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/*
* Copyright (c) 2014-2015 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file
* @brief ARC Timer0 device driver
*
* This module implements a kernel device driver for the ARCv2 processor Timer0
* and provides the standard "system clock driver" interfaces.
*
* If the TICKLESS_IDLE kernel configuration option is enabled, the timer may
* be programmed to wake the system in N >= TICKLESS_IDLE_THRESH ticks. The
* kernel invokes _timer_idle_enter() to program the up counter to trigger an
* interrupt in N ticks. When the timer expires (or when another interrupt is
* detected), the kernel's interrupt stub invokes _timer_idle_exit() to leave
* the tickless idle state.
*
* @internal
* The ARCv2 processor timer provides a 32-bit incrementing, wrap-to-zero
* counter.
*
* Factors that increase the driver's tickless idle complexity:
* 1. As the Timer0 up-counter is a 32-bit value, the number of ticks for which
* the system can be in tickless idle is limited to 'max_system_ticks'.
*
* 2. The act of entering tickless idle may potentially straddle a tick
* boundary. This can be detected in _timer_idle_enter() after Timer0 is
* programmed with the new limit and acted upon in _timer_idle_exit().
*
* 3. Tickless idle may be prematurely aborted due to a straddled tick. See
* previous factor.
*
* 4. Tickless idle may end naturally. This is detected and handled in
* _timer_idle_exit().
*
* 5. Tickless idle may be prematurely aborted due to a non-timer interrupt.
* If this occurs, Timer0 is reprogrammed to trigger at the next tick.
* @endinternal
*/
#include <kernel.h>
#include <arch/cpu.h>
#include <toolchain.h>
#include <linker/sections.h>
#include <misc/__assert.h>
#include <arch/arc/v2/aux_regs.h>
#include <sys_clock.h>
#include <drivers/system_timer.h>
#include <stdbool.h>
#include <misc/__assert.h>
/*
* note: This implementation assumes Timer0 is present. Be sure
* to build the ARC CPU with Timer0.
*/
#include <board.h>
#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 */
/* running total of timer count */
static u32_t __noinit cycles_per_tick;
static volatile u32_t accumulated_cycle_count;
#ifdef CONFIG_TICKLESS_IDLE
static u32_t __noinit max_system_ticks;
static u32_t __noinit programmed_ticks;
extern s32_t _sys_idle_elapsed_ticks;
#ifndef CONFIG_TICKLESS_KERNEL
static u32_t __noinit programmed_limit;
static int straddled_tick_on_idle_enter;
#endif
#endif
#ifdef CONFIG_TICKLESS_KERNEL
static volatile int timer_expired;
#endif
#ifdef CONFIG_DEVICE_POWER_MANAGEMENT
static u32_t arcv2_timer0_device_power_state;
static u32_t saved_limit;
static u32_t saved_control;
#endif
/**
*
* @brief Get contents of Timer0 count register
*
* @return Current Timer0 count
*/
static ALWAYS_INLINE u32_t timer0_count_register_get(void)
{
return _arc_v2_aux_reg_read(_ARC_V2_TMR0_COUNT);
}
/**
*
* @brief Set Timer0 count register to the specified value
*
* @return N/A
*/
static ALWAYS_INLINE void timer0_count_register_set(u32_t value)
{
_arc_v2_aux_reg_write(_ARC_V2_TMR0_COUNT, value);
}
/**
*
* @brief Get contents of Timer0 control register
*
* @return N/A
*/
static ALWAYS_INLINE u32_t timer0_control_register_get(void)
{
return _arc_v2_aux_reg_read(_ARC_V2_TMR0_CONTROL);
}
/**
*
* @brief Set Timer0 control register to the specified value
*
* @return N/A
*/
static ALWAYS_INLINE void timer0_control_register_set(u32_t value)
{
_arc_v2_aux_reg_write(_ARC_V2_TMR0_CONTROL, value);
}
/**
*
* @brief Get contents of Timer0 limit register
*
* @return N/A
*/
static ALWAYS_INLINE u32_t timer0_limit_register_get(void)
{
return _arc_v2_aux_reg_read(_ARC_V2_TMR0_LIMIT);
}
/**
*
* @brief Set Timer0 limit register to the specified value
*
* @return N/A
*/
static ALWAYS_INLINE void timer0_limit_register_set(u32_t count)
{
_arc_v2_aux_reg_write(_ARC_V2_TMR0_LIMIT, count);
}
#ifdef CONFIG_TICKLESS_IDLE
static ALWAYS_INLINE void update_accumulated_count(void)
{
accumulated_cycle_count += (_sys_idle_elapsed_ticks * cycles_per_tick);
}
#else /* CONFIG_TICKLESS_IDLE */
static ALWAYS_INLINE void update_accumulated_count(void)
{
accumulated_cycle_count += cycles_per_tick;
}
#endif /* CONFIG_TICKLESS_IDLE */
#ifdef CONFIG_TICKLESS_KERNEL
static inline void program_max_cycles(void)
{
timer0_limit_register_set(max_system_ticks * cycles_per_tick);
timer_expired = 0;
}
#endif
/**
*
* @brief System clock periodic tick handler
*
* This routine handles the system clock periodic tick interrupt. It always
* announces one tick.
