linux 3.10.49カーネルベースの文字ドライバの追加

linux 3.10.49カーネルベースの文字ドライバの追加
linux kernel 3.10.49+
文字駆動はカーネルにコンパイルされる.
1.driversディレクトリの下にMyDemoディレクトリを新規作成する.
2.MyDemoディレクトリ新規3ファイル:demo.c  Kconfig  Makefile
3.Kconfigファイルを修正する:
MyDemo-> cat Kconfig

#
# TPM device configuration
#

config MY_DEMO 
	bool "my demo test driver!!!"
    default y
	---help---
	  If you have a TPM security chip that is compliant with the
	  TCG TIS 1.2 TPM specification say Yes and it will be accessible
	  from within Linux.  To compile this driver as a module, choose
	  M here; the module will be called tpm_tis.

このKconfigはCONFIGを生成しますMY_DEMOというマクロは、defaulty 4のため、デフォルトで生成されます.Makefileを変更するには:
MyDemo-> cat Makefile 

obj-$(CONFIG_MY_DEMO) += demo.o

5.demoを修正する.c:
MyDemo-> cat demo.c

/// @file demo.c
/// @brief 
/// @author EastonWoo <[email protected]>
/// 0.01
/// @date 2016-05-26

#include   
#include   
#include   
#include   
#include   
#include   
#include   
  
#include 

#define MYDEMO_MAJOR 105
#define MYDEMO_MINNOR 9 
#define MYDEMO_BUF_LEN 100

static loff_t g_llMyDemoPos = 0;

static int mydemodev_open(struct inode *inode, struct file *file)
{
	unsigned int minor = iminor(inode);
    char *demo_buf;

	demo_buf = kzalloc(MYDEMO_BUF_LEN, GFP_KERNEL);
    memset(demo_buf, 0, MYDEMO_BUF_LEN);
	if (!demo_buf) {
		return -ENOMEM;
	}

	file->private_data = demo_buf;
    printk(KERN_WARNING "[%s %s %d] minor = %u
", __FILE__, __func__, __LINE__, minor);
	return 0;
}

static int mydemodev_release(struct inode *inode, struct file *file)
{
	unsigned int minor = iminor(inode);
    char *demo_buf = file->private_data;
	kfree(demo_buf);
	file->private_data = NULL;
    printk(KERN_WARNING "[%s %s %d] minor = %u
", __FILE__, __func__, __LINE__, minor);

	return 0;
}

/// @brief 
///
/// @param file
/// @param buf          :    read(int fildes, void *buf, size_t nbyte) buf
/// @param count        :    read(int fildes, void *buf, size_t nbyte) nbyte
/// @param offset       :        &file->f_pos,     file->f_pos     
///
/// @return             :    read(int fildes, void *buf, size_t nbyte)    
ssize_t mydemodev_read(struct file *file, char __user *buf, size_t count, loff_t *offset) {
    loff_t pos = file->f_pos + count;
    size_t really_cnt = count;
    int ret = 0;
    
    if (NULL == buf) {
        return -EINVAL;
    }
    if (pos >= MYDEMO_BUF_LEN) {
        really_cnt = MYDEMO_BUF_LEN - 1 - file->f_pos;
    }

    /* ret = copy_to_user(buf, file->private_data + file->f_pos, really_cnt) ? -EFAULT : ret; */  //       , file->f_pos     
    ret = copy_to_user(buf, file->private_data + g_llMyDemoPos, really_cnt) ? -EFAULT : ret;
    if (ret != -EFAULT)
        file->f_pos += really_cnt;

    printk(KERN_WARNING "[%s %s %d] really_cnt = %d
", __FILE__, __func__, __LINE__, really_cnt);
    g_llMyDemoPos = file->f_pos;
    return really_cnt;
}

