USB: gmidi: New USB MIDI Gadget class driver.

This driver is glue between the USB gadget interface
and the ALSA MIDI interface. It allows us to appear
as a MIDI Streaming device to a host system on the
other end of a USB cable.

This includes linux/usb/audio.h and linux/usb/midi.h
containing definitions from the relevant USB specifications
for USB audio and USB MIDI devices.

The following changes have been made since the first RFC
posting:

* Bug fixes to endpoint handling.
* Workaround for USB_REQ_SET_CONFIGURATION handling,
  not understood yet.
* Added SND and SND_RAWMIDI dependencies in Kconfig.
* Moved usb_audio.h and usb_midi.h to usb/*.h
* Added module parameters for ALSA card index and id.
* Added module parameters for USB descriptor IDs and strings.
* Removed some unneeded stuff inherited from zero.c, more to go.
* Provide DECLARE_* macros for the variable-length structs.
* Use kmalloc instead of usb_ep_alloc_buffer.
* Limit source to 80 columns.
* Return actual error code instead of -ENOMEM in a few places.

Signed-off-by: Ben Williamson <ben.williamson@greyinnovation.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1337 insertions, 0 deletions

diff --git a/drivers/usb/gadget/gmidi.c b/drivers/usb/gadget/gmidi.c
new file mode 100644
index 00000000000..b68cecd5741
--- /dev/null
+++ b/drivers/usb/gadget/gmidi.c
@@ -0,0 +1,1337 @@
+/*
+ * gmidi.c -- USB MIDI Gadget Driver
+ *
+ * Copyright (C) 2006 Thumtronics Pty Ltd.
+ * Developed for Thumtronics by Grey Innovation
+ * Ben Williamson <ben.williamson@greyinnovation.com>
+ *
+ * This software is distributed under the terms of the GNU General Public
+ * License ("GPL") version 2, as published by the Free Software Foundation.
+ *
+ * This code is based in part on:
+ *
+ * Gadget Zero driver, Copyright (C) 2003-2004 David Brownell.
+ * USB Audio driver, Copyright (C) 2002 by Takashi Iwai.
+ * USB MIDI driver, Copyright (C) 2002-2005 Clemens Ladisch.
+ *
+ * Refer to the USB Device Class Definition for MIDI Devices:
+ * http://www.usb.org/developers/devclass_docs/midi10.pdf
+ */
+
+#define DEBUG 1
+// #define VERBOSE
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/utsname.h>
+#include <linux/device.h>
+#include <linux/moduleparam.h>
+
+#include <sound/driver.h>
+#include <sound/core.h>
+#include <sound/initval.h>
+#include <sound/rawmidi.h>
+
+#include <linux/usb_ch9.h>
+#include <linux/usb_gadget.h>
+#include <linux/usb/audio.h>
+#include <linux/usb/midi.h>
+
+#include "gadget_chips.h"
+
+MODULE_AUTHOR("Ben Williamson");
+MODULE_LICENSE("GPL v2");
+
+#define DRIVER_VERSION "25 Jul 2006"
+
+static const char shortname[] = "g_midi";
+static const char longname[] = "MIDI Gadget";
+
+static int index = SNDRV_DEFAULT_IDX1;
+static char *id = SNDRV_DEFAULT_STR1;
+
+module_param(index, int, 0444);
+MODULE_PARM_DESC(index, "Index value for the USB MIDI Gadget adapter.");
+module_param(id, charp, 0444);
+MODULE_PARM_DESC(id, "ID string for the USB MIDI Gadget adapter.");
+
+/* Some systems will want different product identifers published in the
+ * device descriptor, either numbers or strings or both.  These string
+ * parameters are in UTF-8 (superset of ASCII's 7 bit characters).
+ */
+
+static ushort idVendor;
+module_param(idVendor, ushort, S_IRUGO);
+MODULE_PARM_DESC(idVendor, "USB Vendor ID");
+
+static ushort idProduct;
+module_param(idProduct, ushort, S_IRUGO);
+MODULE_PARM_DESC(idProduct, "USB Product ID");
+
+static ushort bcdDevice;
+module_param(bcdDevice, ushort, S_IRUGO);
+MODULE_PARM_DESC(bcdDevice, "USB Device version (BCD)");
+
+static char *iManufacturer;
+module_param(iManufacturer, charp, S_IRUGO);
+MODULE_PARM_DESC(iManufacturer, "USB Manufacturer string");
+
+static char *iProduct;
+module_param(iProduct, charp, S_IRUGO);
+MODULE_PARM_DESC(iProduct, "USB Product string");
+
+static char *iSerialNumber;
+module_param(iSerialNumber, charp, S_IRUGO);
+MODULE_PARM_DESC(iSerialNumber, "SerialNumber");
+
+/*
+ * this version autoconfigures as much as possible,
+ * which is reasonable for most "bulk-only" drivers.
