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// STM32F0 timer support
//
// Copyright (C) 2019 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "board/armcm_boot.h" // armcm_enable_irq
#include "board/armcm_timer.h" // udelay
#include "board/internal.h" // TIM3
#include "board/io.h" // readl
#include "board/irq.h" // irq_disable
#include "board/misc.h" // timer_read_time
#include "sched.h" // DECL_INIT
#include "command.h" // DECL_SHUTDOWN
#include "board/timer_irq.h" // timer_dispatch_many
/****************************************************************
* Low level timer code
****************************************************************/
// Use 32bit TIM2 timer if available (otherwise use 16bit TIM3 timer)
#ifdef TIM2
#define TIMx TIM2
#define TIMx_IRQn TIM2_IRQn
#define HAVE_TIMER_32BIT 1
#else
#define TIMx TIM3
#define TIMx_IRQn TIM3_IRQn
#define HAVE_TIMER_32BIT 0
#endif
static inline uint32_t
timer_get(void)
{
return TIMx->CNT;
}
static inline void
timer_set(uint32_t next)
{
TIMx->CCR1 = next;
TIMx->SR = 0;
}
// Activate timer dispatch as soon as possible
void
timer_kick(void)
{
timer_set(timer_get() + 50);
}
/****************************************************************
* 16bit hardware timer to 32bit conversion
****************************************************************/
// High bits of timer (top 17 bits)
static uint32_t timer_high;
// Return the current time (in absolute clock ticks).
uint32_t __always_inline
timer_read_time(void)
{
if (HAVE_TIMER_32BIT)
return timer_get();
uint32_t th = readl(&timer_high);
uint32_t cur = timer_get();
// Combine timer_high (high 17 bits) and current time (low 16
// bits) using method that handles rollovers correctly.
return (th ^ cur) + (th & 0xffff);
}
// Update timer_high every 0x8000 clock ticks
static uint_fast8_t
timer_event(struct timer *t)
{
timer_high += 0x8000;
t->waketime = timer_high + 0x8000;
return SF_RESCHEDULE;
}
static struct timer wrap_timer = {
.func = timer_event,
.waketime = 0x8000,
};
void
timer_reset(void)
{
if (!HAVE_TIMER_32BIT)
sched_add_timer(&wrap_timer);
}
DECL_SHUTDOWN(timer_reset);
/****************************************************************
* Setup and irqs
****************************************************************/
// Hardware timer IRQ handler - dispatch software timers
void __aligned(16)
TIMx_IRQHandler(void)
{
irq_disable();
uint32_t next = timer_dispatch_many();
timer_set(next);
irq_enable();
}
void
timer_init(void)
{
irqstatus_t flag = irq_save();
enable_pclock((uint32_t)TIMx);
TIMx->CNT = 0;
TIMx->DIER = TIM_DIER_CC1IE;
TIMx->CCER = TIM_CCER_CC1E;
armcm_enable_irq(TIMx_IRQHandler, TIMx_IRQn, 2);
timer_kick();
timer_reset();
TIMx->CR1 = TIM_CR1_CEN;
irq_restore(flag);
}
DECL_INIT(timer_init);
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