ldd3 chapter3 字元驅動簡單記錄

動態分配節點號：

int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,

const char *name)

void unregister_chrdev_region(dev_t from, unsigned count)

struct cdev *cdev_alloc(void)

void cdev_init(struct cdev *cdev, const struct file_operations *fops)

int cdev_add(struct cdev *, dev_t, unsigned);

void cdev_del(struct cdev *p)

#include #include #include #include #include #include #include #include #include #include loff_t scull_llseek(struct file *filp, loff_t f_ops, int flag);

ssize_t scull_read(struct file *filp, char __user * buf, size_t count, loff_t *f_ops);
ssize_t scull_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_ops);
int scull_ioctl(struct inode *p_inode, struct file *filp, unsigned int cmd, unsigned long args);
int scull_open(struct inode *p_inode, struct file *filp);
int scull_release(struct inode *p_inode, struct file *filp);
struct file_operations scull_fops = 
;struct scull_qset
;struct scull_dev
;struct scull_dev g_scull_dev;
//根據index 返回p_qset結構，如果沒有就建立乙個
struct scull_qset *scull_follow(struct scull_dev* dev, int index)
} p_qset = (struct scull_qset *)kmalloc(sizeof(struct scull_qset), gfp_kernel);
if (p_qset == null)
return null;
memset(p_qset, 0, sizeof(struct scull_qset));
p_qset->data = kmalloc(dev->qset * sizeof(char *), gfp_kernel);
if (p_qset->data == null)
memset(p_qset->data, 0, dev->qset * sizeof(char *));
list_add_tail(&p_qset->qset_node, &dev->qset_head);
return p_qset;
}int scull_trim(struct scull_dev *dev)
list_del(p_qset_node);
kfree(p_qset);
} dev->size = 0;
return 0;
}loff_t scull_llseek(struct file *filp, loff_t f_ops, int flag)
ssize_t scull_read(struct file *filp, char __user * buf, size_t count, loff_t *f_ops)
p_qset = scull_follow(dev, qset_index);
if (p_qset == null || p_qset->data == null || p_qset->data[quan_index] == null)
if (count > (dev->quantum - quan_rest)) 
if (copy_to_user(buf, p_qset->data[quan_index] + quan_rest, count))
*f_ops += count;
retval = count;
out:
up(&dev->sem);
return retval;
}ssize_t scull_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_ops)
if (count > (dev->quantum - quan_rest)) 
if (copy_from_user(p_qset->data[quan_index] + quan_rest, buf, count))
*f_ops += count;
retval = count;
if (dev->size < *f_ops)
dev->size = *f_ops; 
out:
up(&dev->sem);
return retval;
}int scull_ioctl(struct inode *p_inode, struct file *filp, unsigned int cmd, unsigned long args)
int scull_open(struct inode *p_inode, struct file *filp)
//如果以trunc模式開啟，則將dev內容清除
if (filp->f_flags & o_trunc) 
printk(kern_err"file size = %ld\n",dev->size);
return 0;
}int scull_release(struct inode *p_inode, struct file *filp)
static int scull_init(void)
//初始化cdev結構，並繫結file_operations和節點號
cdev_init(&g_scull_dev.cdev, &scull_fops);
cdev_add(&g_scull_dev.cdev, g_scull_dev.dev_t, 4);
printk(kern_err"major = %d,minor = %d\n",major(g_scull_dev.dev_t),minor(g_scull_dev.dev_t));
//初始化裝置結構體
g_scull_dev.qset = 4096;
g_scull_dev.quantum = 4096;
init_list_head(&g_scull_dev.qset_head);
sema_init(&g_scull_dev.sem, 1);
return 0;
}static void scull_exit(void)
module_init(scull_init);
module_exit(scull_exit);
module_license("dual bsd/gpl");

obj-m += scull.o

kdir := /home/linux-2.6.32.2
pwd = $(shell pwd)
all:
make -c $(kdir) m=$(pwd) modules
clean:
rm -rf *.o

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