source: rtems/c/src/lib/libbsp/i386/go32/clock/ckinit.c @ 4ca27cf

4.104.114.84.95
Last change on this file since 4ca27cf was 637df35, checked in by Joel Sherrill <joel.sherrill@…>, on Jul 12, 1995 at 7:47:25 PM

Ada95, gnat, go32

  • Property mode set to 100644
File size: 3.5 KB
Line 
1/*  Clock_initialize
2 *
3 *  This routine initializes the 8254 timer under GO32.
4 *  The tick frequency is 1 millisecond.
5 *
6 *  Input parameters:  NONE
7 *
8 *  Output parameters:  NONE
9 *
10 *  $Id$
11 */
12
13#include <bsp.h>
14#include <clockdrv.h>
15#include <stdlib.h>
16
17volatile rtems_unsigned32 Clock_driver_ticks;
18rtems_unsigned32 Clock_isrs_per_tick;           /* ISRs per tick */
19rtems_unsigned32 Clock_isrs;                    /* ISRs until next tick */
20rtems_isr_entry  Old_ticker;
21
22rtems_device_driver Clock_initialize(
23  rtems_device_major_number major,
24  rtems_device_minor_number minor,
25  void *pargp,
26  rtems_id tid,
27  rtems_unsigned32 *rval
28)
29{
30  Install_clock( Clock_isr );
31}
32
33void ReInstall_clock(
34  rtems_isr_entry clock_isr
35)
36{
37  rtems_unsigned32 isrlevel = 0;
38
39  rtems_interrupt_disable( isrlevel );
40   (void) set_vector( clock_isr, 0x8, 1 );
41  rtems_interrupt_enable( isrlevel );
42}
43
44void Install_clock(
45  rtems_isr_entry clock_isr
46)
47{
48    unsigned int        microseconds_per_isr;
49
50#if 0
51    /* Initialize clock from on-board real time clock.  This breaks the */
52    /* test code which assumes which assumes the application will do it. */
53    {
54        rtems_time_of_day Now;
55        extern void init_rtc( void );
56        extern long rtc_read( rtems_time_of_day * tod );
57        init_rtc();
58        if ( rtc_read( &Now ) >= 0 )
59            clock_set( &Now );
60    }
61#endif
62
63    /* Start by assuming hardware counter is large enough, then */
64    /* scale it until it actually fits.                         */
65    Clock_driver_ticks = 0;
66    Clock_isrs_per_tick = 1;
67
68    if ( BSP_Configuration.microseconds_per_tick == 0 )
69        microseconds_per_isr = 10000;   /* default 10 ms */
70    else
71        microseconds_per_isr = BSP_Configuration.microseconds_per_tick;
72    while ( US_TO_TICK(microseconds_per_isr) > 65535 )  {
73        Clock_isrs_per_tick  *= 10;
74        microseconds_per_isr /= 10;
75    }
76
77    /* Initialize count in ckisr.c */
78    Clock_isrs = Clock_isrs_per_tick;
79
80#if 0
81    /* This was dropped in the last revision.  Its a nice thing to know. */
82    TICKS_PER_SECOND = 1000000 / (Clock_isrs_per_tick * microseconds_per_isr);
83#endif
84
85    if ( BSP_Configuration.ticks_per_timeslice )  {
86        /* 105/88 approximates TIMER_TICK*1e-6 */
87        unsigned int count = US_TO_TICK( microseconds_per_isr );
88
89        Old_ticker = (rtems_isr_entry) set_vector( clock_isr, 0x8, 1 );
90        outport_byte( TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN );
91        outport_byte( TIMER_CNTR0, count >> 0 & 0xff );
92        outport_byte( TIMER_CNTR0, count >> 8 & 0xff );
93    } 
94    atexit( Clock_exit );
95}
96
97void Clock_exit( void )
98{
99  if ( BSP_Configuration.ticks_per_timeslice ) {
100        extern void rtc_set_dos_date( void );
101
102        /* reset to DOS value: */
103        outport_byte( TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN );
104        outport_byte( TIMER_CNTR0, 0 );
105        outport_byte( TIMER_CNTR0, 0 );
106
107        /* reset time-of-day */
108        rtc_set_dos_date();
109       
110        /* re-enable old handler: assume it was one of ours */
111        set_vector( (rtems_isr_entry)Old_ticker, 0x8, 1 );
112  }
113}
114
115
116#if 0 && defined(pentium)
117/* This can be used to get extremely accurate timing on a pentium.      */
118/* It isn't supported. [bryce]                                          */
119#define HZ 90.0
120volatile long long Last_RDTSC;
121#define RDTSC()\
122  ({ long long _now; __asm __volatile (".byte 0x0F,0x31":"=A"(_now)); _now; })
123long long Kernel_Time_ns( void )
124{
125    extern rtems_unsigned32 _TOD_Ticks_per_second;
126    unsigned isrs_per_second = Clock_isrs_per_tick * _TOD_Ticks_per_second;
127    long long now;
128    int flags;
129    disable_intr( flags );
130    now = 1e9 * Clock_driver_ticks / isrs_per_second
131              + (RDTSC() - Last_RDTSC) * (1000.0/HZ);
132    enable_intr( flags );
133    return now;
134}
135#endif
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