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Christoph-Anton Schwierz
EmbeddedLinuxProject
Commits
b3707fdb
Unverified
Commit
b3707fdb
authored
4 months ago
by
CyberKatze2077
Committed by
GitHub
4 months ago
Browse files
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Merge pull request #1 from fesolix/Kernel_Module
Kernel module
parents
1f42c0a2
ad7f5738
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2 changed files
Kernel/Makefile
+7
-0
7 additions, 0 deletions
Kernel/Makefile
Kernel/kernel_M.c
+277
-0
277 additions, 0 deletions
Kernel/kernel_M.c
with
284 additions
and
0 deletions
Kernel/Makefile
0 → 100644
+
7
−
0
View file @
b3707fdb
obj-m
:=
kernel_M.o
KVERSION
=
$(
shell
uname
-r
)
all
:
make
-C
/lib/modules/
$(
KVERSION
)
/build
M
=
$(
PWD
)
modules
clean
:
make
-C
/lib/modules/
$(
KVERSION
)
/build
M
=
$(
PWD
)
clean
\ No newline at end of file
This diff is collapsed.
Click to expand it.
Kernel/kernel_M.c
0 → 100644
+
277
−
0
View file @
b3707fdb
#include
<linux/init.h>
#include
<linux/module.h>
#include
<linux/kernel.h>
#include
<linux/fs.h>
// For file_operations
#include
<linux/uaccess.h>
// For copy_from_user
#include
<linux/cdev.h>
// For cdev
#include
<linux/device.h>
// For device_create, class_create
#include
<linux/slab.h>
// For kmalloc, kfree
#include
<linux/crc32.h>
// Include CRC32
#include
<linux/gpio.h>
// GPIO support
#include
<linux/delay.h>
// Delay functions
#include
<linux/jiffies.h>
// Time measurement
#include
<linux/kthread.h>
// Kernel threads
#include
<linux/sched.h>
// Task scheduling
#define DEVICE_NAME "packet_receiver"
#define CLASS_NAME "packet_class"
// cat /sys/kernel/debug/gpio
#define GPIO_DATA 17 // GPIO for data transmission
#define GPIO_CLOCK 27 // GPIO for clock control
MODULE_LICENSE
(
"GPL"
);
MODULE_AUTHOR
(
"Me :)"
);
MODULE_DESCRIPTION
(
"A kernel module to receive packets from userspace."
);
MODULE_VERSION
(
"1.7"
);
// The size of the receive buffer
#define RECV_BUF_SIZE 512
// Global variables for device number, class, device.
static
dev_t
dev_number
;
static
struct
class
*
packet_class
=
NULL
;
static
struct
cdev
packet_cdev
;
// Store last valid data packet
static
char
last_valid_packet
[
256
]
=
{
0
};
// Time of last transmission
static
struct
task_struct
*
transmit_thread
;
// Flag to control loop in the thread
static
int
keep_sending
=
0
;
// This buffer will temporarily store data from userspace
static
char
*
recv_buffer
;
// Forward declarations for file operations
static
int
packet_open
(
struct
inode
*
inode
,
struct
file
*
file
);
//not used
static
int
packet_release
(
struct
inode
*
inode
,
struct
file
*
file
);
//not used
static
ssize_t
packet_read
(
struct
file
*
filp
,
char
__user
*
buf
,
size_t
len
,
loff_t
*
offset
);
//not used
static
ssize_t
packet_write
(
struct
file
*
filp
,
const
char
__user
*
buf
,
size_t
len
,
loff_t
*
offset
);
static
unsigned
long
calculate_crc32
(
const
char
*
data
,
size_t
len
);
static
int
transmit_loop
(
void
*
data
);
// Kernel thread function
// File operations structure
static
struct
file_operations
fops
=
{
.
owner
=
THIS_MODULE
,
.
open
=
packet_open
,
//not used
.
read
=
packet_read
,
//not used
.
write
=
packet_write
,
.
release
=
packet_release
,
//not used
};
// CRC32 Calculation Function
// uses the same polynomial as zlib’s standard CRC32
static
u32
calculate_crc32
(
const
char
*
data
,
size_t
len
)
{
return
crc32
(
0
,
data
,
len
);
}
// ====================== Device Open ======================
static
int
packet_open
(
struct
inode
*
inode
,
struct
file
*
file
)
{
printk
(
KERN_INFO
"packet_receiver: Device opened.
