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kvm,serial: Implement 16550A FIFO support

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This patch implements 16550A FIFO support to the serial console emulation
layer. There's still a bug lurking somewhere which the hypervisor in some busy
loop taking up 100% of CPU. However, this patch is a definite improvement over
the previous hacks.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
This commit is contained in:
Pekka Enberg
2015-06-01 16:39:41 +01:00
committed by Will Deacon
parent 19a2bb7d9f
commit 369c01c0e7
1 changed files with 82 additions and 71 deletions
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8250-serial.c
+82 -71
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@@ -22,9 +22,8 @@ struct serial8250_device {
uint8_t lcr;
uint8_t mcr;
uint8_t lsr;
uint8_t msr;
uint8_t scr;
uint8_t counter;
};
static struct serial8250_device devices[] = {
@@ -34,6 +33,7 @@ static struct serial8250_device devices[] = {
.irq = 4,
.lsr = UART_LSR_TEMT | UART_LSR_THRE,
.iir = UART_IIR_NO_INT,
},
/* ttyS1 */
[1] = {
@@ -75,9 +75,6 @@ static void serial8250__receive(struct kvm *self, struct serial8250_device *dev)
{
int c;
if (dev->lsr & UART_LSR_DR)
return;
if (!is_readable(fileno(stdin)))
return;
@@ -85,6 +82,9 @@ static void serial8250__receive(struct kvm *self, struct serial8250_device *dev)
if (c < 0)
return;
if (dev->lsr & UART_LSR_DR)
dev->lsr |= UART_LSR_OE;
dev->rbr = c;
dev->lsr |= UART_LSR_DR;
}
@@ -95,27 +95,17 @@ static void serial8250__receive(struct kvm *self, struct serial8250_device *dev)
void serial8250__interrupt(struct kvm *self)
{
struct serial8250_device *dev = &devices[0];
uint8_t new_iir;
dev->iir = UART_IIR_NO_INT;
/* No interrupts enabled. Exit... */
if (!(dev->ier & (UART_IER_THRI|UART_IER_RDI)))
return;
serial8250__receive(self, dev);
new_iir = 0;
if (dev->lsr & UART_LSR_DR)
new_iir |= UART_IIR_RDI;
if (dev->ier & UART_IER_RDI && dev->lsr & UART_LSR_DR)
dev->iir = UART_IIR_RDI;
else if (dev->ier & UART_IER_THRI)
new_iir |= UART_IIR_THRI;
dev->iir = UART_IIR_THRI;
else
dev->iir = UART_IIR_NO_INT;
/* Only send an IRQ if there's work to do. */
if (new_iir) {
dev->counter = 0;
dev->iir = new_iir;
if (dev->iir != UART_IIR_NO_INT) {
kvm__irq_line(self, dev->irq, 0);
kvm__irq_line(self, dev->irq, 1);
}
@@ -145,36 +135,34 @@ static bool serial8250_out(struct kvm *self, uint16_t port, void *data, int size
offset = port - dev->iobase;
/* LSR is factory test and MSR is not used for writes */
if (offset == UART_LSR || offset == UART_MSR)
return true;
/* FCR, LCR, MCR, and SCR have the same meaning regardless of DLAB */
switch (offset) {
case UART_FCR:
dev->fcr = ioport__read8(data);
return true;
case UART_LCR:
dev->lcr = ioport__read8(data);
return true;
case UART_MCR:
dev->mcr = ioport__read8(data);
return true;
case UART_SCR:
dev->scr = ioport__read8(data);
return true;
default:
break;
}
if (dev->lcr & UART_LCR_DLAB) {
switch (offset) {
case UART_DLL:
dev->dll = ioport__read8(data);
dev->dll = ioport__read8(data);
break;
case UART_DLM:
dev->dlm = ioport__read8(data);
dev->dlm = ioport__read8(data);
break;
case UART_FCR:
dev->fcr = ioport__read8(data);
break;
case UART_LCR:
dev->lcr = ioport__read8(data);
break;
case UART_MCR:
dev->mcr = ioport__read8(data);
break;
case UART_LSR:
/* Factory test */
break;
case UART_MSR:
/* Not used */
break;
case UART_SCR:
dev->scr = ioport__read8(data);
break;
default:
return false;
}
} else {
switch (offset) {
@@ -182,23 +170,41 @@ static bool serial8250_out(struct kvm *self, uint16_t port, void *data, int size
char *p = data;
int i;
while (count--) {
for (i = 0; i < size; i++)
fprintf(stdout, "%c", *p++);
if (!(dev->mcr & UART_MCR_LOOP)) {
while (count--) {
for (i = 0; i < size; i++)
fprintf(stdout, "%c", *p++);
}
fflush(stdout);
}
fflush(stdout);
if (dev->counter++ > 10)
dev->iir = UART_IIR_NO_INT;
dev->iir = UART_IIR_NO_INT;
break;
}
case UART_IER:
dev->ier = ioport__read8(data);
case UART_FCR:
dev->fcr = ioport__read8(data);
break;
case UART_IER:
dev->ier = ioport__read8(data) & 0x3f;
break;
case UART_LCR:
dev->lcr = ioport__read8(data);
break;
case UART_MCR:
dev->mcr = ioport__read8(data);
break;
case UART_LSR:
/* Factory test */
break;
case UART_MSR:
/* Not used */
break;
case UART_SCR:
dev->scr = ioport__read8(data);
break;
default:
return false;
}
}
return true;
}
@@ -213,7 +219,6 @@ static bool serial8250_in(struct kvm *self, uint16_t port, void *data, int size,
offset = port - dev->iobase;
/* DLAB only changes the meaning of the first two registers */
if (dev->lcr & UART_LCR_DLAB) {
switch (offset) {
case UART_DLL:
@@ -222,29 +227,34 @@ static bool serial8250_in(struct kvm *self, uint16_t port, void *data, int size,
case UART_DLM:
ioport__write8(data, dev->dlm);
return true;
default:
break;
}
} else {
switch (offset) {
case UART_RX:
if (dev->lsr & UART_LSR_DR) {
dev->iir = UART_IIR_NO_INT;
dev->lsr &= ~UART_LSR_DR;
ioport__write8(data, dev->rbr);
}
ioport__write8(data, dev->rbr);
dev->lsr &= ~UART_LSR_DR;
dev->iir = UART_IIR_NO_INT;
return true;
case UART_IER:
ioport__write8(data, dev->ier);
return true;
default:
break;
}
}
/* All other registers have the same meaning regardless of DLAB */
switch (offset) {
case UART_IIR:
dev->iir &= 0x3f; /* no FIFO for 8250 */
ioport__write8(data, dev->iir);
case UART_IIR: {
uint8_t iir = dev->iir;
if (dev->fcr & UART_FCR_ENABLE_FIFO)
iir |= 0xc0;
ioport__write8(data, iir);
break;
}
case UART_LCR:
ioport__write8(data, dev->lcr);
break;
@@ -253,16 +263,17 @@ static bool serial8250_in(struct kvm *self, uint16_t port, void *data, int size,
break;
case UART_LSR:
ioport__write8(data, dev->lsr);
dev->lsr &= ~(UART_LSR_OE|UART_LSR_PE|UART_LSR_FE|UART_LSR_BI);
break;
case UART_MSR:
ioport__write8(data, UART_MSR_CTS);
ioport__write8(data, dev->msr);
break;
case UART_SCR:
/* No SCR for 8250 */
ioport__write8(data, 0);
ioport__write8(data, dev->scr);
break;
default:
return false;
}
return true;
}