+ */
+static const char *EP_IN_NAME;
+static const char *EP_OUT_NAME;
+
+
+/* big enough to hold our biggest descriptor */
+#define USB_BUFSIZ 256
+
+
+/* This is a gadget, and the IN/OUT naming is from the host's perspective.
+   USB -> OUT endpoint -> rawmidi
+   USB <- IN endpoint  <- rawmidi */
+struct gmidi_in_port {
+	struct gmidi_device* dev;
+	int active;
+	uint8_t cable;		/* cable number << 4 */
+	uint8_t state;
+#define STATE_UNKNOWN	0
+#define STATE_1PARAM	1
+#define STATE_2PARAM_1	2
+#define STATE_2PARAM_2	3
+#define STATE_SYSEX_0	4
+#define STATE_SYSEX_1	5
+#define STATE_SYSEX_2	6
+	uint8_t data[2];
+};
+
+struct gmidi_device {
+	spinlock_t		lock;
+	struct usb_gadget	*gadget;
+	struct usb_request	*req;		/* for control responses */
+	u8			config;
+	struct usb_ep		*in_ep, *out_ep;
+	struct snd_card 	*card;
+	struct snd_rawmidi	*rmidi;
+	struct snd_rawmidi_substream *in_substream;
+	struct snd_rawmidi_substream *out_substream;
+
+	/* For the moment we only support one port in
+	   each direction, but in_port is kept as a
+	   separate struct so we can have more later. */
+	struct gmidi_in_port	in_port;
+	unsigned long		out_triggered;
+	struct tasklet_struct	tasklet;
+};
+
+static void gmidi_transmit(struct gmidi_device* dev, struct usb_request* req);
+
+
+#define xprintk(d,level,fmt,args...) \
+	dev_printk(level , &(d)->gadget->dev , fmt , ## args)
+
+#ifdef DEBUG
+#define DBG(dev,fmt,args...) \
+	xprintk(dev , KERN_DEBUG , fmt , ## args)
+#else
+#define DBG(dev,fmt,args...) \
+	do { } while (0)
+#endif /* DEBUG */
+
+#ifdef VERBOSE
+#define VDBG	DBG
+#else
+#define VDBG(dev,fmt,args...) \
+	do { } while (0)
+#endif /* VERBOSE */
+
+#define ERROR(dev,fmt,args...) \
+	xprintk(dev , KERN_ERR , fmt , ## args)
+#define WARN(dev,fmt,args...) \
+	xprintk(dev , KERN_WARNING , fmt , ## args)
+#define INFO(dev,fmt,args...) \
+	xprintk(dev , KERN_INFO , fmt , ## args)
+
+
+static unsigned buflen = 256;
+static unsigned qlen = 32;
+
+module_param(buflen, uint, S_IRUGO);
+module_param(qlen, uint, S_IRUGO);
+
+
+/* Thanks to Grey Innovation for donating this product ID.
+ *
+ * DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!
+ * Instead:  allocate your own, using normal USB-IF procedures.
+ */
+#define DRIVER_VENDOR_NUM	0x17b3		/* Grey Innovation */
+#define DRIVER_PRODUCT_NUM	0x0004		/* Linux-USB "MIDI Gadget" */
+
+
+/*
+ * DESCRIPTORS ... most are static, but strings and (full)
+ * configuration descriptors are built on demand.
