From 24bf11eca11947d961cc9bb5f7d92dabff169e93 Mon Sep 17 00:00:00 2001 From: Sebastian Huber Date: Wed, 12 Feb 2014 10:31:38 +0100 Subject: score: Add CPU counter support Add a CPU counter interface to allow access to a free-running counter. It is useful to measure short time intervals. This can be used for example to enable profiling of critical low-level functions. Add two busy wait functions rtems_counter_delay_ticks() and rtems_counter_delay_nanoseconds() implemented via the CPU counter. --- cpukit/sapi/Makefile.am | 4 + cpukit/sapi/include/rtems/counter.h | 160 ++++++++++++++++++++++++++++++++++ cpukit/sapi/preinstall.am | 4 + cpukit/sapi/src/cpucounterconverter.c | 39 +++++++++ cpukit/sapi/src/delaynano.c | 27 ++++++ cpukit/sapi/src/delayticks.c | 35 ++++++++ 6 files changed, 269 insertions(+) create mode 100644 cpukit/sapi/include/rtems/counter.h create mode 100644 cpukit/sapi/src/cpucounterconverter.c create mode 100644 cpukit/sapi/src/delaynano.c create mode 100644 cpukit/sapi/src/delayticks.c (limited to 'cpukit/sapi') diff --git a/cpukit/sapi/Makefile.am b/cpukit/sapi/Makefile.am index 65acfc7a01..63eb60595f 100644 --- a/cpukit/sapi/Makefile.am +++ b/cpukit/sapi/Makefile.am @@ -6,6 +6,7 @@ include_rtemsdir = $(includedir)/rtems include_rtems_HEADERS = include/confdefs.h include_rtems_HEADERS += include/rtems/chain.h include_rtems_HEADERS += include/rtems/config.h +include_rtems_HEADERS += include/rtems/counter.h include_rtems_HEADERS += include/rtems/extension.h include_rtems_HEADERS += include/rtems/extensionimpl.h include_rtems_HEADERS += include/rtems/fatal.h @@ -32,6 +33,9 @@ libsapi_a_SOURCES = src/debug.c src/extension.c src/extensioncreate.c \ src/chainprependnotify.c src/rbheap.c src/interrtext.c \ src/fatal2.c src/fatalsrctext.c libsapi_a_SOURCES += src/chainsmp.c +libsapi_a_SOURCES += src/cpucounterconverter.c +libsapi_a_SOURCES += src/delayticks.c +libsapi_a_SOURCES += src/delaynano.c libsapi_a_CPPFLAGS = $(AM_CPPFLAGS) include $(srcdir)/preinstall.am diff --git a/cpukit/sapi/include/rtems/counter.h b/cpukit/sapi/include/rtems/counter.h new file mode 100644 index 0000000000..31b808ad8b --- /dev/null +++ b/cpukit/sapi/include/rtems/counter.h @@ -0,0 +1,160 @@ +/** + * @file + * + * @ingroup ClassicCounter + * + * @brief Free-Running Counter and Busy Wait Delay API + */ + +/* + * Copyright (c) 2014 embedded brains GmbH. All rights reserved. + * + * embedded brains GmbH + * Dornierstr. 4 + * 82178 Puchheim + * Germany + * + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.com/license/LICENSE. + */ + +#ifndef _RTEMS_SAPI_COUNTER_H +#define _RTEMS_SAPI_COUNTER_H + +#include + +#ifdef __cplusplus +extern "C" { +#endif /* __cplusplus */ + +/** + * @defgroup ClassicCounter Free-Running Counter and Busy Wait Delay + * + * @ingroup ClassicRTEMS + * + * @brief Free-running counter and busy wait delay functions. + * + * The RTEMS counter is some free-running counter. It ticks usually with a + * frequency close to the CPU or system bus clock. + * + * The counter can be used in case the overhead of the + * rtems_clock_get_uptime_nanoseconds() is too high. The step from counter + * ticks to/from nanoseconds is explicit in this API unlike to + * rtems_clock_get_uptime_nanoseconds() which performs the conversion on each + * invocation. + * + * This counter works without a clock driver and during system initialization. + * + * The counter can be used to profile low-level operations like SMP locks or + * interrupt disabled critical sections. The counter can act also as an + * entropy source for a random number generator. + * + * The period of the counter depends on the actual hardware. + * + * @{ + */ + +/** + * @brief Unsigned integer type for counter values. + */ +typedef CPU_Counter_ticks rtems_counter_ticks; + +/** + * @brief Reads the current counter values. + * + * @return The current counter values. + */ +static inline rtems_counter_ticks rtems_counter_read( void ) +{ + return _CPU_Counter_read(); +} + +/** + * @brief Returns the difference between the second and first CPU counter + * value. + * + * This operation may be carried out as a modulo operation depending on the + * range of the CPU counter device. + * + * @param[in] second The second CPU counter value. + * @param[in] first The first CPU counter value. + * + * @return Returns second minus first modulo counter period. + */ +static inline rtems_counter_ticks rtems_counter_difference( + rtems_counter_ticks second, + rtems_counter_ticks first +) +{ + return _CPU_Counter_difference( second, first ); +} + +/** + * brief Converts counter ticks into nanoseconds. + * + * @param[in] ticks Some counter ticks. + * + * @return The nanoseconds corresponding to the counter ticks. The value is + * rounded up. + */ +uint64_t rtems_counter_ticks_to_nanoseconds( + rtems_counter_ticks ticks +); + +/** + * brief Converts nanoseconds into counter ticks. + * + * @param[in] nanoseconds Some nanoseconds. + * + * @return The counter ticks corresponding to the nanoseconds. The value is + * rounded up. + */ +rtems_counter_ticks