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/*
* Copyright (c) 2014-2015 Wind River Systems, Inc.
* Copyright (c) 2018 Synopsys Inc, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/init.h>
#include <zephyr/drivers/timer/system_timer.h>
#include <zephyr/sys_clock.h>
#include <zephyr/spinlock.h>
#include <zephyr/arch/arc/v2/aux_regs.h>
#include <zephyr/irq.h>
/*
* note: This implementation assumes Timer0 is present. Be sure
* to build the ARC CPU with Timer0.
*
* If secureshield is present and secure firmware is configured,
* use secure Timer 0
*/
#ifdef CONFIG_ARC_SECURE_FIRMWARE
#undef _ARC_V2_TMR0_COUNT
#undef _ARC_V2_TMR0_CONTROL
#undef _ARC_V2_TMR0_LIMIT
#define _ARC_V2_TMR0_COUNT _ARC_V2_S_TMR0_COUNT
#define _ARC_V2_TMR0_CONTROL _ARC_V2_S_TMR0_CONTROL
#define _ARC_V2_TMR0_LIMIT _ARC_V2_S_TMR0_LIMIT
#define IRQ_TIMER0 DT_IRQN(DT_NODELABEL(sectimer0))
#else
#define IRQ_TIMER0 DT_IRQN(DT_NODELABEL(timer0))
#endif
#define _ARC_V2_TMR_CTRL_IE 0x1 /* interrupt enable */
#define _ARC_V2_TMR_CTRL_NH 0x2 /* count only while not halted */
#define _ARC_V2_TMR_CTRL_W 0x4 /* watchdog mode enable */
#define _ARC_V2_TMR_CTRL_IP 0x8 /* interrupt pending flag */
/* Minimum cycles in the future to try to program. */
#define MIN_DELAY 1024
/* arc timer has 32 bit, here use 31 bit to avoid the possible
* overflow,e.g, 0xffffffff + any value will cause overflow
*/
#define COUNTER_MAX 0x7fffffff
#define TIMER_STOPPED 0x0
#define CYC_PER_TICK (sys_clock_hw_cycles_per_sec() \
/ CONFIG_SYS_CLOCK_TICKS_PER_SEC)
#define MAX_TICKS ((COUNTER_MAX / CYC_PER_TICK) - 1)
#define MAX_CYCLES (MAX_TICKS * CYC_PER_TICK)
#define TICKLESS (IS_ENABLED(CONFIG_TICKLESS_KERNEL))
#define SMP_TIMER_DRIVER (CONFIG_SMP && CONFIG_MP_MAX_NUM_CPUS > 1)
#if defined(CONFIG_TEST)
const int32_t z_sys_timer_irq_for_test = IRQ_TIMER0;
#endif
static struct k_spinlock lock;
#if SMP_TIMER_DRIVER
volatile static uint64_t last_time;
volatile static uint64_t start_time;
#else
static uint32_t last_load;
/*
* This local variable holds the amount of timer cycles elapsed
* and it is updated in timer_int_handler and sys_clock_set_timeout().
*
* Note:
* At an arbitrary point in time the "current" value of the
* HW timer is calculated as:
*
* t = cycle_counter + elapsed();
*/
static uint32_t cycle_count;
/*
* This local variable holds the amount of elapsed HW cycles
* that have been announced to the kernel.
*/
static uint32_t announced_cycles;
/*
* This local variable holds the amount of elapsed HW cycles due to
* timer wraps ('overflows') and is used in the calculation
* in elapsed() function, as well as in the updates to cycle_count.
*
* Note:
* Each time cycle_count is updated with the value from overflow_cycles,
* the overflow_cycles must be reset to zero.
*/
static volatile uint32_t overflow_cycles;
#endif
/**
* @brief Get contents of Timer0 count register
*
* @return Current Timer0 count
*/
static ALWAYS_INLINE uint32_t timer0_count_register_get(void)
{
return z_arc_v2_aux_reg_read(_ARC_V2_TMR0_COUNT);
}
/**
* @brief Set Timer0 count register to the specified value
*/
static ALWAYS_INLINE void timer0_count_register_set(uint32_t value)
{
z_arc_v2_aux_reg_write(_ARC_V2_TMR0_COUNT, value);
}
/**
* @brief Get contents of Timer0 control register
*
* @return Contents of Timer0 control register.
*/
static ALWAYS_INLINE uint32_t timer0_control_register_get(void)
{
return z_arc_v2_aux_reg_read(_ARC_V2_TMR0_CONTROL);
}
/**
* @brief Set Timer0 control register to the specified value
*/
static ALWAYS_INLINE void timer0_control_register_set(uint32_t value)
{
z_arc_v2_aux_reg_write(_ARC_V2_TMR0_CONTROL, value);
}
/**
* @brief Get contents of Timer0 limit register
*
* @return Contents of Timer0 limit register.
