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/*
* Copyright (c) 2005 The Regents of The University of Michigan
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* 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;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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 COPYRIGHT
* OWNER OR CONTRIBUTORS 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.
*
* Authors: Ali Saidi
*/
/** @file
* Implements a 8250 UART
*/
#include "dev/serial/uart8250.hh"
#include <string>
#include <vector>
#include "base/inifile.hh"
#include "base/trace.hh"
#include "config/the_isa.hh"
#include "debug/Uart.hh"
#include "dev/platform.hh"
#include "mem/packet.hh"
#include "mem/packet_access.hh"
using namespace std;
using namespace TheISA;
void
Uart8250::processIntrEvent(int intrBit)
{
if (intrBit & IER) {
DPRINTF(Uart, "UART InterEvent, interrupting\n");
platform->postConsoleInt();
status |= intrBit;
lastTxInt = curTick();
}
else
DPRINTF(Uart, "UART InterEvent, not interrupting\n");
}
/* The linux serial driver (8250.c about line 1182) loops reading from
* the device until the device reports it has no more data to
* read. After a maximum of 255 iterations the code prints "serial8250
* too much work for irq X," and breaks out of the loop. Since the
* simulated system is so much slower than the actual system, if a
* user is typing on the keyboard it is very easy for them to provide
* input at a fast enough rate to not allow the loop to exit and thus
* the error to be printed. This magic number provides a delay between
* the time the UART receives a character to send to the simulated
* system and the time it actually notifies the system it has a
* character to send to alleviate this problem. --Ali
*/
void
Uart8250::scheduleIntr(Event *event)
{
static const Tick interval = 225 * SimClock::Int::ns;
DPRINTF(Uart, "Scheduling IER interrupt for %s, at cycle %lld\n",
event->name(), curTick() + interval);
if (!event->scheduled())
schedule(event, curTick() + interval);
else
reschedule(event, curTick() + interval);
}
Uart8250::Uart8250(const Params *p)
: Uart(p, 8), IER(0), DLAB(0), LCR(0), MCR(0), lastTxInt(0),
txIntrEvent([this]{ processIntrEvent(TX_INT); }, "TX"),
rxIntrEvent([this]{ processIntrEvent(RX_INT); }, "RX")
{
}
Tick
Uart8250::read(PacketPtr pkt)
{
assert(pkt->getAddr() >= pioAddr && pkt->getAddr() < pioAddr + pioSize);
assert(pkt->getSize() == 1);
Addr daddr = pkt->getAddr() - pioAddr;
DPRINTF(Uart, " read register %#x\n", daddr);
switch (daddr) {
case 0x0:
if (!(LCR & 0x80)) { // read byte
if (device->dataAvailable())
pkt->set(device->readData());
else {
pkt->set((uint8_t)0);
// A limited amount of these are ok.
DPRINTF(Uart, "empty read of RX register\n");
}
status &= ~RX_INT;
platform->clearConsoleInt();
if (device->dataAvailable() && (IER & UART_IER_RDI))
scheduleIntr(&rxIntrEvent);
} else { // dll divisor latch
;
}
break;
case 0x1:
if (!(LCR & 0x80)) { // Intr Enable Register(IER)
pkt->set(IER);
} else { // DLM divisor latch MSB
;
}
break;
case 0x2: // Intr Identification Register (IIR)
DPRINTF(Uart, "IIR Read, status = %#x\n", (uint32_t)status);
if (status & RX_INT) /* Rx data interrupt has a higher priority */
pkt->set(IIR_RXID);
else if (status & TX_INT) {
pkt->set(IIR_TXID);
//Tx interrupts are cleared on IIR reads
status &= ~TX_INT;
} else
pkt->set(IIR_NOPEND);
break;
case 0x3: // Line Control Register (LCR)
pkt->set(LCR);
break;
case 0x4: // Modem Control Register (MCR)
pkt->set(MCR);
break;
case 0x5: // Line Status Register (LSR)
uint8_t lsr;
lsr = 0;
// check if there are any bytes to be read
if (device->dataAvailable())
lsr = UART_LSR_DR;
lsr |= UART_LSR_TEMT | UART_LSR_THRE;
pkt->set(lsr);
break;
case 0x6: // Modem Status Register (MSR)
pkt->set((uint8_t)0);
break;
case 0x7: // Scratch Register (SCR)
pkt->set((uint8_t)0); // doesn't exist with at 8250.
