diff --git a/Kernel/kernel_M.c b/Kernel/kernel_M.c
index 67a1fa516ffdcd7d76156024d27029554b330903..24b72cb5ff359f8959f8640bb9af7d7e5dc26ec4 100644
--- a/Kernel/kernel_M.c
+++ b/Kernel/kernel_M.c
@@ -1,30 +1,32 @@
#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"
+#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("1.0");
-/*
-// Structure to hold our packet data
-struct packet_data {
- int sender_id;
- int value_id_1;
- int value_1;
- int value_id_2;
- int value_2;
-};
-*/
+MODULE_VERSION("1.7");
// The size of the receive buffer
#define RECV_BUF_SIZE 512
@@ -34,6 +36,15 @@ 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;
@@ -42,6 +53,8 @@ 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 = {
@@ -53,6 +66,7 @@ static struct file_operations fops = {
};
// 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);
}
@@ -63,6 +77,36 @@ static int packet_open(struct inode *inode, struct file *file) {
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");
@@ -86,61 +130,39 @@ static ssize_t packet_write(struct file *filp, const char __user *buf, size_t le
// Ensure null-termination
recv_buffer[to_copy] = '\0';
- /* // Placeholders for the fields:
- struct packet_data p_data;
- p_data.sender_id = -1;
- p_data.value_id_1 = -1;
- p_data.value_1 = -1;
- p_data.value_id_2 = -1;
- p_data.value_2 = -1;
-*/
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;
-
- // Example format:
- // "SENDER=1 ID1=100 VAL1=222 ID2=101 VAL2=333"
- // "SENDER=10 VID1=11 VAL1=100 VID2=12 VAL2=200"
-/*
- sscanf(recv_buffer, "SENDER=%d VID1=%d VAL1=%d VID2=%d VAL2=%d",
- &p_data.sender_id,
- &p_data.value_id_1,
- &p_data.value_1,
- &p_data.value_id_2,
- &p_data.value_2);
-*/
- int matches = sscanf(recv_buffer,
- "SENDER=0x%x VALUE_ID=%d VALUE=%63s VALUE_ID=%d VALUE=%63s CRC=0x%lx",
- &sender_hex,
- &value_id_0, value_str_0,
- &value_id_1, value_str_1,
- &crc_val);
- // Print the received packet data
- /* printk(KERN_INFO "packet_receiver: Received packet -> "
- "sender=0x%x, valID1=%d, val1=%d, valID2=%d, val2=%d\n",
- p_data.sender_id,
- p_data.value_id_1, p_data.value_1,
- p_data.value_id_2, p_data.value_2);
-*/
+
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
- size_t crc_len = strrchr(recv_buffer, 'C') - recv_buffer;
- u32 calculated_crc = calculate_crc32(recv_buffer, crc_len);
-
- if (calculated_crc == received_crc) {
- printk(KERN_INFO "packet_receiver: CRC check passed!\n");
- } else {
- printk(KERN_ERR "packet_receiver: CRC mismatch! Expected: 0x%08X, Received: 0x%08lX\n",
- calculated_crc, received_crc);
+ 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;
}
@@ -205,16 +227,35 @@ static int __init packet_init(void) {
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
- if (recv_buffer) {
- kfree(recv_buffer);
- }
+ kfree(recv_buffer);
// Remove device node
device_destroy(packet_class, dev_number);
@@ -224,6 +265,9 @@ static void __exit packet_exit(void) {
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");
}