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sortix--sortix/kernel/com.cpp
2014-03-01 14:37:39 +01:00

456 lines
12 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
This file is part of Sortix.
Sortix is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.
Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
You should have received a copy of the GNU General Public License along with
Sortix. If not, see <http://www.gnu.org/licenses/>.
com.cpp
Handles communication to COM serial ports.
*******************************************************************************/
#include <errno.h>
#include <sortix/stat.h>
#include <sortix/kernel/descriptor.h>
#include <sortix/kernel/inode.h>
#include <sortix/kernel/interlock.h>
#include <sortix/kernel/interrupt.h>
#include <sortix/kernel/ioctx.h>
#include <sortix/kernel/kernel.h>
#include <sortix/kernel/kthread.h>
#include <sortix/kernel/process.h>
#include <sortix/kernel/refcount.h>
#include <sortix/kernel/thread.h>
#include "com.h"
namespace Sortix {
namespace COM {
// It appears this code is unable to get interrupts working correctly. Somehow
// we don't get interrupts upon receiving data, at least under VirtualBox. This
// hack changes the code such that it polls occasionally instead. Hopefully this
// won't cause data loss, but I suspect that it will.
// TODO: It appears that this code causes kernel instability, possibly due to
// the broken way blocking system calls are implemented in Sortix.
#define POLL_HACK 1
// Another alternative is to use the polling code in a completely blocking
// manner. While this may give nicer transfer speeds and less data loss, it
// locks up the whole system.
#define POLL_BLOCKING 0
// Yet another alternative is to use POLL_HACK, but return EGAIN and let user-
// space call retry, rather than relying on the broken syscall interstructure.
#define POLL_EAGAIN 1
#if !POLL_EAGAIN && !POLL_HACK
#error The interrupt-based code was broken in the kthread branch.
#error You need to port this to the new thread/interrupt API.
#warning Oh, and fix the above mentioned bugs too.
#endif
const uint16_t TXR = 0; // Transmit register
const uint16_t RXR = 0; // Receive register
const uint16_t IER = 1; // Interrupt Enable
const uint16_t IIR = 2; // Interrupt ID
const uint16_t FCR = 2; // FIFO control
const uint16_t LCR = 3; // Line control
const uint16_t MCR = 4; // Modem control
const uint16_t LSR = 5; // Line Status
const uint16_t MSR = 6; // Modem Status
const uint16_t SCR = 7; // Scratch Register
const uint16_t DLL = 0; // Divisor Latch Low
const uint16_t DLM = 1; // Divisor latch High
const uint8_t LCR_DLAB = 0x80; // Divisor latch access bit
const uint8_t LCR_SBC = 0x40; // Set break control
const uint8_t LCR_SPAR = 0x20; // Stick parity (?)
const uint8_t LCR_EPAR = 0x10; // Even parity select
const uint8_t LCR_PARITY = 0x08; // Parity Enable
const uint8_t LCR_STOP = 0x04; // Stop bits: 0=1 bit, 1=2 bits
const uint8_t LCR_WLEN5 = 0x00; // Wordlength: 5 bits
const uint8_t LCR_WLEN6 = 0x01; // Wordlength: 6 bits
const uint8_t LCR_WLEN7 = 0x02; // Wordlength: 7 bits
const uint8_t LCR_WLEN8 = 0x03; // Wordlength: 8 bits
const uint8_t LSR_TEMT = 0x40; // Transmitter empty
const uint8_t LSR_THRE = 0x20; // Transmit-hold-register empty
const uint8_t LSR_READY = 0x1; // Data received
const uint8_t LSR_BOTH_EMPTY = LSR_TEMT | LSR_THRE;
const uint8_t IIR_NO_INTERRUPT = (1U<<0U);
const uint8_t IIR_INTERRUPT_TYPE = ((1U<<1U) | (1U<<2U) | (1U<<3U));
const uint8_t IIR_TIMEOUT = ((1U<<2U) | (1U<<3U));
const uint8_t IIR_RECV_LINE_STATUS = ((1U<<1U) | (1U<<2U));
const uint8_t IIR_RECV_DATA = (1U<<2U);
const uint8_t IIR_SENT_DATA = (1U<<1U);
const uint8_t IIR_MODEM_STATUS = 0;
const uint8_t IER_DATA = (1U<<0U);
const uint8_t IER_SENT = (1U<<1U);
const uint8_t IER_LINE_STATUS = (1U<<2U);
const uint8_t IER_MODEM_STATUS = (1U<<3U);
const uint8_t IER_SLEEP_MODE = (1U<<4U);
const uint8_t IER_LOW_POWER = (1U<<5U);
const unsigned BASE_BAUD = 1843200/16;
const unsigned UART8250 = 1;
const unsigned UART16450 = 2;
const unsigned UART16550 = 3;
const unsigned UART16550A = 4;
const unsigned UART16750 = 5;
const size_t NUMCOMPORTS = 4;
// The IO base ports of each COM port.
