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sortix--sortix/kernel/com.cpp
2015-08-21 21:25:00 +02:00

317 lines
8.9 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2014.
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 <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <sortix/fcntl.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/ioport.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"
extern "C" unsigned char nullpage[4096];
namespace Sortix {
namespace COM {
static const uint16_t TXR = 0; // Transmit register
static const uint16_t RXR = 0; // Receive register
static const uint16_t IER = 1; // Interrupt Enable
static const uint16_t IIR = 2; // Interrupt ID
static const uint16_t FCR = 2; // FIFO control
static const uint16_t LCR = 3; // Line control
static const uint16_t MCR = 4; // Modem control
static const uint16_t LSR = 5; // Line Status
static const uint16_t MSR = 6; // Modem Status
static const uint16_t SCR = 7; // Scratch Register
static const uint16_t DLL = 0; // Divisor Latch Low
static const uint16_t DLM = 1; // Divisor latch High
static const uint8_t LCR_DLAB = 0x80; // Divisor latch access bit
static const uint8_t LCR_SBC = 0x40; // Set break control
static const uint8_t LCR_SPAR = 0x20; // Stick parity (?)
static const uint8_t LCR_EPAR = 0x10; // Even parity select
static const uint8_t LCR_PARITY = 0x08; // Parity Enable
static const uint8_t LCR_STOP = 0x04; // Stop bits: 0=1 bit, 1=2 bits
static const uint8_t LCR_WLEN5 = 0x00; // Wordlength: 5 bits
static const uint8_t LCR_WLEN6 = 0x01; // Wordlength: 6 bits
static const uint8_t LCR_WLEN7 = 0x02; // Wordlength: 7 bits
static const uint8_t LCR_WLEN8 = 0x03; // Wordlength: 8 bits
static const uint8_t LSR_TEMT = 0x40; // Transmitter empty
static const uint8_t LSR_THRE = 0x20; // Transmit-hold-register empty
static const uint8_t LSR_READY = 0x01; // Data received
static const uint8_t LSR_BOTH_EMPTY = LSR_TEMT | LSR_THRE;
static const uint8_t IIR_NO_INTERRUPT = 1 << 0;
static const uint8_t IIR_INTERRUPT_TYPE = 1 << 1 | 1 << 2 | 1 << 3;
static const uint8_t IIR_TIMEOUT = 1 << 2 | 1 << 3;
static const uint8_t IIR_RECV_LINE_STATUS = 1 << 1 | 1 << 2;
static const uint8_t IIR_RECV_DATA = 1 << 2;
static const uint8_t IIR_SENT_DATA = 1 << 1;
static const uint8_t IIR_MODEM_STATUS = 0;
static const uint8_t IER_DATA = 1 << 0;
static const uint8_t IER_SENT = 1 << 1;
static const uint8_t IER_LINE_STATUS = 1 << 2;
static const uint8_t IER_MODEM_STATUS = 1 << 3;
static const uint8_t IER_SLEEP_MODE = 1 << 4;
static const uint8_t IER_LOW_POWER = 1 << 5;
static const unsigned BASE_BAUD = 1843200 / 16;
static const unsigned int UART_8250 = 1;
static const unsigned int UART_16450 = 2;
static const unsigned int UART_16550 = 3;
static const unsigned int UART_16550A = 4;
static const unsigned int UART_16750 = 5;
static const size_t NUM_COM_PORTS = 4;
// Uses various characteristics of the UART chips to determine the hardware.
static unsigned int HardwareProbe(uint16_t port)
{
// Set the value "0xE7" to the FCR to test the status of the FIFO flags.
