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modules/nrfx/drivers/src/nrfx_systick.c

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+/**
+ * Copyright (c) 2016 - 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.
+ *
+ */
+#include <nrfx.h>
+
+#if NRFX_CHECK(NRFX_SYSTICK_ENABLED)
+#include <nrfx_systick.h>
+
+/**
+ * @brief Maximum number of ticks to delay
+ *
+ * The maximum number of ticks should be much lower than
+ * Physical maximum count of the SysTick timer.
+ * It is dictated by the fact that it would be impossible to detect delay
+ * properly when the timer value warps around the starting point.
+ */
+#define NRFX_SYSTICK_TICKS_MAX (NRF_SYSTICK_VAL_MASK / 2UL)
+
+/**
+ * @brief Number of milliseconds in a second
+ */
+#define NRFX_SYSTICK_MS (1000UL)
+
+/**
+ * @brief Number of microseconds in a second
+ */
+#define NRFX_SYSTICK_US (1000UL * NRFX_SYSTICK_MS)
+
+/**
+ * @brief Number of milliseconds to wait in single loop
+ *
+ * Constant used by @ref nrd_drv_systick_delay_ms function
+ * to split waiting into loops and rest.
+ *
+ * It describes the number of milliseconds to wait in single loop.
+ *
+ * See @ref nrfx_systick_delay_ms source code for details.
+ */
+#define NRFX_SYSTICK_MS_STEP (64U)
+
+/**
+ * @brief Checks if the given time is in correct range
+ *
+ * Function tests given time is not to big for this library.
+ * Assertion is used for testing.
+ *
+ * @param us Time in microseconds to check
+ */
+#define NRFX_SYSTICK_ASSERT_TIMEOUT(us) \
+    NRFX_ASSERT(us <= (NRFX_SYSTICK_TICKS_MAX / ((SystemCoreClock) / NRFX_SYSTICK_US)));
+
+/**
+ * @brief Function that converts microseconds to ticks
+ *
+ * Function converts from microseconds to CPU ticks.
+ *
+ * @param us Number of microseconds
+ *
+ * @return Number of ticks
+ *
+ * @sa nrfx_systick_ms_tick
+ */
+static inline uint32_t nrfx_systick_us_tick(uint32_t us)
+{
+    return us * ((SystemCoreClock) / NRFX_SYSTICK_US);
+}
+
+/**
+ * @brief Function that converts milliseconds to ticks
+ *
+ * Function converts from milliseconds to CPU ticks.
+ *
+ * @param us Number of milliseconds
+ *
+ * @return Number of ticks
+ *
+ * @sa nrfx_systick_us_tick
+ */
+static inline uint32_t nrfx_systick_ms_tick(uint32_t ms)
+{
+    return ms * ((SystemCoreClock) / NRFX_SYSTICK_MS);
+}
+
+void nrfx_systick_init(void)
+{
+    nrf_systick_load_set(NRF_SYSTICK_VAL_MASK);
+    nrf_systick_csr_set(
+        NRF_SYSTICK_CSR_CLKSOURCE_CPU |
+        NRF_SYSTICK_CSR_TICKINT_DISABLE |
+        NRF_SYSTICK_CSR_ENABLE);
+}
+
+void nrfx_systick_get(nrfx_systick_state_t * p_state)
+{
+    p_state->time = nrf_systick_val_get();
+}
+
+bool nrfx_systick_test(nrfx_systick_state_t const * p_state, uint32_t us)
+{
+    NRFX_SYSTICK_ASSERT_TIMEOUT(us);
+
+    const uint32_t diff = NRF_SYSTICK_VAL_MASK & ((p_state->time) - nrf_systick_val_get());
+    return (diff >= nrfx_systick_us_tick(us));
+}
+
+void nrfx_systick_delay_ticks(uint32_t ticks)
+{
+    NRFX_ASSERT(ticks <= NRFX_SYSTICK_TICKS_MAX);
+
+    const uint32_t start = nrf_systick_val_get();
+    while ((NRF_SYSTICK_VAL_MASK & (start - nrf_systick_val_get())) < ticks)
+    {
+        /* Nothing to do */
+    }
+}
+
+void nrfx_systick_delay_us(uint32_t us)
+{
+    NRFX_SYSTICK_ASSERT_TIMEOUT(us);
+    nrfx_systick_delay_ticks(nrfx_systick_us_tick(us));
+}
+
+void nrfx_systick_delay_ms(uint32_t ms)
+{
+    uint32_t n = ms / NRFX_SYSTICK_MS_STEP;
+    uint32_t r = ms % NRFX_SYSTICK_MS_STEP;
+    while (0 != (n--))
+    {
+        nrfx_systick_delay_ticks(nrfx_systick_ms_tick(NRFX_SYSTICK_MS_STEP));
+    }
+    nrfx_systick_delay_ticks(nrfx_systick_ms_tick(r));
+}
+
+#endif // NRFX_CHECK(NRFX_SYSTICK_ENABLED)