text: /*
   * Copyright (c) 2018 Intel Corporation
   *
   * SPDX-License-Identifier: Apache-2.0
   */
  #include <drivers/timer/system_timer.h>
  #include <sys_clock.h>
  #include <spinlock.h>
  
  #define TIMER_IRQ UTIL_CAT(XCHAL_TIMER,		\
  			   UTIL_CAT(CONFIG_XTENSA_TIMER_ID, _INTERRUPT))
  
  #define CYC_PER_TICK (sys_clock_hw_cycles_per_sec()	\
  		      / CONFIG_SYS_CLOCK_TICKS_PER_SEC)
  #define MAX_CYC 0xffffffffu
  #define MAX_TICKS ((MAX_CYC - CYC_PER_TICK) / CYC_PER_TICK)
  #define MIN_DELAY 1000
  
  static struct k_spinlock lock;
  static unsigned int last_count;
  
  static void set_ccompare(uint32_t val)
  {
  	__asm__ volatile ("wsr.CCOMPARE" STRINGIFY(CONFIG_XTENSA_TIMER_ID) " %0"
  			  :: "r"(val));
  }
  
  static uint32_t ccount(void)
  {
  	uint32_t val;
  
  	__asm__ volatile ("rsr.CCOUNT %0" : "=r"(val));
  	return val;
  }
  
  static void ccompare_isr(const void *arg)
  {
  	ARG_UNUSED(arg);
  
  	k_spinlock_key_t key = k_spin_lock(&lock);
  	uint32_t curr = ccount();
  	uint32_t dticks = (curr - last_count) / CYC_PER_TICK;
  
  	last_count += dticks * CYC_PER_TICK;
  
  	if (!IS_ENABLED(CONFIG_TICKLESS_KERNEL)) {
  		uint32_t next = last_count + CYC_PER_TICK;
  
  		if ((int32_t)(next - curr) < MIN_DELAY) {
  			next += CYC_PER_TICK;
  		}
  		set_ccompare(next);
  	}
  
  	k_spin_unlock(&lock, key);
  	sys_clock_announce(IS_ENABLED(CONFIG_TICKLESS_KERNEL) ? dticks : 1);
  }
  
  int sys_clock_driver_init(const struct device *dev)
  {
  	ARG_UNUSED(dev);
  
  	IRQ_CONNECT(TIMER_IRQ, 0, ccompare_isr, 0, 0);
  	set_ccompare(ccount() + CYC_PER_TICK);
  	irq_enable(TIMER_IRQ);
  	return 0;
  }
  
  void sys_clock_set_timeout(int32_t ticks, bool idle)
  {
  	ARG_UNUSED(idle);
  
  #if defined(CONFIG_TICKLESS_KERNEL)
  	ticks = ticks == K_TICKS_FOREVER ? MAX_TICKS : ticks;
  	ticks = CLAMP(ticks - 1, 0, (int32_t)MAX_TICKS);
  
  	k_spinlock_key_t key = k_spin_lock(&lock);
  	uint32_t curr = ccount(), cyc, adj;
  
  	/* Round up to next tick boundary */
  	cyc = ticks * CYC_PER_TICK;
  	adj = (curr - last_count) + (CYC_PER_TICK - 1);
  	if (cyc <= MAX_CYC - adj) {
  		cyc += adj;
  	} else {
  		cyc = MAX_CYC;
  	}
  	cyc = (cyc / CYC_PER_TICK) * CYC_PER_TICK;
  	cyc += last_count;
  
  	if ((cyc - curr) < MIN_DELAY) {
  		cyc += CYC_PER_TICK;
  	}
  
  	set_ccompare(cyc);
  	k_spin_unlock(&lock, key);
  #endif
  }
  
  uint32_t sys_clock_elapsed(void)
  {
  	if (!IS_ENABLED(CONFIG_TICKLESS_KERNEL)) {
  		return 0;
  	}
  
  	k_spinlock_key_t key = k_spin_lock(&lock);
  	uint32_t ret = (ccount() - last_count) / CYC_PER_TICK;
  
  	k_spin_unlock(&lock, key);
  	return ret;
  }
  
  uint32_t sys_clock_cycle_get_32(void)
  {
  	return ccount();
  }
  
  #ifdef CONFIG_SMP
  void smp_timer_init(void)
  {
  	set_ccompare(ccount() + CYC_PER_TICK);
  	irq_enable(TIMER_IRQ);
  }
  #endif
  