/// @brief 
///
/// @param file
/// @param buf          :    write(int fildes, const void *buf, size_t nbyte) buf
/// @param count        :    write(int fildes, const void *buf, size_t nbyte) nbyte
/// @param offset       :        &file->f_pos,     file->f_pos     
///
/// @return             :    write(int fildes, const void *buf, size_t nbyte)    
ssize_t mydemodev_write(struct file *file, const char __user *buf, size_t count, loff_t *offset) {
    int ret = 0;
    
    if (NULL == buf) {
        return -EINVAL;
    }
    if (file->f_pos + count >= MYDEMO_BUF_LEN) {
        return -EINVAL;
    }
    /* ret = copy_from_user(file->private_data + file->f_pos, buf, count) ? -EFAULT : ret; */ //       , file->f_pos     
    ret = copy_from_user(file->private_data + g_llMyDemoPos, buf, count) ? -EFAULT : ret;
    if (ret != -EFAULT)
        file->f_pos += count;

    printk(KERN_WARNING "[%s %s %d] count = %d
", __FILE__, __func__, __LINE__, count);

    g_llMyDemoPos = file->f_pos;
    return count;
}

/// @brief 
///
/// @param file
/// @param offset   :    lseek(int fd, off_t offset, int whence) offset
/// @param where    :    lseek(int fd, off_t offset, int whence) whence
///
/// @return         :    lseek(int fd, off_t offset, int whence)    
loff_t mydemodev_llseek(struct file *file, loff_t offset, int where) {
    //      
    loff_t pos = file->f_pos + offset;

    switch(where) {
        case SEEK_SET:
            if (offset >= MYDEMO_BUF_LEN || offset < 0) {
                return -EINVAL;
            }
            file->f_pos = offset;
            break;
        case SEEK_CUR:
        case SEEK_END:
            if (pos >= MYDEMO_BUF_LEN || pos < 0) {
                return -EINVAL;
            }
            file->f_pos = pos;
            break;
        default:
            return -EINVAL;
            break;
    }
    printk(KERN_WARNING "[%s %s %d] pos = %lld iminor(file->f_inode) = %u
", __FILE__, __func__, __LINE__, file->f_pos, iminor(file->f_inode));

    g_llMyDemoPos = file->f_pos;
    return file->f_pos;
}

static const struct file_operations mydemodev_fops = {
	.owner		= THIS_MODULE,
    .llseek		= mydemodev_llseek,                   // 1-2  --| 
    .read		= mydemodev_read,                     // 1-2  --|
    .write		= mydemodev_write,                    // 1-2  --|     ,     . 
	// .unlocked_ioctl	= i2cdev_ioctl,
    .open		= mydemodev_open,                     // 1-1  --|
    .release	= mydemodev_release,                  // 1-1  --|      ,            .
};

static struct class *mydemo_dev_class;


static int __init mydemo_dev_init(void)
{
	int res;

	printk(KERN_INFO "my char dev demo entries driver
");

	res = register_chrdev(MYDEMO_MAJOR, "mydemo", &mydemodev_fops);             //1.       
	if (res)
		goto out;

	mydemo_dev_class = class_create(THIS_MODULE, "mydemo-class");               //2.   class,   /sys/class/    mydemo-class   
	if (IS_ERR(mydemo_dev_class)) {
		res = PTR_ERR(mydemo_dev_class);
		goto out_unreg_chrdev;
	}
    device_create(mydemo_dev_class,NULL,MKDEV(MYDEMO_MAJOR, MYDEMO_MINNOR),NULL,"mydemo-dev" "%d", MYDEMO_MINNOR); //3.   class,   /dev/    mydemo-dev9  .

	return 0;

	class_destroy(mydemo_dev_class);
out_unreg_chrdev:
	unregister_chrdev(MYDEMO_MAJOR, "mydemo");
out:
	printk(KERN_ERR "%s: Driver Initialisation failed
", __FILE__);
	return res;
}

static void __exit mydemo_dev_exit(void)
{
	printk(KERN_INFO "my char dev demo out driver
");
	class_destroy(mydemo_dev_class);
	unregister_chrdev(MYDEMO_MAJOR, "mydemo");
}

MODULE_AUTHOR("EastonWoo <[email protected]>");
MODULE_DESCRIPTION("my char dev demo entries driver");
MODULE_LICENSE("GPL");

module_init(mydemo_dev_init);
module_exit(mydemo_dev_exit);

6.drivers/Makefileを変更するには:
Obj-$(CONFIG_MY_DEMO)+=MyDemo/を追加
7.drivers/char/Kconfigを修正する:
ソース「drivers/MyDemo/Kconfig」を追加
これで完成です.テストをコンパイルできます.