1 | /* |
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2 | * This routine initializes Timer 1 for an MC68302. |
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3 | * The tick frequency is 1 millisecond. |
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4 | */ |
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5 | |
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6 | /* |
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7 | * COPYRIGHT (c) 1989-2014. |
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8 | * On-Line Applications Research Corporation (OAR). |
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9 | * |
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10 | * The license and distribution terms for this file may be |
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11 | * found in the file LICENSE in this distribution or at |
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12 | * http://www.rtems.org/license/LICENSE. |
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13 | */ |
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14 | |
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15 | #include <stdlib.h> /* for atexit() */ |
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16 | |
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17 | #include <bsp.h> |
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18 | #include <rtems/m68k/m68302.h> |
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19 | |
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20 | #define CLOCK_VECTOR 137 |
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21 | |
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22 | #define TMR1_VAL ( RBIT_TMR_RST /* software reset the timer */\ |
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23 | | RBIT_TMR_ICLK_MASTER16 /* master clock divided by 16 */\ |
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24 | | RBIT_TMR_FRR /* restart timer after ref reached */\ |
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25 | | RBIT_TMR_ORI) /* enable interrupt when ref reached */ |
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26 | #define TRR1_VAL 1000 /* 1000 ticks @ 16MHz/16 |
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27 | * = 1 millisecond tick. |
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28 | */ |
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29 | |
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30 | /* |
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31 | * Clock_driver_ticks is a monotonically increasing counter of the |
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32 | * number of clock ticks since the driver was initialized. |
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33 | */ |
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34 | volatile uint32_t Clock_driver_ticks; |
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35 | |
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36 | /* |
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37 | * Clock_isrs is the number of clock ISRs until the next invocation of |
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38 | * the RTEMS clock tick routine. The clock tick device driver |
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39 | * gets an interrupt once a millisecond and counts down until the |
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40 | * length of time between the user configured microseconds per tick |
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41 | * has passed. |
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42 | */ |
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43 | uint32_t Clock_isrs; |
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44 | |
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45 | void Clock_exit( void ); |
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46 | |
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47 | /* |
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48 | * ISR Handler |
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49 | */ |
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50 | static rtems_isr Clock_isr( |
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51 | rtems_vector_number vector |
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52 | ) |
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53 | { |
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54 | Clock_driver_ticks += 1; |
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55 | |
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56 | m302.reg.isr = RBIT_ISR_TIMER1; /* clear in-service bit */ |
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57 | m302.reg.ter1 = (RBIT_TER_REF | RBIT_TER_CAP); /* clear timer intr request */ |
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58 | |
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59 | if ( Clock_isrs == 1 ) { |
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60 | rtems_clock_tick(); |
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61 | Clock_isrs = rtems_configuration_get_microseconds_per_tick() / 1000; |
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62 | } |
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63 | else |
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64 | Clock_isrs -= 1; |
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65 | } |
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66 | |
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67 | static void Install_clock( |
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68 | rtems_isr_entry clock_isr |
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69 | ) |
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70 | { |
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71 | |
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72 | Clock_driver_ticks = 0; |
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73 | Clock_isrs = rtems_configuration_get_microseconds_per_tick() / 1000; |
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74 | |
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75 | set_vector( clock_isr, CLOCK_VECTOR, 1 ); |
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76 | |
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77 | m302.reg.trr1 = TRR1_VAL; /* set timer reference register */ |
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78 | m302.reg.tmr1 = TMR1_VAL; /* set timer mode register & enable */ |
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79 | /* |
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80 | * Enable TIMER1 interrupts only. |
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81 | */ |
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82 | m302.reg.imr |= RBIT_IMR_TIMER1; /* set 68302 int-mask to allow ints */ |
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83 | |
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84 | atexit( Clock_exit ); |
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85 | } |
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86 | |
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87 | void Clock_exit( void ) |
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88 | { |
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89 | /* TODO: figure out what to do here */ |
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90 | /* do not restore old vector */ |
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91 | } |
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92 | |
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93 | rtems_device_driver Clock_initialize( |
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94 | rtems_device_major_number major, |
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95 | rtems_device_minor_number minor, |
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96 | void *pargp |
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97 | ) |
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98 | { |
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99 | Install_clock( Clock_isr ); |
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100 | |
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101 | return RTEMS_SUCCESSFUL; |
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102 | } |
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