static uint16_t comports[1+NUMCOMPORTS];
// The results of running HardwareProbe on each COM port.
unsigned hwversion[1+NUMCOMPORTS];
// Uses various characteristics of the UART chips to determine the hardware.
static unsigned HardwareProbe(uint16_t port)
{
// Set the value "0xE7" to the FCR to test the status of the FIFO flags.
CPU::OutPortB(port + FCR, 0xE7);
uint8_t iir = CPU::InPortB(port + IIR);
if ( iir & (1U<<6U) )
{
if ( iir & (1<<7U) )
{
return (iir & (1U<<5U)) ? UART16750 : UART16550A;
}
return UART16550;
}
// See if the scratch register returns what we write into it. The 8520
// doesn't do it. This is technically undefined behavior, but it is useful
// to detect hardware versions.
uint16_t anyvalue = 0x2A;
CPU::OutPortB(port + SCR, anyvalue);
return CPU::InPortB(port + SCR) == anyvalue ? UART16450 : UART8250;
}
static inline void WaitForEmptyBuffers(uint16_t port)
{
while ( (CPU::InPortB(port + LSR) & LSR_BOTH_EMPTY) != LSR_BOTH_EMPTY ) { }
}
static inline bool IsLineReady(uint16_t port)
{
return CPU::InPortB(port + LSR) & LSR_READY;
}
static inline bool CanWriteByte(uint16_t port)
{
return CPU::InPortB(port + LSR) & LSR_THRE;
}
ssize_t ReadBlocking(uint16_t port, void* buf, size_t size)
{
if ( SSIZE_MAX < size ) { size = SSIZE_MAX; }
uint8_t* buffer = (uint8_t*) buf;
uint8_t interruptsenabled = CPU::InPortB(port + IER);
CPU::OutPortB(port + IER, 0);
for ( size_t i = 0; i < size; i++ )
{
while ( !IsLineReady(port) ) { }
buffer[i] = CPU::InPortB(port + RXR);
}
WaitForEmptyBuffers(port);
CPU::OutPortB(port + IER, interruptsenabled);
return size;
}
ssize_t WriteBlocking(uint16_t port, const void* buf, size_t size)
{
if ( SSIZE_MAX < size ) { size = SSIZE_MAX; }
const uint8_t* buffer = (const uint8_t*) buf;
uint8_t interruptsenabled = CPU::InPortB(port + IER);
CPU::OutPortB(port + IER, 0);
for ( size_t i = 0; i < size; i++ )
{
while ( !CanWriteByte(port) ) { }
CPU::OutPortB(port + TXR, buffer[i]);
}
WaitForEmptyBuffers(port);
CPU::OutPortB(port + IER, interruptsenabled);
return size;
}
void EarlyInit()
{
// We can fetch COM port information from the BIOS Data Area.
