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| 1 | + |
| 2 | +/** \addtogroup hal */ |
| 3 | +/** @{*/ |
| 4 | +/* mbed Microcontroller Library |
| 5 | + * Copyright (c) 2018-2019 ARM Limited |
| 6 | + * SPDX-License-Identifier: Apache-2.0 |
| 7 | + * |
| 8 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 9 | + * you may not use this file except in compliance with the License. |
| 10 | + * You may obtain a copy of the License at |
| 11 | + * |
| 12 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 13 | + * |
| 14 | + * Unless required by applicable law or agreed to in writing, software |
| 15 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 16 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 17 | + * See the License for the specific language governing permissions and |
| 18 | + * limitations under the License. |
| 19 | + */ |
| 20 | +#ifndef MBED_LOW_POWER_TICKER_WRAPPER_H |
| 21 | +#define MBED_LOW_POWER_TICKER_WRAPPER_H |
| 22 | + |
| 23 | +#include "device.h" |
| 24 | + |
| 25 | +#include "hal/ticker_api.h" |
| 26 | +#include "hal/us_ticker_api.h" |
| 27 | +#include "drivers/Timeout.h" |
| 28 | + |
| 29 | +#include "platform/mbed_chrono.h" |
| 30 | +#include "platform/mbed_critical.h" |
| 31 | + |
| 32 | + |
| 33 | +class LowPowerTickerWrapper { |
| 34 | +public: |
| 35 | + |
| 36 | + |
| 37 | + /** |
| 38 | + * Create a new wrapped low power ticker object |
| 39 | + * |
| 40 | + * @param data Low power ticker data to wrap |
| 41 | + * @param interface new ticker interface functions |
| 42 | + * @param min_cycles_between_writes The number of whole low power clock periods |
| 43 | + * which must complete before subsequent calls to set_interrupt |
| 44 | + * @param min_cycles_until_match The minimum number of whole low power clock periods |
| 45 | + * from the current time for which the match timestamp passed to set_interrupt is |
| 46 | + * guaranteed to fire. |
| 47 | + * |
| 48 | + * N = min_cycles_between_writes |
| 49 | + * |
| 50 | + * 0 1 N - 1 N N + 1 N + 2 N + 3 |
| 51 | + * |-------|------...------|-------|-------|-------|-------| |
| 52 | + * ^ ^ |
| 53 | + * | | |
| 54 | + * set_interrupt Next set_interrupt allowed |
| 55 | + * |
| 56 | + * N = min_cycles_until_match |
| 57 | + * |
| 58 | + * 0 1 N - 1 N N + 1 N + 2 N + 3 |
| 59 | + * |-------|------...------|-------|-------|-------|-------| |
| 60 | + * ^ ^ |
| 61 | + * | | |
| 62 | + * set_interrupt Earliest match timestamp allowed |
| 63 | + * |
| 64 | + * |
| 65 | + */ |
| 66 | + |
| 67 | + LowPowerTickerWrapper(const ticker_data_t *data, const ticker_interface_t *interface, uint32_t min_cycles_between_writes, uint32_t min_cycles_until_match); |
| 68 | + |
| 69 | + /** |
| 70 | + * Interrupt handler called by the underlying driver/hardware |
| 71 | + * |
| 72 | + * @param handler The callback which would normally be called by the underlying driver/hardware |
| 73 | + */ |
| 74 | + void irq_handler(ticker_irq_handler_type handler); |
| 75 | + |
| 76 | + /** |
| 77 | + * Suspend wrapper operation and pass through interrupts. |
| 78 | + * |
| 79 | + * This stops to wrapper layer from using the microsecond ticker. |
| 80 | + * This should be called before using the low power ticker APIs directly. |
| 81 | + * |
| 82 | + * @warning: Make sure to suspend the LP ticker first (call ticker_suspend()), |
| 83 | + * otherwise the behavior is undefined. |
| 84 | + */ |
| 85 | + void suspend(); |
| 86 | + |
| 87 | + /** |
| 88 | + * Resume wrapper operation and filter interrupts normally |
| 89 | + */ |
| 90 | + void resume(); |
| 91 | + |
| 92 | + /** |
| 93 | + * Check if a Timeout object is being used |
| 94 | + * |
| 95 | + * @return true if Timeout is used for scheduling false otherwise |
| 96 | + */ |
| 97 | + bool timeout_pending(); |
| 98 | + |
| 99 | + /* |
| 100 | + * Implementation of ticker_init |
| 101 | + */ |
| 102 | + void init(); |
| 103 | + |
| 104 | + /* |
| 105 | + * Implementation of free |
| 106 | + */ |
| 107 | + void free(); |
| 108 | + |
| 109 | + /* |
| 110 | + * Implementation of read |
| 111 | + */ |
