usb-serial: add support for USB Wishbone-serial adapters

Wishbone is an open hardware SoC bus commonly used in FPGA
designs. Bus access can be serialized using the Etherbone
protocol <http://www.ohwr.org/projects/etherbone-core>.

This driver is intended to be used with devices which attach
their internal Wishbone bus to a USB serial interface using
the Etherbone protocol. A userspace library is required to
speak the protocol made available by this driver as ttyUSBx.

Signed-off-by: Wesley W. Terpstra <w.terpstra@gsi.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 113 insertions, 0 deletions

diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig
index bf3733629b09..1d55762afbb1 100644
--- a/drivers/usb/serial/Kconfig
+++ b/drivers/usb/serial/Kconfig
@@ -667,6 +667,23 @@ config USB_SERIAL_ZIO
           To compile this driver as a module, choose M here: the
           module will be called zio.
 
+config USB_SERIAL_WISHBONE
+        tristate "USB-Wishbone adapter interface driver"
+        help
+          Say Y here if you want to use a USB attached Wishbone bus.
+
+          Wishbone is an open hardware SoC bus commonly used in FPGA
+          designs. Bus access can be serialized using the Etherbone
+          protocol <http://www.ohwr.org/projects/etherbone-core>.
+
+          This driver is intended to be used with devices which attach
+          their internal Wishbone bus to a USB serial interface using
+          the Etherbone protocol. A userspace library is required to
+          speak the protocol made available by this driver as ttyUSBx.
+
+          To compile this driver as a module, choose M here: the
+          module will be called wishbone-serial.
+
 config USB_SERIAL_ZTE
         tristate "ZTE USB serial driver"
         help
diff --git a/drivers/usb/serial/Makefile b/drivers/usb/serial/Makefile
index eaf5ca14dfeb..cec63fa19104 100644
--- a/drivers/usb/serial/Makefile
+++ b/drivers/usb/serial/Makefile
@@ -58,6 +58,7 @@ obj-$(CONFIG_USB_SERIAL_SYMBOL)			+= symbolserial.o
 obj-$(CONFIG_USB_SERIAL_WWAN)                   += usb_wwan.o
 obj-$(CONFIG_USB_SERIAL_TI)                     += ti_usb_3410_5052.o
 obj-$(CONFIG_USB_SERIAL_VISOR)                  += visor.o
+obj-$(CONFIG_USB_SERIAL_WISHBONE)               += wishbone-serial.o
 obj-$(CONFIG_USB_SERIAL_WHITEHEAT)              += whiteheat.o
 obj-$(CONFIG_USB_SERIAL_XIRCOM)                 += keyspan_pda.o
 obj-$(CONFIG_USB_SERIAL_VIVOPAY_SERIAL)         += vivopay-serial.o
diff --git a/drivers/usb/serial/wishbone-serial.c b/drivers/usb/serial/wishbone-serial.c
new file mode 100644
index 000000000000..481ec669bf7c
--- /dev/null
+++ b/drivers/usb/serial/wishbone-serial.c
@@ -0,0 +1,95 @@
+/*
+ * USB Wishbone-Serial adapter driver
+ *
+ * Copyright (C) 2013 Wesley W. Terpstra <w.terpstra@gsi.de>
+ * Copyright (C) 2013 GSI Helmholtz Centre for Heavy Ion Research GmbH
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/tty.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+#include <linux/uaccess.h>
+
+#define GSI_VENDOR_OPENCLOSE 0xB0
+
+static const struct usb_device_id id_table[] = {
+        { USB_DEVICE_AND_INTERFACE_INFO(0x1D50, 0x6062, 0xFF, 0xFF, 0xFF) },
+        { },
+};
+MODULE_DEVICE_TABLE(usb, id_table);
+
+/*
+ * Etherbone must be told that a new stream has begun before data arrives.
+ * This is necessary to restart the negotiation of Wishbone bus parameters.
+ * Similarly, when the stream ends, Etherbone must be told so that the cycle
+ * line can be driven low in the case that userspace failed to do so.
+ */
+static int usb_gsi_openclose(struct usb_serial_port *port, int value)
+{
+        struct usb_device *dev = port->serial->dev;
+
+        return usb_control_msg(
+                dev,
+                usb_sndctrlpipe(dev, 0), /* Send to EP0OUT */
+                GSI_VENDOR_OPENCLOSE,
+                USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
+                value, /* wValue = device is open(1) or closed(0) */
+                port->serial->interface->cur_altsetting->desc.bInterfaceNumber,
+                0, 0,  /* There is no data stage */
+                5000); /* Timeout till operation fails */
+}
+
+static int wishbone_serial_open(struct tty_struct *tty,
+                                struct usb_serial_port *port)
+{
+        int retval;
+
+        retval = usb_gsi_openclose(port, 1);
+        if (retval) {
+                dev_err(&port->serial->dev->dev,
+                       "Could not mark device as open (%d)\n",
+                       retval);
+                return retval;
+        }
+
+        retval = usb_serial_generic_open(tty, port);
+        if (retval)
+                usb_gsi_openclose(port, 0);
+
+        return retval;
+}
+
+static void wishbone_serial_close(struct usb_serial_port *port)
+{
+        usb_serial_generic_close(port);
+        usb_gsi_openclose(port, 0);
+}
+
+static struct usb_serial_driver wishbone_serial_device = {
+        .driver = {
+                .owner =        THIS_MODULE,
+                .name =         "wishbone_serial",
+        },
+        .id_table =             id_table,
+        .num_ports =            1,
+        .open =                 &wishbone_serial_open,
+        .close =                &wishbone_serial_close,
+};
+
+static struct usb_serial_driver * const serial_drivers[] = {
+        &wishbone_serial_device, NULL
+};
+
+module_usb_serial_driver(serial_drivers, id_table);
+
+MODULE_AUTHOR("Wesley W. Terpstra <w.terpstra@gsi.de>");
+MODULE_DESCRIPTION("USB Wishbone-Serial adapter");
+MODULE_LICENSE("GPL");