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timer: hpet: don't force TIMER_READS_ITS_FREQUENCY_AT_RUNTIME

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This allows the HPET timer to use kconfig to specify clock
frequency instead of relying on calculation at runtime.
When the frequency is known at build, this allow the toolchain
to optimize some calculations.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This commit is contained in:
Daniel Leung 2021-05-19 16:42:58 -07:00 • committed by Carles Cufí
commit b9cc043434
2 changed files with 20 additions and 4 deletions
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2
drivers/timer/Kconfig
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@ -83,7 +83,7 @@ config HPET_TIMER
depends on X86
select IOAPIC if X86
select LOAPIC if X86
select TIMER_READS_ITS_FREQUENCY_AT_RUNTIME
imply TIMER_READS_ITS_FREQUENCY_AT_RUNTIME
select TICKLESS_CAPABLE
help
This option selects High Precision Event Timer (HPET) as a

22
drivers/timer/hpet.c
View file

@ -50,11 +50,22 @@ DEVICE_MMIO_TOPLEVEL_STATIC(hpet_regs, DT_DRV_INST(0));
#define HPET_CMP_MIN_DELAY (1000)
#endif
#define MAX_TICKS 0x7FFFFFFFUL
static __pinned_bss struct k_spinlock lock;
static __pinned_bss unsigned int max_ticks;
static __pinned_bss unsigned int cyc_per_tick;
static __pinned_bss unsigned int last_count;
#ifdef CONFIG_TIMER_READS_ITS_FREQUENCY_AT_RUNTIME
static __pinned_bss unsigned int cyc_per_tick;
static __pinned_bss unsigned int max_ticks;
#else
#define cyc_per_tick \
(CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC / CONFIG_SYS_CLOCK_TICKS_PER_SEC)
#define max_ticks \
((MAX_TICKS - cyc_per_tick) / cyc_per_tick)
#endif /* CONFIG_TIMER_READS_ITS_FREQUENCY_AT_RUNTIME */
__isr
static void hpet_isr(const void *arg)
{
@ -124,6 +135,8 @@ int sys_clock_driver_init(const struct device *dev)
uint32_t hz;
ARG_UNUSED(dev);
ARG_UNUSED(hz);
ARG_UNUSED(z_clock_hw_cycles_per_sec);
DEVICE_MMIO_TOPLEVEL_MAP(hpet_regs, K_MEM_CACHE_NONE);
@ -133,10 +146,14 @@ int sys_clock_driver_init(const struct device *dev)
set_timer0_irq(DT_INST_IRQN(0));
irq_enable(DT_INST_IRQN(0));
#ifdef CONFIG_TIMER_READS_ITS_FREQUENCY_AT_RUNTIME
hz = (uint32_t)(HPET_COUNTER_CLK_PERIOD / CLK_PERIOD_REG);
z_clock_hw_cycles_per_sec = hz;
cyc_per_tick = hz / CONFIG_SYS_CLOCK_TICKS_PER_SEC;
max_ticks = (MAX_TICKS - cyc_per_tick) / cyc_per_tick;
#endif
/* Note: we set the legacy routing bit, because otherwise
* nothing in Zephyr disables the PIT which then fires
* interrupts into the same IRQ. But that means we're then
@ -148,7 +165,6 @@ int sys_clock_driver_init(const struct device *dev)
TIMER0_CONF_REG &= ~TCONF_FSB_EN;
TIMER0_CONF_REG |= TCONF_MODE32;
max_ticks = (0x7fffffff - cyc_per_tick) / cyc_per_tick;
last_count = MAIN_COUNTER_REG;
TIMER0_CONF_REG |= TCONF_INT_ENABLE;