[752cd8f] | 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 | * |
---|
[03f2154e] | 16 | * COPYRIGHT (c) 1989-1997. |
---|
[752cd8f] | 17 | * On-Line Applications Research Corporation (OAR). |
---|
[03f2154e] | 18 | * Copyright assigned to U.S. Government, 1994. |
---|
[752cd8f] | 19 | * |
---|
[98e4ebf5] | 20 | * The license and distribution terms for this file may be |
---|
| 21 | * found in the file LICENSE in this distribution or at |
---|
[03f2154e] | 22 | * http://www.OARcorp.com/rtems/license.html. |
---|
[752cd8f] | 23 | * |
---|
| 24 | * $Id$ |
---|
| 25 | */ |
---|
| 26 | |
---|
| 27 | |
---|
| 28 | #include <rtems.h> |
---|
| 29 | #include <bsp.h> |
---|
| 30 | |
---|
| 31 | int Ttimer_val; |
---|
| 32 | rtems_boolean Timer_driver_Find_average_overhead; |
---|
| 33 | |
---|
| 34 | rtems_isr timerisr(); |
---|
| 35 | |
---|
| 36 | #define TMR0 0xF040 |
---|
| 37 | #define TMR1 0xF041 |
---|
| 38 | #define TMR2 0xF042 |
---|
| 39 | #define TMRCON 0xF043 |
---|
| 40 | #define TMRCFG 0xF834 |
---|
| 41 | |
---|
| 42 | void Timer_initialize() |
---|
| 43 | { |
---|
| 44 | |
---|
| 45 | (void) set_vector( timerisr, 0x2a, 0 ); /* install ISR ( IR2 ) was 0x38*/ |
---|
| 46 | |
---|
| 47 | Ttimer_val = 0; /* clear timer ISR count */ |
---|
| 48 | |
---|
| 49 | outport_byte ( TMRCON , 0xb0 ); /* select tmr2, stay in mode 0 */ |
---|
| 50 | outport_byte ( TMR1 , 0xd2 ); /* set to 250 usec interval */ |
---|
| 51 | outport_byte ( TMR1 , 0x00 ); |
---|
| 52 | outport_byte ( TMRCON , 0x64 ); /* change to mode 2 ( starts timer ) */ |
---|
| 53 | /* interrupts ARE enabled */ |
---|
| 54 | /* outport_byte( IERA, 0x41 ); enable interrupt */ |
---|
| 55 | |
---|
| 56 | } |
---|
| 57 | |
---|
| 58 | #define AVG_OVERHEAD 3 /* It typically takes 3.0 microseconds */ |
---|
| 59 | /* (3 ticks) to start/stop the timer. */ |
---|
| 60 | #define LEAST_VALID 4 /* Don't trust a value lower than this */ |
---|
| 61 | |
---|
| 62 | int Read_timer() |
---|
| 63 | { |
---|
| 64 | register rtems_unsigned32 clicks; |
---|
| 65 | register rtems_unsigned32 total; |
---|
| 66 | |
---|
| 67 | /* outport_byte( TBCR, 0x00 ); stop the timer -- not needed on intel */ |
---|
| 68 | |
---|
| 69 | outport_byte ( TMRCON, 0x40 ); /* latch the count */ |
---|
| 70 | inport_byte ( TMR1, clicks ); /* read the count */ |
---|
| 71 | |
---|
| 72 | total = Ttimer_val + 250 - clicks; |
---|
| 73 | |
---|
| 74 | /* outport_byte( TBCR, 0x00 ); initial value */ |
---|
| 75 | /* outport_byte( IERA, 0x40 ); disable interrupt */ |
---|
| 76 | |
---|
| 77 | /* ??? Is "do not restore old vector" causing problems? */ |
---|
| 78 | |
---|
| 79 | if ( Timer_driver_Find_average_overhead == 1 ) |
---|
| 80 | return total; /* in one microsecond units */ |
---|
| 81 | |
---|
| 82 | else { |
---|
| 83 | if ( total < LEAST_VALID ) |
---|
| 84 | return 0; /* below timer resolution */ |
---|
| 85 | return (total - AVG_OVERHEAD); |
---|
| 86 | } |
---|
| 87 | } |
---|
| 88 | |
---|
| 89 | rtems_status_code Empty_function( void ) |
---|
| 90 | { |
---|
| 91 | return RTEMS_SUCCESSFUL; |
---|
| 92 | } |
---|
| 93 | |
---|
| 94 | void Set_find_average_overhead( |
---|
| 95 | rtems_boolean find_flag |
---|
| 96 | ) |
---|
| 97 | { |
---|
| 98 | Timer_driver_Find_average_overhead = find_flag; |
---|
| 99 | } |
---|