22d6bfa0bd
The TPIU supports serializing the data stream both using an UART-like NRZ protocol as well as using Manchester encoding. Using Manchester encoding has the advantage that it enables receivers that support it to recover the clock from the SWO signal itself. This is particularly useful in situations where the clock rate changes dynamically or is unknown (for example when debugging the clock tree setup or working with a device with a misbehaving main oscillator). Add a Kconfig choice to switch the protocol, keeping the current default of using the NRZ encoding. Signed-off-by: Florian Larysch <larysch@fixme.gmbh>
61 lines
1.9 KiB
Plaintext
61 lines
1.9 KiB
Plaintext
# Copyright (c) 2021 Nordic Semiconductor ASA
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# SPDX-License-Identifier: Apache-2.0
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config LOG_BACKEND_SWO
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bool "Serial Wire Output (SWO) backend"
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depends on HAS_SWO
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select LOG_OUTPUT
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select LOG_BACKEND_SUPPORTS_FORMAT_TIMESTAMP
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help
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When enabled, backend will use SWO for logging.
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if LOG_BACKEND_SWO
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config LOG_BACKEND_SWO_REF_FREQ_HZ
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int "SWO reference clock frequency"
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default $(dt_node_int_prop_int,$(dt_nodelabel_path,itm),swo-ref-frequency) if $(dt_nodelabel_enabled,itm)
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default $(dt_node_int_prop_int,/cpus/cpu@0,clock-frequency) if $(dt_node_has_prop,/cpus/cpu@0,clock-frequency)
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default 0
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help
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Set SWO reference frequency. In most cases it is equal to CPU
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frequency.
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config LOG_BACKEND_SWO_FREQ_HZ
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int "Set SWO output frequency"
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default 0
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help
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Set SWO output frequency. Value 0 will select maximum frequency
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supported by the given MCU. Not all debug probes support high
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frequency SWO operation. In this case the frequency has to be set
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manually.
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SWO value defined by this option will be configured at boot. Most SWO
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viewer programs will configure SWO frequency when attached to the
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debug probe. Such configuration will persist only until the device
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reset. To ensure flawless operation the frequency configured here and
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by the SWO viewer program has to match.
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choice
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prompt "SWO protocol"
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default LOG_BACKEND_SWO_PROTOCOL_NRZ
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config LOG_BACKEND_SWO_PROTOCOL_NRZ
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bool "NRZ encoding"
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help
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Use UART-like NRZ encoding. This is the most common option, but requires the SWO output
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frequency to be known on the receiving side.
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config LOG_BACKEND_SWO_PROTOCOL_MANCHESTER
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bool "Manchester encoding"
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help
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Use Manchester encoding. This is less widely supported, but permits the clock to be
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recovered automatically on the receiving side.
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endchoice
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backend = SWO
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backend-str = swo
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source "subsys/logging/Kconfig.template.log_format_config"
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endif # LOG_BACKEND_SWO
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