\n
"
);
return
0
;
}
// ====================== Kernel Thread for Continuous Sending ======================
static
int
transmit_loop
(
void
*
data
)
{
while
(
!
kthread_should_stop
())
{
if
(
keep_sending
&&
strlen
(
last_valid_packet
)
>
0
)
{
// Wait for clock signal
if
(
gpio_get_value
(
GPIO_CLOCK
)
==
1
)
{
printk
(
KERN_INFO
"packet_receiver: Clock HIGH -> Pausing transmission.
\n
"
);
msleep
(
100
);
// Small sleep to avoid busy looping
continue
;
}
// Transmit the last valid packet
for
(
size_t
i
=
0
;
i
<
strlen
(
last_valid_packet
);
i
++
)
{
gpio_set_value
(
GPIO_DATA
,
1
);
msleep
(
1
);
gpio_set_value
(
GPIO_DATA
,
0
);
msleep
(
1
);
}
printk
(
KERN_INFO
"packet_receiver: Sent data to GPIO %d
\n
"
,
GPIO_DATA
);
// Wait 3x the transmission time before sending again
msleep
(
strlen
(
last_valid_packet
)
*
3
);
}
else
{
msleep
(
100
);
// Wait if no valid packet
}
}
return
0
;
}
// ====================== Device Read ======================
static
ssize_t
packet_read
(
struct
file
*
filp
,
char
__user
*
buf
,
size_t
len
,
loff_t
*
offset
)
{
printk
(
KERN_INFO
"packet_receiver: Read called.
\n
"
);
return
0
;
}
// ====================== Device Write ======================
static
ssize_t
packet_write
(
struct
file
*
filp
,
const
char
__user
*
buf
,
size_t
len
,
loff_t
*
offset
)
{
// Bound the incoming size to the size of the buffer
size_t
to_copy
=
min
(
len
,
(
size_t
)
RECV_BUF_SIZE
-
1
);
// Clear the buffer before copying data into it (for safety)
memset
(
recv_buffer
,
0
,
RECV_BUF_SIZE
);
// Copy data from user space into recv_buffer
if
(
copy_from_user
(
recv_buffer
,
buf
,
to_copy
)
!=
0
)
{
printk
(
KERN_ERR
"packet_receiver: copy_from_user failed.
\n
"
);
return
-
EFAULT
;
}
// Ensure null-termination
recv_buffer
[
to_copy
]
=
'\0'
;
unsigned
int
sender_hex
=
0
;
int
value_id_0
=
-
1
,
value_id_1
=
-
1
;
char
value_str_0
[
64
]
=
{
0
};
char
value_str_1
[
64
]
=
{
0
};
unsigned
long
crc_val
=
0
;
printk
(
KERN_INFO
"packet_receiver: Parsed fields [matches=%d]:
\n
"
,
matches
);
printk
(
KERN_INFO
" sender=0x%X
\n
"
,
sender_hex
);
printk
(
KERN_INFO
" value_id_0=%d value_0=
\"
%s
\"\n
"
,
value_id_0
,
value_str_0
);
printk
(
KERN_INFO
" value_id_1=%d value_1=
\"
%s
\"\n
"
,
value_id_1
,
value_str_1
);
printk
(
KERN_INFO
" crc=0x%lX
\n
"
,
crc_val
);
// Prepare the payload for CRC verification
char
crc_buffer
[
256
];
snprintf
(
crc_buffer
,
sizeof
(
crc_buffer
),
"SENDER=0x%x VALUE_ID=%d VALUE=%s VALUE_ID=%d VALUE=%s"
,
sender_hex
,
value_id_0
,
value_str_0
,
value_id_1
,
value_str_1
);
// Calculate CRC32 for the received data excluding the CRC field
unsigned
long
computed_crc
=
calculate_crc32
(
crc_buffer
,
strlen
(
crc_buffer
));
printk
(
KERN_INFO
" computed_crc=0x%lX
\n
"
,
computed_crc
);
// Check CRC32 before transmission
if
(
computed_crc
!=
crc_val
)
{
printk
(
KERN_ERR
"packet_receiver: CRC32 mismatch! Data rejected.
\n
"
);
return
-
EIO
;
}
// Store the valid packet
strcpy
(
last_valid_packet
,
crc_buffer
);
keep_sending
=
1
;
printk
(
KERN_INFO
"packet_receiver: Sent data to GPIO %d
\n
"
,
GPIO_DATA
);
// Return the number of bytes written
return
len
;
}
// ====================== Device Release ======================
static
int
packet_release
(
struct
inode
*
inode
,
struct
file
*
file
)
{
printk
(
KERN_INFO
"packet_receiver: Device closed.
