/*
 * 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;
}