source: rtems/c/src/lib/libbsp/m68k/mvme136/timer/timer.c @ 9977ac6

4.104.114.84.95
Last change on this file since 9977ac6 was 9977ac6, checked in by Joel Sherrill <joel.sherrill@…>, on Sep 4, 2003 at 6:51:59 PM

2003-09-04 Joel Sherrill <joel@…>

  • clock/ckinit.c, console/console.c, include/bsp.h, include/coverhd.h, shmsupp/addrconv.c, shmsupp/getcfg.c, shmsupp/lock.c, shmsupp/mpisr.c, startup/bspclean.c, startup/bspstart.c, startup/linkcmds, timer/timer.c, timer/timerisr.S: URL for license changed.
  • Property mode set to 100644
File size: 3.3 KB
Line 
1/*  Timer_init()
2 *
3 *  This routine initializes the Z8036 timer on the MVME136 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 <bsp.h>
28#include <zilog/z8036.h>
29
30#define TIMER 0xfffb0000   /* address of Z8036 on MVME136 */
31
32int Ttimer_val;
33rtems_boolean Timer_driver_Find_average_overhead;
34
35rtems_isr timerisr();
36
37void Timer_initialize()
38{
39  (void) set_vector( timerisr, 66, 0 );       /* install ISR */
40
41  Ttimer_val = 0;                             /* clear timer ISR count */
42  Z8x36_WRITE( TIMER, MASTER_INTR, 0x01 ); /* reset */
43  Z8x36_WRITE( TIMER, MASTER_INTR, 0x00 ); /* clear reset */
44  Z8x36_WRITE( TIMER, MASTER_INTR, 0xe2 ); /* disable lower chain, no vec */
45                                           /*  set right justified addr */
46                                              /*  and master int enable */
47  Z8x36_WRITE( TIMER, CT1_MODE_SPEC,  0x80 ); /* T1 continuous, and   */
48                                              /* cycle/pulse output   */
49
50  *((rtems_unsigned16 *)0xfffb0016) = 0x0000; /* write countdown value */
51/*
52  Z8x36_WRITE( TIMER, CT1_TIME_CONST_MSB, 0x00 );
53  Z8x36_WRITE( TIMER, CT1_TIME_CONST_LSB, 0x00 );
54*/
55  Z8x36_WRITE( TIMER, MASTER_CFG,         0xc4 ); /* enable timer1        */
56
57  Z8x36_WRITE( TIMER, CT1_CMD_STATUS,     0xc6 ); /* set INTR enable (IE), */
58                                                 /*  trigger command      */
59                                                 /*  (TCB) and gate       */
60                                                 /* command (GCB) bits    */
61  *((rtems_unsigned8 *)0xfffb0038) &= 0xfd;      /* enable timer INTR on  */
62                                                 /*    VME controller     */
63}
64
65#define AVG_OVERHEAD      6  /* It typically takes 3.0 microseconds */
66                             /* (6 countdowns) to start/stop the timer. */
67#define LEAST_VALID       10 /* Don't trust a value lower than this */
68
69int Read_timer()
70{
71/*
72  rtems_unsigned8  msb, lsb;
73*/
74  rtems_unsigned32 remaining, total;
75
76  Z8x36_WRITE( TIMER, CT1_CMD_STATUS,  0xce ); /* read the counter value */
77remaining = 0xffff - *((rtems_unsigned16 *) 0xfffb0010);
78/*
79  Z8x36_READ(  TIMER, CT1_CUR_CNT_MSB, msb );
80  Z8x36_READ(  TIMER, CT1_CUR_CNT_LSB, lsb );
81
82  remaining = 0xffff - ((msb << 8) + lsb);
83*/
84  total = (Ttimer_val * 0x10000) + remaining;
85
86  if ( Timer_driver_Find_average_overhead == 1 )
87    return total;          /* in one-half microsecond units */
88
89  else {
90    if ( total < LEAST_VALID )
91      return 0;            /* below timer resolution */
92    return (total-AVG_OVERHEAD) >> 1;
93  }
94}
95
96rtems_status_code Empty_function( void )
97{
98  return RTEMS_SUCCESSFUL;
99}
100
101void Set_find_average_overhead(
102  rtems_boolean find_flag
103)
104{
105  Timer_driver_Find_average_overhead = find_flag;
106}
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