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[kernel] Fix clock period vs frequency error

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Calling `spinwait()` was hanging due to improper computation of the
clock rate because justin did a dumb at math. Also the period can be
greater than 1ns, so the clock's units were updated to microseconds.
This commit is contained in:
Justin C. Miller
2020-07-12 17:43:37 -07:00
parent 794c86f9b4
commit f4cbb9498f
7 changed files with 41 additions and 23 deletions
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11
src/kernel/hpet.cpp
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@@ -37,7 +37,7 @@ hpet::hpet(uint8_t index, uint64_t *base) :
m_timers = ((caps >> 8) & 0x1f) + 1;
m_period = (caps >> 32);
// setup_timer_interrupts(0, 2, 1000000, true);
setup_timer_interrupts(0, 2, 1000, true);
// bool installed = device_manager::get()
// .install_irq(2, "HPET Timer", hpet_irq_callback, this);
// kassert(installed, "Installing HPET IRQ handler");
@@ -57,6 +57,7 @@ hpet::hpet(uint8_t index, uint64_t *base) :
log::debug(logs::timer, "HPET %d timer %d:", index, i);
log::debug(logs::timer, " int type: %d", (config >> 1) & 1);
log::debug(logs::timer, " int enable: %d", (config >> 2) & 1);
log::debug(logs::timer, " timer type: %d", (config >> 3) & 1);
log::debug(logs::timer, " periodic cap: %d", (config >> 4) & 1);
log::debug(logs::timer, " bits: %d", ((config >> 5) & 1) ? 64 : 32);
@@ -72,10 +73,10 @@ hpet::hpet(uint8_t index, uint64_t *base) :
void
hpet::setup_timer_interrupts(unsigned timer, uint8_t irq, uint64_t interval, bool periodic)
{
constexpr uint64_t femto_per_ns = 1000000ull;
constexpr uint64_t femto_per_us = 1000000000ull;
*timer_comparator(m_base, timer) =
*counter_value(m_base) +
(interval * femto_per_ns) / m_period;
(interval * femto_per_us) / m_period;
*timer_config(m_base, timer) = (irq << 9) | ((periodic ? 1 : 0) << 3);
}
@@ -102,9 +103,7 @@ void
hpet::enable()
{
log::debug(logs::timer, "HPET %d enabling", m_index);
enable_timer(0);
*configuration(m_base) = 1;
*configuration(m_base) = (*configuration(m_base) & 0x3) | 1;
}
uint64_t