source: rtems/c/src/lib/libbsp/i960/cvme961/timer/timer.c @ f7fa7d7

4.104.114.84.95
Last change on this file since f7fa7d7 was 98e4ebf, checked in by Joel Sherrill <joel.sherrill@…>, on Oct 8, 1997 at 3:45:54 PM

Fixed typo in the pointer to the license terms.

  • Property mode set to 100644
File size: 3.8 KB
Line 
1/*  Timer_init()
2 *
3 *  This routine initializes the Z8536 timer on the SQSIO4 SQUALL
4 *  board for the CVME961 board.  The timer is setup to provide a
5 *  tick every 1 millisecond.
6 *
7 *  Input parameters:  NONE
8 *
9 *  Output parameters:  NONE
10 *
11 *  NOTE: This routine will not work if the optimizer is enabled
12 *        for most compilers.  The multiple writes to the Z8536
13 *        will be optimized away.
14 *
15 *        It is important that the timer start/stop overhead be
16 *        determined when porting or modifying this code.
17 *
18 *  COPYRIGHT (c) 1989-1997.
19 *  On-Line Applications Research Corporation (OAR).
20 *  Copyright assigned to U.S. Government, 1994.
21 *
22 *  The license and distribution terms for this file may be
23 *  found in the file LICENSE in this distribution or at
24 *  http://www.OARcorp.com/rtems/license.html.
25 *
26 *  $Id$
27 */
28
29
30#include <rtems.h>
31#include <bsp.h>
32#include <zilog/z8536.h>
33
34#define TIMER       0xc00000a0
35
36int Ttimer_val;
37rtems_boolean Timer_driver_Find_average_overhead;
38
39void flush_reg();
40rtems_isr timerisr();
41
42void Timer_initialize()
43{
44  set_vector( timerisr, 4, 0 );               /* install ISR */
45
46  i960_mask_intr( 5 );                        /* disable VIC068 tick */
47  flush_reg();                                /* timed code starts clean */
48  Ttimer_val = 0;                             /* clear timer ISR count */
49  Z8x36_WRITE( TIMER, MASTER_INTR,    0x01 ); /* reset              */
50  Z8x36_WRITE( TIMER, MASTER_INTR,    0x00 ); /* clear reset        */
51  Z8x36_WRITE( TIMER, MASTER_CFG,     0x00 ); /* disable everything */
52  Z8x36_WRITE( TIMER, CNT_TMR_VECTOR, 0x72 ); /* clear intr vector  */
53  Z8x36_WRITE( TIMER, MASTER_CFG,     0x20 ); /* clear intr info    */
54  Z8x36_WRITE( TIMER, MASTER_CFG,     0xe0 ); /* disable interrupts */
55  Z8x36_WRITE( TIMER, MASTER_CFG,     0x20 ); /* clear intr info    */
56  Z8x36_WRITE( TIMER, MASTER_CFG,     0xe0 ); /* disable interrupts */
57  Z8x36_WRITE( TIMER, MASTER_INTR,    0xe2 ); /* disable lower chain,   */
58                                              /*   no vector, set right */
59                                              /*   justified addr and   */
60                                              /*   master int enable    */
61  Z8x36_WRITE( TIMER, CT1_MODE_SPEC,      0x80 ); /* T1 continuous, and   */
62                                                  /*   cycle/pulse output */
63  Z8x36_WRITE( TIMER, CT1_TIME_CONST_MSB, 0x00 );
64  Z8x36_WRITE( TIMER, CT1_TIME_CONST_LSB, 0x00 );
65  Z8x36_WRITE( TIMER, CT1_CMD_STATUS,     0xc0 ); /* set INTR enable (IE) */
66  Z8x36_WRITE( TIMER, MASTER_CFG,         0x40 ); /* enable timer1        */
67  Z8x36_WRITE( TIMER, CT1_CMD_STATUS,     0x06 ); /* set trigger command  */
68                                                  /*   (TCB) and gate     */
69                                                  /* command (GCB) bits   */
70}
71
72#define AVG_OVERHEAD      11 /* It typically takes 5.5 microseconds */
73                             /* (11 countdowns) to start/stop the timer. */
74#define LEAST_VALID       15 /* Don't trust a value lower than this */
75
76int Read_timer()
77{
78  rtems_unsigned8  msb, lsb;
79  rtems_unsigned32 remaining, total;
80
81  Z8x36_WRITE( TIMER, CT1_CMD_STATUS,  0xce );  /* read the counter value */
82  Z8x36_READ(  TIMER, CT1_CUR_CNT_MSB, msb );
83  Z8x36_READ(  TIMER, CT1_CUR_CNT_LSB, lsb );
84
85  remaining = 0xffff - ((msb << 8) + lsb);
86  total = (Ttimer_val * 0x10000) + remaining;
87
88  if ( Timer_driver_Find_average_overhead == 1 )
89    return total;          /* in one-half microsecond units */
90  else {
91    if ( total < LEAST_VALID )
92      return 0;            /* below timer resolution */
93    return (total-AVG_OVERHEAD) >> 1;
94  }
95}
96
97rtems_status_code Empty_function( void )
98{
99  return RTEMS_SUCCESSFUL;
100}
101
102void Set_find_average_overhead(
103  rtems_boolean find_flag
104)
105{
106  Timer_driver_Find_average_overhead = find_flag;
107}
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