58 lines
3.0 KiB
Plaintext
58 lines
3.0 KiB
Plaintext
/*
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* Copyright (c) 2015-2016, The Linux Foundation. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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* * Neither the name of The Linux Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
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* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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@page pps Pulse Per Second
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The pulse per second (PPS) signal is used by the Wi-Fi modem (e.g., QCA6584) for channel switching operations
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when configured for alternate channel switching, as described in IEEE 1609.4. The rising edge of this signal is
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required to be synchronized to a UTC 1 sec roll. In the event that this signal stops due to a loss of
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the source, the alternating mode will cease and continue in a single channel mode. The channel configured
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for index 0 will be used in single channel mode. The alternating mode will resume with the PPS signal.
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The PPS signal is also required for QCA6584 to broadcast the Timing Advertisement frames.
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UTC time maintained in the modem will be disciplined with the PPS signal.
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These are the specifications of the 1PPS pulse (1 pulse per second):
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- Allowable delta from UTC: +/- 440 uSec
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- Amplitude: Voltage level of the SDIO domain on QCA6584<br>
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If the SDIO voltage domain is 3.3 V, the 1PPS should be 0 V to 3.3 V<br>
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If the SDIO voltage domain is 1.8 V, the 1PPS should be 0 V to 1.8 V<br>
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e.g., on MDM9x15, the SDIO domain is 1.8 V
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- Connection: GPIO1 on QCA6584
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When no PPS pulse is present:
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- The dual channel mode will revert to single channel.
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- If the PPS pulse resumes, the dual channel mode will also resume.
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Known issue:
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- In the firmware release 1.0.3 for QCA6584, the Timing Advertisement appears to continue after the PPS signal stops;
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this will be resolved in a subsequent firmware release.
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*/
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