1 | /* timer.c |
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2 | * |
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3 | * NOTE: These routines will not work if the optimizer is enabled |
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4 | * for some compilers. The multiple writes to the Z8036 |
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5 | * may be optimized away. |
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6 | * |
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7 | * It is important that the timer start/stop overhead be |
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8 | * determined when porting or modifying this code. |
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9 | * |
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10 | * COPYRIGHT (c) 1989-1998. |
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11 | * On-Line Applications Research Corporation (OAR). |
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12 | * Copyright assigned to U.S. Government, 1994. |
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13 | * |
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14 | * The license and distribution terms for this file may be |
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15 | * found in the file LICENSE in this distribution or at |
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16 | * http://www.OARcorp.com/rtems/license.html. |
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17 | * |
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18 | * $Id$ |
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19 | */ |
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20 | |
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21 | |
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22 | #include <rtems.h> |
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23 | #include <bsp.h> |
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24 | |
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25 | int Ttimer_val; |
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26 | rtems_boolean Timer_driver_Find_average_overhead; |
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27 | |
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28 | rtems_isr timerisr(); |
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29 | |
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30 | void Timer_initialize() |
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31 | { |
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32 | rtems_unsigned8 data; |
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33 | |
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34 | (void) set_vector( timerisr, TIMER_VECTOR, 0 ); /* install ISR */ |
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35 | |
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36 | Ttimer_val = 0; /* clear timer ISR count */ |
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37 | Z8x36_READ ( TIMER, MASTER_INTR, data ); |
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38 | Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0x01) ); |
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39 | |
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40 | Z8x36_WRITE( TIMER, MASTER_CFG, 0xd4 ); |
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41 | Z8x36_READ ( TIMER, MASTER_INTR, data ); |
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42 | Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0x7E) ); |
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43 | Z8x36_WRITE( TIMER, CT1_TIME_CONST_MSB, 0x00 ); |
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44 | Z8x36_WRITE( TIMER, CT1_TIME_CONST_LSB, 0x00 ); |
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45 | Z8x36_WRITE( TIMER, CT1_MODE_SPEC, 0x87 ); |
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46 | Z8x36_WRITE( TIMER, CNT_TMR_VECTOR, TIMER_VECTOR ); |
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47 | Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0x20 ); |
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48 | Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0x26 ); |
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49 | Z8x36_READ ( TIMER, MASTER_INTR, data ); |
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50 | Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0xDA) | 0x80 ); |
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51 | |
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52 | Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0xC6 ); |
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53 | |
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54 | /* |
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55 | * ACC_IC54 - interrupt 5 will be vectored and mapped to level 6 |
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56 | */ |
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57 | |
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58 | data = (*(rtems_unsigned8 *)0x0D00000B); |
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59 | (*(rtems_unsigned8 *)0x0D00000B) = (data & 0x0F) | 0x60; |
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60 | |
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61 | } |
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62 | |
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63 | #define AVG_OVERHEAD 9 /* It typically takes 3.65 microseconds */ |
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64 | /* (9 countdowns) to start/stop the timer. */ |
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65 | #define LEAST_VALID 10 /* Don't trust a value lower than this */ |
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66 | |
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67 | int Read_timer() |
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68 | { |
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69 | rtems_unsigned8 data; |
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70 | rtems_unsigned8 msb, lsb; |
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71 | rtems_unsigned32 remaining, total; |
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72 | |
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73 | Z8x36_WRITE( TIMER, CT1_CMD_STATUS, 0xce ); /* read the counter value */ |
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74 | Z8x36_READ( TIMER, CT1_CUR_CNT_MSB, msb ); |
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75 | Z8x36_READ( TIMER, CT1_CUR_CNT_LSB, lsb ); |
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76 | |
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77 | remaining = 0x10000 - ((msb << 8) + lsb); |
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78 | total = (Ttimer_val * 0x10000) + remaining; |
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79 | |
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80 | Z8x36_READ ( TIMER, MASTER_INTR, data ); |
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81 | Z8x36_WRITE( TIMER, MASTER_INTR, (data & 0x01) ); |
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82 | |
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83 | /* do not restore old vector */ |
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84 | if ( Timer_driver_Find_average_overhead == 1 ) |
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85 | return total; /* in countdown units */ |
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86 | |
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87 | if ( total < LEAST_VALID ) |
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88 | return 0; /* below timer resolution */ |
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89 | |
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90 | /* Clocked at 2.4615 Mhz */ |
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91 | |
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92 | return (int)(((float)(total-AVG_OVERHEAD)) / 2.4615 * 2.0); |
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93 | } |
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94 | |
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95 | rtems_status_code Empty_function( void ) |
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96 | { |
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97 | return RTEMS_SUCCESSFUL; |
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98 | } |
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99 | |
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100 | void Set_find_average_overhead( |
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101 | rtems_boolean find_flag |
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102 | ) |
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103 | { |
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104 | Timer_driver_Find_average_overhead = find_flag; |
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105 | } |
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