Linux驱动:阻塞式读写测试
Linux驱动:阻塞式读写测试
环境:
主机:Fedora 12
目标板:MINI6410
目标板LINUX内核版本:2.6.38
实现功能:
开辟一个256字节的循环缓冲,可以同时读写,如果数据量不足,则读进程会被阻塞,直到有数据写入
驱动源代码:
test_driver.c:
[cpp]
- #include <linux/miscdevice.h>
- #include <linux/delay.h>
- #include <asm/irq.h>
- //#include <mach/regs-gpio.h>
- #include <mach/hardware.h>
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/init.h>
- #include <linux/mm.h>
- #include <linux/fs.h>
- #include <linux/types.h>
- #include <linux/delay.h>
- #include <linux/moduleparam.h>
- #include <linux/slab.h>
- #include <linux/errno.h>
- #include <linux/ioctl.h>
- #include <linux/cdev.h>
- #include <linux/string.h>
- #include <linux/list.h>
- #include <linux/pci.h>
- #include <asm/uaccess.h>
- #include <asm/atomic.h>
- #include <asm/unistd.h>
- #include <linux/major.h>
- #include <mach/map.h>
- #include <mach/regs-clock.h>
- #include <mach/regs-gpio.h>
- #include <plat/gpio-cfg.h>
- #include <mach/gpio-bank-e.h>
- #include <mach/gpio-bank-k.h>
- #include <mach/gpio-bank-h.h>
- #include <mach/gpio-bank-n.h>
- #include <mach/gpio-bank-l.h>
- #include <mach/gpio-bank-p.h>
- #include <linux/device.h>
- #include <linux/jiffies.h>
- #include <linux/string.h>
- #include <linux/semaphore.h>
- #include <linux/sched.h>
- #include <linux/wait.h>
- #define DEVICE_NAME "test_driver"
- #define T_MAJORS 800
- //设备结构
- static struct _Test_Driver_Device
- {
- struct cdev fun_cdev;
- //定义缓冲
- unsigned char *buffer,*end;
- //读写指针
- unsigned char *rp,*wp;
- //读信号量
- struct semaphore sem_r;
- //写信号量
- struct semaphore sem_w;
- //等待队列头
- struct wait_queue_head_t *wq;
- };
- struct _Test_Driver_Device *Test_Driver_Device;
- static dev_t dev;
- static struct class *test_class;
- //开辟缓存,用来读写
- #define LEN_BUF 256
- static unsigned char Buffer[LEN_BUF];
- //功能:初始化缓存
- static void init_buf(void)
- {
- memset(Buffer,0,LEN_BUF);
- }
- //功能:读取缓存
- //返回:读取的字节数
- ssize_t test_driver_read(struct file *filp,char __user *buf,size_t count,loff_t *f_pos)
- {
- int temp1 = 0,temp2 = 0,temp3 = 0;
- //获取信号量
- if (down_interruptible(&Test_Driver_Device->sem_r))
- {
- return -ERESTARTSYS;
- }
- //循环防止解除阻塞时的竞争
- while (Test_Driver_Device->wp == Test_Driver_Device->rp)
- {
- //读不到数据
- //释放信号量
- up(&Test_Driver_Device->sem_r);
- //判断是否是非阻塞读
- if (filp->f_flags & O_NONBLOCK)
- {
- return -EAGAIN;
- }
- //如果是阻塞式读,则阻塞
- if (wait_event_interruptible(Test_Driver_Device->wq,Test_Driver_Device->wp != Test_Driver_Device->rp))
- {
- return -ERESTARTSYS;
- }
- //获取信号量
- if (down_interruptible(&Test_Driver_Device->sem_r))
- {
- return -ERESTARTSYS;
- }
- }
- if (Test_Driver_Device->wp > Test_Driver_Device->rp)
- {
- count = min(count,(size_t)(Test_Driver_Device->wp - Test_Driver_Device->rp));
- //拷贝数据到用户空间
- if (copy_to_user(buf,Test_Driver_Device->rp,count))
- {
- return -EFAULT;
- }
- Test_Driver_Device->rp += count;
- }
- else
- {
- temp1 = Test_Driver_Device->end - Test_Driver_Device->rp + 1;
- temp2 = Test_Driver_Device->wp - Test_Driver_Device->buffer;
- if (count <= temp1)
- {
- //拷贝数据到用户空间
- if (copy_to_user(buf,Test_Driver_Device->rp,count))
- {
- return -EFAULT;
- }
- Test_Driver_Device->rp += count;
- }
- else
- {
- //拷贝数据到用户空间
- if (copy_to_user(buf,Test_Driver_Device->rp,temp1))
- {
- return -EFAULT;
- }
- Test_Driver_Device->rp = Test_Driver_Device->buffer;
- temp3 = min(count - temp1,temp2);
- count = temp1 + temp3;