+ */
+
+#define STRING_MANUFACTURER	25
+#define STRING_PRODUCT		42
+#define STRING_SERIAL		101
+#define STRING_MIDI_GADGET	250
+
+/* We only have the one configuration, it's number 1. */
+#define	GMIDI_CONFIG		1
+
+/* We have two interfaces- AudioControl and MIDIStreaming */
+#define GMIDI_AC_INTERFACE	0
+#define GMIDI_MS_INTERFACE	1
+#define GMIDI_NUM_INTERFACES	2
+
+DECLARE_USB_AC_HEADER_DESCRIPTOR(1);
+DECLARE_USB_MIDI_OUT_JACK_DESCRIPTOR(1);
+DECLARE_USB_MS_ENDPOINT_DESCRIPTOR(1);
+
+/* B.1  Device Descriptor */
+static struct usb_device_descriptor device_desc = {
+	.bLength =		USB_DT_DEVICE_SIZE,
+	.bDescriptorType =	USB_DT_DEVICE,
+	.bcdUSB =		__constant_cpu_to_le16(0x0200),
+	.bDeviceClass =		USB_CLASS_PER_INTERFACE,
+	.idVendor =		__constant_cpu_to_le16(DRIVER_VENDOR_NUM),
+	.idProduct =		__constant_cpu_to_le16(DRIVER_PRODUCT_NUM),
+	.iManufacturer =	STRING_MANUFACTURER,
+	.iProduct =		STRING_PRODUCT,
+	.bNumConfigurations =	1,
+};
+
+/* B.2  Configuration Descriptor */
+static struct usb_config_descriptor config_desc = {
+	.bLength =		USB_DT_CONFIG_SIZE,
+	.bDescriptorType =	USB_DT_CONFIG,
+	/* compute wTotalLength on the fly */
+	.bNumInterfaces =	GMIDI_NUM_INTERFACES,
+	.bConfigurationValue =	GMIDI_CONFIG,
+	.iConfiguration =	STRING_MIDI_GADGET,
+	/*
+	 * FIXME: When embedding this driver in a device,
+	 * these need to be set to reflect the actual
+	 * power properties of the device. Is it selfpowered?
+	 */
+	.bmAttributes =		USB_CONFIG_ATT_ONE,
+	.bMaxPower =		1,
+};
+
+/* B.3.1  Standard AC Interface Descriptor */
+static const struct usb_interface_descriptor ac_interface_desc = {
+	.bLength =		USB_DT_INTERFACE_SIZE,
+	.bDescriptorType =	USB_DT_INTERFACE,
+	.bInterfaceNumber =	GMIDI_AC_INTERFACE,
+	.bNumEndpoints =	0,
+	.bInterfaceClass =	USB_CLASS_AUDIO,
+	.bInterfaceSubClass =	USB_SUBCLASS_AUDIOCONTROL,
+	.iInterface =		STRING_MIDI_GADGET,
+};
+
+/* B.3.2  Class-Specific AC Interface Descriptor */
+static const struct usb_ac_header_descriptor_1 ac_header_desc = {
+	.bLength =		USB_DT_AC_HEADER_SIZE(1),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	USB_MS_HEADER,
+	.bcdADC =		__constant_cpu_to_le16(0x0100),
+	.wTotalLength =		USB_DT_AC_HEADER_SIZE(1),
+	.bInCollection =	1,
+	.baInterfaceNr = {
+		[0] =		GMIDI_MS_INTERFACE,
+	}
+};
+
+/* B.4.1  Standard MS Interface Descriptor */
+static const struct usb_interface_descriptor ms_interface_desc = {
+	.bLength =		USB_DT_INTERFACE_SIZE,
+	.bDescriptorType =	USB_DT_INTERFACE,
+	.bInterfaceNumber =	GMIDI_MS_INTERFACE,
+	.bNumEndpoints =	2,
+	.bInterfaceClass =	USB_CLASS_AUDIO,
+	.bInterfaceSubClass =	USB_SUBCLASS_MIDISTREAMING,
+	.iInterface =		STRING_MIDI_GADGET,
+};
+
+/* B.4.2  Class-Specific MS Interface Descriptor */
+static const struct usb_ms_header_descriptor ms_header_desc = {
+	.bLength =		USB_DT_MS_HEADER_SIZE,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	USB_MS_HEADER,
+	.bcdMSC =		__constant_cpu_to_le16(0x0100),
+	.wTotalLength =		USB_DT_MS_HEADER_SIZE
+				+ 2*USB_DT_MIDI_IN_SIZE
+				+ 2*USB_DT_MIDI_OUT_SIZE(1),
+};
+
+#define JACK_IN_EMB	1
+#define JACK_IN_EXT	2
+#define JACK_OUT_EMB	3
+#define JACK_OUT_EXT	4
+
+/* B.4.3  MIDI IN Jack Descriptors */
