# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1265625413 0
# Node ID e42b5532ac856e5f6f851e0e6d98af3315e533f4
# Parent 85e852ef0d7468ad7a54b5413b7ad99077de1d99
Handle bogus serial ports that appear normal, but don't generate
interrupts e.g. the "remote serial console" on Blades.
Authored-by: Gary Grebus <Gary.Grebus@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
xen-unstable changeset: 20909:12fc55dffb6b
xen-unstable date: Mon Feb 08 08:49:19 2010 +0000
---
xen/drivers/char/ns16550.c | 36 +++++++++++++++++++++++++++++-------
1 files changed, 29 insertions(+), 7 deletions(-)
diff -r 85e852ef0d74 -r e42b5532ac85 xen/drivers/char/ns16550.c
--- a/xen/drivers/char/ns16550.c Mon Feb 08 10:36:26 2010 +0000
+++ b/xen/drivers/char/ns16550.c Mon Feb 08 10:36:53 2010 +0000
@@ -38,6 +38,7 @@ static struct ns16550 {
/* UART with no IRQ line: periodically-polled I/O. */
struct timer timer;
unsigned int timeout_ms;
+ int probing, intr_works;
} ns16550_com[2] = { { 0 } };
/* Register offsets */
@@ -126,6 +127,13 @@ static void ns16550_interrupt(
struct serial_port *port = dev_id;
struct ns16550 *uart = port->uart;
+ if (uart->intr_works == 0)
+ {
+ uart->probing = 0;
+ uart->intr_works = 1;
+ stop_timer(&uart->timer);
+ }
+
while ( !(ns_read_reg(uart, IIR) & IIR_NOINT) )
{
char lsr = ns_read_reg(uart, LSR);
@@ -142,6 +150,15 @@ static void ns16550_poll(void *data)
struct ns16550 *uart = port->uart;
struct cpu_user_regs *regs = guest_cpu_user_regs();
+ if ( uart->intr_works )
+ return; /* Interrupts work - no more polling */
+
+ if ( uart->probing ) {
+ uart->probing = 0;
+ if ( (ns_read_reg(uart, LSR) & 0xff) == 0xff )
+ return; /* All bits set - probably no UART present */
+ }
+
while ( ns_read_reg(uart, LSR) & LSR_DR )
serial_rx_interrupt(port, regs);
@@ -228,15 +245,14 @@ static void __devinit ns16550_init_posti
serial_async_transmit(port);
+ init_timer(&uart->timer, ns16550_poll, port, 0);
+ /* Calculate time to fill RX FIFO and/or empty TX FIFO for polling. */
+ bits = uart->data_bits + uart->stop_bits + !!uart->parity;
+ uart->timeout_ms = max_t(
+ unsigned int, 1, (bits * port->tx_fifo_size * 1000) / uart->baud);
+
if ( uart->irq == 0 )
- {
- /* Polled mode. Calculate time to fill RX FIFO and/or empty TX FIFO. */
- bits = uart->data_bits + uart->stop_bits + !!uart->parity;
- uart->timeout_ms = max_t(
- unsigned int, 1, (bits * port->tx_fifo_size * 1000) / uart->baud);
- init_timer(&uart->timer, ns16550_poll, port, 0);
set_timer(&uart->timer, NOW() + MILLISECS(uart->timeout_ms));
- }
else
{
uart->irqaction.handler = ns16550_interrupt;
@@ -250,6 +266,12 @@ static void __devinit ns16550_init_posti
/* Enable receive and transmit interrupts. */
ns_write_reg(uart, IER, IER_ERDAI | IER_ETHREI);
+
+ /* Do a timed write to make sure we are getting interrupts. */
+ uart->probing = 1;
+ uart->intr_works = 0;
+ ns_write_reg(uart, THR, 0xff);
+ set_timer(&uart->timer, NOW() + MILLISECS(uart->timeout_ms));
}
}
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