volatile uint16_t* const bioscomports = (uint16_t* const) 0x0400UL;
for ( size_t i = 1; i <= NUMCOMPORTS; i++ )
{
comports[i] = bioscomports[i-1];
if ( !comports[i] ) { continue; }
hwversion[i] = HardwareProbe(comports[i]);
CPU::OutPortB(comports[i] + IER, 0x0);
}
}
class DevCOMPort : public AbstractInode
{
public:
DevCOMPort(dev_t dev, uid_t owner, gid_t group, mode_t mode, uint16_t port);
virtual ~DevCOMPort();
virtual int sync(ioctx_t* ctx);
virtual ssize_t read(ioctx_t* ctx, uint8_t* buf, size_t count);
virtual ssize_t write(ioctx_t* ctx, const uint8_t* buf, size_t count);
public:
void OnInterrupt();
private:
kthread_mutex_t portlock;
uint16_t port;
};
DevCOMPort::DevCOMPort(dev_t dev, uid_t owner, gid_t group, mode_t mode,
uint16_t port)
{
inode_type = INODE_TYPE_STREAM;
this->port = port;
this->portlock = KTHREAD_MUTEX_INITIALIZER;
this->stat_uid = owner;
this->stat_gid = group;
this->type = S_IFCHR;
this->stat_mode = (mode & S_SETABLE) | this->type;
this->dev = dev;
this->ino = (ino_t) this;
}
DevCOMPort::~DevCOMPort()
{
}
int DevCOMPort::sync(ioctx_t* /*ctx*/)
{
// TODO: Not implemented yet, please wait for all outstanding requests.
return 0;
}
#if POLL_HACK
ssize_t DevCOMPort::read(ioctx_t* ctx, uint8_t* dest, size_t count)
{
if ( !count ) { return 0; }
if ( SSIZE_MAX < count ) { count = SSIZE_MAX; }
ScopedLock lock(&portlock);
while ( !(CPU::InPortB(port + LSR) & LSR_READY) )
if ( Signal::IsPending() )
{
errno = EINTR;
return -1;
}
size_t sofar = 0;
do
{
if ( count <= sofar ) { break; }
uint8_t val = CPU::InPortB(port + RXR);
if ( !ctx->copy_to_dest(dest + sofar++, &val, sizeof(val)) )
return -1;
} while ( CPU::InPortB(port + LSR) & LSR_READY);
return sofar;
}
ssize_t DevCOMPort::write(ioctx_t* ctx, const uint8_t* src, size_t count)
{
if ( !count ) { return 0; }
if ( SSIZE_MAX < count ) { count = SSIZE_MAX; };
ScopedLock lock(&portlock);
while ( !(CPU::InPortB(port + LSR) & LSR_THRE) )
if ( Signal::IsPending() )
{
errno = EINTR;
return -1;
}
size_t sofar = 0;
do
{
if ( count <= sofar ) { break; }
uint8_t val;
if ( !ctx->copy_from_src(&val, src + sofar++, sizeof(val)) )
return -1;
CPU::OutPortB(port + TXR, val);
} while ( CPU::InPortB(port + LSR) & LSR_THRE );
return sofar;
}
#else
#error Yeah, please port these to the new IO interface.