+static const struct usb_midi_in_jack_descriptor jack_in_emb_desc = {
+	.bLength =		USB_DT_MIDI_IN_SIZE,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	USB_MS_MIDI_IN_JACK,
+	.bJackType =		USB_MS_EMBEDDED,
+	.bJackID =		JACK_IN_EMB,
+};
+
+static const struct usb_midi_in_jack_descriptor jack_in_ext_desc = {
+	.bLength =		USB_DT_MIDI_IN_SIZE,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	USB_MS_MIDI_IN_JACK,
+	.bJackType =		USB_MS_EXTERNAL,
+	.bJackID =		JACK_IN_EXT,
+};
+
+/* B.4.4  MIDI OUT Jack Descriptors */
+static const struct usb_midi_out_jack_descriptor_1 jack_out_emb_desc = {
+	.bLength =		USB_DT_MIDI_OUT_SIZE(1),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	USB_MS_MIDI_OUT_JACK,
+	.bJackType =		USB_MS_EMBEDDED,
+	.bJackID =		JACK_OUT_EMB,
+	.bNrInputPins =		1,
+	.pins = {
+		[0] = {
+			.baSourceID =	JACK_IN_EXT,
+			.baSourcePin =	1,
+		}
+	}
+};
+
+static const struct usb_midi_out_jack_descriptor_1 jack_out_ext_desc = {
+	.bLength =		USB_DT_MIDI_OUT_SIZE(1),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype =	USB_MS_MIDI_OUT_JACK,
+	.bJackType =		USB_MS_EXTERNAL,
+	.bJackID =		JACK_OUT_EXT,
+	.bNrInputPins =		1,
+	.pins = {
+		[0] = {
+			.baSourceID =	JACK_IN_EMB,
+			.baSourcePin =	1,
+		}
+	}
+};
+
+/* B.5.1  Standard Bulk OUT Endpoint Descriptor */
+static struct usb_endpoint_descriptor bulk_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_AUDIO_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+/* B.5.2  Class-specific MS Bulk OUT Endpoint Descriptor */
+static const struct usb_ms_endpoint_descriptor_1 ms_out_desc = {
+	.bLength =		USB_DT_MS_ENDPOINT_SIZE(1),
+	.bDescriptorType =	USB_DT_CS_ENDPOINT,
+	.bDescriptorSubtype =	USB_MS_GENERAL,
+	.bNumEmbMIDIJack =	1,
+	.baAssocJackID = {
+		[0] =		JACK_IN_EMB,
+	}
+};
+
+/* B.6.1  Standard Bulk IN Endpoint Descriptor */
+static struct usb_endpoint_descriptor bulk_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_AUDIO_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+/* B.6.2  Class-specific MS Bulk IN Endpoint Descriptor */
+static const struct usb_ms_endpoint_descriptor_1 ms_in_desc = {
+	.bLength =		USB_DT_MS_ENDPOINT_SIZE(1),
+	.bDescriptorType =	USB_DT_CS_ENDPOINT,
+	.bDescriptorSubtype =	USB_MS_GENERAL,
+	.bNumEmbMIDIJack =	1,
+	.baAssocJackID = {
+		[0] =		JACK_OUT_EMB,
+	}
+};
+
+static const struct usb_descriptor_header *gmidi_function [] = {
+	(struct usb_descriptor_header *)&ac_interface_desc,
+	(struct usb_descriptor_header *)&ac_header_desc,
+	(struct usb_descriptor_header *)&ms_interface_desc,
+
+	(struct usb_descriptor_header *)&ms_header_desc,
+	(struct usb_descriptor_header *)&jack_in_emb_desc,
+	(struct usb_descriptor_header *)&jack_in_ext_desc,
+	(struct usb_descriptor_header *)&jack_out_emb_desc,
+	(struct usb_descriptor_header *)&jack_out_ext_desc,
+	/* If you add more jacks, update ms_header_desc.wTotalLength */
+
+	(struct usb_descriptor_header *)&bulk_out_desc,
+	(struct usb_descriptor_header *)&ms_out_desc,
+	(struct usb_descriptor_header *)&bulk_in_desc,
+	(struct usb_descriptor_header *)&ms_in_desc,
+	NULL,
+};
+
+static char manufacturer[50];
+static char product_desc[40] = "MIDI Gadget";
+static char serial_number[20];
+
