekeeping.
 */
static int test_init(void)
{
	int result;
	dev_t dev = MKDEV(test_major, 0);

	/* Figure out our device number. */
	if (test_major)
		result = register_chrdev_region(dev, 1, "nosem");
	else {
		result = alloc_chrdev_region(&dev, 0, 1, "nosem");
		test_major = MAJOR(dev);
	}
	if (result < 0) {
		printk(KERN_WARNING "test: unable to get major %d\n", test_major);
		return result;
	}
	if (test_major == 0)
		test_major = result;

	/* Now set up cdev. */
	test_setup_cdev(&TestDevs, 0, &test_remap_ops);
	printk("test device installed, with major %d\n", test_major);
	return 0;
}


static void test_cleanup(void)
{
	cdev_del(&TestDevs);
	unregister_chrdev_region(MKDEV(test_major, 0), 1);
	printk("test device uninstalled\n");
}


module_init(test_init);
module_exit(test_cleanup); 



2、 
Mafefile文件


   ifeq ($(KERNELRELEASE),)

#KERNELDIR ?= /your/target/source/directory/
KERNELDIR ?=/home/student/linux-2.6.32.2 
PWD := $(shell pwd)

modules:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules

modules_install:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install

clean:
	rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions

.PHONY: modules modules_install clean

else
    obj-m := nosem.o
endif



 


3、  
nosem\user\ main.c测试程序


  #include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>

int main(int argc, char *argv[])
{
	int i = 0;
	int dev_fd;
	char wr_buf[60];
	int cnt = 0;
	int input = 0;
	
	if(argc > 1)
	{
		input = atoi(argv[1]);
	}else{
		printf("usage: nosem_test number\n");
		exit(1); 
	}
	dev_fd = open("/dev/nosem",O_RDWR);
	if ( dev_fd == -1 ) {
		printf("Can't open file /dev/nosem\n");
		exit(1);
	}
	memset(wr_buf, input, sizeof(wr_buf));
	/*print out 100 line number, there are 60 one every line*/
	while(1)
	{
		lseek(dev_fd,0,SEEK_SET);
		write(dev_fd,wr_buf,sizeof(wr_buf));		
		cnt ++;
		if(cnt > 100)break;
		usleep(8);
	}
	close(dev_fd);
	return 0;
}


4、 
Makefile文件


         


 KERNELDIR ?=/home/student/linux-2.6.32.2/include
all: nosem_test

nosem_test : main.c
	#arm-linux-gcc -I$(KERNELDIR) -s -Wl,-warn-common --static -o $@ $^
	arm-linux-gcc -I$(KERNELDIR) -o $@ $^

clean :
	rm nosem_test





 


5、run_nosemtests多个测试


 ./nosem_test 1 &


./nosem_test 2 &


./nosem_test 3 &


 


实例二：带信号量的程序


6、  
\sem\driver\ Sem.c驱动源代码


  #include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/init.h>
#include <linux/serio.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/miscdevice.h>
#include <linux/gpio.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <mach/regs-clock.h>
#include <plat/regs-timer.h>
	 
#include <mach/regs-gpio.h>
#include <linux/cdev.h>

DECLARE_MUTEX(sem); //声明一个互斥体
static int test_major = 0;

MODULE_AUTHOR("Hanson He");
MODULE_LICENSE("Dual BSD/GPL");

#define GLOBALMEM_SIZE	0x1000	/*全局内存最大4K字节*/
unsigned char mem[GLOBALMEM_SIZE]; /*全局内存*/

/*
 * Open the device; in fact, there's nothing to do here.
 */
int test_open (struct inode *inode, struct file *filp)
{
	return 0;
}

ssize_t test_read(struct file *file, char __user *buff, size_t count, loff_t *offp)
{
	return 0;
}

ssize_t test_write(struct file *file, const char __user *buff, size_t count, loff_t *offp)
{
	int i;

	unsigned long p =  *offp;
	int ret = 0;

	/*分析和获取有效的写长度*/
	if (p >= GLOBALMEM_SIZE)
		return count ?  - ENXIO: 0;
	if (count > GLOBALMEM_SIZE - p)
		count = GLOBALMEM_SIZE - p;

	if(down_interruptible(&sem))
	{
		return -ERESTARTSYS;
	}

	/*用户空间->内核空间 以下是临界区*/
	  if (copy_from_user(mem + p, buff, count))
	    ret =  - EFAULT;
	  else
	  {
	    *offp += count;
	    ret = count;

