Counter reader

counter.c

@@ -10,7 +10,7 @@
 #include <linux/kthread.h>
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Inex Code");
-MODULE_DESCRIPTION("A counter device");
+MODULE_DESCRIPTION("A counter_reader device");
 MODULE_VERSION("0.0.3");
 
 #define DEVICE_NAME "inex_counter"
@@ -53,7 +53,7 @@ static int counter_thread(void *data) {
 }
 
 static int __init counter_init(void) {
-	printk(KERN_INFO "Counter: Initializing the counter device.\n");
+	printk(KERN_INFO "Counter: Initializing the counter_reader device.\n");
 	Major = register_chrdev(0, DEVICE_NAME, &counter_fops);
 	if (Major < 0) {
 		printk(KERN_ALERT "Registering char device failed with %d\n", Major);
@@ -93,7 +93,7 @@ static int device_release(struct inode *inode, struct file *file) {
 }
 
 static ssize_t device_read(struct file *filp, char __user *buffer, size_t length, loff_t *offset) {
-	// Output the counter value to the user.
+	// Output the counter_reader value to the user.
 	int bytes_read = 0;
 	char buf[32];
 	int len = sprintf(buf, "%d\n", counter);
@@ -107,13 +107,13 @@ static ssize_t device_read(struct file *filp, char __user *buffer, size_t length
 		return -EINVAL;
 	}
 	bytes_read = len;
-	printk("Counter: Read %d bytes, counter = %d", bytes_read, counter);
+	printk("Counter: Read %d bytes, counter_reader = %d", bytes_read, counter);
 	is_read = 1;
 	return bytes_read;
 }
 
 static ssize_t device_write(struct file *filp, const char __user *buffer, size_t length, loff_t *offset) {
-	// Input the counter value from the user.
+	// Input the counter_reader value from the user.
 	char buf[32];
 	int len = length;
 	if (len > sizeof(buf)) {

counter_reader/counter_reader.py

@@ -0,0 +1,16 @@
+"""
+This file is used to read the counter_reader value from the /dev/inex_counter device.
+The value is then send as a notification.
+"""
+
+from subprocess import run
+
+
+def __main__():
+    """
+    This function is called when the script is executed.
+    """
+    # Read the counter_reader value from the device.
+    counter_value = run(["cat", "/dev/inex_counter"], capture_output=True).stdout.decode("utf-8")
+    # Send the counter_reader value as a notification.
+    run(["notify-send", "Counter value", counter_value])

counter_reader/counter_reader.service

@@ -0,0 +1,14 @@
+[Unit]
+# A short human readable title of the unit
+Description=Counter Reader
+
+[Service]
+# Configures the process start-up type for this service unit, one of:
+# simple - The process defined in ExecStart= will stay in the foreground while the unit is activated.
+# forking - The process defined in ExecStart= will fork a background process and exit right away.
+# oneshot - The process will exit right away, use with RemainAfterExit= to ensure the serice is marked as active.
+# Consult the documentantion for types (https://www.freedesktop.org/software/systemd/man/systemd.service.html#Type=) other options.
+Type=oneshot
+# Command with arguments to invoke when the unit is activated.
+# This runs a python script that reads the counter
+ExecStart=/usr/bin/python3 /home/inex/dev/Linux/counter_reader/counter_reader.py

counter_reader/counter_reader.timer

@@ -0,0 +1,21 @@
+[Unit]
+# A short human readable title of the unit
+Description=Counter Reader launcher
+# A list of units whose activations will occur before this unit starts.
+After=network.target
+
+[Timer]
+# The syntax for timers is described in (https://www.freedesktop.org/software/systemd/man/systemd.time.html#)
+# A shorthand version is that you can specify timers by specifying values using (us, ms, s, m, h, days, weeks, months, years)
+# e.g., 2 weeks 1 hours or 1 year 6 months or 5 m 30 s
+
+# Defines a timer relative to the moment the timer unit itself is activated.
+OnActiveSec=30s
+
+# In addition to the above, OnCalendar takes a cron like syntax or values such as (minutely, hourly, daily, monthly, weekly,...)
+# Defines realtime (i.e. wallclock) timers with calendar event expressions
+OnCalendar=daily
+
+[Install]
+# A list of units who when activated will try and activate this unit
+WantedBy=multi-user.target