+/* static strings, in UTF-8 */
+static struct usb_string strings [] = {
+	{ STRING_MANUFACTURER, manufacturer, },
+	{ STRING_PRODUCT, product_desc, },
+	{ STRING_SERIAL, serial_number, },
+	{ STRING_MIDI_GADGET, longname, },
+	{  }			/* end of list */
+};
+
+static struct usb_gadget_strings stringtab = {
+	.language	= 0x0409,	/* en-us */
+	.strings	= strings,
+};
+
+static int config_buf(struct usb_gadget *gadget,
+		u8 *buf, u8 type, unsigned index)
+{
+	int len;
+
+	/* only one configuration */
+	if (index != 0) {
+		return -EINVAL;
+	}
+	len = usb_gadget_config_buf(&config_desc,
+			buf, USB_BUFSIZ, gmidi_function);
+	if (len < 0) {
+		return len;
+	}
+	((struct usb_config_descriptor *)buf)->bDescriptorType = type;
+	return len;
+}
+
+static struct usb_request* alloc_ep_req(struct usb_ep *ep, unsigned length)
+{
+	struct usb_request	*req;
+
+	req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+	if (req) {
+		req->length = length;
+		req->buf = kmalloc(length, GFP_ATOMIC);
+		if (!req->buf) {
+			usb_ep_free_request(ep, req);
+			req = NULL;
+		}
+	}
+	return req;
+}
+
+static void free_ep_req(struct usb_ep *ep, struct usb_request *req)
+{
+	kfree(req->buf);
+	usb_ep_free_request(ep, req);
+}
+
+static const uint8_t gmidi_cin_length[] = {
+	0, 0, 2, 3, 3, 1, 2, 3, 3, 3, 3, 3, 2, 2, 3, 1
+};
+
+/*
+ * Receives a chunk of MIDI data.
+ */
+static void gmidi_read_data(struct usb_ep *ep, int cable,
+				   uint8_t* data, int length)
+{
+	struct gmidi_device *dev = ep->driver_data;
+	/* cable is ignored, because for now we only have one. */
+
+	if (!dev->out_substream) {
+		/* Nobody is listening - throw it on the floor. */
+		return;
+	}
+	if (!test_bit(dev->out_substream->number, &dev->out_triggered)) {
+		return;
+	}
+	snd_rawmidi_receive(dev->out_substream, data, length);
+}
+
+static void gmidi_handle_out_data(struct usb_ep *ep, struct usb_request *req)
+{
+	unsigned i;
+	u8 *buf = req->buf;
+
+	for (i = 0; i + 3 < req->actual; i += 4) {
+		if (buf[i] != 0) {
+			int cable = buf[i] >> 4;
+			int length = gmidi_cin_length[buf[i] & 0x0f];
+			gmidi_read_data(ep, cable, &buf[i + 1], length);
+		}
+	}
+}
+
+static void gmidi_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct gmidi_device *dev = ep->driver_data;
+	int status = req->status;
+
+	switch (status) {
+	case 0: 			/* normal completion */
+		if (ep == dev->out_ep) {
+			/* we received stuff.
+			   req is queued again, below */
+			gmidi_handle_out_data(ep, req);
+		} else if (ep == dev->in_ep) {
+			/* our transmit completed.
+			   see if there's more to go.
+			   gmidi_transmit eats req, don't queue it again. */
+			gmidi_transmit(dev, req);
+			return;
+		}
+		break;
+
+	/* this endpoint is normally active while we're configured */
+	case -ECONNABORTED: 		/* hardware forced ep reset */
+	case -ECONNRESET:		/* request dequeued */
+	case -ESHUTDOWN:		/* disconnect from host */
+		VDBG(dev, "%s gone (%d), %d/%d\n", ep->name, status,
+				req->actual, req->length);
+		if (ep == dev->out_ep) {
+			gmidi_handle_out_data(ep, req);
+		}
+		free_ep_req(ep, req);
+		return;
+
+	case -EOVERFLOW:		/* buffer overrun on read means that
+					 * we didn't provide a big enough
+					 * buffer.
