usb gadget: new "CDC Composite" gadget driver

This is a simple example of a composite gadget, combining two
Communications Class Device (CDC) functions:  ECM and ACM.

This provides a clear example of how the composite gadget framework
is intended to work.  It's surprising that MS-Windows (or at least,
XP and previous) won't "just work" with something this simple...

One /proc/bus/usb/devices listing looks like:

  T:  Bus=03 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 46 Spd=480 MxCh= 0
  D:  Ver= 2.00 Cls=02(comm.) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
  P:  Vendor=0525 ProdID=a4aa Rev= 3.01
  S:  Manufacturer=Linux 2.6.26-rc6-pnut with net2280
  S:  Product=CDC Composite Gadget
  C:* #Ifs= 4 Cfg#= 1 Atr=c0 MxPwr=  2mA
  I:* If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=06 Prot=00 Driver=cdc_ether
  E:  Ad=83(I) Atr=03(Int.) MxPS=  16 Ivl=32ms
  I:  If#= 1 Alt= 0 #EPs= 0 Cls=0a(data ) Sub=00 Prot=00 Driver=cdc_ether
  I:* If#= 1 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=cdc_ether
  E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
  E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
  I:* If#= 2 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=cdc_acm
  E:  Ad=86(I) Atr=03(Int.) MxPS=   8 Ivl=32ms
  I:* If#= 3 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=cdc_acm
  E:  Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
  E:  Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms

Not all USB peripheral controller hardware can support this driver.
All the highspeed-capable peripheral controllers with drivers now in
the mainline kernel seem to support this, as does omap_udc.  But
many full speed controllers don't have enough endpoints, or (as with
the PXA controllers) don't support altsettings.

Lightly tested.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Kconfig

@@ -586,6 +586,19 @@ config USB_G_PRINTER
 	  For more information, see Documentation/usb/gadget_printer.txt
 	  which includes sample code for accessing the device file.
 
+config USB_CDC_COMPOSITE
+	tristate "CDC Composite Device (Ethernet and ACM)"
+	help
+	  This driver provides two functions in one configuration:
+	  a CDC Ethernet (ECM) link, and a CDC ACM (serial port) link.
+
+	  This driver requires four bulk and two interrupt endpoints,
+	  plus the ability to handle altsettings.  Not all peripheral
+	  controllers are that capable.
+
+	  Say "y" to link the driver statically, or "m" to build a
+	  dynamically linked module.
+
 # put drivers that need isochronous transfer support (for audio
 # or video class gadget drivers), or specific hardware, here.
 

drivers/usb/gadget/Makefile

@@ -33,6 +33,8 @@ g_file_storage-objs		:= file_storage.o usbstring.o config.o \
 					epautoconf.o
 g_printer-objs			:= printer.o usbstring.o config.o \
 					epautoconf.o
+g_cdc-objs			:= cdc2.o u_ether.o f_ecm.o \
+					u_serial.o f_acm.o $(C_UTILS)
 
 ifeq ($(CONFIG_USB_ETH_RNDIS),y)
 	g_ether-objs		+= f_rndis.o rndis.o
@@ -45,4 +47,5 @@ obj-$(CONFIG_USB_FILE_STORAGE)	+= g_file_storage.o
 obj-$(CONFIG_USB_G_SERIAL)	+= g_serial.o
 obj-$(CONFIG_USB_G_PRINTER)	+= g_printer.o
 obj-$(CONFIG_USB_MIDI_GADGET)	+= g_midi.o
+obj-$(CONFIG_USB_CDC_COMPOSITE) += g_cdc.o
 

