fdfbb3f5b1
option to invert the polarity in software. Also add an option to capture very narrow pulses by using the hardware's MSR delta-bit capability of latching line state changes. This effectively reverts the mistake I made in r286595 which was based on empirical measurements made on hardware using TTL-level signaling, in which the logic levels are inverted from RS-232. Thus, this re-syncs the polarity with the requirements of RFC 2783, which is writen in terms of RS-232 signaling. Narrow-pulse mode uses the ability of most ns8250 and similar chips to provide a delta indication in the modem status register. The hardware is able to notice and latch the change when the pulse width is shorter than interrupt latency, which results in the signal no longer being asserted by time the interrupt service code runs. When running in this mode we get notified only that "a pulse happened" so the driver synthesizes both an ASSERT and a CLEAR event (with the same timestamp for each). When the pulse width is about equal to the interrupt latency the driver may intermittantly see both edges of the pulse. To prevent generating spurious events, the driver implements a half-second lockout period after generating an event before it will generate another. Differential Revision: https://reviews.freebsd.org/D4477
47 lines
1.7 KiB
C
47 lines
1.7 KiB
C
/*-
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* Copyright (c) 2015 Ian Lepore
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* 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
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* are met:
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*
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* 1. 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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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _DEV_UART_PPSTYPES_H_
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#define _DEV_UART_PPSTYPES_H_
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/*
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* These constants are shared by several drivers including uart and usb_serial.
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*/
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#define UART_PPS_SIGNAL_MASK 0x0f
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#define UART_PPS_OPTION_MASK 0xf0
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#define UART_PPS_DISABLED 0x00
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#define UART_PPS_CTS 0x01
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#define UART_PPS_DCD 0x02
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#define UART_PPS_INVERT_PULSE 0x10
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#define UART_PPS_NARROW_PULSE 0x20
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#endif /* _DEV_UART_PPSTYPES_H_ */
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