*
* @return N/A
*/
void _timer_int_handler(void *unused)
{
ARG_UNUSED(unused);
/* clear the interrupt by writing 0 to IP bit of the control register */
timer0_control_register_set(_ARC_V2_TMR_CTRL_NH | _ARC_V2_TMR_CTRL_IE);
#ifdef CONFIG_TICKLESS_KERNEL
if (!programmed_ticks) {
if (_sys_clock_always_on) {
_sys_clock_tick_count = _get_elapsed_clock_time();
program_max_cycles();
}
return;
}
_sys_idle_elapsed_ticks = programmed_ticks;
/*
* Clear programmed ticks before announcing elapsed time so
* that recursive calls to _update_elapsed_time() will not
* announce already consumed elapsed time
*/
programmed_ticks = 0;
timer_expired = 1;
_sys_clock_tick_announce();
/* _sys_clock_tick_announce() could cause new programming */
if (!programmed_ticks && _sys_clock_always_on) {
_sys_clock_tick_count = _get_elapsed_clock_time();
program_max_cycles();
}
#else
#if defined(CONFIG_TICKLESS_IDLE)
timer0_limit_register_set(cycles_per_tick - 1);
__ASSERT_EVAL({},
u32_t timer_count = timer0_count_register_get(),
timer_count <= (cycles_per_tick - 1),
"timer_count: %d, limit %d\n", timer_count, cycles_per_tick - 1);
_sys_clock_final_tick_announce();
#else
_sys_clock_tick_announce();
#endif
update_accumulated_count();
#endif
}
#ifdef CONFIG_TICKLESS_KERNEL
u32_t _get_program_time(void)
{
return programmed_ticks;
}
u32_t _get_remaining_program_time(void)
{
if (programmed_ticks == 0) {
return 0;
}
if (timer0_control_register_get() & _ARC_V2_TMR_CTRL_IP) {
return 0;
}
return programmed_ticks -
(timer0_count_register_get() / cycles_per_tick);
}
u32_t _get_elapsed_program_time(void)
{
if (programmed_ticks == 0) {
return 0;
}
if (timer0_control_register_get() & _ARC_V2_TMR_CTRL_IP) {
return programmed_ticks;
}
return timer0_count_register_get() / cycles_per_tick;
}
void _set_time(u32_t time)
{
if (!time) {
programmed_ticks = 0;
return;
}
programmed_ticks = time > max_system_ticks ? max_system_ticks : time;
_sys_clock_tick_count = _get_elapsed_clock_time();
timer0_limit_register_set(programmed_ticks * cycles_per_tick);
timer0_count_register_set(0);
timer_expired = 0;
}
void _enable_sys_clock(void)
{
if (!programmed_ticks) {
program_max_cycles();
}
}
static inline u64_t get_elapsed_count(void)
{
u64_t elapsed;
if (timer_expired
|| (timer0_control_register_get() & _ARC_V2_TMR_CTRL_IP)) {
elapsed = timer0_limit_register_get();
} else {
elapsed = timer0_count_register_get();
}
elapsed += _sys_clock_tick_count * cycles_per_tick;
return elapsed;
}
u64_t _get_elapsed_clock_time(void)
{
return get_elapsed_count() / cycles_per_tick;
}
#endif
#if defined(CONFIG_TICKLESS_IDLE)
/*
* @brief initialize the tickless idle feature
*
* This routine initializes the tickless idle feature.
