kmod.c

#include "../common/include/measurement.h"
#include <linux/cdev.h>
#include <linux/crc32.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/gpio.h>
#include <linux/hrtimer.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <linux/vmalloc.h>

#define DEVICE_NAME "sibyl"
#define CLASS_NAME "sibyl_class"

#define SLOTS 4
#define SLOT_INTERVAL_NS 100000000

#define MAX_MEASUREMENTS 16

#define BAUD_RATE 9600
#define BIT_TIME_US (1000000 / BAUD_RATE)
#define GPIO_PIN 575

static int major_number;
static struct class *class = NULL;
static struct cdev mycdev;

typedef struct packet {
  uint8_t magic;
  data_t data;
  uint32_t crc;
} packet_t;

static packet_t *packet;

static struct hrtimer timer;
static ktime_t interval;

static struct task_struct *timed_thread;

static DECLARE_WAIT_QUEUE_HEAD(wq);
static atomic_t wake_counter = ATOMIC_INIT(0);

// Send Buffers
#define SEND_BUFFER_SIZE 4096

static struct mutex send_buffer_mutex;

static uint8_t *primary_send_buffer;
static size_t primary_send_buffer_size = 0;

static uint8_t *secondary_send_buffer;
static size_t secondary_send_buffer_size = 0;

static int slot = 0;

static int device_open(struct inode *inode, struct file *file) { return 0; }

static int device_release(struct inode *inode, struct file *file) { return 0; }

static uint32_t calculate_crc32(const packet_t *packet) {
  uint32_t crc = crc32(0, (void *)&packet->magic, sizeof(uint8_t));
  crc = crc32(crc, (void *)&packet->data.sender_id, sizeof(uint8_t));
  crc = crc32(crc, (void *)&packet->data.count, sizeof(uint8_t));
  crc = crc32(crc, (void *)&packet->data.measurements,
              sizeof(measurement_t) * packet->data.count);
  return crc;