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// #################################################################################################
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// # << NEORV32: neorv32_mtime.c - Machine System Timer (MTIME) HW Driver >> #
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// # ********************************************************************************************* #
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// # BSD 3-Clause License #
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// # #
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// # Copyright (c) 2020, Stephan Nolting. All rights reserved. #
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// # #
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// # Redistribution and use in source and binary forms, with or without modification, are #
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// # permitted provided that the following conditions are met: #
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// # #
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// # 1. Redistributions of source code must retain the above copyright notice, this list of #
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// # conditions and the following disclaimer. #
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// # #
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// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
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// # conditions and the following disclaimer in the documentation and/or other materials #
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// # provided with the distribution. #
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// # #
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// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
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// # endorse or promote products derived from this software without specific prior written #
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// # permission. #
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// # #
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// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
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// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
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// # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
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// # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
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// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
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// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
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// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
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// # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
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// # OF THE POSSIBILITY OF SUCH DAMAGE. #
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// # ********************************************************************************************* #
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// # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting #
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// #################################################################################################
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/**********************************************************************//**
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* @file neorv32_mtime.c
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* @author Stephan Nolting
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* @brief Machine System Timer (MTIME) HW driver source file.
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*
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* @note These functions should only be used if the MTIME unit was synthesized (IO_MTIME_USE = true).
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**************************************************************************/
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#include "neorv32.h"
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#include "neorv32_wdt.h"
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/**********************************************************************//**
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* Check if MTIME unit was synthesized.
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*
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* @return 0 if MTIME was not synthesized, 1 if MTIME is available.
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**************************************************************************/
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int neorv32_mtime_available(void) {
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if (neorv32_cpu_csr_read(CSR_MFEATURES) & (1 << CPU_MFEATURES_IO_MTIME)) {
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return 1;
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}
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else {
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return 0;
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}
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}
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/**********************************************************************//**
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* Set new system time.
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*
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* @note The MTIME timer increments with the primary processor clock.
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*
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* @param[in] time New system time (uint64_t)
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**************************************************************************/
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void neorv32_mtime_set_time(uint64_t time) {
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MTIME = time;
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}
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/**********************************************************************//**
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* Get current system time since reset.
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*
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* @note The MTIME timer increments with the primary processor clock.
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*
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* @return Current system time (uint64_t)
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**************************************************************************/
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uint64_t neorv32_mtime_get_time(void) {
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union {
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uint64_t uint64;
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uint32_t uint32[sizeof(uint64_t)/2];
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} sys_mtime;
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uint32_t tmp;
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// make sure there is no overflow in mtime_lo during read
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while (1) {
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sys_mtime.uint32[1] = MTIME_HI;
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sys_mtime.uint32[0] = MTIME_LO;
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tmp = MTIME_HI;
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if (sys_mtime.uint32[1] == tmp) {
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break;
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}
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}
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return sys_mtime.uint64;
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}
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/**********************************************************************//**
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* Set compare time register (MTIMECMP) for generating interrupts.
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*
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* @note The interrupt is triggered when MTIME >= MTIMECMP.
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* @note The interrupt is acknwoledged by writing to the MTIMECMP.HI register.
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* @note The timer interrupt is enabled via neorv32_cpu_mti_enable(void) and disabled via neorv32_cpu_mti_disable(void).
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* @note Global interrupts have to be enabled via neorv32_cpu_eint(void).
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*
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* @param[in] timecmp System time for interrupt (uint64_t)
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**************************************************************************/
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void neorv32_mtime_set_timecmp(uint64_t timecmp) {
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MTIMECMP_LO = 0xFFFFFFFF; // prevent mtimecmp from temporarily becoming smaller than the lesser of the old and new values
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MTIMECMP = timecmp;
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}
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/**********************************************************************//**
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* Get compare time register (MTIMECMP).
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*
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* @return Current MTIMECMP value.
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**************************************************************************/
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uint64_t neorv32_mtime_get_timecmp(void) {
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return MTIMECMP;
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}
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