usb gadget: cdc obex glue

The following patch introduces a new f_obex.c function driver.
It allows userspace obex servers to use usb as transport layer
for their messages.

[ [e-mail]: various fixes and cleanups ]

Signed-off-by: Felipe Balbi <[e-mail]>
Signed-off-by: David Brownell <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/DocBook/gadget.tmpl

···
 </para>
 
 !Edrivers/usb/gadget/f_acm.c
+!Edrivers/usb/gadget/f_ecm.c
+!Edrivers/usb/gadget/f_subset.c
+!Edrivers/usb/gadget/f_obex.c
 !Edrivers/usb/gadget/f_serial.c
 
 </sect1>

drivers/usb/gadget/Kconfig

···
 	  normal operation.
 
 config USB_G_SERIAL
-	tristate "Serial Gadget (with CDC ACM support)"
+	tristate "Serial Gadget (with CDC ACM and CDC OBEX support)"
 	help
 	  The Serial Gadget talks to the Linux-USB generic serial driver.
 	  This driver supports a CDC-ACM module option, which can be used
 	  to interoperate with MS-Windows hosts or with the Linux-USB
 	  "cdc-acm" driver.
 
+	  This driver also supports a CDC-OBEX option.  You will need a
+	  user space OBEX server talking to /dev/ttyGS*, since the kernel
+	  itself doesn't implement the OBEX protocol.
+
 	  Say "y" to link the driver statically, or "m" to build a
 	  dynamically linked module called "g_serial".
 
 	  For more information, see Documentation/usb/gadget_serial.txt
 	  which includes instructions and a "driver info file" needed to
-	  make MS-Windows work with this driver.
+	  make MS-Windows work with CDC ACM.
 
 config USB_MIDI_GADGET
 	tristate "MIDI Gadget (EXPERIMENTAL)"