rtems_counter_nanoseconds_to_ticks( + uint32_t nanoseconds +); + +/** + * brief Initializes the counter ticks to/from nanoseconds converter functions. + * + * This function must be used to initialize the + * rtems_counter_ticks_to_nanoseconds() and + * rtems_counter_nanoseconds_to_ticks() functions. It should be called during + * system initialization by the board support package. + * + * @param[in] uint32_t frequency The current counter frequency in Hz. + */ +void rtems_counter_initialize_converter( uint32_t frequency ); + +/** + * @brief Busy wait for some counter ticks. + * + * This function does not disable interrupts. Thus task switches and + * interrupts can interfere with this busy wait may prolong the delay. This + * function busy waits at least the specified time. Due to some overhead the + * actual delay may be longer. + * + * @param[in] ticks The minimum busy wait time in counter ticks. + */ +void rtems_counter_delay_ticks( rtems_counter_ticks ticks ); + +/** + * @brief Busy wait for some nanoseconds. + * + * This function does not disable interrupts. Thus task switches and + * interrupts can interfere with this busy wait may prolong the delay. This + * function busy waits at least the specified time. Due to some overhead the + * actual delay may be longer. + * + * @param[in] nanoseconds The minimum busy wait time in nanoseconds. + */ +void rtems_counter_delay_nanoseconds( uint32_t nanoseconds ); + +/** @} */ + +#ifdef __cplusplus +} +#endif /* __cplusplus */ + +#endif /* _RTEMS_SAPI_COUNTER_H */ diff --git a/cpukit/sapi/preinstall.am b/cpukit/sapi/preinstall.am index 2b247bce58..79eceef405 100644 --- a/cpukit/sapi/preinstall.am +++ b/cpukit/sapi/preinstall.am @@ -40,6 +40,10 @@ $(PROJECT_INCLUDE)/rtems/config.h: include/rtems/config.h $(PROJECT_INCLUDE)/rte $(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/config.h PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/config.h +$(PROJECT_INCLUDE)/rtems/counter.h: include/rtems/counter.h $(PROJECT_INCLUDE)/rtems/$(dirstamp) + $(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/counter.h +PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/counter.h + $(PROJECT_INCLUDE)/rtems/extension.h: include/rtems/extension.h $(PROJECT_INCLUDE)/rtems/$(dirstamp) $(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/extension.h PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/extension.h diff --git a/cpukit/sapi/src/cpucounterconverter.c b/cpukit/sapi/src/cpucounterconverter.c new file mode 100644 index 0000000000..5b03d3c7a1 --- /dev/null +++ b/cpukit/sapi/src/cpucounterconverter.c @@ -0,0 +1,39 @@ +/* + * Copyright (c) 2014 embedded brains GmbH. All rights reserved. + * + * embedded brains GmbH + * Dornierstr. 4 + * 82178 Puchheim + * Germany + * + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.com/license/LICENSE. + */ + +#include + +RTEMS_STATIC_ASSERT(sizeof(rtems_counter_ticks) <= sizeof(uint32_t), type); + +static uint64_t to_ns_scaler = UINT64_C(1) << 32; + +static uint64_t from_ns_scaler = UINT64_C(1) << 32; + +uint64_t rtems_counter_ticks_to_nanoseconds( rtems_counter_ticks counter ) +{ + return (uint32_t) ((counter * to_ns_scaler) >> 32); +} + +rtems_counter_ticks rtems_counter_nanoseconds_to_ticks( uint32_t nanoseconds ) +{ + return (rtems_counter_ticks) ((nanoseconds * from_ns_scaler) >> 32); +} + +void rtems_counter_initialize_converter( uint32_t frequency ) +{ + uint64_t ns_per_s = UINT64_C(1000000000); + + to_ns_scaler = ((ns_per_s << 32) + frequency - 1) / frequency; + from_ns_scaler = ((UINT64_C(1) << 32) * frequency + ns_per_s - 1) / ns_per_s; +} diff --git a/cpukit/sapi/src/delaynano.c b/cpukit/sapi/src/delaynano.c new file mode 100644 index 0000000000..f8a49e2da8 --- /dev/null +++ b/cpukit/sapi/src/delaynano.c @@ -0,0 +1,27 @@ +/* + * Copyright (c) 2014 embedded brains GmbH. All rights reserved. + * + * embedded brains GmbH + * Dornierstr. 4 + * 82178 Puchheim + * Germany + * + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.com/license/LICENSE. + */ + +#ifdef HAVE_CONFIG_H + #include "config.h" +#endif + +#include + +void rtems_counter_delay_nanoseconds( uint32_t nanoseconds ) +{ + rtems_counter_ticks ticks = + rtems_counter_nanoseconds_to_ticks( nanoseconds ); + + rtems_counter_delay_ticks( ticks ); +} diff --git a/cpukit/sapi/src/delayticks.c b/cpukit/sapi/src/delayticks.c new file mode 100644 index 0000000000..45198adecb --- /dev/null +++ b/cpukit/sapi/src/delayticks.c @@ -0,0 +1,35 @@ +/* + * Copyright (c) 2014 embedded brains GmbH. All rights reserved. + * + * embedded brains GmbH + * Dornierstr. 4 + * 82178 Puchheim + * Germany + * + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.com/license/LICENSE. + */ + +#ifdef HAVE_CONFIG_H + #include "config.h" +#endif + +#include + +void rtems_counter_delay_ticks( rtems_counter_ticks ticks ) +{ + rtems_counter_ticks a = rtems_counter_read(); + rtems_counter_ticks delta = 0; + + do { + rtems_counter_ticks b; + + ticks -= delta; + + b = rtems_counter_read(); + delta = rtems_counter_difference( b, a ); + a = b; + } while ( ticks > delta ); +} -- cgit v1.2.3