source: rtems/c/src/lib/libbsp/i386/i386ex/timer/timer.c @ 6ff7e2c

4.104.114.84.95
Last change on this file since 6ff7e2c was 6ff7e2c, checked in by Joel Sherrill <joel.sherrill@…>, on Sep 4, 2003 at 6:51:20 PM

2003-09-04 Joel Sherrill <joel@…>

  • clock/ckinit.c, console/console.c, include/bsp.h, include/coverhd.h, start/80386ex.h, start/80386ex.inc, start/macros.inc, start/start.S, startup/bspstart.c, startup/linkcmds, startup/setvec.c, timer/timer.c, timer/timerisr.S: URL for license changed.
  • Property mode set to 100644
File size: 3.7 KB
Line 
1/*  Timer_init()
2 *
3 *  This routine initializes the timer on the FORCE CPU-386 board.
4 *
5 *  Input parameters:  NONE
6 *
7 *  Output parameters:  NONE
8 *
9 *  NOTE: This routine will not work if the optimizer is enabled
10 *        for some compilers.  The multiple writes to the Z8036
11 *        may be optimized away.
12 *
13 *        It is important that the timer start/stop overhead be
14 *        determined when porting or modifying this code.
15 *
16 *  COPYRIGHT (c) 1989-1999.
17 *  On-Line Applications Research Corporation (OAR).
18 *
19 *  The license and distribution terms for this file may be
20 *  found in the file LICENSE in this distribution or at
21 *  http://www.rtems.com/license/LICENSE.
22 *
23 *  $Id$
24 */
25
26
27#include <rtems.h>
28#include <bsp.h>
29#include <stdlib.h>
30
31int Ttimer_val;
32rtems_boolean Timer_driver_Find_average_overhead;
33
34extern void timerisr();
35extern int ClockIsOn(const rtems_raw_irq_connect_data*);
36
37#define TMR0      0xF040
38#define TMR1      0xF041
39#define TMR2      0xF042
40#define TMRCON    0xF043
41#define TMRCFG    0xF834
42
43void TimerOn(const rtems_raw_irq_connect_data* used)
44{
45
46  Ttimer_val = 0;                           /* clear timer ISR count */
47
48  outport_byte  ( TMRCON , 0xb0 ); /* select tmr2, stay in mode 0 */
49  outport_byte  ( TMR1   , 0xfa ); /* set to 250 usec interval */
50  outport_byte  ( TMR1   , 0x00 );
51  outport_byte  ( TMRCON , 0x64 ); /* change to mode 2 ( starts timer ) */ 
52                                   /* interrupts ARE enabled */
53  /*  outport_byte( IERA, 0x41 );             enable interrupt */
54  /*
55   * enable interrrupt at i8259 level
56   */
57  BSP_irq_enable_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);
58}
59
60void TimerOff(const rtems_raw_irq_connect_data* used)
61{
62    /*
63     * disable interrrupt at i8259 level
64     */
65     BSP_irq_disable_at_i8259s(used->idtIndex - BSP_IRQ_VECTOR_BASE);
66     /* reset timer mode to standard (DOS) value */
67}
68
69static rtems_raw_irq_connect_data timer_raw_irq_data = {
70  BSP_RT_TIMER3 + BSP_IRQ_VECTOR_BASE,
71  timerisr,
72  TimerOn,
73  TimerOff,
74  ClockIsOn
75};
76
77void Timer_exit()
78{
79 if (!i386_delete_idt_entry(&timer_raw_irq_data)) {
80      printk("Timer_exit:Timer raw handler removal failed\n");
81      rtems_fatal_error_occurred(1);
82 }
83}
84
85void Timer_initialize()
86{
87
88  static rtems_boolean First = TRUE;
89
90  if (First)
91  {
92    First = FALSE;
93
94    atexit(Timer_exit); /* Try not to hose the system at exit. */
95    if (!i386_set_idt_entry (&timer_raw_irq_data)) {
96      printk("Timer_initialize: raw handler installation failed\n");
97      rtems_fatal_error_occurred(1);
98    }
99  }
100  /* wait for ISR to be called at least once */
101  Ttimer_val = 0;
102  while (Ttimer_val == 0)
103    continue;
104  Ttimer_val = 0;
105}
106
107#define AVG_OVERHEAD      3  /* It typically takes 3.0 microseconds */
108                             /* (3 ticks) to start/stop the timer. */
109#define LEAST_VALID       4  /* Don't trust a value lower than this */
110
111int Read_timer()
112{
113  register rtems_unsigned32 clicks;
114  register rtems_unsigned32 total;
115
116/*  outport_byte( TBCR, 0x00 );  stop the timer -- not needed on intel */
117
118  outport_byte ( TMRCON, 0x40 );   /* latch the count */
119  inport_byte  ( TMR1,   clicks ); /* read the count */ 
120
121  total = Ttimer_val + 250 - clicks;
122
123/*  outport_byte( TBCR, 0x00 );   initial value */
124/*  outport_byte( IERA, 0x40 );   disable interrupt */
125
126  /* ??? Is "do not restore old vector" causing problems? */
127
128  if ( Timer_driver_Find_average_overhead == 1 )
129    return total;          /* in one microsecond units */
130
131  else {
132    if ( total < LEAST_VALID )
133      return 0;            /* below timer resolution */
134    return (total - AVG_OVERHEAD);
135  }
136}
137
138rtems_status_code Empty_function( void )
139{
140  return RTEMS_SUCCESSFUL;
141}
142
143void Set_find_average_overhead(
144  rtems_boolean find_flag
145)
146{
147  Timer_driver_Find_average_overhead = find_flag;
148}
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