*/
static ALWAYS_INLINE uint32_t timer0_limit_register_get(void)
{
return z_arc_v2_aux_reg_read(_ARC_V2_TMR0_LIMIT);
}
/**
* @brief Set Timer0 limit register to the specified value
*/
static ALWAYS_INLINE void timer0_limit_register_set(uint32_t count)
{
z_arc_v2_aux_reg_write(_ARC_V2_TMR0_LIMIT, count);
}
#if !SMP_TIMER_DRIVER
/* This internal function calculates the amount of HW cycles that have
* elapsed since the last time the absolute HW cycles counter has been
* updated. 'cycle_count' may be updated either by the ISR, or
* in sys_clock_set_timeout().
*
* Additionally, the function updates the 'overflow_cycles' counter, that
* holds the amount of elapsed HW cycles due to (possibly) multiple
* timer wraps (overflows).
*
* Prerequisites:
* - reprogramming of LIMIT must be clearing the COUNT
* - ISR must be clearing the 'overflow_cycles' counter.
* - no more than one counter-wrap has occurred between
* - the timer reset or the last time the function was called
* - and until the current call of the function is completed.
* - the function is invoked with interrupts disabled.
*/
static uint32_t elapsed(void)
{
uint32_t val, ctrl;
do {
val = timer0_count_register_get();
ctrl = timer0_control_register_get();
} while (timer0_count_register_get() < val);
if (ctrl & _ARC_V2_TMR_CTRL_IP) {
overflow_cycles += last_load;
/* clear the IP bit of the control register */
timer0_control_register_set(_ARC_V2_TMR_CTRL_NH |
_ARC_V2_TMR_CTRL_IE);
/* use sw triggered irq to remember the timer irq request
* which may be cleared by the above operation. when elapsed ()
* is called in timer_int_handler, no need to do this.
*/
if (!z_arc_v2_irq_unit_is_in_isr() ||
z_arc_v2_aux_reg_read(_ARC_V2_ICAUSE) != IRQ_TIMER0) {
z_arc_v2_aux_reg_write(_ARC_V2_AUX_IRQ_HINT,
IRQ_TIMER0);
}
}
return val + overflow_cycles;
}
#endif
/**
* @brief System clock periodic tick handler
*
* This routine handles the system clock tick interrupt. It always
* announces one tick when TICKLESS is not enabled, or multiple ticks
* when TICKLESS is enabled.
*/
static void timer_int_handler(const void *unused)
{
ARG_UNUSED(unused);
uint32_t dticks;
#if defined(CONFIG_SMP) && CONFIG_MP_MAX_NUM_CPUS > 1
uint64_t curr_time;
k_spinlock_key_t key;
/* clear the IP bit of the control register */
timer0_control_register_set(_ARC_V2_TMR_CTRL_NH |
_ARC_V2_TMR_CTRL_IE);
key = k_spin_lock(&lock);
/* gfrc is the wall clock */
curr_time = z_arc_connect_gfrc_read();
dticks = (curr_time - last_time) / CYC_PER_TICK;
/* last_time should be aligned to ticks */
last_time += dticks * CYC_PER_TICK;
k_spin_unlock(&lock, key);
sys_clock_announce(dticks);
#else
/* timer_int_handler may be triggered by timer irq or
* software helper irq
*/
/* irq with higher priority may call sys_clock_set_timeout
* so need a lock here
*/
uint32_t key;
key = arch_irq_lock();
elapsed();
cycle_count += overflow_cycles;
overflow_cycles = 0;
arch_irq_unlock(key);
dticks = (cycle_count - announced_cycles) / CYC_PER_TICK;
announced_cycles += dticks * CYC_PER_TICK;
sys_clock_announce(TICKLESS ? dticks : 1);
#endif
}
void sys_clock_set_timeout(int32_t ticks, bool idle)
{
/* If the kernel allows us to miss tick announcements in idle,
* then shut off the counter. (Note: we can assume if idle==true
* that interrupts are already disabled)
*/
#if SMP_TIMER_DRIVER
/* as 64-bits GFRC is used as wall clock, it's ok to ignore idle
* systick will not be missed.
* However for single core using 32-bits arc timer, idle cannot
* be ignored, as 32-bits timer will overflow in a not-long time.
*/
if (IS_ENABLED(CONFIG_TICKLESS_KERNEL) && ticks == K_TICKS_FOREVER) {
timer0_control_register_set(0);
timer0_count_register_set(0);
timer0_limit_register_set(0);
return;
}
#if defined(CONFIG_TICKLESS_KERNEL)
uint32_t delay;
uint32_t key;
ticks = MIN(MAX_TICKS, ticks);
/* Desired delay in the future
* use MIN_DEALY here can trigger the timer
* irq more soon, no need to go to CYC_PER_TICK
* later.
