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freebsd-dev/sys/dev/uart/uart_dev_ns8250.c
Colin Percival 1c60b24baa Add a loader tunable "hw.broken_txfifo" which enables a workaround for a 
bug in old versions of QEMU (and Xen, and other places using QEMU code).
On those buggy emulated UARTs, the "TX idle" interrupt gets lost; with
this workaround, we spinwait for the TX to happen and then send ourselves
the interrupt.  It's ugly but it works, while minimizing the impact on
the code for the !broken_txfifo case.

MFC after:	2 weeks
2013-01-27 23:33:42 +00:00

881 lines
21 KiB
C
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/*-
* Copyright (c) 2003 Marcel Moolenaar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <machine/bus.h>
#include <dev/uart/uart.h>
#include <dev/uart/uart_cpu.h>
#include <dev/uart/uart_bus.h>
#include <dev/ic/ns16550.h>
#include "uart_if.h"
#define DEFAULT_RCLK 1843200
/*
* Clear pending interrupts. THRE is cleared by reading IIR. Data
* that may have been received gets lost here.
*/
static void
ns8250_clrint(struct uart_bas *bas)
{
uint8_t iir, lsr;
iir = uart_getreg(bas, REG_IIR);
while ((iir & IIR_NOPEND) == 0) {
iir &= IIR_IMASK;
if (iir == IIR_RLS) {
lsr = uart_getreg(bas, REG_LSR);
if (lsr & (LSR_BI|LSR_FE|LSR_PE))
(void)uart_getreg(bas, REG_DATA);
} else if (iir == IIR_RXRDY || iir == IIR_RXTOUT)
(void)uart_getreg(bas, REG_DATA);
else if (iir == IIR_MLSC)
(void)uart_getreg(bas, REG_MSR);
uart_barrier(bas);
iir = uart_getreg(bas, REG_IIR);
}
}
static int
ns8250_delay(struct uart_bas *bas)
{
int divisor;
u_char lcr;
lcr = uart_getreg(bas, REG_LCR);
uart_setreg(bas, REG_LCR, lcr | LCR_DLAB);
uart_barrier(bas);
divisor = uart_getreg(bas, REG_DLL) | (uart_getreg(bas, REG_DLH) << 8);
uart_barrier(bas);
uart_setreg(bas, REG_LCR, lcr);
uart_barrier(bas);
/* 1/10th the time to transmit 1 character (estimate). */
if (divisor <= 134)
return (16000000 * divisor / bas->rclk);
return (16000 * divisor / (bas->rclk / 1000));
}
static int
ns8250_divisor(int rclk, int baudrate)
{
int actual_baud, divisor;
int error;
if (baudrate == 0)
return (0);
divisor = (rclk / (baudrate << 3) + 1) >> 1;
if (divisor == 0 || divisor >= 65536)
return (0);
actual_baud = rclk / (divisor << 4);
/* 10 times error in percent: */
error = ((actual_baud - baudrate) * 2000 / baudrate + 1) >> 1;
/* 3.0% maximum error tolerance: */
if (error < -30 || error > 30)
return (0);
return (divisor);
}
static int
ns8250_drain(struct uart_bas *bas, int what)
{
int delay, limit;
delay = ns8250_delay(bas);
if (what & UART_DRAIN_TRANSMITTER) {
/*
* Pick an arbitrary high limit to avoid getting stuck in
* an infinite loop when the hardware is broken. Make the
* limit high enough to handle large FIFOs.
*/
limit = 10*1024;
while ((uart_getreg(bas, REG_LSR) & LSR_TEMT) == 0 && --limit)
DELAY(delay);
if (limit == 0) {
/* printf("ns8250: transmitter appears stuck... "); */
return (EIO);
}
}
if (what & UART_DRAIN_RECEIVER) {
/*
* Pick an arbitrary high limit to avoid getting stuck in
* an infinite loop when the hardware is broken. Make the
* limit high enough to handle large FIFOs and integrated
* UARTs. The HP rx2600 for example has 3 UARTs on the
* management board that tend to get a lot of data send
* to it when the UART is first activated.
