1 | /* |
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2 | * This routine initializes the MC68340/349 Periodic Interval Timer |
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3 | */ |
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4 | |
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5 | /* |
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6 | * Based on the `gen68360' board support package, and covered by the |
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7 | * original distribution terms. |
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8 | * |
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9 | * Geoffroy Montel |
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10 | * France Telecom - CNET/DSM/TAM/CAT |
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11 | * 4, rue du Clos Courtel |
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12 | * 35512 CESSON-SEVIGNE |
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13 | * FRANCE |
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14 | * |
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15 | * e-mail: g_montel@yahoo.com |
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16 | */ |
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17 | |
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18 | /* |
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19 | * COPYRIGHT (c) 1989-2014. |
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20 | * On-Line Applications Research Corporation (OAR). |
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21 | * |
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22 | * The license and distribution terms for this file may be |
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23 | * found in the file LICENSE in this distribution or at |
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24 | * http://www.rtems.org/license/LICENSE. |
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25 | */ |
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26 | |
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27 | #include <stdlib.h> /* for atexit() */ |
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28 | #include <bsp.h> |
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29 | #include <m68340.h> |
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30 | #include <rtems/clockdrv.h> |
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31 | |
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32 | #define CLOCK_VECTOR 120 /* clock isr routine vector in the vbr */ |
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33 | #define CLOCK_IRQ_LEVEL 6 /* clock isr level */ |
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34 | |
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35 | /* |
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36 | * Clock_driver_ticks is a monotonically increasing counter of the |
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37 | * number of clock ticks since the driver was initialized. |
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38 | */ |
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39 | volatile uint32_t Clock_driver_ticks; |
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40 | |
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41 | /* |
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42 | * Periodic interval timer interrupt handler |
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43 | */ |
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44 | static rtems_isr |
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45 | Clock_isr (rtems_vector_number vector) |
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46 | { |
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47 | /* |
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48 | * Announce the clock tick |
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49 | */ |
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50 | Clock_driver_ticks++; |
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51 | rtems_clock_tick(); |
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52 | } |
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53 | |
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54 | void |
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55 | Clock_exit (void) |
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56 | { |
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57 | /* |
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58 | * Turn off periodic interval timer |
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59 | */ |
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60 | SIMPITR = 0; |
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61 | } |
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62 | |
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63 | static void |
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64 | Install_clock (rtems_isr_entry clock_isr) |
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65 | { |
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66 | uint32_t pitr_tmp; |
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67 | uint32_t usecs_per_tick; |
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68 | |
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69 | Clock_driver_ticks = 0; |
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70 | |
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71 | set_vector (clock_isr, CLOCK_VECTOR, 1); |
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72 | |
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73 | /* sets the Periodic Interrupt Control Register PICR */ |
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74 | SIMPICR = ( CLOCK_IRQ_LEVEL << 8 ) | ( CLOCK_VECTOR ); |
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75 | |
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76 | /* sets the PITR count value */ |
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77 | /* this assumes a 32.765 kHz crystal */ |
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78 | |
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79 | usecs_per_tick = rtems_configuration_get_microseconds_per_tick(); |
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80 | /* find out whether prescaler should be enabled or not */ |
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81 | if ( usecs_per_tick <= 31128 ) { |
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82 | pitr_tmp = ( usecs_per_tick * 8192 ) / 1000000 ; |
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83 | } else { |
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84 | pitr_tmp = ( usecs_per_tick / 1000000 ) * 16; |
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85 | /* enable it */ |
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86 | pitr_tmp |= 0x100; |
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87 | } |
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88 | |
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89 | SIMPITR = (unsigned char) pitr_tmp; |
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90 | |
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91 | atexit (Clock_exit); |
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92 | } |
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93 | |
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94 | rtems_device_driver |
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95 | Clock_initialize( |
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96 | rtems_device_major_number major, |
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97 | rtems_device_minor_number minor, |
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98 | void *pargp |
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99 | ) |
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100 | { |
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101 | Install_clock (Clock_isr); |
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102 | |
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103 | return RTEMS_SUCCESSFUL; |
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104 | } |
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