/*-------------------------------------------------------------------------+
| timer.c v1.1 - PC386 BSP - 1997/08/07
+--------------------------------------------------------------------------+
| This file contains the PC386 timer package.
+--------------------------------------------------------------------------+
| NOTE: It is important that the timer start/stop overhead be determined
| when porting or modifying this code.
+--------------------------------------------------------------------------+
| (C) Copyright 1997 -
| - NavIST Group - Real-Time Distributed Systems and Industrial Automation
|
| http://pandora.ist.utl.pt
|
| Instituto Superior Tecnico * Lisboa * PORTUGAL
+--------------------------------------------------------------------------+
| Disclaimer:
|
| This file is provided "AS IS" without warranty of any kind, either
| expressed or implied.
+--------------------------------------------------------------------------+
| This code is base on:
| timer.c,v 1.7 1995/12/19 20:07:43 joel Exp - go32 BSP
|
| Rosimildo daSilva -ConnectTel, Inc - Fixed infinite loop in the Calibration
| routine. I've seen this problems with faster machines ( pentiums ). Sometimes
| RTEMS just hangs at startup.
|
| With the following copyright notice:
| **************************************************************************
| * COPYRIGHT (c) 1989-1999.
| * On-Line Applications Research Corporation (OAR).
| *
| * The license and distribution terms for this file may be
| * found in found in the file LICENSE in this distribution or at
| * http://www.OARcorp.com/rtems/license.html.
| **************************************************************************
|
| $Id$
+--------------------------------------------------------------------------*/
#include <stdlib.h>
#include <bsp.h>
#include <irq.h>
/*-------------------------------------------------------------------------+
| Constants
+--------------------------------------------------------------------------*/
#define AVG_OVERHEAD 0 /* 0.1 microseconds to start/stop timer. */
#define LEAST_VALID 1 /* Don't trust a value lower than this. */
#define SLOW_DOWN_IO 0x80 /* io which does nothing */
#define TWO_MS (rtems_unsigned32)(2000) /* TWO_MS = 2000us (sic!) */
#define MSK_NULL_COUNT 0x40 /* bit counter available for reading */
#define CMD_READ_BACK_STATUS 0xE2 /* command read back status */
/*-------------------------------------------------------------------------+
| Global Variables
+--------------------------------------------------------------------------*/
volatile rtems_unsigned32 Ttimer_val;
rtems_boolean Timer_driver_Find_average_overhead = TRUE;
volatile unsigned int fastLoop1ms, slowLoop1ms;
/*-------------------------------------------------------------------------+
| External Prototypes
+--------------------------------------------------------------------------*/
extern void timerisr(void);
/* timer (int 08h) Interrupt Service Routine (defined in 'timerisr.s') */
/*-------------------------------------------------------------------------+
| Pentium optimized timer handling.
+--------------------------------------------------------------------------*/
#if defined(pentium)
/*-------------------------------------------------------------------------+
| Function: rdtsc
| Description: Read the value of PENTIUM on-chip cycle counter.
| Global Variables: None.
| Arguments: None.
| Returns: Value of PENTIUM on-chip cycle counter.
+--------------------------------------------------------------------------*/
static inline unsigned long long
rdtsc(void)
{
/* Return the value of the on-chip cycle counter. */
unsigned long long result;
asm volatile(".byte 0x0F, 0x31" : "=A" (result));
return result;
} /* rdtsc */
/*-------------------------------------------------------------------------+
| Function: Timer_exit
| Description: Timer cleanup routine at RTEMS exit. NOTE: This routine is
| not really necessary, since there will be a reset at exit.
| Global Variables: None.
| Arguments: None.
| Returns: Nothing.
+--------------------------------------------------------------------------*/
void
Timer_exit(void)
{
} /* Timer_exit */
/*-------------------------------------------------------------------------+
| Function: Timer_initialize
| Description: Timer initialization routine.
| Global Variables: Ttimer_val.
| Arguments: None.
| Returns: Nothing.
+--------------------------------------------------------------------------*/
void
Timer_initialize(void)
{
static rtems_boolean First = TRUE;
if (First)
{
First = FALSE;
atexit(Timer_exit); /* Try not to hose the system at exit. */
}
Ttimer_val = rdtsc(); /* read starting time */
} /* Timer_initialize */
/*-------------------------------------------------------------------------+
| Function: Read_timer
| Description: Read hardware timer value.
| Global Variables: Ttimer_val, Timer_driver_Find_average_overhead.
| Arguments: None.
| Returns: Nothing.