*/
limit=10*4096;
while ((uart_getreg(bas, REG_LSR) & LSR_RXRDY) && --limit) {
(void)uart_getreg(bas, REG_DATA);
uart_barrier(bas);
DELAY(delay << 2);
}
if (limit == 0) {
/* printf("ns8250: receiver appears broken... "); */
return (EIO);
}
}
return (0);
}
/*
* We can only flush UARTs with FIFOs. UARTs without FIFOs should be
* drained. WARNING: this function clobbers the FIFO setting!
*/
static void
ns8250_flush(struct uart_bas *bas, int what)
{
uint8_t fcr;
fcr = FCR_ENABLE;
if (what & UART_FLUSH_TRANSMITTER)
fcr |= FCR_XMT_RST;
if (what & UART_FLUSH_RECEIVER)
fcr |= FCR_RCV_RST;
uart_setreg(bas, REG_FCR, fcr);
uart_barrier(bas);
}
static int
ns8250_param(struct uart_bas *bas, int baudrate, int databits, int stopbits,
int parity)
{
int divisor;
uint8_t lcr;
lcr = 0;
if (databits >= 8)
lcr |= LCR_8BITS;
else if (databits == 7)
lcr |= LCR_7BITS;
else if (databits == 6)
lcr |= LCR_6BITS;
else
lcr |= LCR_5BITS;
if (stopbits > 1)
lcr |= LCR_STOPB;
lcr |= parity << 3;
/* Set baudrate. */
if (baudrate > 0) {
divisor = ns8250_divisor(bas->rclk, baudrate);
if (divisor == 0)
return (EINVAL);
uart_setreg(bas, REG_LCR, lcr | LCR_DLAB);
uart_barrier(bas);
uart_setreg(bas, REG_DLL, divisor & 0xff);
uart_setreg(bas, REG_DLH, (divisor >> 8) & 0xff);
uart_barrier(bas);
}
/* Set LCR and clear DLAB. */
uart_setreg(bas, REG_LCR, lcr);
uart_barrier(bas);
return (0);
}
/*
* Low-level UART interface.
*/
static int ns8250_probe(struct uart_bas *bas);
static void ns8250_init(struct uart_bas *bas, int, int, int, int);
static void ns8250_term(struct uart_bas *bas);
static void ns8250_putc(struct uart_bas *bas, int);
static int ns8250_rxready(struct uart_bas *bas);
static int ns8250_getc(struct uart_bas *bas, struct mtx *);
static struct uart_ops uart_ns8250_ops = {
.probe = ns8250_probe,
.init = ns8250_init,
.term = ns8250_term,
.putc = ns8250_putc,
.rxready = ns8250_rxready,
.getc = ns8250_getc,
};
static int
ns8250_probe(struct uart_bas *bas)
{
u_char val;
/* Check known 0 bits that don't depend on DLAB. */
val = uart_getreg(bas, REG_IIR);
if (val & 0x30)
return (ENXIO);
/*
* Bit 6 of the MCR (= 0x40) appears to be 1 for the Sun1699
* chip, but otherwise doesn't seem to have a function. In
* other words, uart(4) works regardless. Ignore that bit so
* the probe succeeds.
*/
val = uart_getreg(bas, REG_MCR);
if (val & 0xa0)
return (ENXIO);
return (0);
}
static void
ns8250_init(struct uart_bas *bas, int baudrate, int databits, int stopbits,
int parity)
{
u_char ier;
if (bas->rclk == 0)
bas->rclk = DEFAULT_RCLK;
ns8250_param(bas, baudrate, databits, stopbits, parity);
/* Disable all interrupt sources. */
/*
* We use 0xe0 instead of 0xf0 as the mask because the XScale PXA
* UARTs split the receive time-out interrupt bit out separately as
* 0x10. This gets handled by ier_mask and ier_rxbits below.