+					 */
+	default:
+		DBG(dev, "%s complete --> %d, %d/%d\n", ep->name,
+				status, req->actual, req->length);
+		break;
+	case -EREMOTEIO:		/* short read */
+		break;
+	}
+
+	status = usb_ep_queue(ep, req, GFP_ATOMIC);
+	if (status) {
+		ERROR(dev, "kill %s:  resubmit %d bytes --> %d\n",
+				ep->name, req->length, status);
+		usb_ep_set_halt(ep);
+		/* FIXME recover later ... somehow */
+	}
+}
+
+static int set_gmidi_config(struct gmidi_device *dev, gfp_t gfp_flags)
+{
+	int err = 0;
+	struct usb_request *req;
+	struct usb_ep* ep;
+	unsigned i;
+
+	err = usb_ep_enable(dev->in_ep, &bulk_in_desc);
+	if (err) {
+		ERROR(dev, "can't start %s: %d\n", dev->in_ep->name, err);
+		goto fail;
+	}
+	dev->in_ep->driver_data = dev;
+
+	err = usb_ep_enable(dev->out_ep, &bulk_out_desc);
+	if (err) {
+		ERROR(dev, "can't start %s: %d\n", dev->out_ep->name, err);
+		goto fail;
+	}
+	dev->out_ep->driver_data = dev;
+
+	/* allocate a bunch of read buffers and queue them all at once. */
+	ep = dev->out_ep;
+	for (i = 0; i < qlen && err == 0; i++) {
+		req = alloc_ep_req(ep, buflen);
+		if (req) {
+			req->complete = gmidi_complete;
+			err = usb_ep_queue(ep, req, GFP_ATOMIC);
+			if (err) {
+				DBG(dev, "%s queue req: %d\n", ep->name, err);
+			}
+		} else {
+			err = -ENOMEM;
+		}
+	}
+fail:
+	/* caller is responsible for cleanup on error */
+	return err;
+}
+
+
+static void gmidi_reset_config(struct gmidi_device *dev)
+{
+	if (dev->config == 0) {
+		return;
+	}
+
+	DBG(dev, "reset config\n");
+
+	/* just disable endpoints, forcing completion of pending i/o.
+	 * all our completion handlers free their requests in this case.
+	 */
+	usb_ep_disable(dev->in_ep);
+	usb_ep_disable(dev->out_ep);
+	dev->config = 0;
+}
+
+/* change our operational config.  this code must agree with the code
+ * that returns config descriptors, and altsetting code.
+ *
+ * it's also responsible for power management interactions. some
+ * configurations might not work with our current power sources.
+ *
+ * note that some device controller hardware will constrain what this
+ * code can do, perhaps by disallowing more than one configuration or
+ * by limiting configuration choices (like the pxa2xx).
+ */
+static int
+gmidi_set_config(struct gmidi_device *dev, unsigned number, gfp_t gfp_flags)
+{
+	int result = 0;
+	struct usb_gadget *gadget = dev->gadget;
+
+#if 0
+	/* FIXME */
+	/* Hacking this bit out fixes a bug where on receipt of two
+	   USB_REQ_SET_CONFIGURATION messages, we end up with no
+	   buffered OUT requests waiting for data. This is clearly
+	   hiding a bug elsewhere, because if the config didn't
+	   change then we really shouldn't do anything. */
+	/* Having said that, when we do "change" from config 1
+	   to config 1, we at least gmidi_reset_config() which
+	   clears out any requests on endpoints, so it's not like
+	   we leak or anything. */
+	if (number == dev->config) {
+		return 0;
+	}
+#endif
+
+	if (gadget_is_sa1100(gadget) && dev->config) {
+		/* tx fifo is full, but we can't clear it...*/
+		INFO(dev, "can't change configurations\n");
+		return -ESPIPE;
+	}
+	gmidi_reset_config(dev);
+
+	switch (number) {
+	case GMIDI_CONFIG:
+		result = set_gmidi_config(dev, gfp_flags);
+		break;
+	default:
+		result = -EINVAL;
+		/* FALL THROUGH */
+	case 0:
+		return result;
+	}
+
+	if (!result && (!dev->in_ep || !dev->out_ep)) {
+		result = -ENODEV;
+	}
+	if (result) {
+		gmidi_reset_config(dev);
+	} else {
+		char *speed;
+
+		switch (gadget->speed) {
+		case USB_SPEED_LOW:	speed = "low"; break;
+		case USB_SPEED_FULL:	speed = "full"; break;
+		case USB_SPEED_HIGH:	speed = "high"; break;
+		default: 		speed = "?"; break;
+		}
+
+		dev->config = number;
+		INFO(dev, "%s speed\n", speed);
+	}
+	return result;
+}
+
+
+static void gmidi_setup_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	if (req->status || req->actual != req->length) {
+		DBG((struct gmidi_device *) ep->driver_data,
+				"setup complete --> %d, %d/%d\n",
+				req->status, req->actual, req->length);
+	}
+}
+
+/*
+ * The setup() callback implements all the ep0 functionality that's
+ * not handled lower down, in hardware or the hardware driver (like
+ * device and endpoint feature flags, and their status).  It's all
+ * housekeeping for the gadget function we're implementing.  Most of
+ * the work is in config-specific setup.
