/* * 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 #include #include "base/inifile.hh" #include "base/str.hh" // for to_number #include "base/trace.hh" #include "dev/simconsole.hh" #include "dev/uart8250.hh" #include "dev/platform.hh" #include "mem/packet.hh" #include "mem/packet_access.hh" using namespace std; using namespace TheISA; Uart8250::IntrEvent::IntrEvent(Uart8250 *u, int bit) : Event(&mainEventQueue), uart(u) { DPRINTF(Uart, "UART Interrupt Event Initilizing\n"); intrBit = bit; } const char * Uart8250::IntrEvent::description() { return "uart interrupt delay event"; } void Uart8250::IntrEvent::process() { if (intrBit & uart->IER) { DPRINTF(Uart, "UART InterEvent, interrupting\n"); uart->platform->postConsoleInt(); uart->status |= intrBit; uart->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::IntrEvent::scheduleIntr() { static const Tick interval = (Tick)((Clock::Float::s / 2e9) * 450); DPRINTF(Uart, "Scheduling IER interrupt for %#x, at cycle %lld\n", intrBit, curTick + interval); if (!scheduled()) schedule(curTick + interval); else reschedule(curTick + interval); } Uart8250::Uart8250(const Params *p) : Uart(p), IER(0), DLAB(0), LCR(0), MCR(0), lastTxInt(0), txIntrEvent(this, TX_INT), rxIntrEvent(this, RX_INT) { pioSize = 8; } Tick Uart8250::read(PacketPtr pkt) { assert(pkt->result == Packet::Unknown); assert(pkt->getAddr() >= pioAddr && pkt->getAddr() < pioAddr + pioSize); assert(pkt->getSize() == 1); Addr daddr = pkt->getAddr() - pioAddr; pkt->allocate(); DPRINTF(Uart, " read register %#x\n", daddr); switch (daddr) { case 0x0: if (!(LCR & 0x80)) { // read byte if (cons->dataAvailable()) pkt->set(cons->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 (cons->dataAvailable() && (IER & UART_IER_RDI)) rxIntrEvent.scheduleIntr(); } 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) break; case 0x5: // Line Status Register (LSR) uint8_t lsr; lsr = 0; // check if there are any bytes to be read if (cons->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->result = Packet::Success; return pioDelay; } Tick Uart8250::write(PacketPtr pkt) { assert(pkt->result == Packet::Unknown); 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()); switch (daddr) { case 0x0: if (!(LCR & 0x80)) { // write byte cons->out(pkt->get()); platform->clearConsoleInt(); status &= ~TX_INT; if (UART_IER_THRI & IER) txIntrEvent.scheduleIntr(); } else { // dll divisor latch ; } break; case 0x1: if (!(LCR & 0x80)) { // Intr Enable Register(IER) IER = pkt->get(); if (UART_IER_THRI & IER) { DPRINTF(Uart, "IER: IER_THRI set, scheduling TX intrrupt\n"); if (curTick - lastTxInt > (Tick)((Clock::Float::s / 2e9) * 450)) { DPRINTF(Uart, "-- Interrupting Immediately... %d,%d\n", curTick, lastTxInt); txIntrEvent.process(); } else { DPRINTF(Uart, "-- Delaying interrupt... %d,%d\n", curTick, lastTxInt); txIntrEvent.scheduleIntr(); } } else { DPRINTF(Uart, "IER: IER_THRI cleared, descheduling TX intrrupt\n"); if (txIntrEvent.scheduled()) txIntrEvent.deschedule(); if (status & TX_INT) platform->clearConsoleInt(); status &= ~TX_INT; } if ((UART_IER_RDI & IER) && cons->dataAvailable()) { DPRINTF(Uart, "IER: IER_RDI set, scheduling RX intrrupt\n"); rxIntrEvent.scheduleIntr(); } else { DPRINTF(Uart, "IER: IER_RDI cleared, descheduling RX intrrupt\n"); if (rxIntrEvent.scheduled()) rxIntrEvent.deschedule(); 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(); break; case 0x4: // Modem Control Register (MCR) if (pkt->get() == (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->result = Packet::Success; 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; } } void Uart8250::addressRanges(AddrRangeList &range_list) { assert(pioSize != 0); range_list.clear(); range_list.push_back(RangeSize(pioAddr, pioSize)); } void Uart8250::serialize(ostream &os) { 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(Checkpoint *cp, const std::string §ion) { 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) rxIntrEvent.schedule(rxintrwhen); if (txintrwhen != 0) txIntrEvent.schedule(txintrwhen); } Uart8250 * Uart8250Params::create() { return new Uart8250(this); }