*/
ier = uart_getreg(bas, REG_IER) & 0xe0;
uart_setreg(bas, REG_IER, ier);
uart_barrier(bas);
/* Disable the FIFO (if present). */
uart_setreg(bas, REG_FCR, 0);
uart_barrier(bas);
/* Set RTS & DTR. */
uart_setreg(bas, REG_MCR, MCR_IE | MCR_RTS | MCR_DTR);
uart_barrier(bas);
ns8250_clrint(bas);
}
static void
ns8250_term(struct uart_bas *bas)
{
/* Clear RTS & DTR. */
uart_setreg(bas, REG_MCR, MCR_IE);
uart_barrier(bas);
}
static void
ns8250_putc(struct uart_bas *bas, int c)
{
int limit;
limit = 250000;
while ((uart_getreg(bas, REG_LSR) & LSR_THRE) == 0 && --limit)
DELAY(4);
uart_setreg(bas, REG_DATA, c);
uart_barrier(bas);
limit = 250000;
while ((uart_getreg(bas, REG_LSR) & LSR_TEMT) == 0 && --limit)
DELAY(4);
}
static int
ns8250_rxready(struct uart_bas *bas)
{
return ((uart_getreg(bas, REG_LSR) & LSR_RXRDY) != 0 ? 1 : 0);
}
static int
ns8250_getc(struct uart_bas *bas, struct mtx *hwmtx)
{
int c;
uart_lock(hwmtx);
while ((uart_getreg(bas, REG_LSR) & LSR_RXRDY) == 0) {
uart_unlock(hwmtx);
DELAY(4);
uart_lock(hwmtx);
}
c = uart_getreg(bas, REG_DATA);
uart_unlock(hwmtx);
return (c);
}
/*
* High-level UART interface.
*/
struct ns8250_softc {
struct uart_softc base;
uint8_t fcr;
uint8_t ier;
uint8_t mcr;
uint8_t ier_mask;
uint8_t ier_rxbits;
};
static int ns8250_bus_attach(struct uart_softc *);
static int ns8250_bus_detach(struct uart_softc *);
static int ns8250_bus_flush(struct uart_softc *, int);
static int ns8250_bus_getsig(struct uart_softc *);
static int ns8250_bus_ioctl(struct uart_softc *, int, intptr_t);
static int ns8250_bus_ipend(struct uart_softc *);
static int ns8250_bus_param(struct uart_softc *, int, int, int, int);
static int ns8250_bus_probe(struct uart_softc *);
static int ns8250_bus_receive(struct uart_softc *);
static int ns8250_bus_setsig(struct uart_softc *, int);
static int ns8250_bus_transmit(struct uart_softc *);
static kobj_method_t ns8250_methods[] = {
KOBJMETHOD(uart_attach, ns8250_bus_attach),
KOBJMETHOD(uart_detach, ns8250_bus_detach),
KOBJMETHOD(uart_flush, ns8250_bus_flush),
KOBJMETHOD(uart_getsig, ns8250_bus_getsig),
KOBJMETHOD(uart_ioctl, ns8250_bus_ioctl),
KOBJMETHOD(uart_ipend, ns8250_bus_ipend),
KOBJMETHOD(uart_param, ns8250_bus_param),
KOBJMETHOD(uart_probe, ns8250_bus_probe),
KOBJMETHOD(uart_receive, ns8250_bus_receive),
KOBJMETHOD(uart_setsig, ns8250_bus_setsig),
KOBJMETHOD(uart_transmit, ns8250_bus_transmit),
{ 0, 0 }
};
struct uart_class uart_ns8250_class = {
"ns8250",
ns8250_methods,
sizeof(struct ns8250_softc),
.uc_ops = &uart_ns8250_ops,
.uc_range = 8,
.uc_rclk = DEFAULT_RCLK
};
#define SIGCHG(c, i, s, d) \
if (c) { \
i |= (i & s) ? s : s | d; \
} else { \
i = (i & s) ? (i & ~s) | d : i; \
}
static int
ns8250_bus_attach(struct uart_softc *sc)
{
struct ns8250_softc *ns8250 = (struct ns8250_softc*)sc;
struct uart_bas *bas;
unsigned int ivar;