*
* @return N/A
*/
static void tickless_idle_init(void)
{
/* calculate the max number of ticks with this 32-bit H/W counter */
max_system_ticks = 0xffffffff / cycles_per_tick;
}
/*
* @brief Place the system timer into idle state
*
* Re-program the timer to enter into the idle state for either the given
* number of ticks or the maximum number of ticks that can be programmed
* into hardware.
*
* @return N/A
*/
void _timer_idle_enter(s32_t ticks)
{
#ifdef CONFIG_TICKLESS_KERNEL
if (ticks != K_FOREVER) {
/* Need to reprogram only if current program is smaller */
if (ticks > programmed_ticks) {
_set_time(ticks);
}
} else {
programmed_ticks = 0;
timer0_control_register_set(timer0_control_register_get() &
~_ARC_V2_TMR_CTRL_IE);
}
#else
u32_t status;
if ((ticks == K_FOREVER) || (ticks > max_system_ticks)) {
/*
* The number of cycles until the timer must fire next might not fit
* in the 32-bit counter register. To work around this, program
* the counter to fire in the maximum number of ticks.
*/
ticks = max_system_ticks;
}
programmed_ticks = ticks;
programmed_limit = (programmed_ticks * cycles_per_tick) - 1;
timer0_limit_register_set(programmed_limit);
/*
* If Timer0's IP bit is set, then it is known that we have straddled
* a tick boundary while entering tickless idle.
*/
status = timer0_control_register_get();
if (status & _ARC_V2_TMR_CTRL_IP) {
straddled_tick_on_idle_enter = 1;
}
__ASSERT_EVAL({},
u32_t timer_count = timer0_count_register_get(),
timer_count <= programmed_limit,
"timer_count: %d, limit %d\n", timer_count, programmed_limit);
#endif
}
/*
* @brief handling of tickless idle when interrupted
*
* The routine, called by _SysPowerSaveIdleExit, is responsible for taking the
* timer out of idle mode and generating an interrupt at the next tick
* interval. It is expected that interrupts have been disabled.
*
* RETURNS: N/A
*/
void _timer_idle_exit(void)
{
#ifdef CONFIG_TICKLESS_KERNEL
if (!programmed_ticks && _sys_clock_always_on) {
if (!(timer0_control_register_get() & _ARC_V2_TMR_CTRL_IE)) {
timer0_control_register_set(_ARC_V2_TMR_CTRL_NH |
_ARC_V2_TMR_CTRL_IE);
}
program_max_cycles();
}
#else
if (straddled_tick_on_idle_enter) {
/* Aborting the tickless idle due to a straddled tick. */
straddled_tick_on_idle_enter = 0;
__ASSERT_EVAL({},
u32_t timer_count = timer0_count_register_get(),
timer_count <= programmed_limit,
"timer_count: %d, limit %d\n", timer_count, programmed_limit);
return;
}
u32_t control;
u32_t current_count;
current_count = timer0_count_register_get();
control = timer0_control_register_get();
if (control & _ARC_V2_TMR_CTRL_IP) {
/*
* The timer has expired. The handler _timer_int_handler() is
* guaranteed to execute. Track the number of elapsed ticks. The
* handler _timer_int_handler() will account for the final tick.
*/
_sys_idle_elapsed_ticks = programmed_ticks - 1;
update_accumulated_count();
_sys_clock_tick_announce();
__ASSERT_EVAL({},
u32_t timer_count = timer0_count_register_get(),
timer_count <= programmed_limit,
"timer_count: %d, limit %d\n", timer_count, programmed_limit);
return;
}
/*
* A non-timer interrupt occurred. Announce any
* ticks that have elapsed during the tickless idle.