- if (copy_to_user(buf + temp1,Test_Driver_Device->rp,temp3))
- {
- return -EFAULT;
- }
- Test_Driver_Device->rp += temp3;
- }
- }
- if (Test_Driver_Device->rp == Test_Driver_Device->end + 1)
- {
- Test_Driver_Device->rp = Test_Driver_Device->buffer;
- }
- //释放信号量
- up(&Test_Driver_Device->sem_r);
- printk (DEVICE_NAME"\tjdh:rp zhi zhen = %d\n",Test_Driver_Device->rp - Test_Driver_Device->buffer);
- return count;
- }
- //功能:写入缓存
- //返回:写入的字节数
- ssize_t test_driver_write(struct file *filp,const char __user *buf,size_t count,loff_t *f_pos)
- {
- int temp1 = 0,temp2 = 0;;
- //判断需要写入的字节数是否大于缓存
- if (count > LEN_BUF)
- {
- return -ENOMEM;
- }
- //获取信号量
- if (down_interruptible(&Test_Driver_Device->sem_w))
- {
- return -ERESTARTSYS;
- }
- //写入缓存
- if (count <= (Test_Driver_Device->end - Test_Driver_Device->wp + 1))
- {
- //从用户空间拷贝数据
- if (copy_from_user(Test_Driver_Device->wp,buf,count))
- {
- return -EFAULT;
- }
- Test_Driver_Device->wp += count;
- }
- else
- {
- temp1 = Test_Driver_Device->end - Test_Driver_Device->wp + 1;
- temp2 = count - temp1;
- //从用户空间拷贝数据
- if (copy_from_user(Test_Driver_Device->wp,buf,temp1))
- {
- return -EFAULT;
- }
- Test_Driver_Device->wp = Test_Driver_Device->buffer;
- //从用户空间拷贝数据
- if (copy_from_user(Test_Driver_Device->wp,buf + temp1,temp2))
- {
- return -EFAULT;
- }
- Test_Driver_Device->wp += temp2;
- }
- if (Test_Driver_Device->wp == Test_Driver_Device->end + 1)
- {
- Test_Driver_Device->wp = Test_Driver_Device->buffer;
- }
- //唤醒阻塞进程
- wake_up_interruptible(&Test_Driver_Device->wq);
- //释放信号量
- up(&Test_Driver_Device->sem_w);
- printk (DEVICE_NAME"\tjdh:wp zhi zhen = %d\n",Test_Driver_Device->wp - Test_Driver_Device->buffer);
- return count;
- }
- static struct file_operations io_dev_fops = {
- .owner = THIS_MODULE,
- .write = test_driver_write,
- .read = test_driver_read,
- };
- static int __init dev_init(void)
- {
- int ret;
- unsigned temp;
- init_buf();
- //分配结构体
- Test_Driver_Device = kmalloc(sizeof(struct _Test_Driver_Device),GFP_KERNEL);
- if (!Test_Driver_Device)
- {
- unregister_chrdev_region(dev,1);
- device_destroy(test_class, dev);
- class_destroy(test_class);
- return -ENOMEM;
- }
- //定义缓冲的开始和结束的指针
- Test_Driver_Device->buffer = Buffer;
- Test_Driver_Device->end = Buffer + LEN_BUF - 1;
- Test_Driver_Device->rp = Test_Driver_Device->buffer;
- Test_Driver_Device->wp = Test_Driver_Device->buffer;
- //初始化读信号量
- sema_init(&Test_Driver_Device->sem_r,1);
- //初始化写信号量
- sema_init(&Test_Driver_Device->sem_w,1);
- //初始化等待队列头
- init_waitqueue_head(&Test_Driver_Device->wq);
- dev = MKDEV(T_MAJORS,0);
- cdev_init(&Test_Driver_Device->fun_cdev,&io_dev_fops);
- ret = register_chrdev_region(dev,1,DEVICE_NAME);
- if (ret < 0) return 0;
- ret = cdev_add(&Test_Driver_Device->fun_cdev,dev,1);
- if (ret < 0) return 0;
- printk (DEVICE_NAME"\tjdh:test_driver initialized!!\n");
- test_class = class_create(THIS_MODULE, "test_class1");
- if (IS_ERR(test_class))
- {
- printk(KERN_INFO "create class error\n");
- return -1;
- }
- device_create(test_class, NULL, dev, NULL, "test_driver");
- return ret;
- }
- static void __exit dev_exit(void)
- {
- unregister_chrdev_region(dev,1);
- device_destroy(test_class, dev);
- class_destroy(test_class);
- }
- module_init(dev_init);
- module_exit(dev_exit);
- MODULE_LICENSE("GPL");
- MODULE_AUTHOR("JDH");
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