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- /**
- * Copyright (c) 2018 - 2020, Nordic Semiconductor ASA
- *
- * 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, except as embedded into a Nordic
- * Semiconductor ASA integrated circuit in a product or a software update for
- * such product, 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 Nordic Semiconductor ASA nor the names of its
- * contributors may be used to endorse or promote products derived from this
- * software without specific prior written permission.
- *
- * 4. This software, with or without modification, must only be used with a
- * Nordic Semiconductor ASA integrated circuit.
- *
- * 5. Any software provided in binary form under this license must not be reverse
- * engineered, decompiled, modified and/or disassembled.
- *
- * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
- * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA 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.
- *
- */
- #ifndef NRFX_COREDEP_H__
- #define NRFX_COREDEP_H__
- /**
- * @defgroup nrfx_coredep Core-dependent functionality
- * @{
- * @ingroup nrfx
- * @brief Module containing functions with core-dependent implementation, like delay.
- */
- #if defined(__NRFX_DOXYGEN__)
- /** @brief Core frequency (in MHz). */
- #define NRFX_DELAY_CPU_FREQ_MHZ
- /** @brief Availability of Data Watchpoint and Trace (DWT) unit in the given SoC. */
- #define NRFX_DELAY_DWT_PRESENT
- /**
- * @brief Number of cycles consumed by one iteration of the internal loop
- * in the function @ref nrfx_coredep_delay_us.
- *
- * This value can be specified externally (for example, when the SoC is emulated).
- */
- #define NRFX_COREDEP_DELAY_US_LOOP_CYCLES
- #elif defined(NRF51)
- #define NRFX_DELAY_CPU_FREQ_MHZ 16
- #define NRFX_DELAY_DWT_PRESENT 0
- #elif defined(NRF52810_XXAA) || defined(NRF52811_XXAA) || defined(NRF52820_XXAA)
- #define NRFX_DELAY_CPU_FREQ_MHZ 64
- #define NRFX_DELAY_DWT_PRESENT 0
- #elif defined(NRF52832_XXAA) || defined(NRF52832_XXAB) || \
- defined(NRF52833_XXAA) || defined(NRF52840_XXAA) || \
- defined(NRF9160_XXAA)
- #define NRFX_DELAY_CPU_FREQ_MHZ 64
- #define NRFX_DELAY_DWT_PRESENT 1
- #else
- #error "Unknown device."
- #endif
- /**
- * @brief Function for delaying execution for a number of microseconds.
- *
- * The value of @p time_us is multiplied by the frequency in MHz. Therefore, the delay is limited to
- * maximum uint32_t capacity divided by frequency. For example:
- * - For SoCs working at 64MHz: 0xFFFFFFFF/64 = 0x03FFFFFF (67108863 microseconds)
- * - For SoCs working at 16MHz: 0xFFFFFFFF/16 = 0x0FFFFFFF (268435455 microseconds)
- *
- * @sa NRFX_COREDEP_DELAY_US_LOOP_CYCLES
- *
- * @param time_us Number of microseconds to wait.
- */
- __STATIC_INLINE void nrfx_coredep_delay_us(uint32_t time_us);
- /** @} */
- #ifndef SUPPRESS_INLINE_IMPLEMENTATION
- #if NRFX_CHECK(NRFX_DELAY_DWT_BASED)
- #if !NRFX_DELAY_DWT_PRESENT
- #error "DWT unit not present in the SoC that is used."
- #endif
- __STATIC_INLINE void nrfx_coredep_delay_us(uint32_t time_us)
- {
- if (time_us == 0)
- {
- return;
- }
- uint32_t time_cycles = time_us * NRFX_DELAY_CPU_FREQ_MHZ;
- // Save the current state of the DEMCR register to be able to restore it before exiting
- // this function. Enable the trace and debug blocks (including DWT).
- uint32_t core_debug = CoreDebug->DEMCR;
- CoreDebug->DEMCR = core_debug | CoreDebug_DEMCR_TRCENA_Msk;
- // Save the current state of the CTRL register in the DWT block. Make sure
- // that the cycle counter is enabled.
- uint32_t dwt_ctrl = DWT->CTRL;
- DWT->CTRL = dwt_ctrl | DWT_CTRL_CYCCNTENA_Msk;
- // Store start value of the cycle counter.
- uint32_t cyccnt_initial = DWT->CYCCNT;
- // Delay required time.
- while ((DWT->CYCCNT - cyccnt_initial) < time_cycles)
- {}
- // Restore preserved registers.
- DWT->CTRL = dwt_ctrl;
- CoreDebug->DEMCR = core_debug;
- }
- #else // NRFX_CHECK(NRFX_DELAY_DWT_BASED)
- __STATIC_INLINE void nrfx_coredep_delay_us(uint32_t time_us)
- {
- if (time_us == 0)
- {
- return;
- }
- // Allow overriding the number of cycles per loop iteration, in case it is
- // needed to adjust this number externally (for example, when the SoC is
- // emulated).
- #ifndef NRFX_COREDEP_DELAY_US_LOOP_CYCLES
- #if defined(NRF51)
- // The loop takes 4 cycles: 1 for SUBS, 3 for BHI.
- #define NRFX_COREDEP_DELAY_US_LOOP_CYCLES 4
- #elif defined(NRF52810_XXAA) || defined(NRF52811_XXAA) || defined(NRF52820_XXAA)
- // The loop takes 7 cycles: 1 for SUBS, 2 for BHI, 2 wait states
- // for each instruction.
- #define NRFX_COREDEP_DELAY_US_LOOP_CYCLES 7
- #else
- // The loop takes 3 cycles: 1 for SUBS, 2 for BHI.
- #define NRFX_COREDEP_DELAY_US_LOOP_CYCLES 3
- #endif
- #endif // NRFX_COREDEP_DELAY_US_LOOP_CYCLES
- // Align the machine code, so that it can be cached properly and no extra
- // wait states appear.
- __ALIGN(16)
- static const uint16_t delay_machine_code[] = {
- 0x3800 + NRFX_COREDEP_DELAY_US_LOOP_CYCLES, // SUBS r0, #loop_cycles
- 0xd8fd, // BHI .-2
- 0x4770 // BX LR
- };
- typedef void (* delay_func_t)(uint32_t);
- const delay_func_t delay_cycles =
- // Set LSB to 1 to execute the code in the Thumb mode.
- (delay_func_t)((((uint32_t)delay_machine_code) | 1));
- uint32_t cycles = time_us * NRFX_DELAY_CPU_FREQ_MHZ;
- delay_cycles(cycles);
- }
- #endif // !NRFX_CHECK(NRFX_DELAY_DWT_BASED_DELAY)
- #endif // SUPPRESS_INLINE_IMPLEMENTATION
- #endif // NRFX_COREDEP_H__
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