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Christian Löpke
bs
Commits
7c8b38b5
Commit
7c8b38b5
authored
9 years ago
by
Peter Gerwinski
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Beispiele für Kernel-Modul-Entwicklung
parent
a749b710
Branches
main
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20160425/Makefile
+8
-0
8 additions, 0 deletions
20160425/Makefile
20160425/chardev-1.c
+166
-0
166 additions, 0 deletions
20160425/chardev-1.c
20160425/hellomod-1.c
+20
-0
20 additions, 0 deletions
20160425/hellomod-1.c
with
194 additions
and
0 deletions
20160425/Makefile
0 → 100644
+
8
−
0
View file @
7c8b38b5
obj-m
+=
hellomod-1.o
obj-m
+=
chardev-1.o
all
:
make
-C
/lib/modules/
$(
shell
uname
-r
)
/build
M
=
$(
PWD
)
modules
clean
:
make
-C
/lib/modules/
$(
shell
uname
-r
)
/build
M
=
$(
PWD
)
clean
This diff is collapsed.
Click to expand it.
20160425/chardev-1.c
0 → 100644
+
166
−
0
View file @
7c8b38b5
/*
* chardev.c: Creates a read-only char device that says how many times
* you've read from the dev file
*/
#include
<linux/kernel.h>
#include
<linux/module.h>
#include
<linux/fs.h>
#include
<asm/uaccess.h>
/* for put_user */
/*
* Prototypes - this would normally go in a .h file
*/
int
init_module
(
void
);
void
cleanup_module
(
void
);
static
int
device_open
(
struct
inode
*
,
struct
file
*
);
static
int
device_release
(
struct
inode
*
,
struct
file
*
);
static
ssize_t
device_read
(
struct
file
*
,
char
*
,
size_t
,
loff_t
*
);
static
ssize_t
device_write
(
struct
file
*
,
const
char
*
,
size_t
,
loff_t
*
);
#define SUCCESS 0
#define DEVICE_NAME "chardev"
/* Dev name as it appears in /proc/devices */
#define BUF_LEN 80
/* Max length of the message from the device */
/*
* Global variables are declared as static, so are global within the file.
*/
static
int
Major
;
/* Major number assigned to our device driver */
static
int
Device_Open
=
0
;
/* Is device open?
* Used to prevent multiple access to device */
static
char
msg
[
BUF_LEN
];
/* The msg the device will give when asked */
static
char
*
msg_Ptr
;
static
struct
file_operations
fops
=
{
.
read
=
device_read
,
.
write
=
device_write
,
.
open
=
device_open
,
.
release
=
device_release
};
/*
* This function is called when the module is loaded
*/
int
init_module
(
void
)
{
Major
=
register_chrdev
(
0
,
DEVICE_NAME
,
&
fops
);
if
(
Major
<
0
)
{
printk
(
KERN_ALERT
"Registering char device failed with %d
\n
"
,
Major
);
return
Major
;
}
printk
(
KERN_INFO
"I was assigned major number %d. To talk to
\n
"
,
Major
);
printk
(
KERN_INFO
"the driver, create a dev file with
\n
"
);
printk
(
KERN_INFO
"'mknod /dev/%s c %d 0'.
\n
"
,
DEVICE_NAME
,
Major
);
printk
(
KERN_INFO
"Try various minor numbers. Try to cat and echo to
\n
"
);
printk
(
KERN_INFO
"the device file.
\n
"
);
printk
(
KERN_INFO
"Remove the device file and module when done.
\n
"
);
return
SUCCESS
;
}
/*
* This function is called when the module is unloaded
*/
void
cleanup_module
(
void
)
{
/*
* Unregister the device
*/
unregister_chrdev
(
Major
,
DEVICE_NAME
);
}
/*
* Methods
*/
/*
* Called when a process tries to open the device file, like
* "cat /dev/mycharfile"
*/
static
int
device_open
(
struct
inode
*
inode
,
struct
file
*
file
)
{
static
int
counter
=
0
;
if
(
Device_Open
)
return
-
EBUSY
;
Device_Open
++
;
sprintf
(
msg
,
"I already told you %d times Hello world!
\n
"
,
counter
++
);
msg_Ptr
=
msg
;
try_module_get
(
THIS_MODULE
);
return
SUCCESS
;
}
/*
* Called when a process closes the device file.
*/
static
int
device_release
(
struct
inode
*
inode
,
struct
file
*
file
)
{
Device_Open
--
;
/* We're now ready for our next caller */
/*
* Decrement the usage count, or else once you opened the file, you'll
* never get get rid of the module.
*/
module_put
(
THIS_MODULE
);
return
0
;
}
/*
* Called when a process, which already opened the dev file, attempts to
* read from it.
*/
static
ssize_t
device_read
(
struct
file
*
filp
,
/* see include/linux/fs.h */
char
*
buffer
,
/* buffer to fill with data */
size_t
length
,
/* length of the buffer */
loff_t
*
offset
)
{
/*
* Number of bytes actually written to the buffer
*/
int
bytes_read
=
0
;
/*
* If we're at the end of the message,
* return 0 signifying end of file
*/
if
(
*
msg_Ptr
==
0
)
return
0
;
/*
* Actually put the data into the buffer
*/
while
(
length
&&
*
msg_Ptr
)
{
/*
* The buffer is in the user data segment, not the kernel
* segment so "*" assignment won't work. We have to use
* put_user which copies data from the kernel data segment to
* the user data segment.
*/
put_user
(
*
(
msg_Ptr
++
),
buffer
++
);
length
--
;
bytes_read
++
;
}
/*
* Most read functions return the number of bytes put into the buffer
*/
return
bytes_read
;
}
/*
* Called when a process writes to dev file: echo "hi" > /dev/hello
*/
static
ssize_t
device_write
(
struct
file
*
filp
,
const
char
*
buff
,
size_t
len
,
loff_t
*
off
)
{
printk
(
KERN_ALERT
"Sorry, this operation isn't supported.
\n
"
);
return
-
EINVAL
;
}
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20160425/hellomod-1.c
0 → 100644
+
20
−
0
View file @
7c8b38b5
/*
* hello-1.c - The simplest kernel module.
*/
#include
<linux/module.h>
/* Needed by all modules */
#include
<linux/kernel.h>
/* Needed for KERN_INFO */
int
init_module
(
void
)
{
printk
(
KERN_INFO
"Hello world 1.
\n
"
);
/*
* A non 0 return means init_module failed; module can't be loaded.
*/
return
0
;
}
void
cleanup_module
(
void
)
{
printk
(
KERN_INFO
"Goodbye world 1.
\n
"
);
}
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