diff options
Diffstat (limited to 'hw/timer/aspeed_timer.c')
| -rw-r--r-- | hw/timer/aspeed_timer.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/hw/timer/aspeed_timer.c b/hw/timer/aspeed_timer.c index ed81d5c..59c2bbe 100644 --- a/hw/timer/aspeed_timer.c +++ b/hw/timer/aspeed_timer.c @@ -44,6 +44,13 @@ enum timer_ctrl_op { op_pulse_enable }; +/* + * Minimum value of the reload register to filter out short period + * timers which have a noticeable impact in emulation. 5us should be + * enough, use 20us for "safety". + */ +#define TIMER_MIN_NS (20 * SCALE_US) + /** * Avoid mutual references between AspeedTimerCtrlState and AspeedTimer * structs, as it's a waste of memory. The ptimer BH callback needs to know @@ -98,6 +105,14 @@ static inline uint32_t calculate_ticks(struct AspeedTimer *t, uint64_t now_ns) return t->reload - MIN(t->reload, ticks); } +static uint32_t calculate_min_ticks(AspeedTimer *t, uint32_t value) +{ + uint32_t rate = calculate_rate(t); + uint32_t min_ticks = muldiv64(TIMER_MIN_NS, rate, NANOSECONDS_PER_SECOND); + + return value < min_ticks ? min_ticks : value; +} + static inline uint64_t calculate_time(struct AspeedTimer *t, uint32_t ticks) { uint64_t delta_ns; @@ -261,7 +276,7 @@ static void aspeed_timer_set_value(AspeedTimerCtrlState *s, int timer, int reg, switch (reg) { case TIMER_REG_RELOAD: old_reload = t->reload; - t->reload = value; + t->reload = calculate_min_ticks(t, value); /* If the reload value was not previously set, or zero, and * the current value is valid, try to start the timer if it is |