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https://github.com/ARM-software/arm-trusted-firmware.git
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0bcedb2212
Add delay timer implementation based on the system generic counter. This either uses the platform's implementation of `plat_get_syscnt_freq()` or explicit clock multiplier/divider values provided by the platform. The current implementation of udelay has been modified to avoid unnecessary calculations while waiting on the loop and to make it easier to check for overflows. Change-Id: I9062e1d506dc2f68367fd9289250b93444721732
90 lines
3.2 KiB
C
90 lines
3.2 KiB
C
/*
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* Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of ARM nor the names of its contributors may be used
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* to endorse or promote products derived from this software without specific
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* prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <assert.h>
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#include <delay_timer.h>
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#include <platform_def.h>
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/***********************************************************
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* The delay timer implementation
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***********************************************************/
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static const timer_ops_t *ops;
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/***********************************************************
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* Delay for the given number of microseconds. The driver must
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* be initialized before calling this function.
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***********************************************************/
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void udelay(uint32_t usec)
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{
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assert(ops != 0 &&
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(ops->clk_mult != 0) &&
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(ops->clk_div != 0) &&
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(ops->get_timer_value != 0));
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uint32_t start, delta, total_delta;
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assert(usec < UINT32_MAX / ops->clk_div);
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start = ops->get_timer_value();
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total_delta = (usec * ops->clk_div) / ops->clk_mult;
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do {
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/*
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* If the timer value wraps around, the subtraction will
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* overflow and it will still give the correct result.
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*/
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delta = start - ops->get_timer_value(); /* Decreasing counter */
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} while (delta < total_delta);
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}
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/***********************************************************
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* Delay for the given number of milliseconds. The driver must
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* be initialized before calling this function.
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***********************************************************/
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void mdelay(uint32_t msec)
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{
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udelay(msec*1000);
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}
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/***********************************************************
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* Initialize the timer. The fields in the provided timer
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* ops pointer must be valid.
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***********************************************************/
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void timer_init(const timer_ops_t *ops_ptr)
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{
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assert(ops_ptr != 0 &&
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(ops_ptr->clk_mult != 0) &&
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(ops_ptr->clk_div != 0) &&
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(ops_ptr->get_timer_value != 0));
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ops = ops_ptr;
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}
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