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| 1 | +/* |
| 2 | + * This file is part of the MicroPython project, http://micropython.org/ |
| 3 | + * |
| 4 | + * The MIT License (MIT) |
| 5 | + * |
| 6 | + * Copyright (c) 2021 Damien P. George |
| 7 | + * |
| 8 | + * Permission is hereby granted, free of charge, to any person obtaining a copy |
| 9 | + * of this software and associated documentation files (the "Software"), to deal |
| 10 | + * in the Software without restriction, including without limitation the rights |
| 11 | + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 12 | + * copies of the Software, and to permit persons to whom the Software is |
| 13 | + * furnished to do so, subject to the following conditions: |
| 14 | + * |
| 15 | + * The above copyright notice and this permission notice shall be included in |
| 16 | + * all copies or substantial portions of the Software. |
| 17 | + * |
| 18 | + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 19 | + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 20 | + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 21 | + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 22 | + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 23 | + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| 24 | + * THE SOFTWARE. |
| 25 | + */ |
| 26 | + |
| 27 | +#include "py/mphal.h" |
| 28 | +#include "ticks.h" |
| 29 | +#include "fsl_gpt.h" |
| 30 | + |
| 31 | +// General purpose timer for keeping microsecond and millisecond tick values. |
| 32 | +#define GPTx GPT2 |
| 33 | +#define GPTx_IRQn GPT2_IRQn |
| 34 | +#define GPTx_IRQHandler GPT2_IRQHandler |
| 35 | + |
| 36 | +static uint32_t ticks_us64_upper; |
| 37 | +static uint32_t ticks_ms_upper; |
| 38 | + |
| 39 | +void ticks_init(void) { |
| 40 | + ticks_us64_upper = 0; |
| 41 | + ticks_ms_upper = 0; |
| 42 | + |
| 43 | + gpt_config_t config; |
| 44 | + config.clockSource = kGPT_ClockSource_Osc; |
| 45 | + config.divider = 24; // XTAL is 24MHz |
| 46 | + config.enableFreeRun = true; |
| 47 | + config.enableRunInWait = true; |
| 48 | + config.enableRunInStop = true; |
| 49 | + config.enableRunInDoze = true; |
| 50 | + config.enableRunInDbg = false; |
| 51 | + config.enableMode = true; |
| 52 | + GPT_Init(GPTx, &config); |
| 53 | + |
| 54 | + GPT_EnableInterrupts(GPTx, kGPT_RollOverFlagInterruptEnable); |
| 55 | + NVIC_SetPriority(GPTx_IRQn, 0); // highest priority |
| 56 | + NVIC_EnableIRQ(GPTx_IRQn); |
| 57 | + |
| 58 | + GPT_StartTimer(GPTx); |
| 59 | +} |
| 60 | + |
| 61 | +void GPTx_IRQHandler(void) { |
| 62 | + if (GPT_GetStatusFlags(GPTx, kGPT_OutputCompare1Flag)) { |
| 63 | + GPT_ClearStatusFlags(GPTx, kGPT_OutputCompare1Flag); |
| 64 | + GPT_DisableInterrupts(GPTx, kGPT_OutputCompare1InterruptEnable); |
| 65 | + __SEV(); |
| 66 | + } |
| 67 | + if (GPT_GetStatusFlags(GPTx, kGPT_RollOverFlag)) { |
| 68 | + GPT_ClearStatusFlags(GPTx, kGPT_RollOverFlag); |
| 69 | + ++ticks_us64_upper; |
| 70 | + if (++ticks_ms_upper >= 1000) { |
| 71 | + // Wrap upper counter at a multiple of 1000 so that when mp_hal_ticks_ms() |
| 72 | + // wraps due to overflow it wraps smoothly. |
| 73 | + ticks_ms_upper = 0; |
| 74 | + } |
| 75 | + } |
| 76 | +} |
| 77 | + |
| 78 | +static void ticks_wake_after_us32(uint32_t us) { |
| 79 | + if (us < 2) { |
| 80 | + // Delay too short to guarantee that we won't miss it when setting the OCR below. |
| 81 | + __SEV(); |
| 82 | + } else { |
| 83 | + // Disable IRQs so setting the OCR is done without any interruption. |
| 84 | + uint32_t irq_state = DisableGlobalIRQ(); |
| 85 | + GPT_EnableInterrupts(GPTx, kGPT_OutputCompare1InterruptEnable); |
| 86 | + uint32_t oc = GPT_GetCurrentTimerCount(GPTx) + us; |
| 87 | + GPT_SetOutputCompareValue(GPTx, kGPT_OutputCompare_Channel1, oc); |
| 88 | + EnableGlobalIRQ(irq_state); |
| 89 | + } |
| 90 | +} |
| 91 | + |
| 92 | +static uint64_t ticks_us64_with(uint32_t *upper_ptr) { |
| 93 | + uint32_t irq_state = DisableGlobalIRQ(); |
| 94 | + uint32_t lower = GPT_GetCurrentTimerCount(GPTx); |
| 95 | + uint32_t upper = *upper_ptr; |
| 96 | + uint32_t overflow = GPT_GetStatusFlags(GPTx, kGPT_RollOverFlag); |
| 97 | + EnableGlobalIRQ(irq_state); |
| 98 | + if (overflow && lower < 0x80000000) { |
| 99 | + // The timer counter overflowed before reading it but the IRQ handler |
| 100 | + // has not yet been called, so perform the IRQ arithmetic now. |
| 101 | + ++upper; |
| 102 | + } |
| 103 | + return (uint64_t)upper << 32 | (uint64_t)lower; |
| 104 | +} |
| 105 | + |
| 106 | +uint32_t ticks_us32(void) { |
| 107 | + return GPT_GetCurrentTimerCount(GPTx); |
| 108 | +} |
| 109 | + |
| 110 | +uint64_t ticks_us64(void) { |
| 111 | + return ticks_us64_with(&ticks_us64_upper); |
| 112 | +} |
| 113 | + |
| 114 | +uint32_t ticks_ms32(void) { |
| 115 | + // This will return a value that only has the lower 32-bits valid. |
| 116 | + return ticks_us64_with(&ticks_ms_upper) / 1000; |
| 117 | +} |
| 118 | + |
| 119 | +void ticks_delay_us64(uint64_t us) { |
| 120 | + uint64_t t0 = ticks_us64(); |
| 121 | + for (;;) { |
| 122 | + uint64_t dt = ticks_us64() - t0; |
| 123 | + if (dt >= us) { |
| 124 | + return; |
| 125 | + } |
| 126 | + dt = us - dt; |
| 127 | + if (dt > 0xffffffff) { |
| 128 | + dt = 0xffffffff; |
| 129 | + } |
| 130 | + ticks_wake_after_us32((uint32_t)dt); |
| 131 | + if (dt < 50) { |
| 132 | + __WFE(); |
| 133 | + } else { |
| 134 | + MICROPY_EVENT_POLL_HOOK |
| 135 | + } |
| 136 | + } |
| 137 | +} |
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