국립한밭대학교 반도체설계실artoa.hanbat.ac.kr/lecture_data/embedded_sw/10.pdf · 2012-08-02 · Embedded System Software I ! " #" $%&’( )˜ * +˝, -. " /01 2 3 /0 45

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Lee, J a e H eu n gLee, J a e H eu n g

Embedded System Software I

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myDriver

Device

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IO System

osDriver

Device


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Device file

VFS

Device Driver

Real Device

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brw------- 1 root floppy 2, 0 May 6 1998 fd0brw-rw---- 1 root disk 3, 0 May 6 1998 hdabrw-rw---- 1 root disk 3, 1 May 6 1998 hda1brw-rw---- 1 root disk 8, 0 May 6 1998 sdabrw-rw---- 1 root disk 8, 1 May 6 1998 sda1

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Major & Minor Number

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Application

System Call Interface

VFS

Network SubsystemBuffer Cache

Network D/DBlock D/DChar Device Driver

Device Interface

Hardware

Applicationarea

Kernelarea

Hardware


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init_module( )insmod register_capability( )

capabilities[ ]

printk( )…..

cleanup_module( ) unregister_capability( )rmmod


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-c : �� object �� insmod�� runtime � � � � � � � � �-O2 : � � � � � , � � inline function� � � �-Wall : � � waning� � !-D__KERNEL__ : " # � � # $ % � & � (user process � % ' ( ) )-DMODULE : � � * $ + , - . � � � - / 0 1 2 3 4 5 6 7 �� 8 9 !

CC = gccCFALGS = -D__KERNEL__ -DMODULE -O2 -WallOBJS = hello.o

all : $(OBJS)clean:

rm -f *.o *.~


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userprogram

openclosereadwrite

file operationsdev_opendev_closedev_readdev_write

isrrx_isrtx_isr

device

systemcall

interrupt

kernel

device driver


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#include <linux/kernel.h>#include <linux/module.h>#include <linux/init.h>

Header Files

int device_open( … ) { … }int device_release( … ) { … }ssize_t device_write( … ) { … }ssize_t device_read( … ) { … }

Function Prototypes

static struct file_operations device_fops = { …ssize_t (*read) (…);ssize_t (*write) (…); …int (*open) (…);int (*release) (…);…

};

File Operation

int init_module(void) { … } �!�!�!�! 1 21 21 21 2 3333 4 - 54 - 54 - 54 - 5 6 76 76 76 7

void cleanup_module(void) { … } �!�!�!�! / 0/ 0/ 0/ 0 3333 8 98 98 98 9 : ; 6 7: ; 6 7: ; 6 7: ; 6 7

22


Device Driver $ �$ �$ �$ � (1)� D e v i ce s t r u ct u r e

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26

struct file_operations dummy_fops = { open : dummy_open, // openread : dummy_read, // read write : dummy_write, // write release : dummy_release, // release

};

struct file_operations dummy_fops = { open : dummy_open, // openread : dummy_read, // read write : dummy_write, // write release : dummy_release, // release

};


Device Driver $�$�$�$�(5)

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27

struct file_operations { /* <linux/fs.h> */struct module *owner;loff_t (*llseek) (struct file *, loff_t, int);ssize_t (*read) (struct file *, char *, size_t, loff_t *);ssize_t (*write) (struct file *, const char *, size_t, loff_t *);int (*readdir) (struct file *, void *, filldir_t);unsigned int (*poll) (struct file *, struct poll_table_struct *);int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);int (*mmap) (struct file *, struct vm_area_struct *);int (*open) (struct inode *, struct file *);int (*flush) (struct file *);int (*release) (struct inode *, struct file *);int (*fsync) (struct file *, struct dentry *, int datasync);int (*fasync) (int, struct file *, int);int (*lock) (struct file *, int, struct file_lock *);ssize_t (*readv) (struct file *, const struct iovec *, unsigned long, loff_t *);ssize_t (*writev) (struct file *, const struct iovec *, unsigned long, loff_t *);