*/
delay = MAX(ticks * CYC_PER_TICK, MIN_DELAY);
key = arch_irq_lock();
timer0_limit_register_set(delay - 1);
timer0_count_register_set(0);
timer0_control_register_set(_ARC_V2_TMR_CTRL_NH |
_ARC_V2_TMR_CTRL_IE);
arch_irq_unlock(key);
#endif
#else
if (IS_ENABLED(CONFIG_TICKLESS_KERNEL) && idle && ticks == K_TICKS_FOREVER) {
timer0_control_register_set(0);
timer0_count_register_set(0);
timer0_limit_register_set(0);
last_load = TIMER_STOPPED;
return;
}
#if defined(CONFIG_TICKLESS_KERNEL)
uint32_t delay;
uint32_t unannounced;
ticks = MIN(MAX_TICKS, (uint32_t)(MAX((int32_t)(ticks - 1), 0)));
k_spinlock_key_t key = k_spin_lock(&lock);
cycle_count += elapsed();
/* clear counter early to avoid cycle loss as few as possible,
* between cycle_count and clearing 0, few cycles are possible
* to loss
*/
timer0_count_register_set(0);
overflow_cycles = 0U;
/* normal case */
unannounced = cycle_count - announced_cycles;
if ((int32_t)unannounced < 0) {
/* We haven't announced for more than half the 32-bit
* wrap duration, because new timeouts keep being set
* before the existing one fires. Force an announce
* to avoid loss of a wrap event, making sure the
* delay is at least the minimum delay possible.
*/
last_load = MIN_DELAY;
} else {
/* Desired delay in the future */
delay = ticks * CYC_PER_TICK;
/* Round delay up to next tick boundary */
delay += unannounced;
delay = DIV_ROUND_UP(delay, CYC_PER_TICK) * CYC_PER_TICK;
delay -= unannounced;
delay = MAX(delay, MIN_DELAY);
last_load = MIN(delay, MAX_CYCLES);
}
timer0_limit_register_set(last_load - 1);
timer0_control_register_set(_ARC_V2_TMR_CTRL_NH | _ARC_V2_TMR_CTRL_IE);
k_spin_unlock(&lock, key);
#endif
#endif
}
uint32_t sys_clock_elapsed(void)
{
if (!TICKLESS) {
return 0;
}
uint32_t cyc;
k_spinlock_key_t key = k_spin_lock(&lock);
#if SMP_TIMER_DRIVER
cyc = (z_arc_connect_gfrc_read() - last_time);
#else
cyc = elapsed() + cycle_count - announced_cycles;
#endif
k_spin_unlock(&lock, key);
return cyc / CYC_PER_TICK;
}
uint32_t sys_clock_cycle_get_32(void)
{
#if SMP_TIMER_DRIVER
return z_arc_connect_gfrc_read() - start_time;
#else
k_spinlock_key_t key = k_spin_lock(&lock);
uint32_t ret = elapsed() + cycle_count;
k_spin_unlock(&lock, key);
return ret;
#endif
}
#if SMP_TIMER_DRIVER
void smp_timer_init(void)
{
/* set the initial status of timer0 of each slave core
*/
timer0_control_register_set(0);
timer0_count_register_set(0);
timer0_limit_register_set(0);
z_irq_priority_set(IRQ_TIMER0, CONFIG_ARCV2_TIMER_IRQ_PRIORITY, 0);
irq_enable(IRQ_TIMER0);
}
#endif
/**
*
* @brief Initialize and enable the system clock
*
* This routine is used to program the ARCv2 timer to deliver interrupts at the
* rate specified via the CYC_PER_TICK.
*
* @return 0
*/
static int sys_clock_driver_init(void)
{
/* ensure that the timer will not generate interrupts */
timer0_control_register_set(0);
#if SMP_TIMER_DRIVER
IRQ_CONNECT(IRQ_TIMER0, CONFIG_ARCV2_TIMER_IRQ_PRIORITY,
timer_int_handler, NULL, 0);
timer0_limit_register_set(CYC_PER_TICK - 1);
last_time = z_arc_connect_gfrc_read();
start_time = last_time;
#else
last_load = CYC_PER_TICK;
overflow_cycles = 0;
announced_cycles = 0;
IRQ_CONNECT(IRQ_TIMER0, CONFIG_ARCV2_TIMER_IRQ_PRIORITY,
timer_int_handler, NULL, 0);
timer0_limit_register_set(last_load - 1);
#endif
timer0_count_register_set(0);
timer0_control_register_set(_ARC_V2_TMR_CTRL_NH | _ARC_V2_TMR_CTRL_IE);
/* everything has been configured: safe to enable the interrupt */
irq_enable(IRQ_TIMER0);
return 0;
}
SYS_INIT(sys_clock_driver_init, PRE_KERNEL_2,
CONFIG_SYSTEM_CLOCK_INIT_PRIORITY);