drivers/usb/gadget/f_obex.c

···
+/*
+ * f_obex.c -- USB CDC OBEX function driver
+ *
+ * Copyright (C) 2008 Nokia Corporation
+ * Contact: Felipe Balbi <[e-mail]>
+ *
+ * Based on f_acm.c by Al Borchers and David Brownell.
+ *
+ * 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
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/kernel.h>
+#include <linux/utsname.h>
+#include <linux/device.h>
+
+#include "u_serial.h"
+#include "gadget_chips.h"
+
+
+/*
+ * This CDC OBEX function support just packages a TTY-ish byte stream.
+ * A user mode server will put it into "raw" mode and handle all the
+ * relevant protocol details ... this is just a kernel passthrough.
+ *
+ * REVISIT this driver shouldn't actually activate before that user mode
+ * server is ready to respond!  When the "serial gadget" utility code
+ * adds open/close notifications, this driver should use them with new
+ * (TBS) composite gadget hooks that wrap usb_gadget_disconnect() and
+ * usb_gadget_connect() calls with refcounts ... disconnect() when we
+ * bind, then connect() when the user server code is ready to respond.
+ */
+
+struct obex_ep_descs {
+	struct usb_endpoint_descriptor	*obex_in;
+	struct usb_endpoint_descriptor	*obex_out;
+};
+
+struct f_obex {
+	struct gserial			port;
+	u8				ctrl_id;
+	u8				data_id;
+	u8				port_num;
+
+	struct obex_ep_descs		fs;
+	struct obex_ep_descs		hs;
+};
+
+static inline struct f_obex *func_to_obex(struct usb_function *f)
+{
+	return container_of(f, struct f_obex, port.func);
+}
+
+/*-------------------------------------------------------------------------*/
+
+#define OBEX_CTRL_IDX	0
+#define OBEX_DATA_IDX	1
+
+static struct usb_string obex_string_defs[] = {
+	[OBEX_CTRL_IDX].s	= "CDC Object Exchange (OBEX)",
+	[OBEX_DATA_IDX].s	= "CDC OBEX Data",
+	{  },	/* end of list */
+};
+
+static struct usb_gadget_strings obex_string_table = {
+	.language		= 0x0409,	/* en-US */
+	.strings		= obex_string_defs,
+};
+
+static struct usb_gadget_strings *obex_strings[] = {
+	&obex_string_table,
+	NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static struct usb_interface_descriptor obex_control_intf __initdata = {
+	.bLength		= sizeof(obex_control_intf),
+	.bDescriptorType	= USB_DT_INTERFACE,
+	.bInterfaceNumber	= 0,
+
+	.bAlternateSetting	= 0,
+	.bNumEndpoints		= 0,
+	.bInterfaceClass	= USB_CLASS_COMM,
+	.bInterfaceSubClass	= USB_CDC_SUBCLASS_OBEX,
+};
+
+static struct usb_interface_descriptor obex_data_nop_intf __initdata = {
+	.bLength		= sizeof(obex_data_nop_intf),
+	.bDescriptorType	= USB_DT_INTERFACE,
+	.bInterfaceNumber	= 1,
+
+	.bAlternateSetting	= 0,
+	.bNumEndpoints		= 0,
+	.bInterfaceClass	= USB_CLASS_CDC_DATA,
+};
+
+static struct usb_interface_descriptor obex_data_intf __initdata = {
+	.bLength		= sizeof(obex_data_intf),
+	.bDescriptorType	= USB_DT_INTERFACE,
+	.bInterfaceNumber	= 2,
+
+	.bAlternateSetting	= 1,
+	.bNumEndpoints		= 2,
+	.bInterfaceClass	= USB_CLASS_CDC_DATA,
+};
+
+static struct usb_cdc_header_desc obex_cdc_header_desc __initdata = {
+	.bLength		= sizeof(obex_cdc_header_desc),
+	.bDescriptorType	= USB_DT_CS_INTERFACE,
+	.bDescriptorSubType	= USB_CDC_HEADER_TYPE,
+	.bcdCDC			= __constant_cpu_to_le16(0x0120),
+};
+
+static struct usb_cdc_union_desc obex_cdc_union_desc __initdata = {
+	.bLength		= sizeof(obex_cdc_union_desc),
+	.bDescriptorType	= USB_DT_CS_INTERFACE,
+	.bDescriptorSubType	= USB_CDC_UNION_TYPE,
+	.bMasterInterface0	= 1,
+	.bSlaveInterface0	= 2,
+};
+
+static struct usb_cdc_obex_desc obex_desc __initdata = {
+	.bLength		= sizeof(obex_desc),
+	.bDescriptorType	= USB_DT_CS_INTERFACE,
+	.bDescriptorSubType	= USB_CDC_OBEX_TYPE,
+	.bcdVersion		= __constant_cpu_to_le16(0x0100),
+};
+
+/* High-Speed Support */
+
+static struct usb_endpoint_descriptor obex_hs_ep_out_desc __initdata = {
+	.bLength		= USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType	= USB_DT_ENDPOINT,
+
+	.bEndpointAddress	= USB_DIR_OUT,
+	.bmAttributes		= USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize		= __constant_cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor obex_hs_ep_in_desc __initdata = {
