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nuttx/include/nuttx/clock.h
patacongo f2df8af310 Add clock_synchronize() which may be used to re-synchonize the system time with an RTC after recovering from a low power state 
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4503 42af7a65-404d-4744-a932-0658087f49c3
2012-03-22 14:52:46 +00:00

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/****************************************************************************
* include/nuttx/clock.h
*
* Copyright (C) 2007-2009, 2011-2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 NuttX 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 OWNER 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 _INCLUDE_NUTTX_CLOCK_H
#define _INCLUDE_NUTTX_CLOCK_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <time.h>
#include <nuttx/compiler.h>
/****************************************************************************
* Pro-processor Definitions
****************************************************************************/
/* Configuration ************************************************************/
/* Efficient, direct access to OS global timer variables will be supported
* if the execution environment has direct access to kernel global data.
* The code in this execution context can access the kernel global data
* directly if: (1) this is an un-protected, non-kernel build, or (2)
* this code is being built for execution within the kernel.
*/
#undef __HAVE_KERNEL_GLOBALS
#if !defined(CONFIG_NUTTX_KERNEL) || defined(__KERNEL__)
# define __HAVE_KERNEL_GLOBALS 1
#else
# define __HAVE_KERNEL_GLOBALS 0
#endif
/* If CONFIG_SYSTEM_TIME64 is selected and the CPU supports long long types,
* then a 64-bit system time will be used.
*/
#ifndef CONFIG_HAVE_LONG_LONG
# undef CONFIG_SYSTEM_TIME64
#endif
/* Timing constants *********************************************************/
#define NSEC_PER_SEC 1000000000
#define USEC_PER_SEC 1000000
#define MSEC_PER_SEC 1000
#define DSEC_PER_SEC 10
#define NSEC_PER_DSEC 100000000
#define USEC_PER_DSEC 100000
#define MSEC_PER_DSEC 100
#define NSEC_PER_MSEC 1000000
#define USEC_PER_MSEC 1000
#define NSEC_PER_USEC 1000
/* The interrupt interval of the system timer is given by MSEC_PER_TICK.
* This is the expected number of milliseconds between calls from the
* processor-specific logic to sched_process_timer(). The default value
* of MSEC_PER_TICK is 10 milliseconds (100KHz). However, this default
* setting can be overridden by defining the interval in milliseconds as
* CONFIG_MSEC_PER_TICK in the board configuration file.
*
* The following calculations are only accurate when (1) there is no
* truncation involved and (2) the underlying system timer is an even
* multiple of milliseconds. If (2) is not true, you will probably want
* to redefine all of the following.
*/
#ifdef CONFIG_MSEC_PER_TICK
# define MSEC_PER_TICK (CONFIG_MSEC_PER_TICK)
#else
# define MSEC_PER_TICK (10)
#endif
#define TICK_PER_DSEC (MSEC_PER_DSEC / MSEC_PER_TICK) /* Truncates! */
#define TICK_PER_SEC (MSEC_PER_SEC / MSEC_PER_TICK) /* Truncates! */
#define NSEC_PER_TICK (MSEC_PER_TICK * NSEC_PER_MSEC) /* Exact */
#define USEC_PER_TICK (MSEC_PER_TICK * USEC_PER_MSEC) /* Exact */
#define NSEC2TICK(nsec) (((nsec)+(NSEC_PER_TICK/2))/NSEC_PER_TICK) /* Rounds */
#define USEC2TICK(usec) (((usec)+(USEC_PER_TICK/2))/USEC_PER_TICK) /* Rounds */
#define MSEC2TICK(msec) (((msec)+(MSEC_PER_TICK/2))/MSEC_PER_TICK) /* Rounds */
#define DSEC2TICK(dsec) MSEC2TICK((dsec)*MSEC_PER_DSEC)
#define SEC2TICK(sec) MSEC2TICK((sec)*MSEC_PER_SEC)
#define TICK2NSEC(tick) ((tick)*NSEC_PER_TICK) /* Exact */
#define TICK2USEC(tick) ((tick)*USEC_PER_TICK) /* Exact */
#define TICK2MSEC(tick) ((tick)*MSEC_PER_TICK) /* Exact */
#define TICK2DSEC(tick) (((tick)+(TICK_PER_DSEC/2))/TICK_PER_DSEC) /* Rounds */
#define TICK2SEC(tick) (((tick)+(TICK_PER_SEC/2))/TICK_PER_SEC) /* Rounds */
/****************************************************************************
* Global Data
****************************************************************************/
#if !defined(CONFIG_DISABLE_CLOCK)
/* Access to raw system clock ***********************************************/
/* Direct access to the system timer/counter is supported only if (1) the
* system timer counter is available (i.e., we are not configured to use
* a hardware periodic timer), and (2) the execution environment has direct
* access to kernel global data
*/
#if __HAVE_KERNEL_GLOBALS
# ifdef CONFIG_SYSTEM_TIME64
extern volatile uint64_t g_system_timer;
#define clock_systimer() (uint32_t)(g_system_timer & 0x00000000ffffffff)
#define clock_systimer64() g_system_timer
# else
extern volatile uint32_t g_system_timer;
#define clock_systimer() g_system_timer
# endif
#endif
/****************************************************************************
* Global Function Prototypes
****************************************************************************/
#ifdef __cplusplus
#define EXTERN extern "C"
extern "C" {
#else
#define EXTERN extern
#endif
/****************************************************************************
* Function: clock_synchronize
*
* Description:
* Synchronize the system timer to a hardware RTC. This operation is
* normally performed automatically by the system during clock
* initialization. However, the user may also need to explicitly re-
* synchronize the system timer to the RTC under certain conditions where
* the system timer is known to be in error. For example, in certain low-
* power states, the system timer may be stopped but the RTC will continue
* keep correct time. After recovering from such low-power state, this
* function should be called to restore the correct system time.
*
* Calling this function could result in system time going "backward" in
* time, especially with certain lower resolution RTC implementations.
* Time going backward could have bad consequences if there are ongoing
* timers and delays. So use this interface with care.
*
* Parameters:
* None
*
* Return Value:
* None
*
* Assumptions:
*
****************************************************************************/
#ifdef CONFIG_RTC
EXTERN void clock_synchronize(void);
#endif
/****************************************************************************
* Function: clock_systimer
*
* Description:
* Return the current value of the 32-bit system timer counter. Indirect
* access to the system timer counter is required through this function if
* the execution environment does not have direct access to kernel global
* data
*
* Parameters:
* None
*
* Return Value:
* The current value of the system timer counter
*
* Assumptions:
*
****************************************************************************/
#if !__HAVE_KERNEL_GLOBALS
# ifdef CONFIG_SYSTEM_TIME64
# define clock_systimer() (uint32_t)(clock_systimer64() & 0x00000000ffffffff)
# else
EXTERN uint32_t clock_systimer(void);
# endif
#endif
/****************************************************************************
* Function: clock_systimer64
*
* Description:
* Return the current value of the 64-bit system timer counter. Indirect
* access to the system timer counter is required through this function if
* the execution environment does not have direct access to kernel global
* data
*
* Parameters:
* None
*
* Return Value:
* The current value of the system timer counter
*
* Assumptions:
*
****************************************************************************/
#if !__HAVE_KERNEL_GLOBALS && defined(CONFIG_SYSTEM_TIME64)
EXTERN uint64_t clock_systimer64(void);
#endif
#undef EXTERN
#ifdef __cplusplus
}
#endif
#endif /* !CONFIG_DISABLE_CLOCK */
#endif /* _INCLUDE_NUTTX_CLOCK_H */
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