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