+ */
+static int gmidi_setup(struct usb_gadget *gadget,
+			const struct usb_ctrlrequest *ctrl)
+{
+	struct gmidi_device *dev = get_gadget_data(gadget);
+	struct usb_request *req = dev->req;
+	int value = -EOPNOTSUPP;
+	u16 w_index = le16_to_cpu(ctrl->wIndex);
+	u16 w_value = le16_to_cpu(ctrl->wValue);
+	u16 w_length = le16_to_cpu(ctrl->wLength);
+
+	/* usually this stores reply data in the pre-allocated ep0 buffer,
+	 * but config change events will reconfigure hardware.
+	 */
+	req->zero = 0;
+	switch (ctrl->bRequest) {
+
+	case USB_REQ_GET_DESCRIPTOR:
+		if (ctrl->bRequestType != USB_DIR_IN) {
+			goto unknown;
+		}
+		switch (w_value >> 8) {
+
+		case USB_DT_DEVICE:
+			value = min(w_length, (u16) sizeof(device_desc));
+			memcpy(req->buf, &device_desc, value);
+			break;
+		case USB_DT_CONFIG:
+			value = config_buf(gadget, req->buf,
+					w_value >> 8,
+					w_value & 0xff);
+			if (value >= 0) {
+				value = min(w_length, (u16)value);
+			}
+			break;
+
+		case USB_DT_STRING:
+			/* wIndex == language code.
+			 * this driver only handles one language, you can
+			 * add string tables for other languages, using
+			 * any UTF-8 characters
+			 */
+			value = usb_gadget_get_string(&stringtab,
+					w_value & 0xff, req->buf);
+			if (value >= 0) {
+				value = min(w_length, (u16)value);
+			}
+			break;
+		}
+		break;
+
+	/* currently two configs, two speeds */
+	case USB_REQ_SET_CONFIGURATION:
+		if (ctrl->bRequestType != 0) {
+			goto unknown;
+		}
+		if (gadget->a_hnp_support) {
+			DBG(dev, "HNP available\n");
+		} else if (gadget->a_alt_hnp_support) {
+			DBG(dev, "HNP needs a different root port\n");
+		} else {
+			VDBG(dev, "HNP inactive\n");
+		}
+		spin_lock(&dev->lock);
+		value = gmidi_set_config(dev, w_value, GFP_ATOMIC);
+		spin_unlock(&dev->lock);
+		break;
+	case USB_REQ_GET_CONFIGURATION:
+		if (ctrl->bRequestType != USB_DIR_IN) {
+			goto unknown;
+		}
+		*(u8 *)req->buf = dev->config;
+		value = min(w_length, (u16)1);
+		break;
+
+	/* until we add altsetting support, or other interfaces,
+	 * only 0/0 are possible.  pxa2xx only supports 0/0 (poorly)
+	 * and already killed pending endpoint I/O.
+	 */
+	case USB_REQ_SET_INTERFACE:
+		if (ctrl->bRequestType != USB_RECIP_INTERFACE) {
+			goto unknown;
+		}
+		spin_lock(&dev->lock);
+		if (dev->config && w_index < GMIDI_NUM_INTERFACES
+			&& w_value == 0)
+		{
+			u8 config = dev->config;
+
+			/* resets interface configuration, forgets about
+			 * previous transaction state (queued bufs, etc)
+			 * and re-inits endpoint state (toggle etc)
+			 * no response queued, just zero status == success.
+			 * if we had more than one interface we couldn't
+			 * use this "reset the config" shortcut.
+			 */
+			gmidi_reset_config(dev);
+			gmidi_set_config(dev, config, GFP_ATOMIC);
+			value = 0;
+		}
+		spin_unlock(&dev->lock);
+		break;
+	case USB_REQ_GET_INTERFACE:
+		if (ctrl->bRequestType != (USB_DIR_IN|USB_RECIP_INTERFACE)) {
+			goto unknown;
+		}
+		if (!dev->config) {
+			break;
+		}
+		if (w_index >= GMIDI_NUM_INTERFACES) {
+			value = -EDOM;
+			break;
+		}
+		*(u8 *)req->buf = 0;
+		value = min(w_length, (u16)1);
+		break;
+
+	default:
+unknown:
+		VDBG(dev, "unknown control req%02x.%02x v%04x i%04x l%d\n",
+			ctrl->bRequestType, ctrl->bRequest,
+			w_value, w_index, w_length);
+	}
+
+	/* respond with data transfer before status phase? */
+	if (value >= 0) {
+		req->length = value;
+		req->zero = value < w_length;
+		value = usb_ep_queue(gadget->ep0, req, GFP_ATOMIC);
+		if (value < 0) {
+			DBG(dev, "ep_queue --> %d\n", value);
+			req->status = 0;
+			gmidi_setup_complete(gadget->ep0, req);
+		}
+	}
+
+	/* device either stalls (value < 0) or reports success */
+	return value;
+}
+
+static void gmidi_disconnect(struct usb_gadget *gadget)
+{
+	struct gmidi_device *dev = get_gadget_data(gadget);
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	gmidi_reset_config(dev);
+
+	/* a more significant application might have some non-usb
+	 * activities to quiesce here, saving resources like power
+	 * or pushing the notification up a network stack.