+	.bLength		= USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType	= USB_DT_ENDPOINT,
+
+	.bEndpointAddress	= USB_DIR_IN,
+	.bmAttributes		= USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize		= __constant_cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *hs_function[] __initdata = {
+	(struct usb_descriptor_header *) &obex_control_intf,
+	(struct usb_descriptor_header *) &obex_cdc_header_desc,
+	(struct usb_descriptor_header *) &obex_desc,
+	(struct usb_descriptor_header *) &obex_cdc_union_desc,
+
+	(struct usb_descriptor_header *) &obex_data_nop_intf,
+	(struct usb_descriptor_header *) &obex_data_intf,
+	(struct usb_descriptor_header *) &obex_hs_ep_in_desc,
+	(struct usb_descriptor_header *) &obex_hs_ep_out_desc,
+	NULL,
+};
+
+/* Full-Speed Support */
+
+static struct usb_endpoint_descriptor obex_fs_ep_in_desc __initdata = {
+	.bLength		= USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType	= USB_DT_ENDPOINT,
+
+	.bEndpointAddress	= USB_DIR_IN,
+	.bmAttributes		= USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor obex_fs_ep_out_desc __initdata = {
+	.bLength		= USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType	= USB_DT_ENDPOINT,
+
+	.bEndpointAddress	= USB_DIR_OUT,
+	.bmAttributes		= USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *fs_function[] __initdata = {
+	(struct usb_descriptor_header *) &obex_control_intf,
+	(struct usb_descriptor_header *) &obex_cdc_header_desc,
+	(struct usb_descriptor_header *) &obex_desc,
+	(struct usb_descriptor_header *) &obex_cdc_union_desc,
+
+	(struct usb_descriptor_header *) &obex_data_nop_intf,
+	(struct usb_descriptor_header *) &obex_data_intf,
+	(struct usb_descriptor_header *) &obex_fs_ep_in_desc,
+	(struct usb_descriptor_header *) &obex_fs_ep_out_desc,
+	NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int obex_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+	struct f_obex		*obex = func_to_obex(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	if (intf == obex->ctrl_id) {
+		if (alt != 0)
+			goto fail;
+		/* NOP */
+		DBG(cdev, "reset obex ttyGS%d control\n", obex->port_num);
+
+	} else if (intf == obex->data_id) {
+		if (alt > 1)
+			goto fail;
+
+		if (obex->port.in->driver_data) {
+			DBG(cdev, "reset obex ttyGS%d\n", obex->port_num);
+			gserial_disconnect(&obex->port);
+		}
+
+		if (!obex->port.in_desc) {
+			DBG(cdev, "init obex ttyGS%d\n", obex->port_num);
+			obex->port.in_desc = ep_choose(cdev->gadget,
+					obex->hs.obex_in, obex->fs.obex_in);
+			obex->port.out_desc = ep_choose(cdev->gadget,
+					obex->hs.obex_out, obex->fs.obex_out);
+		}
+
+		if (alt == 1) {
+			DBG(cdev, "activate obex ttyGS%d\n", obex->port_num);
+			gserial_connect(&obex->port, obex->port_num);
+		}
+
+	} else
+		goto fail;
+
+	return 0;
+
+fail:
+	return -EINVAL;
+}
+
+static int obex_get_alt(struct usb_function *f, unsigned intf)
+{
+	struct f_obex		*obex = func_to_obex(f);
+
+	if (intf == obex->ctrl_id)
+		return 0;
+
+	return obex->port.in->driver_data ? 1 : 0;
+}
+
+static void obex_disable(struct usb_function *f)
+{
+	struct f_obex	*obex = func_to_obex(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	DBG(cdev, "obex ttyGS%d disable\n", obex->port_num);
+	gserial_disconnect(&obex->port);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int __init
+obex_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct f_obex		*obex = func_to_obex(f);
+	int			status;
+	struct usb_ep		*ep;
+
+	/* allocate instance-specific interface IDs, and patch descriptors */
+
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	obex->ctrl_id = status;
+
+	obex_control_intf.bInterfaceNumber = status;
+	obex_cdc_union_desc.bMasterInterface0 = status;
+
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	obex->data_id = status;
+
+	obex_data_nop_intf.bInterfaceNumber = status;
+	obex_data_intf.bInterfaceNumber = status;
+	obex_cdc_union_desc.bSlaveInterface0 = status;
+
+	/* allocate instance-specific endpoints */
+
+	ep = usb_ep_autoconfig(cdev->gadget, &obex_fs_ep_in_desc);
+	if (!ep)
+		goto fail;