drivers/usb/gadget/cdc2.c

+/*
+ * cdc2.c -- CDC Composite driver, with ECM and ACM support
+ *
+ * Copyright (C) 2008 David Brownell
+ * Copyright (C) 2008 Nokia Corporation
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/utsname.h>
+
+#include "u_ether.h"
+#include "u_serial.h"
+
+
+#define DRIVER_DESC		"CDC Composite Gadget"
+#define DRIVER_VERSION		"King Kamehameha Day 2008"
+
+/*-------------------------------------------------------------------------*/
+
+/* DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!
+ * Instead:  allocate your own, using normal USB-IF procedures.
+ */
+
+/* Thanks to NetChip Technologies for donating this product ID.
+ * It's for devices with only this composite CDC configuration.
+ */
+#define CDC_VENDOR_NUM		0x0525	/* NetChip */
+#define CDC_PRODUCT_NUM		0xa4aa	/* CDC Composite: ECM + ACM */
+
+/*-------------------------------------------------------------------------*/
+
+static struct usb_device_descriptor device_desc = {
+	.bLength =		sizeof device_desc,
+	.bDescriptorType =	USB_DT_DEVICE,
+
+	.bcdUSB =		__constant_cpu_to_le16(0x0200),
+
+	.bDeviceClass =		USB_CLASS_COMM,
+	.bDeviceSubClass =	0,
+	.bDeviceProtocol =	0,
+	/* .bMaxPacketSize0 = f(hardware) */
+
+	/* Vendor and product id can be overridden by module parameters.  */
+	.idVendor =		__constant_cpu_to_le16(CDC_VENDOR_NUM),
+	.idProduct =		__constant_cpu_to_le16(CDC_PRODUCT_NUM),
+	/* .bcdDevice = f(hardware) */
+	/* .iManufacturer = DYNAMIC */
+	/* .iProduct = DYNAMIC */
+	/* NO SERIAL NUMBER */
+	.bNumConfigurations =	1,
+};
+
+static struct usb_otg_descriptor otg_descriptor = {
+	.bLength =		sizeof otg_descriptor,
+	.bDescriptorType =	USB_DT_OTG,
+
+	/* REVISIT SRP-only hardware is possible, although
+	 * it would not be called "OTG" ...
+	 */
+	.bmAttributes =		USB_OTG_SRP | USB_OTG_HNP,
+};
+
+static const struct usb_descriptor_header *otg_desc[] = {
+	(struct usb_descriptor_header *) &otg_descriptor,
+	NULL,
+};
+
+
+/* string IDs are assigned dynamically */
+
+#define STRING_MANUFACTURER_IDX		0
+#define STRING_PRODUCT_IDX		1
+
+static char manufacturer[50];
+
+static struct usb_string strings_dev[] = {
+	[STRING_MANUFACTURER_IDX].s = manufacturer,
+	[STRING_PRODUCT_IDX].s = DRIVER_DESC,
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings stringtab_dev = {
+	.language	= 0x0409,	/* en-us */
+	.strings	= strings_dev,
+};
+
+static struct usb_gadget_strings *dev_strings[] = {
+	&stringtab_dev,
+	NULL,
+};
+
+static u8 hostaddr[ETH_ALEN];
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * We _always_ have both CDC ECM and CDC ACM functions.
+ */
+static int __init cdc_do_config(struct usb_configuration *c)
+{
+	int	status;
+
+	if (gadget_is_otg(c->cdev->gadget)) {
+		c->descriptors = otg_desc;
+		c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
+	}
+
+	status = ecm_bind_config(c, hostaddr);
+	if (status < 0)
+		return status;
+
+	status = acm_bind_config(c, 0);
+	if (status == 0)
+		return status;
+
+	return 0;
+}
+
+static struct usb_configuration cdc_config_driver = {
+	.label			= "CDC Composite (ECM + ACM)",
+	.bind			= cdc_do_config,
+	.bConfigurationValue	= 1,
+	/* .iConfiguration = DYNAMIC */
+	.bmAttributes		= USB_CONFIG_ATT_SELFPOWER,
+	.bMaxPower		= 1,	/* 2 mA, minimal */
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int __init cdc_bind(struct usb_composite_dev *cdev)
+{
+	int			gcnum;
+	struct usb_gadget	*gadget = cdev->gadget;
+	int			status;
+
+	if (!can_support_ecm(cdev->gadget)) {
+		ERROR(cdev, "controller '%s' not usable\n", gadget->name);
+		return -EINVAL;
+	}
+
+	/* set up network link layer */
+	status = gether_setup(cdev->gadget, hostaddr);
+	if (status < 0)
+		return status;
+
+	/* set up serial link layer */
+	status = gserial_setup(cdev->gadget, 1);
+	if (status < 0)
+		goto fail0;
+
+	gcnum = usb_gadget_controller_number(gadget);
+	if (gcnum >= 0)
+		device_desc.bcdDevice = cpu_to_le16(0x0300 | gcnum);
+	else {
+		/* We assume that can_support_ecm() tells the truth;
+		 * but if the controller isn't recognized at all then
+		 * that assumption is a bit more likely to be wrong.
+		 */
+		WARN(cdev, "controller '%s' not recognized; trying %s\n",
+				gadget->name,
+				cdc_config_driver.label);
+		device_desc.bcdDevice =
+			__constant_cpu_to_le16(0x0300 | 0x0099);
+	}
+
+
+	/* Allocate string descriptor numbers ... note that string
+	 * contents can be overridden by the composite_dev glue.
+	 */
+
+	/* device descriptor strings: manufacturer, product */
+	snprintf(manufacturer, sizeof manufacturer, "%s %s with %s",
+		init_utsname()->sysname, init_utsname()->release,
+		gadget->name);
+	status = usb_string_id(cdev);
+	if (status < 0)
+		goto fail1;
+	strings_dev[STRING_MANUFACTURER_IDX].id = status;
+	device_desc.iManufacturer = status;
+
+	status = usb_string_id(cdev);
+	if (status < 0)
+		goto fail1;
+	strings_dev[STRING_PRODUCT_IDX].id = status;
+	device_desc.iProduct = status;
+
+	/* register our configuration */
+	status = usb_add_config(cdev, &cdc_config_driver);
+	if (status < 0)
+		goto fail1;
+
+	INFO(cdev, "%s, version: " DRIVER_VERSION "\n", DRIVER_DESC);
+
+	return 0;
+
+fail1:
+	gserial_cleanup();
+fail0:
+	gether_cleanup();
+	return status;
+}
+
+static int __exit cdc_unbind(struct usb_composite_dev *cdev)
+{
+	gserial_cleanup();
+	gether_cleanup();
+	return 0;
+}
+
+static struct usb_composite_driver cdc_driver = {
+	.name		= "g_cdc",
+	.dev		= &device_desc,
+	.strings	= dev_strings,
+	.bind		= cdc_bind,
+	.unbind		= __exit_p(cdc_unbind),
+};
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR("David Brownell");
+MODULE_LICENSE("GPL");
+
+static int __init init(void)
+{
+	return usb_composite_register(&cdc_driver);
+}
+module_init(init);
+
+static void __exit cleanup(void)
+{
+	usb_composite_unregister(&cdc_driver);
+}
+module_exit(cleanup);