};

struct file_operations { /* <linux/fs.h> */struct module *owner;loff_t (*llseek) (struct file *, loff_t, int);ssize_t (*read) (struct file *, char *, size_t, loff_t *);ssize_t (*write) (struct file *, const char *, size_t, loff_t *);int (*readdir) (struct file *, void *, filldir_t);unsigned int (*poll) (struct file *, struct poll_table_struct *);int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);int (*mmap) (struct file *, struct vm_area_struct *);int (*open) (struct inode *, struct file *);int (*flush) (struct file *);int (*release) (struct inode *, struct file *);int (*fsync) (struct file *, struct dentry *, int datasync);int (*fasync) (int, struct file *, int);int (*lock) (struct file *, int, struct file_lock *);ssize_t (*readv) (struct file *, const struct iovec *, unsigned long, loff_t *);ssize_t (*writev) (struct file *, const struct iovec *, unsigned long, loff_t *);

};


Device Driver $�$�$�$�(6)�File operations

28

loff_t (*llseek)(struct file *, loff_t, int);

�� read/write � � � � � .

ssize_t (*read)(struct file *, char *, size_t, loff_t *);

� � � � � � � � � � � � � � � � � �ssize_t (*write)(struct file*, const char*, size_t, loff_t*);

� � � � � � � � � � � � � � �int (*readdir)(struct file *, void *, filldir_t);

� � � � � � � � �unsigned int (*poll)(struct file*, struct poll_table_struct*);

�� ! � " � # � $ � � � � � �

loff_t (*llseek)(struct file *, loff_t, int);

�� read/write � � � � � .

ssize_t (*read)(struct file *, char *, size_t, loff_t *);

� � � � � � � � � � � � � � � � � �ssize_t (*write)(struct file*, const char*, size_t, loff_t*);

� � � � � � � � � � � � � � �int (*readdir)(struct file *, void *, filldir_t);

� � � � � � � � �unsigned int (*poll)(struct file*, struct poll_table_struct*);

�� ! � " � # � $ � � � � � �



�File operations

29

int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);

� � � � % & ' ( ) * + , - � � � � �Int (*mmap) (struct file *, struct vm_area_struct *);

� � � . / � � � ! . / � � 0 1int (*open) (struct inode *, struct file *);

� � � 2 3 � �� 4 5 6 7 8 9 : ; <int (*flush) (struct file *);

� � � � = � > � / ? � � � � @ .

int (*release) (struct inode *, struct file *);

� � � � = + � 4 5

int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);

� � � � % & ' ( ) * + , - � � � � �Int (*mmap) (struct file *, struct vm_area_struct *);

� � � . / � � � ! . / � � 0 1int (*open) (struct inode *, struct file *);

� � � 2 3 � �� 4 5 6 7 8 9 : ; <int (*flush) (struct file *);

� � � � = � > � / ? � � � � @ .

int (*release) (struct inode *, struct file *);

� � � � = + � 4 5



�File operations

3 0

int (*fsync) (struct file *, struct dentry *);

� A B � C 7 � � � � / D � � � @ int (*fasync) (int, struct file *, int);

int (*check_media_change) (kdev_t dev);

� E F � � � � � � , G H � I J K L � � �

int (*revalidate) (kdev_t dev);

� E F � � � � � � , A B M N � O � P Q O

int (*lock) (struct file *, int, struct file_lock *);

� R S � lock+ T � � � � � �

int (*fsync) (struct file *, struct dentry *);

� A B � C 7 � � � � / D � � � @ int (*fasync) (int, struct file *, int);

int (*check_media_change) (kdev_t dev);

� E F � � � � � � , G H � I J K L � � �

int (*revalidate) (kdev_t dev);

� E F � � � � � � , A B M N � O � P Q O

int (*lock) (struct file *, int, struct file_lock *);

� R S � lock+ T � � � � � �


Device Driver $�$�$�$�(9)� D u m m y C h arac ter d ev ic e � �� . �� . �� . �� . ��

3 1

#define DUMMY_MAJOR_NUMBER 254 /* dummy.c */struct file_operations dummy_fops = {

open : dummy_open, // openread : dummy_read, // read write : dummy_write, // write release : dummy_release, // release

};

char device_name[20];

int init_module(void) // ��, � � � �� !" #!" #!" #!" # register_chrdev$!$!$!$!{

printk("init module start \n"); strcpy(device_name, "Dummy_Device"); register_chrdev( DUMMY_MAJOR_NUMBER, device_name, &dummy_fops); return 0;

}

void cleanup_module(void) // % &% &% &% & , ' (' (' (' ( ) *) *) *) * , � � � �� & + !" #& + !" #& + !" #& + !" # unregister_chrdev $$$$!!!!

