zephyr/drivers/timer/pulpino_timer.c

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/*
* Copyright (c) 2016 Jean-Paul Etienne <fractalclone@gmail.com>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <kernel.h>
#include <arch/cpu.h>
#include <device.h>
#include <system_timer.h>
#include <board.h>
/* Timer Ctrl Bitfields */
#define TIMER_CTRL_EN (1 << 0) /* Timer Enable Bit */
#define TIMER_CTRL_PRE(x) (((x) & 0x07) << 3) /* Prescaler Value */
typedef struct {
uint32_t val;
uint32_t ctrl;
uint32_t cmp;
} pulpino_timer_t;
static volatile pulpino_timer_t *timer = (pulpino_timer_t *)PULP_TIMER_A_BASE;
static uint32_t accumulated_cycle_count;
static void pulpino_timer_irq_handler(void *unused)
{
ARG_UNUSED(unused);
/* Reset counter */
timer->val = 0;
accumulated_cycle_count += sys_clock_hw_cycles_per_tick;
_sys_clock_tick_announce();
}
#ifdef CONFIG_TICKLESS_IDLE
#error "Tickless idle not yet implemented for pulpino timer"
#endif
int _sys_clock_driver_init(struct device *device)
{
ARG_UNUSED(device);
IRQ_CONNECT(PULP_TIMER_A_CMP_IRQ, 0,
pulpino_timer_irq_handler, NULL, 0);
irq_enable(PULP_TIMER_A_CMP_IRQ);
/*
* Initialize timer.
* Reset counter and set timer to generate interrupt
* every sys_clock_hw_cycles_per_tick
*/
timer->val = 0;
timer->cmp = sys_clock_hw_cycles_per_tick;
timer->ctrl = TIMER_CTRL_EN;
return 0;
}
/**
*
* @brief Read the platform's timer hardware
*
* This routine returns the current time in terms of timer hardware clock
* cycles.
*
* @return up counter of elapsed clock cycles
*/
uint32_t k_cycle_get_32(void)
{
return accumulated_cycle_count + timer->val;
}