dev-serial: store flow control and xon/xoff characters

Note that whilst the device does not do anything with these values, they are
logged with trace events and stored to allow future implementation.

The default flow control is set to none at reset as documented in the Linux
ftdi_sio.h header file.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Message-id: 20201027150456.24606-9-mark.cave-ayland@ilande.co.uk
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

2 files changed, 37 insertions, 3 deletions

diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c
index e42ce36295..19e1933f04 100644
--- a/hw/usb/dev-serial.c
+++ b/hw/usb/dev-serial.c
@@ -52,6 +52,7 @@
 
 /* SET_FLOW_CTRL */
 
+#define FTDI_NO_HS         0
 #define FTDI_RTS_CTS_HS    1
 #define FTDI_DTR_DSR_HS    2
 #define FTDI_XON_XOFF_HS   4
@@ -98,6 +99,9 @@ struct USBSerialState {
     uint8_t error_chr;
     uint8_t event_trigger;
     bool always_plugged;
+    uint8_t flow_control;
+    uint8_t xon;
+    uint8_t xoff;
     QEMUSerialSetParams params;
     int latency;        /* ms */
     CharBackend cs;
@@ -181,14 +185,36 @@ static const USBDesc desc_braille = {
     .str  = desc_strings,
 };
 
+static void usb_serial_set_flow_control(USBSerialState *s,
+                                        uint8_t flow_control)
+{
+    USBDevice *dev = USB_DEVICE(s);
+    USBBus *bus = usb_bus_from_device(dev);
+
+    /* TODO: ioctl */
+    s->flow_control = flow_control;
+    trace_usb_serial_set_flow_control(bus->busnr, dev->addr, flow_control);
+}
+
+static void usb_serial_set_xonxoff(USBSerialState *s, int xonxoff)
+{
+    USBDevice *dev = USB_DEVICE(s);
+    USBBus *bus = usb_bus_from_device(dev);
+
+    s->xon = xonxoff & 0xff;
+    s->xoff = (xonxoff >> 8) & 0xff;
+
+    trace_usb_serial_set_xonxoff(bus->busnr, dev->addr, s->xon, s->xoff);
+}
+
 static void usb_serial_reset(USBSerialState *s)
 {
-    /* TODO: Set flow control to none */
     s->event_chr = 0x0d;
     s->event_trigger = 0;
     s->recv_ptr = 0;
     s->recv_used = 0;
     /* TODO: purge in char driver */
+    usb_serial_set_flow_control(s, FTDI_NO_HS);
 }
 
 static void usb_serial_handle_reset(USBDevice *dev)
@@ -285,9 +311,15 @@ static void usb_serial_handle_control(USBDevice *dev, USBPacket *p,
         qemu_chr_fe_ioctl(&s->cs, CHR_IOCTL_SERIAL_SET_TIOCM, &flags);
         break;
     }
-    case VendorDeviceOutRequest | FTDI_SET_FLOW_CTRL:
-        /* TODO: ioctl */
+    case VendorDeviceOutRequest | FTDI_SET_FLOW_CTRL: {
+        uint8_t flow_control = index >> 8;
+
+        usb_serial_set_flow_control(s, flow_control);
+        if (flow_control & FTDI_XON_XOFF_HS) {
+            usb_serial_set_xonxoff(s, value);
+        }
         break;
+    }
     case VendorDeviceOutRequest | FTDI_SET_BAUD: {
         static const int subdivisors8[8] = { 0, 4, 2, 1, 3, 5, 6, 7 };
         int subdivisor8 = subdivisors8[((value & 0xc000) >> 14)
diff --git a/hw/usb/trace-events b/hw/usb/trace-events
index 109da521cf..a3292d4624 100644
--- a/hw/usb/trace-events
+++ b/hw/usb/trace-events
@@ -331,3 +331,5 @@ usb_serial_unsupported_data_bits(int bus, int addr, int value) "dev %d:%u unsupp
 usb_serial_bad_token(int bus, int addr) "dev %d:%u bad token"
 usb_serial_set_baud(int bus, int addr, int baud) "dev %d:%u baud rate %d"
 usb_serial_set_data(int bus, int addr, int parity, int data, int stop) "dev %d:%u parity %c, data bits %d, stop bits %d"
+usb_serial_set_flow_control(int bus, int addr, int index) "dev %d:%u flow control %d"
+usb_serial_set_xonxoff(int bus, int addr, uint8_t xon, uint8_t xoff) "dev %d:%u xon 0x%x xoff 0x%x"