break;
default:
panic("Tried to access a UART port that doesn't exist\n");
break;
}
/* uint32_t d32 = *data;
DPRINTF(Uart, "Register read to register %#x returned %#x\n", daddr, d32);
*/
pkt->makeAtomicResponse();
return pioDelay;
}
Tick
Uart8250::write(PacketPtr pkt)
{
assert(pkt->getAddr() >= pioAddr && pkt->getAddr() < pioAddr + pioSize);
assert(pkt->getSize() == 1);
Addr daddr = pkt->getAddr() - pioAddr;
DPRINTF(Uart, " write register %#x value %#x\n", daddr, pkt->get<uint8_t>());
switch (daddr) {
case 0x0:
if (!(LCR & 0x80)) { // write byte
device->writeData(pkt->get<uint8_t>());
platform->clearConsoleInt();
status &= ~TX_INT;
if (UART_IER_THRI & IER)
scheduleIntr(&txIntrEvent);
} else { // dll divisor latch
;
}
break;
case 0x1:
if (!(LCR & 0x80)) { // Intr Enable Register(IER)
IER = pkt->get<uint8_t>();
if (UART_IER_THRI & IER)
{
DPRINTF(Uart, "IER: IER_THRI set, scheduling TX intrrupt\n");
if (curTick() - lastTxInt > 225 * SimClock::Int::ns) {
DPRINTF(Uart, "-- Interrupting Immediately... %d,%d\n",
curTick(), lastTxInt);
txIntrEvent.process();
} else {
DPRINTF(Uart, "-- Delaying interrupt... %d,%d\n",
curTick(), lastTxInt);
scheduleIntr(&txIntrEvent);
}
}
else
{
DPRINTF(Uart, "IER: IER_THRI cleared, descheduling TX intrrupt\n");
if (txIntrEvent.scheduled())
deschedule(txIntrEvent);
if (status & TX_INT)
platform->clearConsoleInt();
status &= ~TX_INT;
}
if ((UART_IER_RDI & IER) && device->dataAvailable()) {
DPRINTF(Uart, "IER: IER_RDI set, scheduling RX intrrupt\n");
scheduleIntr(&rxIntrEvent);
} else {
DPRINTF(Uart, "IER: IER_RDI cleared, descheduling RX intrrupt\n");
if (rxIntrEvent.scheduled())
deschedule(rxIntrEvent);
if (status & RX_INT)
platform->clearConsoleInt();
status &= ~RX_INT;
}
} else { // DLM divisor latch MSB
;
}
break;
case 0x2: // FIFO Control Register (FCR)
break;
case 0x3: // Line Control Register (LCR)
LCR = pkt->get<uint8_t>();
break;
case 0x4: // Modem Control Register (MCR)
if (pkt->get<uint8_t>() == (UART_MCR_LOOP | 0x0A))
MCR = 0x9A;
break;
case 0x7: // Scratch Register (SCR)
// We are emulating a 8250 so we don't have a scratch reg
break;
default:
panic("Tried to access a UART port that doesn't exist\n");
break;
}
pkt->makeAtomicResponse();
return pioDelay;
}
void
Uart8250::dataAvailable()
{
// if the kernel wants an interrupt when we have data
if (IER & UART_IER_RDI)
{
platform->postConsoleInt();
status |= RX_INT;
}
}
AddrRangeList
Uart8250::getAddrRanges() const
{
AddrRangeList ranges;
ranges.push_back(RangeSize(pioAddr, pioSize));
return ranges;
}
void
Uart8250::serialize(CheckpointOut &cp) const
{
SERIALIZE_SCALAR(status);
SERIALIZE_SCALAR(IER);
SERIALIZE_SCALAR(DLAB);
SERIALIZE_SCALAR(LCR);
SERIALIZE_SCALAR(MCR);
Tick rxintrwhen;
if (rxIntrEvent.scheduled())
rxintrwhen = rxIntrEvent.when();
else
rxintrwhen = 0;
Tick txintrwhen;
if (txIntrEvent.scheduled())
txintrwhen = txIntrEvent.when();
else
txintrwhen = 0;
SERIALIZE_SCALAR(rxintrwhen);
SERIALIZE_SCALAR(txintrwhen);
}
void
Uart8250::unserialize(CheckpointIn &cp)
{
UNSERIALIZE_SCALAR(status);
UNSERIALIZE_SCALAR(IER);
UNSERIALIZE_SCALAR(DLAB);
UNSERIALIZE_SCALAR(LCR);
UNSERIALIZE_SCALAR(MCR);
Tick rxintrwhen;
Tick txintrwhen;
UNSERIALIZE_SCALAR(rxintrwhen);
UNSERIALIZE_SCALAR(txintrwhen);
if (rxintrwhen != 0)
schedule(rxIntrEvent, rxintrwhen);
if (txintrwhen != 0)
schedule(txIntrEvent, txintrwhen);
}
Uart8250 *
Uart8250Params::create()
{
return new Uart8250(this);
}