| 112 | + uint32_t read(); |
| 113 | + |
| 114 | + /* |
| 115 | + * Implementation of set_interrupt |
| 116 | + */ |
| 117 | + void set_interrupt(timestamp_t timestamp); |
| 118 | + |
| 119 | + /* |
| 120 | + * Implementation of disable_interrupt |
| 121 | + */ |
| 122 | + void disable_interrupt(); |
| 123 | + |
| 124 | + /* |
| 125 | + * Implementation of clear_interrupt |
| 126 | + */ |
| 127 | + void clear_interrupt(); |
| 128 | + |
| 129 | + /* |
| 130 | + * Implementation of fire_interrupt |
| 131 | + */ |
| 132 | + void fire_interrupt(); |
| 133 | + |
| 134 | + /* |
| 135 | + * Implementation of get_info |
| 136 | + */ |
| 137 | + const ticker_info_t *get_info(); |
| 138 | + |
| 139 | + ticker_data_t data; |
| 140 | + |
| 141 | +private: |
| 142 | + mbed::Timeout _timeout; |
| 143 | + const ticker_interface_t *const _intf; |
| 144 | + |
| 145 | + /* |
| 146 | + * The number of low power clock cycles which must pass between subsequent |
| 147 | + * calls to intf->set_interrupt |
| 148 | + */ |
| 149 | + const uint32_t _min_count_between_writes; |
| 150 | + |
| 151 | + /* |
| 152 | + * The minimum number of low power clock cycles in the future that |
| 153 | + * a match value can be set to and still fire |
| 154 | + */ |
| 155 | + const uint32_t _min_count_until_match; |
| 156 | + |
| 157 | + /* |
| 158 | + * Flag to indicate if the timer is suspended |
| 159 | + */ |
| 160 | + bool _suspended; |
| 161 | + |
| 162 | + /* |
| 163 | + * _cur_match_time is valid and Timeout is scheduled to fire |
| 164 | + */ |
| 165 | + bool _pending_timeout; |
| 166 | + |
| 167 | + /* |
| 168 | + * set_interrupt has been called and _cur_match_time is valid |
| 169 | + */ |
| 170 | + bool _pending_match; |
| 171 | + |
| 172 | + /* |
| 173 | + * The function LowPowerTickerWrapper::fire_interrupt has been called |
| 174 | + * and an interrupt is expected. |
| 175 | + */ |
| 176 | + bool _pending_fire_now; |
| 177 | + |
| 178 | + /* |
| 179 | + * It is safe to call intf->set_interrupt |
| 180 | + */ |
| 181 | + bool _set_interrupt_allowed; |
| 182 | + |
| 183 | + /* |
| 184 | + * Last value written by LowPowerTickerWrapper::set_interrupt |
| 185 | + */ |
| 186 | + timestamp_t _cur_match_time; |
| 187 | + |
| 188 | + /* |
| 189 | + * Time of last call to LowPowerTickerWrapper::set_interrupt |
| 190 | + */ |
| 191 | + uint32_t _last_set_interrupt; |
| 192 | + |
| 193 | + /* |
| 194 | + * Time of last call to intf->set_interrupt |
| 195 | + */ |
| 196 | + uint32_t _last_actual_set_interrupt; |
| 197 | + |
| 198 | + /* |
| 199 | + * Mask of valid bits from intf->read() |
| 200 | + */ |
| 201 | + uint32_t _mask; |
| 202 | + |
| 203 | + /* |
| 204 | + * Microsecond per low power tick (rounded up) |
| 205 | + */ |
| 206 | + uint32_t _us_per_tick; |
| 207 | + |
| 208 | + |
| 209 | + void _reset(); |
| 210 | + |
| 211 | + /** |
| 212 | + * Set the low power ticker match time when hardware is ready |
| 213 | + * |
| 214 | + * This event is scheduled to set the lp timer after the previous write |
| 215 | + * has taken effect and it is safe to write a new value without blocking. |
| 216 | + * If the time has already passed then this function fires and interrupt |
| 217 | + * immediately. |
| 218 | + */ |
| 219 | + void _timeout_handler(); |
| 220 | + |
| 221 | + /* |
| 222 | + * Check match time has passed |
| 223 | + */ |
| 224 | + bool _match_check(timestamp_t current); |
| 225 | + |
| 226 | + /* |
| 227 | + * Convert low power ticks to approximate microseconds |
| 228 | + * |
| 229 | + * This value is always larger or equal to exact value. |
| 230 | + */ |
| 231 | + mbed::chrono::microseconds_u32 _lp_ticks_to_us(uint32_t); |
| 232 | + |
| 233 | + /* |
| 234 | + * Schedule a match interrupt to fire at the correct time |
| 235 | + * |
| 236 | + * @param current The current low power ticker time |
| 237 | + */ |
| 238 | + void _schedule_match(timestamp_t current); |
| 239 | + |
| 240 | +}; |
| 241 | + |
| 242 | +#endif |
| 243 | + |
| 244 | +/** @}*/ |
| 245 | + |
| 246 | + |
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