decrmntr.c

这是单板上DPRAM的驱动程序

/* @(#) pSOSystem PowerPC/V2.2.2: bsps/devices/powerpc/decrmntr.c 2.30 97/10/06 12:30:59 */
/***********************************************************************/
/*                                                                     */
/*   MODULE:  bsps/devices/powerpc/decrmntr.c                          */
/*   DATE:    97/10/06                                                 */
/*   PURPOSE: Timer driver for ads, sbc, mbx, gn15, pwrplus and pwrcore*/
/*            bsps supplied with pSOSystem.                            */
/*---------------------------------------------------------------------*/
/*                                                                     */
/*           Copyright 1991 - 1997, Integrated Systems, Inc.           */
/*                      ALL RIGHTS RESERVED                            */
/*                                                                     */
/*   Permission is hereby granted to licensees of Integrated Systems,  */
/*   Inc. products to use or abstract this computer program for the    */
/*   sole purpose of implementing a product based on Integrated        */
/*   Systems, Inc. products.   No other rights to reproduce, use,      */
/*   or disseminate this computer program, whether in part or in       */
/*   whole, are granted.                                               */
/*                                                                     */
/*   Integrated Systems, Inc. makes no representation or warranties    */
/*   with respect to the performance of this computer program, and     */
/*   specifically disclaims any responsibility for any damages,        */
/*   special or consequential, connected with the use of this program. */
/*                                                                     */
/*---------------------------------------------------------------------*/
/*                                                                     */
/*DESCRIPTION:This file contains the tick timer driver for the         */
/*            decrementer in the processor and timer chip Intel 82C54. */
/*            Selection of one of the two is controlled by defining    */
/*            DEC_TICK_TIMER. The use of the decrementer alleviates the*/
/*            need for the 8254 in the system.                         */
/*                                                                     */
/***********************************************************************/
#include "bsp.h"
#include "board.h"
#include <bspfuncs.h>
#include <psos.h>
#include <configs.h>
#include <drv_intf.h>
#include <configs.h>
#include "bsplocal.h"

/*---------------------------------------------------------------------*/
/* General Definitions                                                 */
/*---------------------------------------------------------------------*/
 
/*---------------------------------------------------------------------*/
/* The node anchor address is a pointer to the node configuration      */
/* table, which in turn points to the pSOS+ configuration table.  This */
/* driver will look in the pSOS+ configuration table to see how many   */
/* ticks per second are specified, and thus how many interrupts per    */
/* second to generate.                                                 */
/*---------------------------------------------------------------------*/
extern NODE_CT *anchor;

/*---------------------------------------------------------------------*/
/* This field indicates if pSOS+ has initialized.                      */
/*---------------------------------------------------------------------*/
extern ULONG PsosUpFlag;
extern ULONG BoardDecClkRateHz;

/*---------------------------------------------------------------------*/
/* Define function prototypes                                          */
/*---------------------------------------------------------------------*/
void RtcInit(struct ioparms *);
void Delay100ms(void);
void RtcIsr(void);
void DecIsr(void);

/*---------------------------------------------------------------------*/
/* Declarations of external functions & variables                      */
/*---------------------------------------------------------------------*/
extern void  BspInformTick(void);
extern void  ppcDECwr(ULONG);
extern ULONG ppcDECrd(void);
extern ULONG ppcDECcalib(void);
extern ULONG ppcTimeBasseRd(ULONG *);

/*---------------------------------------------------------------------*/
/* This flag indicated that the decrementer is being used for counting */
/* a 100 ms interval.                                                  */
/*---------------------------------------------------------------------*/
ULONG delay100ms;

/*---------------------------------------------------------------------*/
/* The time constant for the decrmenter is stored here.                */
/*---------------------------------------------------------------------*/
ULONG rtcDecTimeConst;

/*---------------------------------------------------------------------*/
/* The decrementer driver should announce a tick to pSOS+ only after   */
/* the tick timer has been initialized.                                */
/*---------------------------------------------------------------------*/
ULONG rtcDecInitDone;

/***********************************************************************/
/* DecIsr:       Tick timer ISR.                                       */
/* INPUTS:       None                                                  */
/* OUTPUTS:      None                                                  */
/* NOTES:        Announces a tick.                                     */
/***********************************************************************/
void DecIsr(void)
{

/*---------------------------------------------------------------------*/
/* If the tick timer has been initialized announce the tick to pSOS+   */
/*---------------------------------------------------------------------*/
if ((rtcDecInitDone != 0) && (PsosUpFlag != 0))
   {
   tm_tick(); 

   /*------------------------------------------------------------------*/
   /* Update the time constant in the decrementer                      */
   /*------------------------------------------------------------------*/
   ppcDECadj(rtcDecTimeConst);

