[Qemu-devel] [PATCH 1/2] usb-serial: implement break event.

[Qemu-devel] [PATCH 1/2] usb-serial: implement break event.

[Jason Wessel]

Implement the serial break via usb serial.

The second data byte in ftdi status packet contains the break status.
The values were already defined in usb-serial.c so it was a matter of
making use of the event_trigger to form a urb to send over to the host
controller with the serial break status set.

This was tested against a linux development image which enables sysrq
via a serial break on the ftdi usb console.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
 hw/usb-serial.c |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/hw/usb-serial.c b/hw/usb-serial.c
index 5208482..2caf498 100644
--- a/hw/usb-serial.c
+++ b/hw/usb-serial.c
@@ -445,7 +445,15 @@ static int usb_serial_handle_data(USBDevice *dev, USBPacket *p)
         }
         *data++ = usb_get_modem_lines(s) | 1;
         /* We do not have the uart details */
-        *data++ = 0;
+        /* handle serial break */
+        if (s->event_trigger && s->event_trigger & FTDI_BI) {
+            s->event_trigger &= ~FTDI_BI;
+            *data++ = FTDI_BI;
+            ret = 2;
+            break;
+        } else {
+            *data++ = 0;
+        }
         len -= 2;
         if (len > s->recv_used)
             len = s->recv_used;
@@ -505,7 +513,7 @@ static void usb_serial_event(void *opaque, int event)
 
     switch (event) {
         case CHR_EVENT_BREAK:
-            /* TODO: Send Break to USB */
+            s->event_trigger |= FTDI_BI;
             break;
         case CHR_EVENT_FOCUS:
             break;
-- 
1.6.3.9.g6345d

[Qemu-devel] [PATCH 2/2] serial: fix lost character after sysrq

[Jason Wessel]

After creating an automated regression test to test the sysrq
responses while running a linux image in qemu, I found that the
simulated uart was eating the character right after the sysrq about
75% of the time.

The problem is that the qemu sets the LSR_DR (data ready) bit on a
serial break.  The automated tests can send a break and the sysrq
character quickly enough that the qemu serial fifo has a real
character available. When there is valid character in the fifo, it
gets consumed by the serial driver in the guest OS.

The real hardware also appears to set the LSR_DR but always appears to
have a null byte in this condition.  This patch changes the qemu
behavior to match the tested characteristics of a real 16550 chip.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
 hw/serial.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/hw/serial.c b/hw/serial.c
index ac089fc..113829c 100644
--- a/hw/serial.c
+++ b/hw/serial.c
@@ -586,6 +586,8 @@ static int serial_can_receive(SerialState *s)
 static void serial_receive_break(SerialState *s)
 {
     s->rbr = 0;
+    /* When the LSR_DR is set a null byte is pushed into the fifo */
+    fifo_put(s, RECV_FIFO, '\0');
     s->lsr |= UART_LSR_BI | UART_LSR_DR;
     serial_update_irq(s);
 }
-- 
1.6.3.9.g6345d