outport8(port + FCR, 0xE7);
uint8_t iir = inport8(port + IIR);
if ( iir & (1 << 6) )
{
if ( iir & (1 << 7) )
return iir & (1 << 5) ? UART_16750 : UART_16550A;
return UART_16550;
}
// 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 any_value = 0x2A;
outport8(port + SCR, any_value);
return inport8(port + SCR) == any_value ? UART_16450 : UART_8250;
}
static inline void WaitForEmptyBuffers(uint16_t port)
{
while ( (inport8(port + LSR) & LSR_BOTH_EMPTY) != LSR_BOTH_EMPTY )
{
}
}
static inline bool IsLineReady(uint16_t port)
{
return inport8(port + LSR) & LSR_READY;
}
static inline bool CanWriteByte(uint16_t port)
{
return inport8(port + LSR) & LSR_THRE;
}
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);
private:
kthread_mutex_t port_lock;
uint16_t port;
uint8_t pending_input_byte;
bool has_pending_input_byte;
};
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->port_lock = 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;
this->has_pending_input_byte = false;
}
DevCOMPort::~DevCOMPort()
{
}
int DevCOMPort::sync(ioctx_t* /*ctx*/)
{
ScopedLock lock(&port_lock);
WaitForEmptyBuffers(port);
return 0;
}
ssize_t DevCOMPort::read(ioctx_t* ctx, uint8_t* dest, size_t count)
{
ScopedLock lock(&port_lock);
for ( size_t i = 0; i < count; i++ )
{
unsigned long attempt = 0;
while ( !has_pending_input_byte && !IsLineReady(port) )
{
attempt++;
if ( attempt <= 10 )
continue;
if ( attempt <= 15 && !(ctx->dflags & O_NONBLOCK) )
{
kthread_yield();
continue;
}
if ( i )
return (ssize_t) i;
if ( ctx->dflags & O_NONBLOCK )
return errno = EWOULDBLOCK, -1;
if ( Signal::IsPending() )
return errno = EINTR, -1;
kthread_yield();
}
uint8_t value = has_pending_input_byte ?
pending_input_byte :
inport8(port + RXR);
if ( !ctx->copy_to_dest(dest + i, &value, sizeof(value)) )
{
has_pending_input_byte = true;
pending_input_byte = value;
return i ? (ssize_t) i : -1;
}
has_pending_input_byte = false;
}
return (ssize_t) count;
}
ssize_t DevCOMPort::write(ioctx_t* ctx, const uint8_t* src, size_t count)
{
ScopedLock lock(&port_lock);
for ( size_t i = 0; i < count; i++ )
{
unsigned long attempt = 0;
while ( !CanWriteByte(port) )
{
attempt++;
if ( attempt <= 10 )
continue;
if ( attempt <= 15 && !(ctx->dflags & O_NONBLOCK) )
{
kthread_yield();
continue;
}
if ( i )
return (ssize_t) i;
if ( ctx->dflags & O_NONBLOCK )
return errno = EWOULDBLOCK, -1;
if ( Signal::IsPending() )
return errno = EINTR, -1;
}
uint8_t value;
if ( !ctx->copy_from_src(&value, src + i, sizeof(value)) )
return i ? (ssize_t) i : -1;
outport8(port + TXR, value);
}
return (ssize_t) count;
}
static Ref<DevCOMPort> com_devices[1 + NUM_COM_PORTS];
void Init(const char* devpath, Ref<Descriptor> slashdev)
{
uint16_t com_ports[1 + NUM_COM_PORTS];
unsigned int hw_version[1 + NUM_COM_PORTS];
const uint16_t* bioscom_ports = (const uint16_t*) (nullpage + 0x400);
for ( size_t i = 1; i <= NUM_COM_PORTS; i++ )
{
if ( !(com_ports[i] = bioscom_ports[i-1]) )
continue;
hw_version[i] = HardwareProbe(com_ports[i]);
outport8(com_ports[i] + IER, 0x0);
}
(void) hw_version;
ioctx_t ctx; SetupKernelIOCtx(&ctx);
for ( size_t i = 1; i <= NUM_COM_PORTS; i++ )
{
uint16_t port = com_ports[i];
if ( !port )
continue;
uint8_t interrupts = 0;
outport8(port + FCR, 0);
outport8(port + LCR, 0x80);
outport8(port + DLL, 0xC);
outport8(port + DLM, 0x0);
outport8(port + LCR, 0x3); // 8n1
outport8(port + MCR, 0x3); // DTR + RTS
outport8(port + IER, interrupts);
}
for ( size_t i = 1; i <= NUM_COM_PORTS; i++ )
{
if ( !com_ports[i] )
{
com_devices[i] = Ref<DevCOMPort>();
continue;
}
com_devices[i] = Ref<DevCOMPort>(new DevCOMPort(slashdev->dev, 0, 0, 0660, com_ports[i]));
if ( !com_devices[i] )
PanicF("Unable to allocate device for COM port %zu", i);
char name[3 + sizeof(size_t) * 3];
snprintf(name, sizeof(name), "com%zu", i);
if ( LinkInodeInDir(&ctx, slashdev, name, com_devices[i]) != 0 )
PanicF("Unable to link %s/%s to COM port driver.", devpath, name);
}
}
} // namespace COM
} // namespace Sortix