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2013-10-31 08:31 |
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签到天数: 16 天 连续签到: 1 天 [LV.4]偶尔看看III
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发表于 2014-5-11 10:37:05
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globalmem.c文件- #include <linux/module.h>
- #include <linux/types.h>
- #include <linux/fs.h>
- #include <linux/errno.h>
- #include <linux/mm.h>
- #include <linux/slab.h>
- #include <linux/sched.h>
- #include <linux/init.h>
- #include <linux/cdev.h>
- #include <asm/io.h>
- #include <asm/system.h>
- #include <asm/uaccess.h>
- #define GLOBALMEM_SIZE 0x1000 /*4KB*/
- #define MEM_CLEAR 0x1 /*clear globale memory*/
- #define GLOBALMEM_MAJOR 199 /**/
- static int globalmem_major = GLOBALMEM_MAJOR;
- struct globalmem_dev
- {
- struct cdev cdev;
- unsigned char mem[GLOBALMEM_SIZE];
- struct semaphore sem;
- };
- struct globalmem_dev *globalmem_devp;
- int globalmem_open(struct inode* inode, struct file * filp)
- {
- filp->private_data = globalmem_devp;
- return 0;
- }
- int globalmem_release(struct inode * inode, struct file * filp)
- {
- return 0;
- }
- //static int globalmem_ioctl(struct inode * inodep, struct file * filp, unsigned int cmd, unsigned long arg)
- static int globalmem_ioctl(struct file * filp, unsigned int cmd, unsigned long arg)
- {
- struct globalmem_dev * dev = filp->private_data;
- switch(cmd)
- {
- case MEM_CLEAR:
- if(down_interruptible(&dev->sem))
- {
- return -ERESTARTSYS;
- }
- memset(dev->mem, 0, GLOBALMEM_SIZE);
- up(&dev->sem);
- printk(KERN_INFO "globalmem is set to 0\n");
- break;
- default:
- return -EINVAL;
- }
- return 0;
- }
- static ssize_t globalmem_read(struct file * filp, char __user * buf, size_t size, loff_t *ppos)
- {
- unsigned long p = *ppos;
- unsigned int count = size;
- int ret = 0;
- struct globalmem_dev *dev = filp->private_data;
- if(p >= GLOBALMEM_SIZE)
- {
- return count ? -ENXIO:0;
- }
- if(count > GLOBALMEM_SIZE - p)
- {
- count = GLOBALMEM_SIZE - p;
- }
- if(down_interruptible(&dev->sem))
- {
- return -ERESTARTSYS;
- }
- if(copy_to_user(buf, (void*)(dev->mem + p), count))
- {
- ret = -EFAULT;
- }
- else
- {
- *ppos += count;
- ret = count;
- printk(KERN_EMERG "read %d byte(s) from %d\n", count, p);
- }
- up(&dev->sem);
- return ret;
- }
- static ssize_t globalmem_write(struct file * filp, const char __user *buf, size_t size, loff_t *ppos)
- {
- unsigned long p = *ppos;
- unsigned int count = size;
- int ret = 0;
- struct globalmem_dev *dev = filp->private_data;
- if(p >= GLOBALMEM_SIZE)
- {
- return (count ? -ENXIO : 0);
- }
- if(count > GLOBALMEM_SIZE - p)
- {
- count = GLOBALMEM_SIZE - p;
- }
- if(down_interruptible(&dev->sem))
- {
- return -ERESTARTSYS;
- }
- if(copy_from_user(dev->mem + p, buf, count))
- {
- ret = -EFAULT;
- }
- else
- {
- *ppos += count;
- ret = count;
- printk(KERN_EMERG "written %d byte(s) from %d\n", count, p);
- }
- up(&dev->sem);
- return ret;
- }
- static loff_t globalmem_llseek(struct file * filp, loff_t offset, int orig)
- {
- loff_t ret = 0;
- switch(orig)
- {
- case 0:
- if(offset < 0)
- {
- ret = -EINVAL;
- break;
- }
- if((unsigned int)offset > GLOBALMEM_SIZE)
- {
- ret = -EINVAL;
- break;
- }
- filp->f_pos = (unsigned int)offset;
- ret = filp->f_pos;
- break;
- case 1:
- if((filp->f_pos + offset) > GLOBALMEM_SIZE)
- {
- ret = -EINVAL;
- break;
- }
- if((filp->f_pos + offset) < 0)
- {
- ret = -EINVAL;
- break;
- }
- filp->f_pos += offset;
- ret = filp->f_pos;
- break;
- }
- return ret;
- }
- static const struct file_operations globalmem_fops =
- {
- .owner = THIS_MODULE,
- .llseek = globalmem_llseek,
- .read = globalmem_read,
- .write = globalmem_write,
- .compat_ioctl = globalmem_ioctl,
- .open = globalmem_open,
- .write = globalmem_write,
- };
- static void globalmem_setup_cdev(struct globalmem_dev *dev, int index)
- {
- int err;
- int devno = MKDEV(globalmem_major, 0);
- cdev_init(&dev->cdev, &globalmem_fops);
- dev->cdev.owner = THIS_MODULE;
- dev->cdev.ops = &globalmem_fops;
- err = cdev_add(&dev->cdev, devno, 1);
- if(err)
- {
- printk(KERN_EMERG "Error %d adding globalmem %d\n", err, index);
- }
- }
- int globalmem_init(void)
- {
- int result;
- dev_t devno = MKDEV(globalmem_major, 0);
- if(globalmem_major)
- {
- result = register_chrdev_region(devno, 1, "globalmem");
- }
- else
- {
- result = alloc_chrdev_region(&devno, 0, 1, "globalmem");
- globalmem_major = MAJOR(devno);
- }
- if(result < 0)
- {
- return result;
- }
- globalmem_devp = kmalloc(sizeof(struct globalmem_dev), GFP_KERNEL);
- if(!globalmem_devp)
- {
- result = -ENOMEM;
- goto fail_malloc;
- }
- memset(globalmem_devp, 0, sizeof(struct globalmem_dev));
- globalmem_setup_cdev(globalmem_devp, 0);
- //init_MUTEX(&globalmem_devp->sem);
- mutex_init(&globalmem_devp->sem);
- return 0;
- fail_malloc:
- unregister_chrdev_region(devno, 1);
- return result;
- }
- void globalmem_exit(void)
- {
- cdev_del(&globalmem_devp->cdev);
- kfree(globalmem_devp);
- unregister_chrdev_region(MKDEV(globalmem_major, 0), 1);
- }
- MODULE_AUTHOR("hmy");
- MODULE_LICENSE("Dual BSD/GPL");
- module_param(globalmem_major, int, S_IRUGO);
- module_init(globalmem_init);
- module_exit(globalmem_exit);
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发表于 2014-5-10 07:16:30
/5 
