为android编写linux内核驱动_android 内核驱动 kthread

#include <linux/init.h>
#include <linux/input.h>
#include <linux/of_device.h>
#include <linux/kthread.h>

#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
#include <linux/device.h>
#include <asm/uaccess.h>
#include <linux/slab.h>
#include "hello.h"

/*主设备和从设备号变量*/
static int hello_major = 0 ;
static int hello_minor = 0 ;
/*设备类别和设备变量*/
static struct class * hello_class = NULL;
static struct hello_android_dev *hello_dev = NULL;
/*传统的设备文件操作方法*/
static int hello_open(struct inode *inode,struct file * filp);
static int hello_release(struct inode * inode,struct file * filp);
static ssize_t hello_read(struct file *filp,char __user *buf,size_t count,loff_t* f_pos);
static ssize_t hello_write(struct file * filp,const char __user *buf ,size_t count ,loff_t * f_ops);
/*设备文件操作方法*/
static struct file_operations hello_fops = {
.owner = THIS_MODULE,
.open  = hello_open,
.release = hello_release,
.read = hello_read,
.write = hello_write,
};
/*访问设置属性方法*/
static ssize_t hello_val_show(struct device *dev,struct device_attribute* attr,char *buf);
static ssize_t hello_val_store(struct device *dev,struct device_attribute* attr,const char* buf ,size_t count);
/*定义设备属性*/
static DEVICE_ATTR(val,S_IRUGO | S_IWUSR,hello_val_show,hello_val_store);

/*打开设备方法*/
static int hello_open(struct inode* inode,struct file* filp)
{
struct hello_android_dev* dev;
 /*将自定义设备结构体保存在文件指针的私有数据域中，以便访问设备时拿来用*/
 dev = container_of(inode->i_cdev,struct hello_android_dev,dev);
 filp->private_data = dev;
 return 0;
}

/*设备文件释放时调用，空实现*/
static int hello_release(struct inode* inode,struct file* file)
{
 return 0;
}
/*读取设备寄存去val的值*/
static ssize_t hello_read(struct file* filp ,char __user *buf ,size_t count,loff_t* f_pos)
{
 ssize_t err = 0;
  struct hello_android_dev* dev = filp->private_data;
 /*同步访问*/
 if(down_interruptible(&(dev->sem)))
 {
  return -ERESTARTSYS;
 }
 if(count < sizeof(dev->val))
 {
  goto out;
 }
 /*将寄存器val的值拷贝到用户提供的缓存区中*/
 if(copy_to_user(buf,&(dev->val),sizeof(dev->val)))
 {
  err= -EFAULT;
  goto out;
 }
 err= sizeof(dev->val);

 out:
 up(&(dev->sem));
 return err;
 }
/*写设备寄存器的值*/
static ssize_t hello_write(struct file * filp,const char __user* buf ,size_t count,loff_t* f_pos)
{
 struct hello_android_dev* dev = filp->private_data;
 ssize_t err = 0 ;
 /*同步访问*/
 if(down_interruptible(&(dev->sem)))
 {
  return -ERESTARTSYS;
 }
 if(count!=sizeof(dev->val))
 {
 goto out;
 }
 /*将用户提供的缓冲区的值写到设备寄存去*/
 if(copy_from_user(&(dev->val),buf,count))
 {
 err = -EFAULT;
 goto out;
 }
 err = sizeof(dev->val);
 out:
 up(&(dev->sem));
 return err;
}

/*---------------------------------------------------------------------*/
/*读取寄存器val的值到缓冲区buf中，内部使用*/
static ssize_t __hello_get_val(struct hello_android_dev* dev,char* buf) 
{
 int val = 0;
 /*同步访问*/
 if(down_interruptible(&(dev->sem)))
 {
  return -ERESTARTSYS;
 }
 val = dev-> val;
 up(&(dev->sem));
 return snprintf(buf,PAGE_SIZE,"%d\n",val);
}
/*把缓冲区buf的值写到寄存器Val中去，内部使用*/
static ssize_t __hello_set_val(struct hello_android_dev* dev,const char* buf,size_t count)
{
 int val= 0;
 /*将字符串转换成数字*/
 val = simple_strtol(buf,NULL,10);
 /*同步访问*/
 if(down_interruptible(&(dev->sem)))
 {
  return -ERESTARTSYS;
 }
 dev->val = val;
 up(&(dev->sem));
 return count ;
}
/*读取设备属性Val*/
static ssize_t hello_val_show(struct device* dev, struct device_attribute* attr,char* buf)
{
 struct hello_android_dev* hdev =(struct hello_android_dev*)dev_get_drvdata(dev);
 return __hello_get_val(hdev,buf);

}
/*写设备属性Val*/
static ssize_t hello_val_store(struct device* dev,struct device_attribute* attr,const char * buf,size_t count)
{
 struct hello_android_dev* hdev = (struct hello_android_dev*)dev_get_drvdata(dev);
 return __hello_set_val(hdev,buf,count);
}