bas = &sc->sc_bas;
ns8250->mcr = uart_getreg(bas, REG_MCR);
ns8250->fcr = FCR_ENABLE;
if (!resource_int_value("uart", device_get_unit(sc->sc_dev), "flags",
&ivar)) {
if (UART_FLAGS_FCR_RX_LOW(ivar))
ns8250->fcr |= FCR_RX_LOW;
else if (UART_FLAGS_FCR_RX_MEDL(ivar))
ns8250->fcr |= FCR_RX_MEDL;
else if (UART_FLAGS_FCR_RX_HIGH(ivar))
ns8250->fcr |= FCR_RX_HIGH;
else
ns8250->fcr |= FCR_RX_MEDH;
} else
ns8250->fcr |= FCR_RX_MEDH;
/* Get IER mask */
ivar = 0xf0;
resource_int_value("uart", device_get_unit(sc->sc_dev), "ier_mask",
&ivar);
ns8250->ier_mask = (uint8_t)(ivar & 0xff);
/* Get IER RX interrupt bits */
ivar = IER_EMSC | IER_ERLS | IER_ERXRDY;
resource_int_value("uart", device_get_unit(sc->sc_dev), "ier_rxbits",
&ivar);
ns8250->ier_rxbits = (uint8_t)(ivar & 0xff);
uart_setreg(bas, REG_FCR, ns8250->fcr);
uart_barrier(bas);
ns8250_bus_flush(sc, UART_FLUSH_RECEIVER|UART_FLUSH_TRANSMITTER);
if (ns8250->mcr & MCR_DTR)
sc->sc_hwsig |= SER_DTR;
if (ns8250->mcr & MCR_RTS)
sc->sc_hwsig |= SER_RTS;
ns8250_bus_getsig(sc);
ns8250_clrint(bas);
ns8250->ier = uart_getreg(bas, REG_IER) & ns8250->ier_mask;
ns8250->ier |= ns8250->ier_rxbits;
uart_setreg(bas, REG_IER, ns8250->ier);
uart_barrier(bas);
return (0);
}
static int
ns8250_bus_detach(struct uart_softc *sc)
{
struct ns8250_softc *ns8250;
struct uart_bas *bas;
u_char ier;
ns8250 = (struct ns8250_softc *)sc;
bas = &sc->sc_bas;
ier = uart_getreg(bas, REG_IER) & ns8250->ier_mask;
uart_setreg(bas, REG_IER, ier);
uart_barrier(bas);
ns8250_clrint(bas);
return (0);
}
static int
ns8250_bus_flush(struct uart_softc *sc, int what)
{
struct ns8250_softc *ns8250 = (struct ns8250_softc*)sc;
struct uart_bas *bas;
int error;
bas = &sc->sc_bas;
uart_lock(sc->sc_hwmtx);
if (sc->sc_rxfifosz > 1) {
ns8250_flush(bas, what);
uart_setreg(bas, REG_FCR, ns8250->fcr);
uart_barrier(bas);
error = 0;
} else
error = ns8250_drain(bas, what);
uart_unlock(sc->sc_hwmtx);
return (error);
}
static int
ns8250_bus_getsig(struct uart_softc *sc)
{
uint32_t new, old, sig;
uint8_t msr;
do {
old = sc->sc_hwsig;
sig = old;
uart_lock(sc->sc_hwmtx);
msr = uart_getreg(&sc->sc_bas, REG_MSR);
uart_unlock(sc->sc_hwmtx);
SIGCHG(msr & MSR_DSR, sig, SER_DSR, SER_DDSR);
SIGCHG(msr & MSR_CTS, sig, SER_CTS, SER_DCTS);
SIGCHG(msr & MSR_DCD, sig, SER_DCD, SER_DDCD);
SIGCHG(msr & MSR_RI, sig, SER_RI, SER_DRI);
new = sig & ~SER_MASK_DELTA;
} while (!atomic_cmpset_32(&sc->sc_hwsig, old, new));
return (sig);
}
static int
ns8250_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
{
struct uart_bas *bas;
int baudrate, divisor, error;
uint8_t efr, lcr;
bas = &sc->sc_bas;
error = 0;
uart_lock(sc->sc_hwmtx);
switch (request) {
case UART_IOCTL_BREAK:
lcr = uart_getreg(bas, REG_LCR);
if (data)
lcr |= LCR_SBREAK;
else
lcr &= ~LCR_SBREAK;
uart_setreg(bas, REG_LCR, lcr);
uart_barrier(bas);
break;
case UART_IOCTL_IFLOW:
