From d89dd0c63736102c49c0b5c8fac7f094163cae13 Mon Sep 17 00:00:00 2001
From: alexanderchamara <alexanderchamara@gmail.com>
Date: Sun, 29 Oct 2017 16:55:27 +0200
Subject: [PATCH] Add files via upload

---
 lesson-04-memory-management/mm/xxx.c | 169 +++++++++++++++++++++++----
 1 file changed, 147 insertions(+), 22 deletions(-)

diff --git a/lesson-04-memory-management/mm/xxx.c b/lesson-04-memory-management/mm/xxx.c
index c15b3cf..f9cfbea 100644
--- a/lesson-04-memory-management/mm/xxx.c
+++ b/lesson-04-memory-management/mm/xxx.c
@@ -1,48 +1,173 @@
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/cdev.h>
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 #include <linux/pci.h>
-#include <linux/version.h>
 #include <linux/init.h>
+#include <linux/err.h>
+#include <linux/jiffies.h>
+#include <linux/time.h>
+#include <linux/timer.h>
 
-#define LEN_MSG 160
-static char buf_msg[ LEN_MSG + 1 ] = "Hello from module!\n";
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Aleksandr Chamara");
+MODULE_DESCRIPTION("sysfc test module");
+MODULE_VERSION("0.1");
 
+//================================================================
+#define MODULE_TAG      "xxx_module --> "
+#define LEN_MSG 32
+#define TIMER_PERIOD_MSEC 1000
+
+//================================================================
+static char *buf_msg;
+static struct class *x_class;
+static struct timer_list timer;
+static unsigned int fib_val;
+
+//================================================================
+static void reload_timer(void)
+{
+	int err;
+	err = mod_timer( &timer, jiffies + msecs_to_jiffies(TIMER_PERIOD_MSEC) );
+	if (err)
+		printk( MODULE_TAG "Timer modification error\n" );
+}
+
+static void timer_func (unsigned long parameter)
+{
+	static unsigned int iter;
+	unsigned int i = 1;
+	unsigned int x = 1;
+	unsigned int y = 0;
+
+	iter++;
+	for (i = 1; i < iter; i++)
+	{
+		x += y;
+		y = x - y;
+	}
+	fib_val = x;
+
+	reload_timer();
+}
+
+static void timer_init(void)
+{
+	setup_timer( &timer, timer_func, 0 );
+	reload_timer();
+}
+
+static int create_buffer(void)
+{
+	buf_msg = kmalloc( LEN_MSG, GFP_KERNEL );
+    if ( NULL == buf_msg )
+        return -ENOMEM;
+    memset( buf_msg, 0, LEN_MSG );
+    return 0;
+}
+
+
+static void cleanup_buffer(void)
+{
+    if ( buf_msg ) {
+        kfree(buf_msg);
+        buf_msg = NULL;
+    }
+}
 
 static ssize_t xxx_show( struct class *class, struct class_attribute *attr, char *buf ) {
-   strcpy( buf, buf_msg );
-   printk( "read %ld\n", (long)strlen( buf ) );
-   return strlen( buf );
+	static unsigned long long read_time_prev;
+	static unsigned char first_call = true;
+	unsigned long long read_time_curr = jiffies/1000;
+	struct timeval absolute_time;
+
+	do_gettimeofday(&absolute_time);
+
+	snprintf(buf_msg, LEN_MSG, "%d\n", fib_val);
+	strcpy( buf, buf_msg );
+	if(first_call){
+		printk( "%ld.%ld:" MODULE_TAG "read %ld\n", absolute_time.tv_sec,
+													absolute_time.tv_usec,
+													(long)strlen( buf ));
+		first_call = false;
+	}
+	else{
+		printk( "%ld.%ld:" MODULE_TAG "read %ld. Previous read was %llu sec ago\n", absolute_time.tv_sec,
+																					absolute_time.tv_usec,
+																					(long)strlen( buf ),
+																					read_time_curr - read_time_prev);
+	}
+
+	read_time_prev = read_time_curr;
+	return strlen( buf );
 }
 
 static ssize_t xxx_store( struct class *class, struct class_attribute *attr, const char *buf, size_t count ) {
-   printk( "write %ld\n", (long)count );
-   strncpy( buf_msg, buf, count );
-   buf_msg[ count ] = '\0';
-   return count;
+
+	size_t byte_number = (count < LEN_MSG) ? count : LEN_MSG;
+	struct timeval absolute_time;
+
+	do_gettimeofday( &absolute_time );
+
+	printk( "%ld.%ld:" MODULE_TAG "write %ld\n", absolute_time.tv_sec,
+												 absolute_time.tv_usec,
+												 (long)byte_number );
+	strncpy( buf_msg, buf, byte_number );
+	buf_msg[ byte_number ] = '\0';
+	return byte_number;
 }
 
 CLASS_ATTR_RW( xxx );
 
-static struct class *x_class;
-
+//================================================================
 int __init x_init(void) {
-   int res;
+   int err;
+
    x_class = class_create( THIS_MODULE, "x-class" );
-   if( IS_ERR( x_class ) ) printk( "bad class create\n" );
-   res = class_create_file( x_class, &class_attr_xxx );
-   printk( "'xxx' module initialized\n" );
-   return res;
+   if( IS_ERR( x_class ) ){
+	   err = PTR_ERR( x_class );
+	   printk( MODULE_TAG "File creation error\n");
+	   goto class_create_err;
+   }
+
+   err = class_create_file( x_class, &class_attr_xxx );
+   if( err ){
+	   printk( MODULE_TAG "Class creation error\n");
+	   goto file_create_err;
+   }
+
+    err = create_buffer();
+	if( err ){
+		printk( MODULE_TAG "Memory allocation error\n" );
+		goto mem_aloc_err;
+	}
+
+
+	timer_init();
+	printk( MODULE_TAG "Module initialized successfully\n" );
+	return 0;
+
+mem_aloc_err:
+	// do nothing here
+
+file_create_err:
+	class_remove_file( x_class, &class_attr_xxx );
+
+class_create_err:
+	class_destroy( x_class );
+    return err;
 }
 
 void x_cleanup(void) {
-   class_remove_file( x_class, &class_attr_xxx );
-   class_destroy( x_class );
-   return;
+	cleanup_buffer();
+	class_remove_file( x_class, &class_attr_xxx );
+	class_destroy( x_class );
+	del_timer( &timer );
+	return;
 }
 
+//================================================================
 module_init( x_init );
 module_exit( x_cleanup );
 
-MODULE_LICENSE( "GPL" );