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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);
+}
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