On 22/9/22 17:58, Tyler Ng wrote:
1. Adds fields to hold the value of mtime in timer_upper0 and timer_lower0.
2. Changes the read and write functions to use the mtime fields.
3. Updates the value of mtime in update_mtime() by extrapolating the
time elapsed. This will need to change if/when the prescalar is
implemented.
4. Adds a qtest for the ibex timer.
Signed-off-by: Tyler Ng <t...@rivosinc.com>
---
hw/timer/ibex_timer.c | 98 +++++++++++++------
include/hw/timer/ibex_timer.h | 6 ++
tests/qtest/ibex-timer-test.c | 178 ++++++++++++++++++++++++++++++++++
tests/qtest/meson.build | 3 +-
4 files changed, 256 insertions(+), 29 deletions(-)
create mode 100644 tests/qtest/ibex-timer-test.c
-static void ibex_timer_update_irqs(IbexTimerState *s)
+/*
+ * The goal of this function is to:
+ * 1. Check if the timer is enabled. If not, return false,
+ * 2. Calculate the amount of time that has passed since.
+ * 3. Extrapolate the number of ticks that have passed, and add it to `mtime`.
+ * 4. Return true.
+ */
+static bool update_mtime(IbexTimerState *s)
{
- uint64_t value = s->timer_compare_lower0 |
- ((uint64_t)s->timer_compare_upper0 << 32);
- uint64_t next, diff;
- uint64_t now = cpu_riscv_read_rtc(s->timebase_freq);
-
if (!(s->timer_ctrl & R_CTRL_ACTIVE_MASK)) {
- /* Timer isn't active */
+ return false;
+ }
+ /* Get the time then extrapolate the number of ticks that have elapsed */
+ uint64_t mtime = get_mtime(s);
+ int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ int64_t elapsed = now - s->timer_last_update;
+ if (elapsed < 0) {
+ /* We jumped back in time. */
+ mtime -= muldiv64((uint64_t)(-elapsed), s->timebase_freq,
+ NANOSECONDS_PER_SECOND);
+ } else {
+ mtime += muldiv64(elapsed, s->timebase_freq, NANOSECONDS_PER_SECOND);
+ }
+ s->timer_lower0 = mtime & 0xffffffff;
+ s->timer_upper0 = (mtime >> 32) & 0xffffffff;
Could use extract64(mtime, 0, 32) and extract64(mtime, 32, 32);
+ /* update last-checkpoint timestamp */
+ s->timer_last_update = now;
+ return true;
+}
