gem5/dev/uart8250.cc

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/*
* Copyright (c) 2004 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.
*/
/** @file
* Implements a 8250 UART
*/
#include <string>
#include <vector>
#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/bus/bus.hh"
#include "mem/bus/pio_interface.hh"
#include "mem/bus/pio_interface_impl.hh"
#include "mem/functional/memory_control.hh"
#include "sim/builder.hh"
using namespace std;
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;
}
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 string &name, SimConsole *c, MemoryController *mmu, Addr a,
Addr s, HierParams *hier, Bus *bus, Tick pio_latency, Platform *p)
: Uart(name, c, mmu, a, s, hier, bus, pio_latency, p),
txIntrEvent(this, TX_INT), rxIntrEvent(this, RX_INT)
{
IER = 0;
DLAB = 0;
LCR = 0;
MCR = 0;
}
Fault
Uart8250::read(MemReqPtr &req, uint8_t *data)
{
Addr daddr = req->paddr - (addr & EV5::PAddrImplMask);
DPRINTF(Uart, " read register %#x\n", daddr);
assert(req->size == 1);
switch (daddr) {
case 0x0:
if (!(LCR & 0x80)) { // read byte
if (cons->dataAvailable())
cons->in(*data);
else {
*(uint8_t*)data = 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)
*(uint8_t*)data = 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)
*(uint8_t*)data = 0;
else
*(uint8_t*)data = 1;
break;
case 0x3: // Line Control Register (LCR)
*(uint8_t*)data = 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;
*(uint8_t*)data = lsr;
break;
case 0x6: // Modem Status Register (MSR)
*(uint8_t*)data = 0;
break;
case 0x7: // Scratch Register (SCR)
*(uint8_t*)data = 0; // doesn't exist with at 8250.
break;
default:
panic("Tried to access a UART port that doesn't exist\n");
break;
}
return No_Fault;
}
Fault
Uart8250::write(MemReqPtr &req, const uint8_t *data)
{
Addr daddr = req->paddr - (addr & EV5::PAddrImplMask);
DPRINTF(Uart, " write register %#x value %#x\n", daddr, *(uint8_t*)data);
switch (daddr) {
case 0x0:
if (!(LCR & 0x80)) { // write byte
cons->out(*(uint8_t *)data);
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 = *(uint8_t*)data;
if (UART_IER_THRI & IER)
{
DPRINTF(Uart, "IER: IER_THRI set, scheduling TX intrrupt\n");
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 = *(uint8_t*)data;
break;
case 0x4: // Modem Control Register (MCR)
if (*(uint8_t*)data == (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;
}
return No_Fault;
}
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::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 &section)
{
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);
}
BEGIN_DECLARE_SIM_OBJECT_PARAMS(Uart8250)
SimObjectParam<SimConsole *> console;
SimObjectParam<MemoryController *> mmu;
SimObjectParam<Platform *> platform;
Param<Addr> addr;
Param<Addr> size;
SimObjectParam<Bus*> io_bus;
Param<Tick> pio_latency;
SimObjectParam<HierParams *> hier;
END_DECLARE_SIM_OBJECT_PARAMS(Uart8250)
BEGIN_INIT_SIM_OBJECT_PARAMS(Uart8250)
INIT_PARAM(console, "The console"),
INIT_PARAM(mmu, "Memory Controller"),
INIT_PARAM(platform, "Pointer to platfrom"),
INIT_PARAM(addr, "Device Address"),
INIT_PARAM_DFLT(size, "Device size", 0x8),
INIT_PARAM_DFLT(io_bus, "The IO Bus to attach to", NULL),
INIT_PARAM_DFLT(pio_latency, "Programmed IO latency in bus cycles", 1),
INIT_PARAM_DFLT(hier, "Hierarchy global variables", &defaultHierParams)
END_INIT_SIM_OBJECT_PARAMS(Uart8250)
CREATE_SIM_OBJECT(Uart8250)
{
return new Uart8250(getInstanceName(), console, mmu, addr, size, hier, io_bus,
pio_latency, platform);
}
REGISTER_SIM_OBJECT("Uart8250", Uart8250)