lcr = uart_getreg(bas, REG_LCR);
uart_barrier(bas);
uart_setreg(bas, REG_LCR, 0xbf);
uart_barrier(bas);
efr = uart_getreg(bas, REG_EFR);
if (data)
efr |= EFR_RTS;
else
efr &= ~EFR_RTS;
uart_setreg(bas, REG_EFR, efr);
uart_barrier(bas);
uart_setreg(bas, REG_LCR, lcr);
uart_barrier(bas);
break;
case UART_IOCTL_OFLOW:
lcr = uart_getreg(bas, REG_LCR);
uart_barrier(bas);
uart_setreg(bas, REG_LCR, 0xbf);
uart_barrier(bas);
efr = uart_getreg(bas, REG_EFR);
if (data)
efr |= EFR_CTS;
else
efr &= ~EFR_CTS;
uart_setreg(bas, REG_EFR, efr);
uart_barrier(bas);
uart_setreg(bas, REG_LCR, lcr);
uart_barrier(bas);
break;
case UART_IOCTL_BAUD:
lcr = uart_getreg(bas, REG_LCR);
uart_setreg(bas, REG_LCR, lcr | LCR_DLAB);
uart_barrier(bas);
divisor = uart_getreg(bas, REG_DLL) |
(uart_getreg(bas, REG_DLH) << 8);
uart_barrier(bas);
uart_setreg(bas, REG_LCR, lcr);
uart_barrier(bas);
baudrate = (divisor > 0) ? bas->rclk / divisor / 16 : 0;
if (baudrate > 0)
*(int*)data = baudrate;
else
error = ENXIO;
break;
default:
error = EINVAL;
break;
}
uart_unlock(sc->sc_hwmtx);
return (error);
}
static int
ns8250_bus_ipend(struct uart_softc *sc)
{
struct uart_bas *bas;
struct ns8250_softc *ns8250;
int ipend;
uint8_t iir, lsr;
ns8250 = (struct ns8250_softc *)sc;
bas = &sc->sc_bas;
uart_lock(sc->sc_hwmtx);
iir = uart_getreg(bas, REG_IIR);
if (iir & IIR_NOPEND) {
uart_unlock(sc->sc_hwmtx);
return (0);
}
ipend = 0;
if (iir & IIR_RXRDY) {
lsr = uart_getreg(bas, REG_LSR);
if (lsr & LSR_OE)
ipend |= SER_INT_OVERRUN;
if (lsr & LSR_BI)
ipend |= SER_INT_BREAK;
if (lsr & LSR_RXRDY)
ipend |= SER_INT_RXREADY;
} else {
if (iir & IIR_TXRDY) {
ipend |= SER_INT_TXIDLE;
uart_setreg(bas, REG_IER, ns8250->ier);
} else
ipend |= SER_INT_SIGCHG;
}
if (ipend == 0)
ns8250_clrint(bas);
uart_unlock(sc->sc_hwmtx);
return (ipend);
}
static int
ns8250_bus_param(struct uart_softc *sc, int baudrate, int databits,
int stopbits, int parity)
{
struct uart_bas *bas;
int error;
bas = &sc->sc_bas;
uart_lock(sc->sc_hwmtx);
error = ns8250_param(bas, baudrate, databits, stopbits, parity);
uart_unlock(sc->sc_hwmtx);
return (error);
}
static int
ns8250_bus_probe(struct uart_softc *sc)
{
struct ns8250_softc *ns8250;
struct uart_bas *bas;
int count, delay, error, limit;
uint8_t lsr, mcr, ier;
ns8250 = (struct ns8250_softc *)sc;
bas = &sc->sc_bas;
error = ns8250_probe(bas);
if (error)
return (error);
mcr = MCR_IE;
if (sc->sc_sysdev == NULL) {
/* By using ns8250_init() we also set DTR and RTS. */
ns8250_init(bas, 115200, 8, 1, UART_PARITY_NONE);
} else
mcr |= MCR_DTR | MCR_RTS;
error = ns8250_drain(bas, UART_DRAIN_TRANSMITTER);
if (error)
return (error);
/*
* Set loopback mode. This avoids having garbage on the wire and
* also allows us send and receive data. We set DTR and RTS to
* avoid the possibility that automatic flow-control prevents
* any data from being sent.
