aspeed/timer: Ensure positive muldiv delta
If the host decrements the counter register that results in a negative delta. This is then passed to muldiv64 which only handles unsigned numbers resulting in bogus results. This fix ensures the delta being operated on is positive. Test case: kexec a kernel using aspeed_timer and it will freeze on the second bootup when the kernel initializes the timer. With this patch that no longer happens and the timer appears to run OK. Signed-off-by: Christian Svensson <bluecmd@google.com> Signed-off-by: Cédric Le Goater <clg@kaod.org> Reviewed-by: Joel Stanley <joel@jms.id.au> Reviewed-by: Andrew Jeffery <andrew@aj.id.au> Message-id: 20190618165311.27066-12-clg@kaod.org Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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@ -275,7 +275,11 @@ static void aspeed_timer_set_value(AspeedTimerCtrlState *s, int timer, int reg,
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int64_t delta = (int64_t) value - (int64_t) calculate_ticks(t, now);
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uint32_t rate = calculate_rate(t);
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if (delta >= 0) {
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t->start += muldiv64(delta, NANOSECONDS_PER_SECOND, rate);
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} else {
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t->start -= muldiv64(-delta, NANOSECONDS_PER_SECOND, rate);
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}
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aspeed_timer_mod(t);
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}
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break;
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