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/*
* Copyright (c) 2015-2019, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <assert.h>
#include <platform_def.h>
#include <drivers/delay_timer.h>
#include <lib/utils_def.h>
/***********************************************************
* The delay timer implementation
***********************************************************/
static const timer_ops_t *timer_ops;
/***********************************************************
* Delay for the given number of microseconds. The driver must
* be initialized before calling this function.
***********************************************************/
void udelay(uint32_t usec)
{
assert((timer_ops != NULL) &&
(timer_ops->clk_mult != 0U) &&
(timer_ops->clk_div != 0U) &&
(timer_ops->get_timer_value != NULL));
uint32_t start, delta;
uint64_t total_delta;
assert(usec < (UINT64_MAX / timer_ops->clk_div));
start = timer_ops->get_timer_value();
/* Add an extra tick to avoid delaying less than requested. */
total_delta =
div_round_up((uint64_t)usec * timer_ops->clk_div,
timer_ops->clk_mult) + 1U;
/*
* Precaution for the total_delta ~ UINT32_MAX and the fact that we
* cannot catch every tick of the timer.
* For example 100MHz timer over 25MHz APB will miss at least 4 ticks.
* 1000U is an arbitrary big number which is believed to be sufficient.
*/
assert(total_delta < (UINT32_MAX - 1000U));
do {
/*
* If the timer value wraps around, the subtraction will
* overflow and it will still give the correct result.
* delta is decreasing counter
*/
delta = start - timer_ops->get_timer_value();
} while (delta < total_delta);
}
/***********************************************************
* Delay for the given number of milliseconds. The driver must
* be initialized before calling this function.
***********************************************************/
void mdelay(uint32_t msec)
{
assert((msec * 1000UL) < UINT32_MAX);
udelay(msec * 1000U);
}
/***********************************************************
* Initialize the timer. The fields in the provided timer
* ops pointer must be valid.
***********************************************************/
void timer_init(const timer_ops_t *ops_ptr)
{
assert((ops_ptr != NULL) &&
(ops_ptr->clk_mult != 0U) &&
(ops_ptr->clk_div != 0U) &&
(ops_ptr->get_timer_value != NULL));
timer_ops = ops_ptr;
}
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