*/
uart_setreg(bas, REG_MCR, MCR_LOOPBACK | MCR_IE | MCR_DTR | MCR_RTS);
uart_barrier(bas);
/*
* Enable FIFOs. And check that the UART has them. If not, we're
* done. Since this is the first time we enable the FIFOs, we reset
* them.
*/
uart_setreg(bas, REG_FCR, FCR_ENABLE);
uart_barrier(bas);
if (!(uart_getreg(bas, REG_IIR) & IIR_FIFO_MASK)) {
/*
* NS16450 or INS8250. We don't bother to differentiate
* between them. They're too old to be interesting.
*/
uart_setreg(bas, REG_MCR, mcr);
uart_barrier(bas);
sc->sc_rxfifosz = sc->sc_txfifosz = 1;
device_set_desc(sc->sc_dev, "8250 or 16450 or compatible");
return (0);
}
uart_setreg(bas, REG_FCR, FCR_ENABLE | FCR_XMT_RST | FCR_RCV_RST);
uart_barrier(bas);
count = 0;
delay = ns8250_delay(bas);
/* We have FIFOs. Drain the transmitter and receiver. */
error = ns8250_drain(bas, UART_DRAIN_RECEIVER|UART_DRAIN_TRANSMITTER);
if (error) {
uart_setreg(bas, REG_MCR, mcr);
uart_setreg(bas, REG_FCR, 0);
uart_barrier(bas);
goto describe;
}
/*
* We should have a sufficiently clean "pipe" to determine the
* size of the FIFOs. We send as much characters as is reasonable
* and wait for the overflow bit in the LSR register to be
* asserted, counting the characters as we send them. Based on
* that count we know the FIFO size.
*/
do {
uart_setreg(bas, REG_DATA, 0);
uart_barrier(bas);
count++;
limit = 30;
lsr = 0;
/*
* LSR bits are cleared upon read, so we must accumulate
* them to be able to test LSR_OE below.
*/
while (((lsr |= uart_getreg(bas, REG_LSR)) & LSR_TEMT) == 0 &&
--limit)
DELAY(delay);
if (limit == 0) {
ier = uart_getreg(bas, REG_IER) & ns8250->ier_mask;
uart_setreg(bas, REG_IER, ier);
uart_setreg(bas, REG_MCR, mcr);
uart_setreg(bas, REG_FCR, 0);
uart_barrier(bas);
count = 0;
goto describe;
}
} while ((lsr & LSR_OE) == 0 && count < 130);
count--;
uart_setreg(bas, REG_MCR, mcr);
/* Reset FIFOs. */
ns8250_flush(bas, UART_FLUSH_RECEIVER|UART_FLUSH_TRANSMITTER);
describe:
if (count >= 14 && count <= 16) {
sc->sc_rxfifosz = 16;
device_set_desc(sc->sc_dev, "16550 or compatible");
} else if (count >= 28 && count <= 32) {
sc->sc_rxfifosz = 32;
device_set_desc(sc->sc_dev, "16650 or compatible");
} else if (count >= 56 && count <= 64) {
sc->sc_rxfifosz = 64;
device_set_desc(sc->sc_dev, "16750 or compatible");
} else if (count >= 112 && count <= 128) {
sc->sc_rxfifosz = 128;
device_set_desc(sc->sc_dev, "16950 or compatible");
} else {
sc->sc_rxfifosz = 16;
device_set_desc(sc->sc_dev,
"Non-standard ns8250 class UART with FIFOs");
}
/*
* Force the Tx FIFO size to 16 bytes for now. We don't program the
* Tx trigger. Also, we assume that all data has been sent when the
* interrupt happens.
