[Lesson 5] Time management and Fibonacci sequence.

lesson-05-time-management/Makefile

@@ -0,0 +1,19 @@
+#
+# Memory management example
+#
+
+ifneq ($(KERNELRELEASE),)
+
+obj-m += xxxtm.o
+
+else
+
+KERNELDIR := $(BUILD_KERNEL)
+
+.PHONY: all clean
+all:
+	$(MAKE) -C $(KERNELDIR) M=$(CURDIR) modules
+clean:
+	$(MAKE) -C $(KERNELDIR) M=$(CURDIR) clean
+
+endif

lesson-05-time-management/xxxtm.c

@@ -0,0 +1,203 @@
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <asm/uaccess.h>
+#include <linux/pci.h>
+#include <linux/version.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+
+static u64 g_last_sys_time = 0;
+static struct timeval g_last_abs_time = {0, 0};
+
+#define FIBO1_INIT 0
+#define FIBO2_INIT 1
+static unsigned int g_fibo1 = FIBO1_INIT;
+static unsigned int g_fibo2 = FIBO2_INIT;
+#define FIBO_NUMBER_BUFFER 10 + 10 + 2
+
+static void compute_fibo_next(unsigned int *fibo1, unsigned int *fibo2)
+{
+   unsigned int fibo_temp = *fibo1 + *fibo2;
+   *fibo1 = *fibo2;
+   *fibo2 = fibo_temp;
+}
+
+static void dump_fibo_sequence(char *buf)
+{
+   unsigned int fibo_max = g_fibo2;
+   unsigned int fibo1 = FIBO1_INIT;
+   unsigned int fibo2 = FIBO2_INIT;
+   while (fibo2 <= fibo_max) {
+      char tem_buf[FIBO_NUMBER_BUFFER] = {0};
+      int count = 0;
+      if (fibo1 == FIBO1_INIT)
+         count = sprintf(tem_buf, "%u %u ", fibo1, fibo2);
+      else
+         count = sprintf(tem_buf, "%u ", fibo2);
+      //pr_info("%s: count %d, buf %p", __FUNCTION__, count, buf);
+      if (count > 0)
+      {
+         strncpy(buf, tem_buf, count);
+         buf += count;
+         buf[0] = '\0';
+         //pr_info("%s: count %d, buf %p/%d", __FUNCTION__, count, buf, buf[0]);
+      }
+      compute_fibo_next(&fibo1, &fibo2);
+   }
+   buf[0] = '\n';
+}
+
+static ssize_t tm_jif_show(struct class *class, struct class_attribute *attr,
+   char *buf)
+{
+   size_t count = 0;
+   u64 sys_time = get_jiffies_64();
+   unsigned int seconds = 0;
+   if (g_last_sys_time) {
+      u64 diff = sys_time - g_last_sys_time;
+      seconds = jiffies_to_msecs(diff) / MSEC_PER_SEC;
+   }
+   sprintf(buf, "%u\n", seconds);
+   count = strlen(buf);
+   g_last_sys_time = sys_time;
+   return count;
+}
+
+static ssize_t tm_absk_show(struct class *class, struct class_attribute *attr,
+   char *buf)
+{
+   size_t count = 0;
+   struct timeval tv;
+   unsigned long time;
+   if (!buf)
+      return count;
+
+   do_gettimeofday(&tv);
+   time = g_last_abs_time.tv_sec
+      ? g_last_abs_time.tv_sec : tv.tv_sec;
+   if (time) {
+      struct tm tm_val;
+      time_to_tm(time, 0, &tm_val);
+      sprintf(buf, "%d-%d-%ld %02d:%02d:%02d\n",
+         tm_val.tm_mday, tm_val.tm_mon + 1, 1900 + tm_val.tm_year,
+         tm_val.tm_hour, tm_val.tm_min, tm_val.tm_sec);
+   }
+   else {
+      buf[0] = '\0';
+   }
+
+   count = strlen(buf);
+   g_last_abs_time = tv;
+   return count;
+}
+
+static void schedule_timer(void);
+#define TIMER_DELAY_MSEC 1000
+
+static void fibo_timer(unsigned long data)
+{
+   compute_fibo_next(&g_fibo1, &g_fibo2);
+   schedule_timer();
+}
+
+struct timer_list g_fibo_timer = __TIMER_INITIALIZER(fibo_timer, 0, 0, TIMER_IRQSAFE);
+
+static void schedule_timer(void)
+{
+   u64 time;
+   int ret;
+
+   time = get_jiffies_64() + msecs_to_jiffies(TIMER_DELAY_MSEC);
+   ret = mod_timer(&g_fibo_timer, time);
+   //pr_info("%s: timer rescheduled: %d\n", __FUNCTION__, ret);
+}
+
+static ssize_t tm_fibo_show(struct class *class, struct class_attribute *attr,
+   char *buf)
+{
+   size_t count = 0;
+   if (!buf)
+      return count;
+
+   dump_fibo_sequence(buf);
+
+   count = strlen(buf);
+   return count;
+}
+
+struct class_attribute class_attr_tm_jif  = __ATTR_RO(tm_jif);
+struct class_attribute class_attr_tm_absk = __ATTR_RO(tm_absk);
+struct class_attribute class_attr_tm_fibo = __ATTR_RO(tm_fibo);
+
+static struct class *tm_jif_class = NULL;
+static struct class *tm_absk_class = NULL;
+static struct class *tm_fibo_class = NULL;
+
+void x_cleanup(void)
+{
+   if (tm_fibo_class) {
+      class_remove_file(tm_fibo_class, &class_attr_tm_fibo);
+      class_destroy(tm_fibo_class);
+   }
+
+   if (tm_absk_class) {
+      class_remove_file(tm_absk_class, &class_attr_tm_absk);
+      class_destroy(tm_absk_class);
+   }
+
+   if (tm_jif_class) {
+      class_remove_file(tm_jif_class, &class_attr_tm_jif);
+      class_destroy(tm_jif_class);
+   }
+
+   del_timer_sync(&g_fibo_timer);
+}
+
+int __init x_init(void)
+{
+   int res = 0;
+   tm_jif_class = class_create(THIS_MODULE, "tm_jif-class");
+   if(IS_ERR(tm_jif_class)) {
+      pr_info("bad class create\n");
+      goto error1;
+   }
+   res = class_create_file(tm_jif_class, &class_attr_tm_jif);
+   if (res != 0)
+      goto error1;
+
+   tm_absk_class = class_create(THIS_MODULE, "tm_absk-class");
+   if(IS_ERR(tm_absk_class)) {
+      pr_info("bad class create\n");
+      goto error1;
+   }
+   res = class_create_file(tm_absk_class, &class_attr_tm_absk);
+   if (res != 0)
+      goto error1;
+
+   tm_fibo_class = class_create(THIS_MODULE, "tm_fibo-class");
+   if(IS_ERR(tm_fibo_class)) {
+      pr_info("bad class create\n");
+      goto error1;
+   }
+   res = class_create_file(tm_fibo_class, &class_attr_tm_fibo);
+   if (res != 0)
+      goto error1;
+
+   schedule_timer();
+
+   pr_info("'xxxtm' module initialized %d\n", res);
+   return res;
+
+error1:
+   pr_err("initialization error\n");
+   x_cleanup();
+   return res;
+}
+
+module_init(x_init);
+module_exit(x_cleanup);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sergii.Romantsov serg.cramser@gmail.com");