USB-console: Add Linux USB serial kernel module

This is a simple kernel module and Makefile for
building it out of tree.  This module just uses
the existing kernel usb serial driver and probes
for the Google VID/Class/SubClass/Protocol that
identifies a valid simple serial interface.

This code should be rolled into the existing kernel
driver at: drivers/usb/serial/usb-serial-simple.c

While that happens, this module is still useful to
developers.

Signed-off-by: Anton Staaf <robotboy@chromium.org>

BRANCH=None
BUG=None
TEST=cd extra/usb_serial; make; sudo insmod raiden.ko
     Connect the discovery-stm32f072 over USB and see
     that its console is discovered and works.

Change-Id: I83661b816643c43b3e2dc9fdc825bc3a796af2f4
Reviewed-on: https://chromium-review.googlesource.com/225923
Reviewed-by: Olof Johansson <olofj@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Anton Staaf <robotboy@chromium.org>
Commit-Queue: Anton Staaf <robotboy@chromium.org>

2 files changed, 56 insertions, 0 deletions

diff --git a/extra/usb_serial/Makefile b/extra/usb_serial/Makefile
new file mode 100644
index 0000000000..9c478050cc
--- /dev/null
+++ b/extra/usb_serial/Makefile
@@ -0,0 +1,10 @@
+obj-m := raiden.o
+
+.PHONY: all
+
+all: modules
+
+.DEFAULT:
+	$(MAKE) -C /lib/modules/$(shell uname -r)/build \
+		M=$(shell pwd) \
+		$(MAKECMDGOALS)
diff --git a/extra/usb_serial/raiden.c b/extra/usb_serial/raiden.c
new file mode 100644
index 0000000000..2733e47a90
--- /dev/null
+++ b/extra/usb_serial/raiden.c
@@ -0,0 +1,46 @@
+/*
+ * USB Serial module for Raiden USB debug serial console forwarding.
+ * SubClass and Protocol allocated in go/usb-ids
+ *
+ * Copyright (c) 2014 The Chromium OS Authors <chromium-os-dev@chromium.org>
+ * Author: Anton Staaf <robotboy@chromium.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/tty.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+
+MODULE_LICENSE("GPL");
+
+#define USB_VENDOR_ID_GOOGLE		0x18d1
+#define USB_SUBCLASS_GOOGLE_SERIAL	0x50
+#define USB_PROTOCOL_GOOGLE_SERIAL	0x01
+
+static struct usb_device_id const ids[] = {
+	{ USB_VENDOR_AND_INTERFACE_INFO(USB_VENDOR_ID_GOOGLE,
+					USB_CLASS_VENDOR_SPEC,
+					USB_SUBCLASS_GOOGLE_SERIAL,
+					USB_PROTOCOL_GOOGLE_SERIAL) },
+        { 0 }
+};
+
+MODULE_DEVICE_TABLE(usb, ids);
+
+static struct usb_serial_driver device =
+{
+	.driver    = { .owner = THIS_MODULE,
+		       .name  = "Google" },
+	.id_table  = ids,
+	.num_ports = 1,
+};
+
+static struct usb_serial_driver * const drivers[] = { &device, NULL };
+
+module_usb_serial_driver(drivers, ids);