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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).
128 lines
3.9 KiB
C
128 lines
3.9 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2013 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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#include "opt_platform.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bus.h>
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#include <sys/conf.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <machine/bus.h>
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#include <dev/fdt/fdt_common.h>
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#include <dev/ofw/ofw_bus.h>
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#include <dev/ofw/ofw_bus_subr.h>
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#include <dev/uart/uart.h>
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#include <dev/uart/uart_cpu.h>
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#include <dev/uart/uart_cpu_fdt.h>
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#include <dev/uart/uart_bus.h>
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#include <dev/uart/uart_dev_ns8250.h>
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#include <arm/ti/ti_sysc.h>
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#include "uart_if.h"
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/*
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* High-level UART interface.
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*/
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struct ti8250_softc {
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struct ns8250_softc ns8250_base;
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/*uint32_t mystuff;*/
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};
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#define MDR1_REG 8
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#define MDR1_MODE_UART 0
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#define MDR1_MODE_DISABLE 7
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#define SYSCC_REG 15
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#define SYSCC_SOFTRESET (1 << 1)
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#define SYSS_REG 16
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#define SYSS_STATUS_RESETDONE (1 << 0)
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static int
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ti8250_bus_probe(struct uart_softc *sc)
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{
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int status;
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if ((status = ti_sysc_clock_enable(device_get_parent(sc->sc_dev))) != 0)
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return (status);
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/*
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* Set the hardware to disabled mode, do a full device reset, then set
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* it to uart mode. Most devices will be reset-and-disabled already,
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* but you never know what a bootloader might have done.
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*/
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uart_setreg(&sc->sc_bas, MDR1_REG, MDR1_MODE_DISABLE);
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uart_setreg(&sc->sc_bas, SYSCC_REG, SYSCC_SOFTRESET);
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while (uart_getreg(&sc->sc_bas, SYSS_REG) & SYSS_STATUS_RESETDONE)
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continue;
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uart_setreg(&sc->sc_bas, MDR1_REG, MDR1_MODE_UART);
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status = ns8250_bus_probe(sc);
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if (status == 0)
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device_set_desc(sc->sc_dev, "TI UART (16550 compatible)");
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return (status);
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}
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static kobj_method_t ti8250_methods[] = {
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KOBJMETHOD(uart_probe, ti8250_bus_probe),
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KOBJMETHOD(uart_attach, ns8250_bus_attach),
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KOBJMETHOD(uart_detach, ns8250_bus_detach),
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KOBJMETHOD(uart_flush, ns8250_bus_flush),
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KOBJMETHOD(uart_getsig, ns8250_bus_getsig),
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KOBJMETHOD(uart_ioctl, ns8250_bus_ioctl),
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KOBJMETHOD(uart_ipend, ns8250_bus_ipend),
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KOBJMETHOD(uart_param, ns8250_bus_param),
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KOBJMETHOD(uart_receive, ns8250_bus_receive),
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KOBJMETHOD(uart_setsig, ns8250_bus_setsig),
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KOBJMETHOD(uart_transmit, ns8250_bus_transmit),
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KOBJMETHOD(uart_txbusy, ns8250_bus_txbusy),
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KOBJMETHOD_END
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};
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static struct uart_class uart_ti8250_class = {
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"ti8250",
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ti8250_methods,
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sizeof(struct ti8250_softc),
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.uc_ops = &uart_ns8250_ops,
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.uc_range = 0x88,
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.uc_rclk = 48000000,
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.uc_rshift = 2
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};
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static struct ofw_compat_data compat_data[] = {
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{"ti,ns16550", (uintptr_t)&uart_ti8250_class},
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{"ti,omap3-uart", (uintptr_t)&uart_ti8250_class},
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{"ti,omap4-uart", (uintptr_t)&uart_ti8250_class},
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{NULL, (uintptr_t)NULL},
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};
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UART_FDT_CLASS_AND_DEVICE(compat_data);
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