+--------------------------------------------------------------------------*/
rtems_unsigned32
Read_timer(void)
{
register rtems_unsigned32 total;
total = (rtems_unsigned32)(rdtsc() - Ttimer_val);
if (Timer_driver_Find_average_overhead)
return total;
else if (total < LEAST_VALID)
return 0; /* below timer resolution */
else
return (total - AVG_OVERHEAD);
} /* Read_timer */
#else /* pentium */
/*-------------------------------------------------------------------------+
| Non-Pentium timer handling.
+--------------------------------------------------------------------------*/
#define US_PER_ISR 250 /* Number of micro-seconds per timer interruption */
/*-------------------------------------------------------------------------+
| Function: Timer_exit
| Description: Timer cleanup routine at RTEMS exit. NOTE: This routine is
| not really necessary, since there will be a reset at exit.
| Global Variables: None.
| Arguments: None.
| Returns: Nothing.
+--------------------------------------------------------------------------*/
static void
timerOff(const rtems_raw_irq_connect_data* used)
{
/*
* disable interrrupt at i8259 level
*/
BSP_irq_disable_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);
/* reset timer mode to standard (DOS) value */
outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN);
outport_byte(TIMER_CNTR0, 0);
outport_byte(TIMER_CNTR0, 0);
} /* Timer_exit */
static void
timerOn(const rtems_raw_irq_connect_data* used)
{
/* load timer for US_PER_ISR microsecond period */
outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN);
outport_byte(TIMER_CNTR0, US_TO_TICK(US_PER_ISR) >> 0 & 0xff);
outport_byte(TIMER_CNTR0, US_TO_TICK(US_PER_ISR) >> 8 & 0xff);
/*
* enable interrrupt at i8259 level
*/
BSP_irq_enable_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);
}
static int
timerIsOn(const rtems_raw_irq_connect_data *used)
{
return BSP_irq_enabled_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);}
static rtems_raw_irq_connect_data timer_raw_irq_data = {
BSP_PERIODIC_TIMER + BSP_IRQ_VECTOR_BASE,
timerisr,
timerOn,
timerOff,
timerIsOn
};
/*-------------------------------------------------------------------------+
| Function: Timer_exit
| Description: Timer cleanup routine at RTEMS exit. NOTE: This routine is
| not really necessary, since there will be a reset at exit.
| Global Variables: None.
| Arguments: None.
| Returns: Nothing.
+--------------------------------------------------------------------------*/
void
Timer_exit(void)
{
i386_delete_idt_entry (&timer_raw_irq_data);
} /* Timer_exit */
/*-------------------------------------------------------------------------+
| Function: Timer_initialize
| Description: Timer initialization routine.
| Global Variables: Ttimer_val.
| Arguments: None.
| Returns: Nothing.
+--------------------------------------------------------------------------*/
void
Timer_initialize(void)
{
static rtems_boolean First = TRUE;
if (First)
{
First = FALSE;
atexit(Timer_exit); /* Try not to hose the system at exit. */
if (!i386_set_idt_entry (&timer_raw_irq_data)) {
printk("raw handler connexion failed\n");
rtems_fatal_error_occurred(1);
}
}
/* wait for ISR to be called at least once */
Ttimer_val = 0;
while (Ttimer_val == 0)
continue;
Ttimer_val = 0;
} /* Timer_initialize */
/*-------------------------------------------------------------------------+
| Function: Read_timer
| Description: Read hardware timer value.
| Global Variables: Ttimer_val, Timer_driver_Find_average_overhead.
| Arguments: None.
| Returns: Nothing.
