timing: add support for nordic SoCs with RTC timer

Add abstraction for nordic SoCs using Nordic RTC as the source for
timestamps and cycles.

Signed-off-by: Anas Nashif <[email protected]>

Author: nashif

soc/arm/nordic_nrf/CMakeLists.txt

@@ -6,3 +6,7 @@ zephyr_sources(
   validate_base_addresses.c
   validate_enabled_instances.c
   )
+
+if(CONFIG_SOC_HAS_TIMING_FUNCTIONS AND NOT CONFIG_BOARD_HAS_TIMING_FUNCTIONS)
+zephyr_library_sources_ifdef(CONFIG_TIMING_FUNCTIONS timing.c)
+endif()

soc/arm/nordic_nrf/Kconfig.defconfig

@@ -33,6 +33,9 @@ config SYS_POWER_MANAGEMENT
 config BUILD_OUTPUT_HEX
 	default y
 
+config SOC_HAS_TIMING_FUNCTIONS
+	default y
+
 config GPIO
 	default y
 	depends on SPI

soc/arm/nordic_nrf/timing.c

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2020 Intel Corporation.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <arch/arm/aarch32/arch.h>
+#include <kernel.h>
+#include <sys_clock.h>
+#include <timing/timing.h>
+#include <nrfx.h>
+
+#if defined(CONFIG_NRF_RTC_TIMER)
+
+
+#define CYCLES_PER_SEC (16000000 / (1 << NRF_TIMER2->PRESCALER))
+
+void timing_init(void)
+{
+	NRF_TIMER2->TASKS_CLEAR = 1; /* Clear Timer */
+	NRF_TIMER2->MODE = 0; /* Timer Mode */
+	NRF_TIMER2->PRESCALER = 0; /* 16M Hz */
+	NRF_TIMER2->BITMODE = 3; /* 32 - bit */
+}
+
+void timing_start(void)
+{
+	NRF_TIMER2->TASKS_START = 1;
+}
+
+void timing_stop(void)
+{
+	NRF_TIMER2->TASKS_STOP = 1; /* Stop Timer */
+}
+
+timing_t timing_counter_get(void)
+{
+	NRF_TIMER2->TASKS_CAPTURE[0] = 1;
+	return NRF_TIMER2->CC[0] * ((SystemCoreClock) / CYCLES_PER_SEC);
+}
+
+uint64_t timing_cycles_get(volatile timing_t *const start,
+			   volatile timing_t *const end)
+{
+	return (*end - *start);
+}
+
+uint64_t timing_freq_get(void)
+{
+	return SystemCoreClock;
+}
+
+uint64_t timing_cycles_to_ns(uint64_t cycles)
+{
+	return (cycles) * (NSEC_PER_SEC) / (SystemCoreClock);
+}
+
+uint64_t timing_cycles_to_ns_avg(uint64_t cycles, uint32_t count)
+{
+	return timing_cycles_to_ns(cycles) / count;
+}
+
+uint32_t timing_freq_get_mhz(void)
+{
+	return (uint32_t)(timing_freq_get() / 1000000);
+}
+
+#endif