| /* |
| * 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/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 "dev/terminal.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 (term->dataAvailable()) |
| pkt->set(term->in()); |
| 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 (term->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 (term->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 |
| term->out(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) && term->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); |
| } |