+--------------------------------------------------------------------------*/
rtems_unsigned32
Read_timer(void)
{
register rtems_unsigned32 total, clicks;
register rtems_unsigned8 lsb, msb;
outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_LATCH);
inport_byte(TIMER_CNTR0, lsb);
inport_byte(TIMER_CNTR0, msb);
clicks = (msb << 8) | lsb;
total = (Ttimer_val * US_PER_ISR) + (US_PER_ISR - TICK_TO_US(clicks));
if (Timer_driver_Find_average_overhead)
return total;
else if (total < LEAST_VALID)
return 0; /* below timer resolution */
else
return (total - AVG_OVERHEAD);
}
#endif /* pentium */
/*-------------------------------------------------------------------------+
| Function: Empty_function
| Description: Empty function used in time tests.
| Global Variables: None.
| Arguments: None.
| Returns: Nothing.
+--------------------------------------------------------------------------*/
rtems_status_code Empty_function(void)
{
return RTEMS_SUCCESSFUL;
} /* Empty function */
/*-------------------------------------------------------------------------+
| Function: Set_find_average_overhead
| Description: Set internal Timer_driver_Find_average_overhead flag value.
| Global Variables: Timer_driver_Find_average_overhead.
| Arguments: find_flag - new value of the flag.
| Returns: Nothing.
+--------------------------------------------------------------------------*/
void
Set_find_average_overhead(rtems_boolean find_flag)
{
Timer_driver_Find_average_overhead = find_flag;
} /* Set_find_average_overhead */
static unsigned short lastLoadedValue;
/*-------------------------------------------------------------------------+
| Description: Loads timer 0 with value passed as arguemnt.
| Returns: Nothing. Loaded value must be a number of clock bits...
+--------------------------------------------------------------------------*/
void loadTimerValue( unsigned short loadedValue )
{
lastLoadedValue = loadedValue;
outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_SQWAVE);
outport_byte(TIMER_CNTR0, loadedValue & 0xff);
outport_byte(TIMER_CNTR0, (loadedValue >> 8) & 0xff);
}
/*-------------------------------------------------------------------------+
| Description: Reads the current value of the timer, and converts the
| number of ticks to micro-seconds.
| Returns: number of clock bits elapsed since last load.
+--------------------------------------------------------------------------*/
unsigned int readTimer0()
{
unsigned short lsb, msb;
unsigned char status;
unsigned int count;
outport_byte(TIMER_MODE, (TIMER_RD_BACK | (RB_COUNT_0 & ~(RB_NOT_STATUS | RB_NOT_COUNT))));
inport_byte(TIMER_CNTR0, status);
inport_byte(TIMER_CNTR0, lsb);
inport_byte(TIMER_CNTR0, msb);
count = ( msb << 8 ) | lsb ;
if (status & RB_OUTPUT )
count += lastLoadedValue;
return (2*lastLoadedValue - count);
}
void Timer0Reset()
{
loadTimerValue(0xffff);
readTimer0();
}
void fastLoop (unsigned int loopCount)
{
unsigned int i;
for( i=0; i < loopCount; i++ )outport_byte( SLOW_DOWN_IO, 0 );
}
void slowLoop (unsigned int loopCount)
{
unsigned int j;
for (j=0; j <100 ; j++) {
fastLoop (loopCount);
}
}
/*
* #define DEBUG_CALIBRATE
*/
void
Calibrate_loop_1ms(void)
{
unsigned int offset, offsetTmp, emptyCall, emptyCallTmp, res, i, j;
unsigned int targetClockBits, currentClockBits;
unsigned int slowLoopGranularity, fastLoopGranularity;
rtems_interrupt_level level;
#ifdef DEBUG_CALIBRATE
printk( "Calibrate_loop_1ms is starting, please wait ( but not too loooong. )\n" );
#endif
targetClockBits = US_TO_TICK(1000);
rtems_interrupt_disable(level);
/*
* Fill up the cache to get a correct offset
*/
Timer0Reset();
readTimer0();
/*
* Compute the minimal offset to apply due to read counter register.