*/
sc->sc_txfifosz = 16;
#if 0
/*
* XXX there are some issues related to hardware flow control and
* it's likely that uart(4) is the cause. This basicly needs more
* investigation, but we avoid using for hardware flow control
* until then.
*/
/* 16650s or higher have automatic flow control. */
if (sc->sc_rxfifosz > 16) {
sc->sc_hwiflow = 1;
sc->sc_hwoflow = 1;
}
#endif
return (0);
}
static int
ns8250_bus_receive(struct uart_softc *sc)
{
struct uart_bas *bas;
int xc;
uint8_t lsr;
bas = &sc->sc_bas;
uart_lock(sc->sc_hwmtx);
lsr = uart_getreg(bas, REG_LSR);
while (lsr & LSR_RXRDY) {
if (uart_rx_full(sc)) {
sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN;
break;
}
xc = uart_getreg(bas, REG_DATA);
if (lsr & LSR_FE)
xc |= UART_STAT_FRAMERR;
if (lsr & LSR_PE)
xc |= UART_STAT_PARERR;
uart_rx_put(sc, xc);
lsr = uart_getreg(bas, REG_LSR);
}
/* Discard everything left in the Rx FIFO. */
while (lsr & LSR_RXRDY) {
(void)uart_getreg(bas, REG_DATA);
uart_barrier(bas);
lsr = uart_getreg(bas, REG_LSR);
}
uart_unlock(sc->sc_hwmtx);
return (0);
}
static int
ns8250_bus_setsig(struct uart_softc *sc, int sig)
{
struct ns8250_softc *ns8250 = (struct ns8250_softc*)sc;
struct uart_bas *bas;
uint32_t new, old;
bas = &sc->sc_bas;
do {
old = sc->sc_hwsig;
new = old;
if (sig & SER_DDTR) {
SIGCHG(sig & SER_DTR, new, SER_DTR,
SER_DDTR);
}
if (sig & SER_DRTS) {
SIGCHG(sig & SER_RTS, new, SER_RTS,
SER_DRTS);
}
} while (!atomic_cmpset_32(&sc->sc_hwsig, old, new));
uart_lock(sc->sc_hwmtx);
ns8250->mcr &= ~(MCR_DTR|MCR_RTS);
if (new & SER_DTR)
ns8250->mcr |= MCR_DTR;
if (new & SER_RTS)
ns8250->mcr |= MCR_RTS;
uart_setreg(bas, REG_MCR, ns8250->mcr);
uart_barrier(bas);
uart_unlock(sc->sc_hwmtx);
return (0);
}
static int broken_txfifo = 0;
SYSCTL_INT(_hw, OID_AUTO, broken_txfifo, CTLFLAG_RW | CTLFLAG_TUN,
&broken_txfifo, 0, "UART FIFO has QEMU emulation bug");
TUNABLE_INT("hw.broken_txfifo", &broken_txfifo);
static int
ns8250_bus_transmit(struct uart_softc *sc)
{
struct ns8250_softc *ns8250 = (struct ns8250_softc*)sc;
struct uart_bas *bas;
int i;
bas = &sc->sc_bas;
uart_lock(sc->sc_hwmtx);
while ((uart_getreg(bas, REG_LSR) & LSR_THRE) == 0)
;
uart_setreg(bas, REG_IER, ns8250->ier | IER_ETXRDY);
uart_barrier(bas);
for (i = 0; i < sc->sc_txdatasz; i++) {
uart_setreg(bas, REG_DATA, sc->sc_txbuf[i]);
uart_barrier(bas);
}
if (broken_txfifo)
ns8250_drain(bas, UART_DRAIN_TRANSMITTER);
else
sc->sc_txbusy = 1;
uart_unlock(sc->sc_hwmtx);
if (broken_txfifo)
uart_sched_softih(sc, SER_INT_TXIDLE);
return (0);
}
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