/*-------------------------------------------------------------*/
/*读取设备寄存器val的值，保存在page缓冲区中*/
 ssize_t hello_proc_read (struct file *file, char __user *buff, size_t len, loff_t *data)
//static ssize_t hello_proc_read(char* page,char** start,off_t off, int count ,int* eof,void* data)
{
 /*off_t off;
 int *eof;
 char *page;
 if(off > 0) 
 {
 *eof = 1;
 return 0; 
 }*/

 return __hello_get_val(hello_dev,buff);
}
/*把缓冲区的值buff保存到设备寄存器val中去*/
ssize_t hello_proc_write (struct file *filp, const char __user *buff, size_t len, loff_t *data)
//static ssize_t hello_proc_write(struct file* filp,const char __user *buff,unsigned long len,void* data)
{
 int err = 0;
// unsigned long len;
 char* page = NULL;
 if(len>PAGE_SIZE)
 {
 printk(KERN_ALERT"The buff is too large : .\n");
 return -EFAULT;
 }
 page = (char*)__get_free_page(GFP_KERNEL);
 if(!page)
 {
 printk(KERN_ALERT"Failed to alloc page.\n");
 return -ENOMEM;
 }
 /*先把用户提供的缓冲区拷贝到内核缓冲区中去*/
 if(copy_from_user(page,buff,len))
 {
  printk(KERN_ALERT"Failed to copy buff from user.\n");
  err = -EFAULT;
  goto out;
 }
 err= __hello_set_val(hello_dev,page,len);
 out:
 free_page((unsigned long)page);
 return err;
}
static const struct file_operations proc_hello_fops={
// .owner = THIS_MODULE,
 .read  = hello_proc_read,
 .write = hello_proc_write,
};
/*创建/proc/hello*/
static void hello_create_proc(void)
{
 static struct proc_dir_entry* entry;
 entry = proc_create(HELLO_DEVICE_PROC_NAME,0,NULL,&proc_hello_fops);
/*create_proc_entry在新版本不能使用*/
/* if(entry)
 {
 entry->owner = THIS_MODULE;
 entry->read_proc = hello_proc_read;
 entry->write_proc = hello_proc_write;
 }*/
}
/*删除/proc/hello文件*/
static void hello_remove_proc(void)
{
 remove_proc_entry(HELLO_DEVICE_PROC_NAME,NULL);
}

/*-------------------------------------------------------*/
static int __hello_setup_dev(struct hello_android_dev* dev)
{
 int err;
 dev_t devno = MKDEV(hello_major,hello_minor);
 memset(dev,0,sizeof(struct hello_android_dev));
 cdev_init(&(dev->dev),&hello_fops);
 dev->dev.owner = THIS_MODULE;
 dev->dev.ops = &hello_fops;
 /*注册字符设备*/
 err= cdev_add(&(dev->dev),devno,1);
 if(err)
 {
 return err;
 }
 /*初始化信号和寄存器val的值*/
 //init_MUTEX(&(dev->sem));新版本不能用，改成sema_init(dev->sem,1);
 sema_init(&dev->sem,1);
 dev->val=0;
 return 0;
}

/*模块加载方法*/
static int __init hello_init(void)
{
 int err = -1 ;
 dev_t dev = 0;
 struct device* temp = NULL;
 printk(KERN_ALERT"Initializing hello device .\n");
 /*动态分配主设备和从设备号*/
 err=alloc_chrdev_region(&dev,0,1,HELLO_DEVICE_NODE_NAME);
 if(err<0)
 {
 printk(KERN_ALERT"Faile to alloc char dev region.\n");
 goto fail;
 }
 hello_major = MAJOR(dev);
 hello_minor = MINOR(dev);
 /*分配hello设备结构体变量*/
 hello_dev = kmalloc(sizeof(struct hello_android_dev),GFP_KERNEL);
 /*kmalloc需要头文件linux/slab.h*/
 if(!hello_dev)
 {
 err = -ENOMEM;
 printk(KERN_ALERT"Failed to alloc hello_dev.\n");
 goto unregister;
 }
 /*初始化设备*/
 err = __hello_setup_dev(hello_dev);
 if(err)
 {
 printk(KERN_ALERT"Failed to alloc hello_dev.\n");
 goto cleanup;
 }
 /*在/sys/class目录下床接设备类别目录hello*/
 hello_class = class_create(THIS_MODULE,HELLO_DEVICE_CLASS_NAME);
 if(IS_ERR(hello_class))
 {
 err=PTR_ERR(hello_class);
 printk(KERN_ALERT"Failed to create hello class. \n");
 goto destroy_cdev;
 }
 /*在dev的目录和/sys/class/hello目录下分别创建文件hello*/
 temp = device_create(hello_class,NULL,dev,"%s",HELLO_DEVICE_FILE_NAME);
 if(IS_ERR(temp))
 {
 printk(KERN_ALERT"Failed to create hello device");
 goto destroy_class;
 }
 /*在/sys/class/hello/hello目录下创建属性文件val*/
 err= device_create_file(temp,&dev_attr_val);
 if(err<0)
 {
 printk(KERN_ALERT"Failed to create attribute val");
 goto destroy_device;
 }
 dev_set_drvdata(temp,hello_dev);
 /*创建/proc/hello文件*/
 hello_create_proc();
 printk(KERN_ALERT"Succedded to initialize hello device.\n");
 return 0 ;
 destroy_device:
 device_destroy(hello_class,dev);
 destroy_class:
 class_destroy(hello_class);
 destroy_cdev:
 cdev_del(&(hello_dev->dev));
 cleanup:
 kfree(hello_dev);
 unregister:
 unregister_chrdev_region(MKDEV(hello_major,hello_minor),1);
 fail:
 return err;
 
} 
/*模块卸载方法*/
static void __exit hello_exit(void)
{
 dev_t devno = MKDEV(hello_major,hello_minor);
 printk(KERN_ALERT"Destroy hello device.\n");
 /*删除/proc/hello文件*/
 hello_remove_proc();
 /*销毁设备类别和设备*/
 if(hello_class)
 {
 device_destroy(hello_class,MKDEV(hello_major,hello_minor));
 class_destroy(hello_class);
 }
 /*删除字符设备和释放设备内存*/
 if(hello_dev)
 {
 cdev_del(&(hello_dev->dev));
 kfree(hello_dev);
 }
 /*释放设备号*/
 unregister_chrdev_region(devno,1);
 
}
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("First Android Driver");
module_init(hello_init);
module_exit(hello_exit);