   /*------------------------------------------------------------------*/
   /* Inform the BSP about Tick. So that BSPs can take different       */
   /* actions depending on the hardware set it has.                    */
   /* This function is in "bspcfg.c" file.                             */
   /*------------------------------------------------------------------*/
   BspInformTick();
   }
else
   {
   /*------------------------------------------------------------------*/
   /* Update delay flag if it was set.                                 */
   /*------------------------------------------------------------------*/
   if (delay100ms != 0)
      delay100ms = 0;

   /*------------------------------------------------------------------*/
   /* Write the decrementer with a large value                         */
   /*------------------------------------------------------------------*/
   ppcDECwr(0x7FFFFFFF);
   }
}

/***********************************************************************/
/* RtcInit:      Initialize real time clock.                           */
/* INPUTS:       None                                                  */
/* OUTPUTS:      None                                                  */
/* NOTES:        Installs the RTC Interrupt handler in Interrupt Table.*/
/***********************************************************************/
#if DEC_TICK_TIMER
void RtcInit (struct ioparms *p)
{
ULONG s;
ULONG AdjustCount;

/*---------------------------------------------------------------------*/
/* Set the count from pSOS+ configuration table                        */
/*---------------------------------------------------------------------*/
if (BD_VALIDATE_TICK2SEC) {
   p->err = TIMR_TICKRATE;
   return;
   }

/*---------------------------------------------------------------------*/
/* Get the time constant specific to the board and the CPU installed   */
/*---------------------------------------------------------------------*/
rtcDecTimeConst = BoardDecClkRateHz / (anchor->psosct->kc_ticks2sec);

/*---------------------------------------------------------------------*/
/* Time constant adjustment may be necessary because of the overhead   */
/* caused by the reading and writing decremneter.                      */
/*---------------------------------------------------------------------*/
#ifdef BD_RTC_ADJUST_COUNT
AdjustCount = BD_RTC_ADJUST_COUNT;        /* user specified adjustment */
#else
AdjustCount = ppcDECcalib();              /* runtime auto adjustment   */
#endif

if(rtcDecTimeConst > AdjustCount)
    rtcDecTimeConst -= AdjustCount;

/*---------------------------------------------------------------------*/
/* Update the decrementer                                              */
/*---------------------------------------------------------------------*/
ppcDECwr(rtcDecTimeConst);

/*---------------------------------------------------------------------*/
/* Set init flag                                                       */
/*---------------------------------------------------------------------*/
rtcDecInitDone = 1;

/*---------------------------------------------------------------------*/
/* Finally, set return values in the I/O driver parameter structure.   */
/*---------------------------------------------------------------------*/
p->used       = 1;
p->err        = 0;
p->out_retval = 0;
}
#endif /*  DEC_TICK_TIMER */

#if 0
/***********************************************************************/
/* Delay100ms: Delay for 100ms                                         */
/* INPUTS:     None                                                    */
/* OUTPUTS:    None                                                    */
/* NOTES:      Provides a delay of 100msec. This routine should be used*/
/*             before pSOS has initialized.                            */
/*                                                                     */
/***********************************************************************/
#if DEC_TICK_TIMER
void Delay100ms(void)
{
ULONG i;
ULONG count100ms;

/*---------------------------------------------------------------------*/
/* Update delay flag                                                   */
/*---------------------------------------------------------------------*/
delay100ms = 1;

count100ms = BoardDecClkRateHz/10;
ppcDECwr(count100ms);

/*---------------------------------------------------------------------*/
/* Poll while the interval elapses                                     */
/*---------------------------------------------------------------------*/
while (delay100ms != 0 && (i = ppcDECrd()) != 0 && i < count100ms);

/*---------------------------------------------------------------------*/
/* Update delay flag                                                   */
/*---------------------------------------------------------------------*/
delay100ms = 0;

}
#endif /* DEC_TICK_TIMER */

/***********************************************************************/
/* DelayNms:   Delay for Nms                                           */
/* INPUTS:     Number of msec to delay for.                            */
/* OUTPUTS:    None                                                    */
/* NOTES:      Provides a delay of Nmsec.                              */
/*                                                                     */
/***********************************************************************/
void DelayNmsec(ULONG msec)
{
register UINT curr_dec, tick_cnt, prev_dec;
register UINT timeout, rollover;

if ((rtcDecInitDone) && (PsosUpFlag))
    rollover = rtcDecTimeConst;

else
    rollover = 0x7FFFFFFF;

if (!msec)
    return;

timeout = (BoardDecClkRateHz / 1000) *  msec;

tick_cnt = 0;
for (prev_dec = ppcDECrd();;)
    {
    curr_dec = ppcDECrd();

    if (curr_dec > prev_dec)
		tick_cnt += (prev_dec + (rollover - curr_dec));
    else
		tick_cnt += (prev_dec - curr_dec);

    prev_dec = curr_dec;

    if (tick_cnt >= timeout)
       return;

    }
}
#endif /* 0 */