\n
"
);
return
0
;
}
// ====================== Module Init ======================
static
int
__init
packet_init
(
void
)
{
int
ret
;
// Allocate a device number dynamically
ret
=
alloc_chrdev_region
(
&
dev_number
,
0
,
1
,
DEVICE_NAME
);
if
(
ret
<
0
)
{
printk
(
KERN_ERR
"packet_receiver: Failed to allocate major/minor.
\n
"
);
return
ret
;
}
printk
(
KERN_INFO
"packet_receiver: Registered with major=%d, minor=%d
\n
"
,
MAJOR
(
dev_number
),
MINOR
(
dev_number
));
// Initialize the cdev structure
cdev_init
(
&
packet_cdev
,
&
fops
);
packet_cdev
.
owner
=
THIS_MODULE
;
// Add the cdev to the kernel
ret
=
cdev_add
(
&
packet_cdev
,
dev_number
,
1
);
if
(
ret
<
0
)
{
printk
(
KERN_ERR
"packet_receiver: Unable to add cdev.
\n
"
);
unregister_chrdev_region
(
dev_number
,
1
);
return
ret
;
}
// Create a class for udev
packet_class
=
class_create
(
CLASS_NAME
);
if
(
IS_ERR
(
packet_class
))
{
printk
(
KERN_ERR
"packet_receiver: Failed to create class.
\n
"
);
cdev_del
(
&
packet_cdev
);
unregister_chrdev_region
(
dev_number
,
1
);
return
PTR_ERR
(
packet_class
);
}
// Create a device node /dev/packet_receiver
if
(
IS_ERR
(
device_create
(
packet_class
,
NULL
,
dev_number
,
NULL
,
DEVICE_NAME
)))
{
printk
(
KERN_ERR
"packet_receiver: Failed to create device.
\n
"
);
class_destroy
(
packet_class
);
cdev_del
(
&
packet_cdev
);
unregister_chrdev_region
(
dev_number
,
1
);
return
-
1
;
}
// Allocate memory for receive buffer
recv_buffer
=
kmalloc
(
RECV_BUF_SIZE
,
GFP_KERNEL
);
if
(
!
recv_buffer
)
{
printk
(
KERN_ERR
"packet_receiver: Failed to allocate recv_buffer.
\n
"
);
device_destroy
(
packet_class
,
dev_number
);
class_destroy
(
packet_class
);
cdev_del
(
&
packet_cdev
);
unregister_chrdev_region
(
dev_number
,
1
);
return
-
ENOMEM
;
}
gpio_request
(
GPIO_DATA
,
"packet_data"
);
gpio_request
(
GPIO_CLOCK
,
"packet_clock"
);
gpio_direction_output
(
GPIO_DATA
,
0
);
gpio_direction_input
(
GPIO_CLOCK
);
// Clock is an input signal
// Start the transmission thread
transmit_thread
=
kthread_run
(
transmit_loop
,
NULL
,
"packet_transmitter"
);
if
(
IS_ERR
(
transmit_thread
))
{
printk
(
KERN_ERR
"packet_receiver: Failed to create transmit_thread.
\n
"
);
kfree
(
recv_buffer
);
device_destroy
(
packet_class
,
dev_number
);
class_destroy
(
packet_class
);
cdev_del
(
&
packet_cdev
);
unregister_chrdev_region
(
dev_number
,
1
);
return
PTR_ERR
(
transmit_thread
);
}
printk
(
KERN_INFO
"packet_receiver: Module loaded.
\n
"
);
return
0
;
}
// ====================== Module Exit ======================
static
void
__exit
packet_exit
(
void
)
{
// Stop the transmission thread
kthread_stop
(
transmit_thread
);
// Free recv_buffer
kfree
(
recv_buffer
);
// Remove device node
device_destroy
(
packet_class
,
dev_number
);
// Destroy class
class_destroy
(
packet_class
);
// Delete cdev
cdev_del
(
&
packet_cdev
);
// Free device numbers
unregister_chrdev_region
(
dev_number
,
1
);
// Free GPIOs
gpio_free
(
GPIO_DATA
);
gpio_free
(
GPIO_CLOCK
);
printk
(
KERN_INFO
"packet_receiver: Module unloaded.
\n
"
);
}
module_init
(
packet_init
);
module_exit
(
packet_exit
);
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