1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup bsp_clock |
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5 | * |
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6 | * @brief Raspberry Pi clock support. |
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7 | */ |
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8 | |
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9 | /* |
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10 | * BCM2835 Clock driver |
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11 | * |
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12 | * Copyright (c) 2013 Alan Cudmore |
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13 | * Copyright (c) 2016 Pavel Pisa |
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14 | * |
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15 | * The license and distribution terms for this file may be |
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16 | * found in the file LICENSE in this distribution or at |
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17 | * |
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18 | * http://www.rtems.org/license/LICENSE |
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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 | #include <bsp/irq.h> |
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25 | #include <bsp/irq-generic.h> |
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26 | #include <bsp/raspberrypi.h> |
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27 | #include <rtems/timecounter.h> |
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28 | |
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29 | /* This is defined in ../../../shared/dev/clock/clockimpl.h */ |
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30 | void Clock_isr(rtems_irq_hdl_param arg); |
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31 | |
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32 | static struct timecounter raspberrypi_tc; |
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33 | |
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34 | static uint32_t raspberrypi_clock_get_timecount(struct timecounter *tc) |
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35 | { |
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36 | return BCM2835_REG(BCM2835_GPU_TIMER_CLO); |
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37 | } |
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38 | |
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39 | static void raspberrypi_clock_at_tick(void) |
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40 | { |
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41 | uint32_t act_val; |
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42 | uint32_t next_cmp = BCM2835_REG(BCM2835_GPU_TIMER_C3); |
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43 | next_cmp += rtems_configuration_get_microseconds_per_tick(); |
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44 | BCM2835_REG(BCM2835_GPU_TIMER_C3) = next_cmp; |
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45 | act_val = BCM2835_REG(BCM2835_GPU_TIMER_CLO); |
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46 | |
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47 | /* |
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48 | * Clear interrupt only if there is time left to the next tick. |
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49 | * If time of the next tick has already passed then interrupt |
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50 | * request stays active and fires immediately after current tick |
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51 | * processing is finished. |
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52 | */ |
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53 | if ((int32_t)(next_cmp - act_val) > 0) |
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54 | BCM2835_REG(BCM2835_GPU_TIMER_CS) = BCM2835_GPU_TIMER_CS_M3; |
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55 | } |
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56 | |
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57 | static void raspberrypi_clock_handler_install_isr( |
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58 | rtems_isr_entry clock_isr |
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59 | ) |
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60 | { |
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61 | rtems_status_code sc = RTEMS_SUCCESSFUL; |
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62 | |
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63 | if (clock_isr != NULL) { |
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64 | sc = rtems_interrupt_handler_install( |
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65 | BCM2835_IRQ_ID_GPU_TIMER_M3, |
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66 | "Clock", |
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67 | RTEMS_INTERRUPT_UNIQUE, |
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68 | (rtems_interrupt_handler) clock_isr, |
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69 | NULL |
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70 | ); |
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71 | } else { |
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72 | /* Remove interrupt handler */ |
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73 | sc = rtems_interrupt_handler_remove( |
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74 | BCM2835_IRQ_ID_GPU_TIMER_M3, |
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75 | (rtems_interrupt_handler) Clock_isr, |
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76 | NULL |
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77 | ); |
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78 | } |
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79 | if ( sc != RTEMS_SUCCESSFUL ) { |
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80 | rtems_fatal_error_occurred(0xdeadbeef); |
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81 | } |
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82 | } |
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83 | |
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84 | static void raspberrypi_clock_initialize_hardware(void) |
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85 | { |
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86 | uint32_t next_cmp = BCM2835_REG(BCM2835_GPU_TIMER_CLO); |
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87 | next_cmp += rtems_configuration_get_microseconds_per_tick(); |
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88 | BCM2835_REG(BCM2835_GPU_TIMER_C3) = next_cmp; |
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89 | BCM2835_REG(BCM2835_GPU_TIMER_CS) = BCM2835_GPU_TIMER_CS_M3; |
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90 | |
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91 | raspberrypi_tc.tc_get_timecount = raspberrypi_clock_get_timecount; |
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92 | raspberrypi_tc.tc_counter_mask = 0xffffffff; |
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93 | raspberrypi_tc.tc_frequency = 1000000; /* 1 MHz */ |
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94 | raspberrypi_tc.tc_quality = RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER; |
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95 | rtems_timecounter_install(&raspberrypi_tc); |
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96 | } |
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97 | |
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98 | #define Clock_driver_support_at_tick() raspberrypi_clock_at_tick() |
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99 | |
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100 | #define Clock_driver_support_initialize_hardware() raspberrypi_clock_initialize_hardware() |
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101 | |
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102 | #define Clock_driver_support_install_isr(clock_isr) \ |
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103 | raspberrypi_clock_handler_install_isr(clock_isr) |
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104 | |
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105 | #define CLOCK_DRIVER_USE_ONLY_BOOT_PROCESSOR 1 |
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106 | |
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107 | #include "../../../shared/dev/clock/clockimpl.h" |
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