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driver: timer: esp32c3: added tickless support

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For esp32c3 system timer clock driver enabling tickless mode
kernel

Signed-off-by: Felipe Neves <felipe.neves@espressif.com>
This commit is contained in:
Felipe Neves 2021-07-26 21:35:48 -03:00 • committed by Christopher Friedt
commit 3917203d52
3 changed files with 82 additions and 12 deletions
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1
boards/riscv/esp32c3_devkitm/esp32c3_devkitm_defconfig
View file

@ -1,6 +1,5 @@
# SPDX-License-Identifier: Apache-2.0
CONFIG_BOARD_ESP32C3_DEVKITM=y
CONFIG_SOC_ESP32C3=y
CONFIG_MAIN_STACK_SIZE=2048

1
drivers/timer/Kconfig
View file

@ -253,6 +253,7 @@ config ESP32C3_SYS_TIMER
bool "ESP32C3 sys-timer support"
depends on SOC_ESP32C3
default y
select TICKLESS_CAPABLE
help
This option enables the system timer driver for the Espressif ESP32C3
and provides the standard "system clock driver" interface.

92
drivers/timer/esp32c3_sys_timer.c
View file

@ -17,13 +17,55 @@
#include <sys_clock.h>
#include <soc.h>
#define SYS_TIMER_CPU_IRQ 1
#define SYS_TIMER_CPU_IRQ 16
#define CYC_PER_TICK ((uint32_t)((uint64_t)sys_clock_hw_cycles_per_sec() \
/ (uint64_t)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
#define TICKLESS IS_ENABLED(CONFIG_TICKLESS_KERNEL)
static struct k_spinlock lock;
static uint64_t last_count;
static void set_systimer_alarm(uint64_t time)
{
systimer_hal_select_alarm_mode(SYSTIMER_ALARM_0, SYSTIMER_ALARM_MODE_ONESHOT);
systimer_hal_set_alarm_target(SYSTIMER_ALARM_0, time);
systimer_hal_enable_alarm_int(SYSTIMER_ALARM_0);
}
static uint64_t systimer_alarm(void)
{
return systimer_hal_get_time(SYSTIMER_COUNTER_1);
}
static void sys_timer_isr(const void *arg)
{
ARG_UNUSED(arg);
systimer_ll_clear_alarm_int(SYSTIMER_ALARM_0);
sys_clock_announce(1);
k_spinlock_key_t key = k_spin_lock(&lock);
uint64_t now = systimer_alarm();
uint32_t dticks = (uint32_t)((now - last_count) / CYC_PER_TICK);
last_count += dticks * CYC_PER_TICK;
if (!TICKLESS) {
uint64_t next = last_count + CYC_PER_TICK;
if ((int64_t)(next - now) < MIN_DELAY) {
next += CYC_PER_TICK;
}
set_systimer_alarm(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)
@ -34,16 +76,13 @@ int sys_clock_driver_init(const struct device *dev)
ETS_SYSTIMER_TARGET0_EDGE_INTR_SOURCE,
SYS_TIMER_CPU_IRQ);
IRQ_CONNECT(SYS_TIMER_CPU_IRQ, 0, sys_timer_isr, NULL, 0);
irq_enable(SYS_TIMER_CPU_IRQ);
systimer_hal_init();
systimer_hal_connect_alarm_counter(SYSTIMER_ALARM_0, SYSTIMER_COUNTER_1);
systimer_hal_enable_counter(SYSTIMER_COUNTER_1);
systimer_hal_counter_can_stall_by_cpu(SYSTIMER_COUNTER_1, 0, true);
systimer_hal_set_alarm_period(SYSTIMER_ALARM_0,
CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC / CONFIG_SYS_CLOCK_TICKS_PER_SEC);
systimer_hal_select_alarm_mode(SYSTIMER_ALARM_0, SYSTIMER_ALARM_MODE_PERIOD);
systimer_hal_enable_alarm_int(SYSTIMER_ALARM_0);
last_count = systimer_alarm();
set_systimer_alarm(last_count + CYC_PER_TICK);
irq_enable(SYS_TIMER_CPU_IRQ);
return 0;
}
@ -51,13 +90,44 @@ int sys_clock_driver_init(const struct device *dev)
void sys_clock_set_timeout(int32_t ticks, bool idle)
{
ARG_UNUSED(idle);
ARG_UNUSED(ticks);
#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);
uint64_t now = systimer_alarm();
uint32_t adj, cyc = ticks * CYC_PER_TICK;
/* Round up to next tick boundary. */
adj = (uint32_t)(now - 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;
if ((int32_t)(cyc + last_count - now) < MIN_DELAY) {
cyc += CYC_PER_TICK;
}
set_systimer_alarm(cyc + last_count);
k_spin_unlock(&lock, key);
#endif
}
uint32_t sys_clock_elapsed(void)
{
/* Tickless is not supported yet */
return 0;
if (!IS_ENABLED(CONFIG_TICKLESS_KERNEL)) {
return 0;
}
k_spinlock_key_t key = k_spin_lock(&lock);
uint32_t ret = ((uint32_t)systimer_alarm() - (uint32_t)last_count) / CYC_PER_TICK;
k_spin_unlock(&lock, key);
return ret;
}
uint32_t sys_clock_cycle_get_32(void)