	    //printk(KERN_INFO "written %d bytes(s) from %d\n", count, p);
	  }
  
	for(i=0;i<count;i++)
	{
		printk("%d",mem[i]);
		msleep(1); //delay 1ms
 	}
	printk("\n");
	up(&sem);
	return 0;
}

static int test_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
	return 0;

}

static int test_release(struct inode *node, struct file *file)
{
	return 0;
}

/*
 * Set up the cdev structure for a device.
 */
static void test_setup_cdev(struct cdev *dev, int minor,
		struct file_operations *fops)
{
	int err, devno = MKDEV(test_major, minor);
    
	cdev_init(dev, fops);
	dev->owner = THIS_MODULE;
	dev->ops = fops;
	err = cdev_add (dev, devno, 1);
	/* Fail gracefully if need be */
	if (err)
		printk (KERN_NOTICE "Error %d adding test%d", err, minor);
}


/*
 * Our various sub-devices.
 */
/* Device 0 uses remap_pfn_range */
static struct file_operations test_remap_ops = {
	.owner   = THIS_MODULE,
	.open    = test_open,
	.release = test_release,
	.read    = test_read,
	.write   = test_write,
	.ioctl   = test_ioctl,	
};

/*
 * There's no need for us to maintain any
 * special housekeeping info, so we just deal with raw cdevs.
 */
static struct cdev TestDevs;

/*
 * Module housekeeping.
 */
static int test_init(void)
{
	int result;
	dev_t dev = MKDEV(test_major, 0);
	char dev_name[]="sem";


	/* Figure out our device number. */
	if (test_major)
		result = register_chrdev_region(dev, 1, dev_name);
	else {
		result = alloc_chrdev_region(&dev, 0, 1, dev_name);
		test_major = MAJOR(dev);
	}
	if (result < 0) {
		printk(KERN_WARNING "test: unable to get major %d\n", test_major);
		return result;
	}
	if (test_major == 0)
		test_major = result;

	/* Now set up cdev. */
	test_setup_cdev(&TestDevs, 0, &test_remap_ops);
	printk("test device installed, with major %d\n", test_major);
	printk("The device name is: %s\n", dev_name);

	return 0;
}


static void test_cleanup(void)
{
	cdev_del(&TestDevs);
	unregister_chrdev_region(MKDEV(test_major, 0), 1);
	printk("test device uninstalled\n");
}


module_init(test_init);
module_exit(test_cleanup);


7、	Mafefile文件
   ifeq ($(KERNELRELEASE),)

#KERNELDIR ?= /your/target/source/directory/
KERNELDIR ?=/home/student/linux-2.6.32.2
PWD := $(shell pwd)

modules:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules

modules_install:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install

clean:
	rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions

.PHONY: modules modules_install clean

else
    obj-m := sem.o
endif

8、	sem\use\ Main.c测试程序
   #include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>

int main(int argc, char *argv[])
{
	int i = 0;
	int dev_fd;
	char wr_buf[60];
	int cnt = 0;
	int input = 0;

	if(argc > 1)
	{
		input = atoi(argv[1]);
	}else{
		printf("usage: sem_test num\n");
		exit(1);
	}
	dev_fd = open("/dev/sem",O_RDWR);
	if ( dev_fd == -1 ) {
		printf("Cann't open file /dev/sem\n");
		exit(1);
	}
	memset(wr_buf, input, sizeof(wr_buf));
	/*print out 100 line input, there are 60 one every line*/
	while(1)
	{
		lseek(dev_fd, 0, SEEK_SET);
		write(dev_fd,wr_buf,sizeof(wr_buf));
		cnt ++;
		if(cnt > 100)break;
		usleep(8);
	}
	close(dev_fd);
	return 0;
}
9、  Makefile
KERNELDIR ?=/home/student/linux-2.6.32.2/include
all: sem_test
 
sem_test : main.c
       #arm-linux-gcc -I$(KERNELDIR) -s -Wl,-warn-common --static -o $@ $^
       arm-linux-gcc -I$(KERNELDIR) -o $@ $^
 
clean :




10、run_semtests多个测试


./sem_test 1 &


./sem_test 2 &


./sem_test 3 &


 


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