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353e4c5a06
In9750d9e5, I brought the equivalent of the TS_BUSY flag back in a mostly hardware-agnostic way in order to fix tty_drain() and, thus, TIOCDRAIN for UARTs with TX FIFOs. This proved to be sufficient for fixing the regression reported. So in light of the release cycle of FreeBSD 10.3, I decided that this change was be good enough for the time being and opted to go with the smallest possible yet generic (for all UARTs driven by uart(4)) solution addressing the problem at hand. However, at least for the NS8250-class the above isn't a complete fix as these UARTs only trigger an interrupt when the TX FIFO became empty. At this point, there still can be an outstanding character left in the transmit shift register as indicated via the LSR. Thus, this change adds the 3rd (besides the tty(4) and generic uart(4) bits) part I had in my tree ever since, adding a uart_txbusy method to be queried in addition for tsw_busy and hooking it up as appropriate for the NS8250-class. As it turns out, the exact equivalent of this 3rd part later on was implemented for uftdi(4) in9ad221a5. While at it, explain the rational behind the deliberately missing locking in uart_tty_busy() (also applying to the generic sc_txbusy testing already present).
64 lines
2.3 KiB
C
64 lines
2.3 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2003 Marcel Moolenaar
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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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#ifndef _DEV_UART_DEV_NS8250_H_
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#define _DEV_UART_DEV_NS8250_H_
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/*
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* High-level UART interface.
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*/
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struct ns8250_softc {
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struct uart_softc base;
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uint8_t fcr;
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uint8_t ier;
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uint8_t mcr;
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uint8_t ier_mask;
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uint8_t ier_rxbits;
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uint8_t busy_detect;
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};
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extern struct uart_ops uart_ns8250_ops;
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int ns8250_bus_attach(struct uart_softc *);
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int ns8250_bus_detach(struct uart_softc *);
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int ns8250_bus_flush(struct uart_softc *, int);
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int ns8250_bus_getsig(struct uart_softc *);
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int ns8250_bus_ioctl(struct uart_softc *, int, intptr_t);
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int ns8250_bus_ipend(struct uart_softc *);
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int ns8250_bus_param(struct uart_softc *, int, int, int, int);
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int ns8250_bus_probe(struct uart_softc *);
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int ns8250_bus_receive(struct uart_softc *);
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int ns8250_bus_setsig(struct uart_softc *, int);
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int ns8250_bus_transmit(struct uart_softc *);
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void ns8250_bus_grab(struct uart_softc *);
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bool ns8250_bus_txbusy(struct uart_softc *);
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void ns8250_bus_ungrab(struct uart_softc *);
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#endif /* _DEV_UART_DEV_NS8250_H_ */
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