{

printk("Clean Up Module\n"); unregister_chrdev(DUMMY_MAJOR_NUMBER,device_name);

}

#define DUMMY_MAJOR_NUMBER 254 /* dummy.c */struct file_operations dummy_fops = {

open : dummy_open, // openread : dummy_read, // read write : dummy_write, // write release : dummy_release, // release

};

char device_name[20];

int init_module(void) // ��, � � � �� !" #!" #!" #!" # register_chrdev$!$!$!$!{

printk("init module start \n"); strcpy(device_name, "Dummy_Device"); register_chrdev( DUMMY_MAJOR_NUMBER, device_name, &dummy_fops); return 0;

}

void cleanup_module(void) // % &% &% &% & , ' (' (' (' ( ) *) *) *) * , � � � �� & + !" #& + !" #& + !" #& + !" # unregister_chrdev $$$$!!!!

{

printk("Clean Up Module\n"); unregister_chrdev(DUMMY_MAJOR_NUMBER,device_name);

}



� S y stem c all : d u m m y _ open� F i l e _ op e r a t i on s n � ! �6 op e n op e r a t i on n X� A p p l i c a t i on p r og r a m�6 ‘op e n ’ � �� 6 � � �

� S y stem c all : d u m m y _ release� F i l e _ op e r a t i on s n � ! �6 r e l e a s e op e r a t i on n X� A p p l i c a t i on p r og r a m�6 ‘c l os e ’ � �� 6 � � �

3 2

int dummy_open(struct inode *inode, struct file *file) {

printk("Open call for Dummy Char Device \n"); return 0;

}

int dummy_open(struct inode *inode, struct file *file) {

printk("Open call for Dummy Char Device \n"); return 0;

}

int dummy_release(struct inode *inode, struct file *file) {

printk("Release call for Dummy Char Device \n"); return 0;

}

int dummy_release(struct inode *inode, struct file *file) {

printk("Release call for Dummy Char Device \n"); return 0;

}

open : dummy_openread : dummy_readwrite : dummy_writerelease : dummy_release



� S y stem c all : d u m m y _ read� F i l e _ op e r a t i on s n � ! �6 r e a d op e r a t i on n X� A p p l i c a t i on p r og r a m�6 ‘r e a d’ � �� 6 � � �

� S y stem c all : d u m m y _ w rite� F i l e _ op e r a t i on s n � ! �6 w r i t e op e r a t i on n X� A p p l i c a t i on p r og r a m�6 ‘w r i t e ’ � �� 6 � � �

3 3

ssize_t dummy_read(struct file *file, char *buffer, size_t length, loff_t *offset) {

printk("Read Call for Dummy Device \n"); buffer[0] = 0x34; return 0;

}

ssize_t dummy_read(struct file *file, char *buffer, size_t length, loff_t *offset) {

printk("Read Call for Dummy Device \n"); buffer[0] = 0x34; return 0;

}

ssize_t dummy_write(struct file *file, const char *buffer, size_t length, loff_t *offset) {

printk("Write Call for Dummy Device : [%x]\n ", buffer[0]); return 0;

}

ssize_t dummy_write(struct file *file, const char *buffer, size_t length, loff_t *offset) {

printk("Write Call for Dummy Device : [%x]\n ", buffer[0]); return 0;

}

open : dummy_openread : dummy_readwrite : dummy_writerelease : dummy_release


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3 4


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3 5

……….�� ……..fd = open("/dev/DUMMY_DEVICE", O_RDWR); if ( fd <= 0 ) {

printf(“Dummy Char Device File Open Fail!\n"); exit(0);

}

buf[0] = 0x12; write(fd, buf, 1); read(fd, buf, 1); printf("%x\n", buf[0]); close(fd);

……….�� ……..fd = open("/dev/DUMMY_DEVICE", O_RDWR); if ( fd <= 0 ) {

printf(“Dummy Char Device File Open Fail!\n"); exit(0);

}

buf[0] = 0x12; write(fd, buf, 1); read(fd, buf, 1); printf("%x\n", buf[0]); close(fd);


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3 6

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국립한밭대학교 반도체설계실artoa.hanbat.ac.kr/lecture_data/embedded_sw/10.pdf · 2012-08-02 · Embedded System Software I ! " #" $%&’( )˜ * +˝, -. " /01 2 3 /0 45