- struct s5p_timer *const timer = s5p_get_base_timer();
- unsigned long tmo, tmp, count_value;
-
- count_value = readl(&timer->tcntb4);
-
- if (usec >= 1000) {
- /*
- * if "big" number, spread normalization
- * to seconds
- * 1. start to normalize for usec to ticks per sec
- * 2. find number of "ticks" to wait to achieve target
- * 3. finish normalize.
- */
- tmo = usec / 1000;
- tmo *= (CONFIG_SYS_HZ * count_value / 10);
- tmo /= 1000;
- } else {
- /* else small number, don't kill it prior to HZ multiply */
- tmo = usec * CONFIG_SYS_HZ * count_value / 10;
- tmo /= (1000 * 1000);
- }
-
- /* get current timestamp */
- tmp = get_timer(0);
-
- /* if setting this fordward will roll time stamp */
- /* reset "advancing" timestamp to 0, set lastinc value */
- /* else, set advancing stamp wake up time */
- if ((tmo + tmp + 1) < tmp)
- reset_timer_masked();
- else
- tmo += tmp;
-
- /* loop till event */
- while (get_timer_masked() < tmo)
- ; /* nop */
+ static unsigned long base_time_us;
+
+ struct s5p_timer *const timer =
+ (struct s5p_timer *)samsung_get_base_timer();
+ unsigned long now_downward_us = readl(&timer->tcnto4);
+
+ if (!base_time_us)
+ base_time_us = now_downward_us;
+
+ /* Note that this timer counts downward. */
+ return base_time_us - now_downward_us;