USB serial device

Hello,

I would like to implement support for braille devices, and for this I'd need to first implement a USB serial device (FTDI chip). Has anybody worked on that already?

Samuel

Hello,

Ok, was easier than expected, Here is a patch. The serial support is incomplete however because qemu still lacks support for flow control and modem lines.

You will notice in tty_serial_init that I made the baud values more relaxed. This is because with divisor/baud conversions, things never get exact, so we need to be laxist with the value. For instance here with FTDI, the base divisor is 48000000/2, so for 57600 bps the guest needs to choose between divisors 416 and 417, which bring to either 57692bps or 57553bps but not exactly 57600bps. It happens that Linux chooses divisor 416, hence 57692bps. Of course, the higher the speed, the worse things get. The 1.1 factor is the smallest factor I could find between usual bps values, notably B110, B134 and B150.

Samuel

Index: Makefile
===================================================================
RCS file: /sources/qemu/qemu/Makefile,v
retrieving revision 1.140

diff -u -p -r1.140 Makefile
@@ -57,7 +57,7 @@ OBJS+=i2c.o smbus.o smbus_eeprom.o max73
 OBJS+=ssd0303.o ssd0323.o ads7846.o stellaris_input.o
 OBJS+=scsi-disk.o cdrom.o
 OBJS+=scsi-generic.o
-OBJS+=usb.o usb-hub.o usb-linux.o usb-hid.o usb-msd.o usb-wacom.o
+OBJS+=usb.o usb-hub.o usb-linux.o usb-hid.o usb-msd.o usb-wacom.o usb-serial.o
 OBJS+=sd.o ssi-sd.o
 
 ifdef CONFIG_WIN32

Index: vl.c
===================================================================
RCS file: /sources/qemu/qemu/vl.c,v
retrieving revision 1.395

Index: hw/usb-serial.c
===================================================================
RCS file: hw/usb-serial.c

Index: hw/usb.h
===================================================================
RCS file: /sources/qemu/qemu/hw/usb.h,v
retrieving revision 1.19

diff -u -p -r1.19 usb.h
@@ -217,6 +217,9 @@ USBDevice *usb_msd_init(const char *file
 /* usb-wacom.c */
 USBDevice *usb_wacom_init(void);
 
+/* usb-serial.c */
+USBDevice *usb_serial_init(const char *filename);
+
 /* usb ports of the VM */
 
 void qemu_register_usb_port(USBPort *port, void *opaque, int index,

Hello,

Here is an updated version, that takes parameters, so as to be able to notably provide the product ID.

Samuel

? .vl.c.swp
? stvJqKpr
Index: Makefile
===================================================================
RCS file: /sources/qemu/qemu/Makefile,v
retrieving revision 1.140

diff -u -p -r1.140 Makefile
@@ -57,7 +57,7 @@ OBJS+=i2c.o smbus.o smbus_eeprom.o max73
 OBJS+=ssd0303.o ssd0323.o ads7846.o stellaris_input.o
 OBJS+=scsi-disk.o cdrom.o
 OBJS+=scsi-generic.o
-OBJS+=usb.o usb-hub.o usb-linux.o usb-hid.o usb-msd.o usb-wacom.o
+OBJS+=usb.o usb-hub.o usb-linux.o usb-hid.o usb-msd.o usb-wacom.o usb-serial.o
 OBJS+=sd.o ssi-sd.o
 
 ifdef CONFIG_WIN32

Index: vl.c
===================================================================
RCS file: /sources/qemu/qemu/vl.c,v
retrieving revision 1.395

Index: hw/usb-serial.c
===================================================================
RCS file: hw/usb-serial.c

Index: hw/usb.h
===================================================================
RCS file: /sources/qemu/qemu/hw/usb.h,v
retrieving revision 1.19

diff -u -p -r1.19 usb.h
@@ -217,6 +217,9 @@ USBDevice *usb_msd_init(const char *file
 /* usb-wacom.c */
 USBDevice *usb_wacom_init(void);
 
+/* usb-serial.c */
+USBDevice *usb_serial_init(const char *filename);
+
 /* usb ports of the VM */
 
 void qemu_register_usb_port(USBPort *port, void *opaque, int index,

Hello,

There was a small bug, here is a fixed version.
I also have a braille device emulation patch which now works, but it probably needs a bit more polishing.

Samuel

Index: Makefile
===================================================================
RCS file: /sources/qemu/qemu/Makefile,v
retrieving revision 1.140

diff -u -p -r1.140 Makefile
@@ -57,7 +57,7 @@ OBJS+=i2c.o smbus.o smbus_eeprom.o max73
 OBJS+=ssd0303.o ssd0323.o ads7846.o stellaris_input.o
 OBJS+=scsi-disk.o cdrom.o
 OBJS+=scsi-generic.o
-OBJS+=usb.o usb-hub.o usb-linux.o usb-hid.o usb-msd.o usb-wacom.o
+OBJS+=usb.o usb-hub.o usb-linux.o usb-hid.o usb-msd.o usb-wacom.o usb-serial.o
 OBJS+=sd.o ssi-sd.o
 
 ifdef CONFIG_WIN32

Index: vl.c
===================================================================
RCS file: /sources/qemu/qemu/vl.c,v
retrieving revision 1.395