*/
offset = 0xffffffff;
for (i=0; i <1000; i++) {
Timer0Reset();
offsetTmp = readTimer0();
offset += offsetTmp;
}
offset = offset / 1000; /* compute average */
/*
* calibrate empty call
*/
fastLoop (0);
emptyCall = 0;
j = 0;
for (i=0; i <10; i++) {
Timer0Reset();
fastLoop (0);
res = readTimer0();
/* res may be inferior to offset on fast
* machine because we took an average for offset
*/
if (res > offset) {
++j;
emptyCallTmp = res - offset;
emptyCall += emptyCallTmp;
}
}
if (j == 0) emptyCall = 0;
else emptyCall = emptyCall / j; /* compute average */
/*
* calibrate fast loop
*/
Timer0Reset();
fastLoop (10000);
res = readTimer0() - offset;
if (res < emptyCall) {
printk("Problem #1 in offset computation in Calibrate_loop_1ms in file libbsp/i386/pc386/timer/timer.c\n");
while (1);
}
fastLoopGranularity = (res - emptyCall) / 10000;
/*
* calibrate slow loop
*/
Timer0Reset();
slowLoop(10);
res = readTimer0();
if (res < offset + emptyCall) {
printk("Problem #2 in offset computation in Calibrate_loop_1ms in file libbsp/i386/pc386/timer/timer.c\n");
while (1);
}
slowLoopGranularity = (res - offset - emptyCall)/ 10;
if (slowLoopGranularity == 0) {
printk("Problem #3 in Calibrate_loop_1ms in file libbsp/i386/pc386/timer/timer.c\n");
while (1);
}
targetClockBits += offset;
#ifdef DEBUG_CALIBRATE
printk("offset = %u, emptyCall = %u, targetClockBits = %u\n",
offset, emptyCall, targetClockBits);
printk("slowLoopGranularity = %u fastLoopGranularity = %u\n",
slowLoopGranularity, fastLoopGranularity);
#endif
slowLoop1ms = (targetClockBits - emptyCall) / slowLoopGranularity;
if (slowLoop1ms != 0) {
fastLoop1ms = targetClockBits % slowLoopGranularity;
if (fastLoop1ms > emptyCall) fastLoop1ms -= emptyCall;
}
else
fastLoop1ms = targetClockBits - emptyCall / fastLoopGranularity;
if (slowLoop1ms != 0) {
/*
* calibrate slow loop
*/
while(1)
{
int previousSign = 0; /* 0 = unset, 1 = incrementing, 2 = decrementing */
Timer0Reset();
slowLoop(slowLoop1ms);
currentClockBits = readTimer0();
if (currentClockBits > targetClockBits) {
if ((currentClockBits - targetClockBits) < slowLoopGranularity) {
/* decrement loop counter anyway to be sure slowLoop(slowLoop1ms) < targetClockBits */
--slowLoop1ms;
break;
}
else {
--slowLoop1ms;
if (slowLoop1ms == 0) break;
if (previousSign == 0) previousSign = 2;
if (previousSign == 1) break;
}
}
else {
if ((targetClockBits - currentClockBits) < slowLoopGranularity) {
break;
}
else {
++slowLoop1ms;
if (previousSign == 0) previousSign = 1;
if (previousSign == 2) break;
}
}
}
}
/*
* calibrate fast loop
*/
if (fastLoopGranularity != 0 ) {
while(1) {
int previousSign = 0; /* 0 = unset, 1 = incrementing, 2 = decrementing */
Timer0Reset();
if (slowLoop1ms != 0) slowLoop(slowLoop1ms);
fastLoop(fastLoop1ms);
currentClockBits = readTimer0();
if (currentClockBits > targetClockBits) {
if ((currentClockBits - targetClockBits) < fastLoopGranularity)
break;
else {
--fastLoop1ms;
if (previousSign == 0) previousSign = 2;
if (previousSign == 1) break;
}
}
else {
if ((targetClockBits - currentClockBits) < fastLoopGranularity)
break;
else {
++fastLoop1ms;
if (previousSign == 0) previousSign = 1;
if (previousSign == 2) break;
}
}
}
}
#ifdef DEBUG_CALIBRATE
printk("slowLoop1ms = %u, fastLoop1ms = %u\n", slowLoop1ms, fastLoop1ms);
#endif
rtems_interrupt_enable(level);
}
/*-------------------------------------------------------------------------+
| Function: Wait_X_1ms
| Description: loop which waits at least timeToWait ms
| Global Variables: loop1ms
| Arguments: timeToWait
| Returns: Nothing.
+--------------------------------------------------------------------------*/
void
Wait_X_ms( unsigned int timeToWait){
unsigned int j;
for (j=0; j<timeToWait ; j++) {
if (slowLoop1ms != 0) slowLoop(slowLoop1ms);
fastLoop(fastLoop1ms);
}
}