ssize_t DevCOMPort::Read(byte* dest, size_t count)
{
if ( !count ) { return 0; }
if ( SSIZE_MAX < count ) { count = SSIZE_MAX; }
#if POLL_BLOCKING
return ReadBlocking(port, dest, 1);
#endif
uint8_t lsr = CPU::InPortB(port + LSR);
if ( !(lsr & LSR_READY) )
{
Panic("Can't wait for com data receive event");
Error::Set(EBLOCKING);
return -1;
}
size_t sofar = 0;
do
{
if ( count <= sofar ) { break; }
dest[sofar++] = CPU::InPortB(port + RXR);
} while ( CPU::InPortB(port + LSR) & LSR_READY);
return sofar;
}
ssize_t DevCOMPort::Write(const uint8_t* src, size_t count)
{
if ( !count ) { return 0; }
if ( SSIZE_MAX < count ) { count = SSIZE_MAX; };
#if POLL_BLOCKING
return WriteBlocking(port, src, 1);
#endif
uint8_t lsr = CPU::InPortB(port + LSR);
if ( !(lsr & LSR_THRE) )
{
Panic("Can't wait for com data sent event");
Error::Set(EBLOCKING);
return -1;
}
size_t sofar = 0;
do
{
if ( count <= sofar ) { break; }
CPU::OutPortB(port + TXR, src[sofar++]);
} while ( CPU::InPortB(port + LSR) & LSR_THRE );
return sofar;
}
#endif
void DevCOMPort::OnInterrupt()
{
#if POLL_HACK || POLL_BLOCKING
return;
#endif
uint8_t iir = CPU::InPortB(port + IIR);
if ( iir & IIR_NO_INTERRUPT ) { return; }
uint8_t intrtype = iir & IIR_INTERRUPT_TYPE;
switch ( intrtype )
{
case IIR_TIMEOUT:
CPU::InPortB(port + RXR);
break;
case IIR_RECV_LINE_STATUS:
// TODO: Proper error handling!
CPU::InPortB(port + LSR);
break;
case IIR_RECV_DATA:
Panic("Can't wait for com data sent event");
break;
case IIR_SENT_DATA:
Panic("Can't wait for com data sent event");
CPU::InPortB(port + IIR);
break;
case IIR_MODEM_STATUS:
CPU::InPortB(port + MSR);
break;
}
}
Ref<DevCOMPort> comdevices[1+NUMCOMPORTS];
static void UARTIRQHandler(CPU::InterruptRegisters* /*regs*/, void* /*user*/)
{
for ( size_t i = 1; i <= NUMCOMPORTS; i++ )
{
if ( !comdevices[i] ) { continue; }
comdevices[i]->OnInterrupt();
}
}
void Init(const char* devpath, Ref<Descriptor> slashdev)
{
ioctx_t ctx; SetupKernelIOCtx(&ctx);
for ( size_t i = 1; i <= NUMCOMPORTS; i++ )
{
if ( !comports[i] ) { comdevices[i] = Ref<DevCOMPort>(); continue; }
comdevices[i] = Ref<DevCOMPort>
(new DevCOMPort(slashdev->dev, 0, 0, 0660, comports[i]));
if ( !comdevices[i] )
{
PanicF("Unable to allocate device for COM port %zu at 0x%x", i,
comports[i]);
}
char name[5] = "comN";
name[3] = '0' + i;
if ( LinkInodeInDir(&ctx, slashdev, name, comdevices[i]) != 0 )
PanicF("Unable to link %s/%s to COM port driver.", devpath, name);
}
Interrupt::RegisterHandler(Interrupt::IRQ3, UARTIRQHandler, NULL);
Interrupt::RegisterHandler(Interrupt::IRQ4, UARTIRQHandler, NULL);
// Initialize the ports so we can transfer data.
for ( size_t i = 1; i <= NUMCOMPORTS; i++ )
{
uint16_t port = comports[i];
if ( !port ) { continue; }
#if POLL_HACK || POLL_BLOCKING
uint8_t interrupts = 0;
#else
uint8_t interrupts = IER_DATA
| IER_SENT
| IER_LINE_STATUS
| IER_MODEM_STATUS;
#endif
CPU::OutPortB(port + FCR, 0);
CPU::OutPortB(port + LCR, 0x80);
CPU::OutPortB(port + DLL, 0xC);
CPU::OutPortB(port + DLM, 0x0);
CPU::OutPortB(port + LCR, 0x3); // 8n1
CPU::OutPortB(port + MCR, 0x3); // DTR + RTS
CPU::OutPortB(port + IER, interrupts);
}
}
} // namespace COM
} // namespace Sortix