+	obex->port.in = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	ep = usb_ep_autoconfig(cdev->gadget, &obex_fs_ep_out_desc);
+	if (!ep)
+		goto fail;
+	obex->port.out = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	/* copy descriptors, and track endpoint copies */
+	f->descriptors = usb_copy_descriptors(fs_function);
+
+	obex->fs.obex_in = usb_find_endpoint(fs_function,
+			f->descriptors, &obex_fs_ep_in_desc);
+	obex->fs.obex_out = usb_find_endpoint(fs_function,
+			f->descriptors, &obex_fs_ep_out_desc);
+
+	/* support all relevant hardware speeds... we expect that when
+	 * hardware is dual speed, all bulk-capable endpoints work at
+	 * both speeds
+	 */
+	if (gadget_is_dualspeed(c->cdev->gadget)) {
+
+		obex_hs_ep_in_desc.bEndpointAddress =
+				obex_fs_ep_in_desc.bEndpointAddress;
+		obex_hs_ep_out_desc.bEndpointAddress =
+				obex_fs_ep_out_desc.bEndpointAddress;
+
+		/* copy descriptors, and track endpoint copies */
+		f->hs_descriptors = usb_copy_descriptors(hs_function);
+
+		obex->hs.obex_in = usb_find_endpoint(hs_function,
+				f->descriptors, &obex_hs_ep_in_desc);
+		obex->hs.obex_out = usb_find_endpoint(hs_function,
+				f->descriptors, &obex_hs_ep_out_desc);
+	}
+
+	DBG(cdev, "obex ttyGS%d: %s speed IN/%s OUT/%s\n",
+			obex->port_num,
+			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+			obex->port.in->name, obex->port.out->name);
+
+	return 0;
+
+fail:
+	/* we might as well release our claims on endpoints */
+	if (obex->port.out)
+		obex->port.out->driver_data = NULL;
+	if (obex->port.in)
+		obex->port.in->driver_data = NULL;
+
+	ERROR(cdev, "%s/%p: can't bind, err %d\n", f->name, f, status);
+
+	return status;
+}
+
+static void
+obex_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	if (gadget_is_dualspeed(c->cdev->gadget))
+		usb_free_descriptors(f->hs_descriptors);
+	usb_free_descriptors(f->descriptors);
+	kfree(func_to_obex(f));
+}
+
+/* Some controllers can't support CDC OBEX ... */
+static inline bool can_support_obex(struct usb_configuration *c)
+{
+	/* Since the first interface is a NOP, we can ignore the
+	 * issue of multi-interface support on most controllers.
+	 *
+	 * Altsettings are mandatory, however...
+	 */
+	if (!gadget_supports_altsettings(c->cdev->gadget))
+		return false;
+
+	/* everything else is *probably* fine ... */
+	return true;
+}
+
+/**
+ * obex_bind_config - add a CDC OBEX function to a configuration
+ * @c: the configuration to support the CDC OBEX instance
+ * @port_num: /dev/ttyGS* port this interface will use
+ * Context: single threaded during gadget setup
+ *
+ * Returns zero on success, else negative errno.
+ *
+ * Caller must have called @gserial_setup() with enough ports to
+ * handle all the ones it binds.  Caller is also responsible
+ * for calling @gserial_cleanup() before module unload.
+ */
+int __init obex_bind_config(struct usb_configuration *c, u8 port_num)
+{
+	struct f_obex	*obex;
+	int		status;
+
+	if (!can_support_obex(c))
+		return -EINVAL;
+
+	/* maybe allocate device-global string IDs, and patch descriptors */
+	if (obex_string_defs[OBEX_CTRL_IDX].id == 0) {
+		status = usb_string_id(c->cdev);
+		if (status < 0)
+			return status;
+		obex_string_defs[OBEX_CTRL_IDX].id = status;
+
+		obex_control_intf.iInterface = status;
+
+		status = usb_string_id(c->cdev);
+		if (status < 0)
+			return status;
+		obex_string_defs[OBEX_DATA_IDX].id = status;
+
+		obex_data_nop_intf.iInterface =
+			obex_data_intf.iInterface = status;
+	}
+
+	/* allocate and initialize one new instance */
+	obex = kzalloc(sizeof *obex, GFP_KERNEL);
+	if (!obex)
+		return -ENOMEM;
+
+	obex->port_num = port_num;
+
+	obex->port.func.name = "obex";
+	obex->port.func.strings = obex_strings;
+	/* descriptors are per-instance copies */
+	obex->port.func.bind = obex_bind;
+	obex->port.func.unbind = obex_unbind;
+	obex->port.func.set_alt = obex_set_alt;
+	obex->port.func.get_alt = obex_get_alt;
+	obex->port.func.disable = obex_disable;
+
+	status = usb_add_function(c, &obex->port.func);
+	if (status)
+		kfree(obex);
+
+	return status;
+}
+
+MODULE_AUTHOR("Felipe Balbi");
+MODULE_LICENSE("GPL");