Index: hw/usb-serial.c
===================================================================
RCS file: hw/usb-serial.c

Index: hw/usb.h
===================================================================
RCS file: /sources/qemu/qemu/hw/usb.h,v
retrieving revision 1.19

diff -u -p -r1.19 usb.h
@@ -217,6 +217,9 @@ USBDevice *usb_msd_init(const char *file
 /* usb-wacom.c */
 USBDevice *usb_wacom_init(void);
 
+/* usb-serial.c */
+USBDevice *usb_serial_init(const char *filename);
+
 /* usb ports of the VM */
 
 void qemu_register_usb_port(USBPort *port, void *opaque, int index,

Can you provide a patch to the .texi docs some time, to document these parameters and an example usb_add line to get the dongle detected under linux?

These parameters probably don't need to be specific to this device but evidently nobody needed them yet with the other USB devices so it's ok.

Regards

Sure, here it is.

Samuel

Index: qemu-doc.texi
===================================================================
RCS file: /sources/qemu/qemu/qemu-doc.texi,v
retrieving revision 1.179

diff -u -p -r1.179 qemu-doc.texi
@@ -525,6 +525,10 @@ Pass through the host device identified 
 @item host:vendor_id:product_id
 Pass through the host device identified by vendor_id:product_id (Linux only).
 
+@item serial:[vendorid=@var{vendor_id}][,productid=@var{product_id}]:@var{dev}
+Serial converter to host character device @var{dev}, see @code{-serial} for the
+available devices.
+
 @end table
 
 @end table

@@ -1562,7 +1566,7 @@ as necessary to connect multiple USB dev
 USB devices can be connected with the @option{-usbdevice} commandline option
 or the @code{usb_add} monitor command.  Available devices are:
 
-@table @var
+@table @code
 @item @code{mouse}
 Virtual Mouse.  This will override the PS/2 mouse emulation when activated.
 @item @code{tablet}

@@ -1583,6 +1587,16 @@ above but it can be used with the tslib 
 coordinates it reports touch pressure.
 @item @code{keyboard}
 Standard USB keyboard.  Will override the PS/2 keyboard (if present).
+@item @code{serial}:[vendorid=@var{vendor_id}][,product_id=@var{product_id}]:@var{dev}
+Serial converter. This emulates an FTDI FT232BM chip connected to host character
+device @var{dev}. The available character devices are the same as for the
+@code{-serial} option. The @code{vendorid} and @code{productid} options can be
+used to override the default 0403:FF00. For instance, 
+@example
+usb_add serial:productid=FA00:tcp:192.168.0.2:4444
+@end example
+will connect to tcp port 4444 of ip 192.168.0.2, and plug that to the virtual
+serial converter, faking a Matrix Orbital LCD Display (USB ID 0403:FA00).
 @end table
 
 @node host_usb_devices

Thanks, committed although I hoped for something that lets easily test that the adapter works, e.g. so that after a usb_add serial:...:stdio you can do cat /dev/ttyXXXN in the guest and see what's being typed on qemu's stdin. I got the device detected without problems but Linux didn't create any new serial ports.

Regards

Oh? That's odd, I've no problem here, /dev/ttyUSB0 appears like a charm and cat & echo work fine. We should probably use another product ID by default, which would be more widely automatically recognized. Here is a patch.

Samuel

Index: hw/usb-serial.c
===================================================================
RCS file: /sources/qemu/qemu/hw/usb-serial.c,v
retrieving revision 1.1

diff -u -p -r1.1 usb-serial.c
@@ -486,7 +486,7 @@ USBDevice *usb_serial_init(const char *f
 {
     USBSerialState *s;
     CharDriverState *cdrv;
-    unsigned short vendorid = 0x0403, productid = 0xFF00;
+    unsigned short vendorid = 0x0403, productid = 0x6001;
 
     while (*filename && *filename != ':') {
         const char *p;

Index: qemu-doc.texi
===================================================================
RCS file: /sources/qemu/qemu/qemu-doc.texi,v
retrieving revision 1.181

diff -u -p -r1.181 qemu-doc.texi
@@ -1594,7 +1594,7 @@ Standard USB keyboard.  Will override th
 Serial converter. This emulates an FTDI FT232BM chip connected to host character
 device @var{dev}. The available character devices are the same as for the
 @code{-serial} option. The @code{vendorid} and @code{productid} options can be
-used to override the default 0403:FF00. For instance, 
+used to override the default 0403:6001. For instance, 
 @example
 usb_add serial:productid=FA00:tcp:192.168.0.2:4444
 @end example

Hi,

Sorry, that was a user error (mine), I had been using the generic usb-serial.ko driver instead of the FTDI specific one. Now it indeed works like a charm.

Thanks, I applied the patch even though the old values worked ok too. If they were better for some reason please tell. I also added a chr_close callback for -serial stdio so that I can do usb_add serial::stdio, then usb_del and usb_add serial::stdio again without getting an error on opening "stdio".

Cheers

The old values weren't in linux 2.6.12 for instance, and it looks like the new ones are the default ones for the FTDI builderr, so it should be fine now.

Good, thanks!

Samuel