*/
_sys_idle_elapsed_ticks = current_count / cycles_per_tick;
if (_sys_idle_elapsed_ticks > 0) {
update_accumulated_count();
_sys_clock_tick_announce();
}
/*
* Ensure the timer will expire at the end of the next tick in case
* the ISR makes any threads ready to run.
*/
timer0_limit_register_set(cycles_per_tick - 1);
timer0_count_register_set(current_count % cycles_per_tick);
__ASSERT_EVAL({},
u32_t timer_count = timer0_count_register_get(),
timer_count <= (cycles_per_tick - 1),
"timer_count: %d, limit %d\n", timer_count, cycles_per_tick-1);
#endif
}
#else
static void tickless_idle_init(void) {}
#endif /* CONFIG_TICKLESS_IDLE */
/**
*
* @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 'sys_clock_us_per_tick' global variable.
*
* @return 0
*/
int _sys_clock_driver_init(struct device *device)
{
ARG_UNUSED(device);
/* ensure that the timer will not generate interrupts */
timer0_control_register_set(0);
timer0_count_register_set(0);
cycles_per_tick = sys_clock_hw_cycles_per_tick;
IRQ_CONNECT(IRQ_TIMER0, CONFIG_ARCV2_TIMER_IRQ_PRIORITY,
_timer_int_handler, NULL, 0);
/*
* Set the reload value to achieve the configured tick rate, enable the
* counter and interrupt generation.
*/
tickless_idle_init();
timer0_limit_register_set(cycles_per_tick - 1);
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;
}
#ifdef CONFIG_DEVICE_POWER_MANAGEMENT
static int sys_clock_suspend(struct device *dev)
{
ARG_UNUSED(dev);
saved_limit = timer0_limit_register_get();
saved_control = timer0_control_register_get();
arcv2_timer0_device_power_state = DEVICE_PM_SUSPEND_STATE;
return 0;
}
static int sys_clock_resume(struct device *dev)
{
ARG_UNUSED(dev);
timer0_limit_register_set(saved_limit);
timer0_control_register_set(saved_control);
/*
* It is difficult to accurately know the time spent in DS.
* Expire the timer to get the scheduler called.
*/
timer0_count_register_set(saved_limit - 1);
arcv2_timer0_device_power_state = DEVICE_PM_ACTIVE_STATE;
return 0;
}
/*
* Implements the driver control management functionality
* the *context may include IN data or/and OUT data
*/
int sys_clock_device_ctrl(struct device *port, u32_t ctrl_command,
void *context)
{
if (ctrl_command == DEVICE_PM_SET_POWER_STATE) {
if (*((u32_t *)context) == DEVICE_PM_SUSPEND_STATE) {
return sys_clock_suspend(port);
} else if (*((u32_t *)context) == DEVICE_PM_ACTIVE_STATE) {
return sys_clock_resume(port);
}
} else if (ctrl_command == DEVICE_PM_GET_POWER_STATE) {
*((u32_t *)context) = arcv2_timer0_device_power_state;
return 0;
}
return 0;
}
#endif /* CONFIG_DEVICE_POWER_MANAGEMENT */
u32_t _timer_cycle_get_32(void)
{
#ifdef CONFIG_TICKLESS_KERNEL
return (u32_t) get_elapsed_count();
#else
u32_t acc, count;
do {
acc = accumulated_cycle_count;
count = timer0_count_register_get();
} while (acc != accumulated_cycle_count);
return acc + count;
#endif
}
#if defined(CONFIG_SYSTEM_CLOCK_DISABLE)
/**
*
* @brief Stop announcing ticks into the kernel
*
* This routine disables timer interrupt generation and delivery.
* Note that the timer's counting cannot be stopped by software.
*
* @return N/A
*/
void sys_clock_disable(void)
{
unsigned int key; /* interrupt lock level */
u32_t control; /* timer control register value */
key = irq_lock();
/* disable interrupt generation */
control = timer0_control_register_get();
timer0_control_register_set(control & ~_ARC_V2_TMR_CTRL_IE);
irq_unlock(key);
/* disable interrupt in the interrupt controller */
irq_disable(ARCV2_TIMER0_INT_LVL);
}
#endif /* CONFIG_SYSTEM_CLOCK_DISABLE */