drivers/usb/gadget/serial.c

···
 #include "epautoconf.c"
 
 #include "f_acm.c"
+#include "f_obex.c"
 #include "f_serial.c"
 #include "u_serial.c"
 
···
 #define GS_VENDOR_ID			0x0525	/* NetChip */
 #define GS_PRODUCT_ID			0xa4a6	/* Linux-USB Serial Gadget */
 #define GS_CDC_PRODUCT_ID		0xa4a7	/* ... as CDC-ACM */
+#define GS_CDC_OBEX_PRODUCT_ID		0xa4a9	/* ... as CDC-OBEX */
 
 /* string IDs are assigned dynamically */
 
···
 module_param(use_acm, bool, 0);
 MODULE_PARM_DESC(use_acm, "Use CDC ACM, default=yes");
 
+static int use_obex = false;
+module_param(use_obex, bool, 0);
+MODULE_PARM_DESC(use_obex, "Use CDC OBEX, default=no");
+
 static unsigned n_ports = 1;
 module_param(n_ports, uint, 0);
 MODULE_PARM_DESC(n_ports, "number of ports to create, default=1");
···
 	for (i = 0; i < n_ports && status == 0; i++) {
 		if (use_acm)
 			status = acm_bind_config(c, i);
+		else if (use_obex)
+			status = obex_bind_config(c, i);
 		else
 			status = gser_bind_config(c, i);
 	}
···
 		device_desc.bDeviceClass = USB_CLASS_COMM;
 		device_desc.idProduct =
 				__constant_cpu_to_le16(GS_CDC_PRODUCT_ID);
+	} else if (use_obex) {
+		serial_config_driver.label = "CDC OBEX config";
+		serial_config_driver.bConfigurationValue = 3;
+		device_desc.bDeviceClass = USB_CLASS_COMM;
+		device_desc.idProduct =
+			__constant_cpu_to_le16(GS_CDC_OBEX_PRODUCT_ID);
 	} else {
 		serial_config_driver.label = "Generic Serial config";
 		serial_config_driver.bConfigurationValue = 1;

drivers/usb/gadget/u_serial.h

···
 /* functions are bound to configurations by a config or gadget driver */
 int acm_bind_config(struct usb_configuration *c, u8 port_num);
 int gser_bind_config(struct usb_configuration *c, u8 port_num);
+int obex_bind_config(struct usb_configuration *c, u8 port_num);
 
 #endif /* __U_SERIAL_H */

include/linux/usb/cdc.h

···
 	__u8	bDetailData[0];
 } __attribute__ ((packed));
 
+/* "OBEX Control Model Functional Descriptor" */
+struct usb_cdc_obex_desc {
+	__u8	bLength;
+	__u8	bDescriptorType;
+	__u8	bDescriptorSubType;
+
+	__le16	bcdVersion;
+} __attribute__ ((packed));
+
 /*-------------------------------------------------------------------------*/
 
 /*