void serial_start_sync(int handle)
{
struct serial_port *port;
unsigned long flags;
if ( handle == -1 )
return;
port = &com[handle & SERHND_IDX];
spin_lock_irqsave(&port->tx_lock, flags);
if ( port->sync++ == 0 )
{
while ( (port->txbufp - port->txbufc) != 0 )
{
while ( !port->driver->tx_ready(port) )
cpu_relax();
port->driver->putc(
port, port->txbuf[mask_serial_txbuf_idx(port->txbufc++)]);
}
if ( port->driver->flush )
port->driver->flush(port);
}
spin_unlock_irqrestore(&port->tx_lock, flags);
}
void serial_tx_interrupt(struct serial_port *port, struct cpu_user_regs *regs)
{
unsigned int i, n;
unsigned long flags;
local_irq_save(flags);
/*
* Avoid spinning for a long time: if there is a long-term lock holder
* then we know that they'll be stuffing bytes into the transmitter which
* will therefore not be empty for long.
*/
while ( !spin_trylock(&port->tx_lock) )
{
if ( !port->driver->tx_ready(port) )
goto out;
cpu_relax();
}
for ( i = 0, n = port->driver->tx_ready(port); i < n; i++ )
{
if ( port->txbufc == port->txbufp )
break;
port->driver->putc(
port, port->txbuf[mask_serial_txbuf_idx(port->txbufc++)]);
}
if ( i && port->driver->flush )
port->driver->flush(port);
spin_unlock(&port->tx_lock);
out:
local_irq_restore(flags);
}
void serial_start_sync(int handle)
{
struct serial_port *port;
unsigned long flags;
if ( handle == -1 )
return;
port = &com[handle & SERHND_IDX];
spin_lock_irqsave(&port->tx_lock, flags);
if ( port->sync++ == 0 )
{
while ( (port->txbufp - port->txbufc) != 0 )
{
int n;
while ( !(n = port->driver->tx_ready(port)) )
cpu_relax();
if ( n < 0 )
/* port is unavailable and might not come up until reenabled by
dom0, we can't really do proper sync */
break;
port->driver->putc(
port, port->txbuf[mask_serial_txbuf_idx(port->txbufc++)]);
}
if ( port->driver->flush )
port->driver->flush(port);
}
spin_unlock_irqrestore(&port->tx_lock, flags);
}
static void __serial_putc(struct serial_port *port, char c)
{
if ( (port->txbuf != NULL) && !port->sync )
{
/* Interrupt-driven (asynchronous) transmitter. */
if ( port->tx_quench )
{
/* Buffer filled and we are dropping characters. */
if ( (port->txbufp - port->txbufc) > (serial_txbufsz / 2) )
return;
port->tx_quench = 0;
}
if ( (port->txbufp - port->txbufc) == serial_txbufsz )
{
if ( port->tx_log_everything )
{
/* Buffer is full: we spin waiting for space to appear. */
unsigned int n;
while ( (n = port->driver->tx_ready(port)) == 0 )
cpu_relax();
while ( n-- )
port->driver->putc(
port,
port->txbuf[mask_serial_txbuf_idx(port->txbufc++)]);
port->txbuf[mask_serial_txbuf_idx(port->txbufp++)] = c;
}
else
{
/* Buffer is full: drop chars until buffer is half empty. */
port->tx_quench = 1;
}
return;
}
if ( ((port->txbufp - port->txbufc) == 0) &&
port->driver->tx_ready(port) )
{
/* Buffer and UART FIFO are both empty. */
port->driver->putc(port, c);
}
else
{
/* Normal case: buffer the character. */
port->txbuf[mask_serial_txbuf_idx(port->txbufp++)] = c;
}
}
else if ( port->driver->tx_ready )
{
/* Synchronous finite-capacity transmitter. */
while ( !port->driver->tx_ready(port) )
cpu_relax();
port->driver->putc(port, c);
}
else
{
/* Simple synchronous transmitter. */
port->driver->putc(port, c);
}
}