34 lines
1.3 KiB
Plaintext
34 lines
1.3 KiB
Plaintext
# Copyright (c) 2023 Antmicro <www.antmicro.com>
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# SPDX-License-Identifier: Apache-2.0
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config GECKO_BURTC_TIMER
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bool "SiLabs Gecko BURTC system clock driver"
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depends on SOC_GECKO_SERIES2
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depends on DT_HAS_SILABS_GECKO_BURTC_ENABLED
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select SOC_GECKO_BURTC
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select TICKLESS_CAPABLE
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select TIMER_READS_ITS_FREQUENCY_AT_RUNTIME
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help
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If you enable this, BURTC will be used to provide hw_cycles and
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kernel ticks instead of Cortex-M SysTick. You need this for system
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to be able to keep track of time and wake up from EM2 & EM3 sleep
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states.
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NOTE:
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Using BURTC instead of SysTick has a large impact on kernel timing
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precision.
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1. You won't be able to use the usual 0.1ms-granularity tickless
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scheduling. Kernel tick duration should be at least 6 BURTC clock
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cycles, that is ~183 us @ 32768 Hz (LFXO, LFRCO) or
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~6 ms @ 1000 Hz (ULFRCO).
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2. In general, accuracy of real-time scheduling by kernel will be
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degraded: all timeout-based facilities, such as timers, delayable
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work, k_sleep, will issue thread wake ups less precisely than when
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using SysTick timer.
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3. hw_cycles granularity will be equal to 1 BURTC clock, that is
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~31 us @ 32768 Hz or ~1 ms @ 1000 Hz. This reduces timing
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precision of all code which relies on cycles API, e.g.
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k_cycle_get_32() and similar functions.
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If unsure, say 'N'.
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