+	 */
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	/* next we may get setup() calls to enumerate new connections;
+	 * or an unbind() during shutdown (including removing module).
+	 */
+}
+
+static void /* __init_or_exit */ gmidi_unbind(struct usb_gadget *gadget)
+{
+	struct gmidi_device *dev = get_gadget_data(gadget);
+	struct snd_card* card;
+
+	DBG(dev, "unbind\n");
+
+	card = dev->card;
+	dev->card = NULL;
+	if (card) {
+		snd_card_free(card);
+	}
+
+	/* we've already been disconnected ... no i/o is active */
+	if (dev->req) {
+		dev->req->length = USB_BUFSIZ;
+		free_ep_req(gadget->ep0, dev->req);
+	}
+	kfree(dev);
+	set_gadget_data(gadget, NULL);
+}
+
+static int gmidi_snd_free(struct snd_device *device)
+{
+	return 0;
+}
+
+static void gmidi_transmit_packet(struct usb_request* req, uint8_t p0,
+					uint8_t p1, uint8_t p2, uint8_t p3)
+{
+	unsigned length = req->length;
+
+	uint8_t* buf = (uint8_t*)req->buf + length;
+	buf[0] = p0;
+	buf[1] = p1;
+	buf[2] = p2;
+	buf[3] = p3;
+	req->length = length + 4;
+}
+
+/*
+ * Converts MIDI commands to USB MIDI packets.
+ */
+static void gmidi_transmit_byte(struct usb_request* req,
+				struct gmidi_in_port* port, uint8_t b)
+{
+	uint8_t p0 = port->cable;
+
+	if (b >= 0xf8) {
+		gmidi_transmit_packet(req, p0 | 0x0f, b, 0, 0);
+	} else if (b >= 0xf0) {
+		switch (b) {
+		case 0xf0:
+			port->data[0] = b;
+			port->state = STATE_SYSEX_1;
+			break;
+		case 0xf1:
+		case 0xf3:
+			port->data[0] = b;
+			port->state = STATE_1PARAM;
+			break;
+		case 0xf2:
+			port->data[0] = b;
+			port->state = STATE_2PARAM_1;
+			break;
+		case 0xf4:
+		case 0xf5:
+			port->state = STATE_UNKNOWN;
+			break;
+		case 0xf6:
+			gmidi_transmit_packet(req, p0 | 0x05, 0xf6, 0, 0);
+			port->state = STATE_UNKNOWN;
+			break;
+		case 0xf7:
+			switch (port->state) {
+			case STATE_SYSEX_0:
+				gmidi_transmit_packet(req,
+					p0 | 0x05, 0xf7, 0, 0);
+				break;
+			case STATE_SYSEX_1:
+				gmidi_transmit_packet(req,
+					p0 | 0x06, port->data[0], 0xf7, 0);
+				break;
+			case STATE_SYSEX_2:
+				gmidi_transmit_packet(req,
+					p0 | 0x07, port->data[0],
+					port->data[1], 0xf7);
+				break;
+			}
+			port->state = STATE_UNKNOWN;
+			break;
+		}
+	} else if (b >= 0x80) {
+		port->data[0] = b;
+		if (b >= 0xc0 && b <= 0xdf)
+			port->state = STATE_1PARAM;
+		else
+			port->state = STATE_2PARAM_1;
+	} else { /* b < 0x80 */
+		switch (port->state) {
+		case STATE_1PARAM:
+			if (port->data[0] < 0xf0) {
+				p0 |= port->data[0] >> 4;
+			} else {
+				p0 |= 0x02;
+				port->state = STATE_UNKNOWN;
+			}
+			gmidi_transmit_packet(req, p0, port->data[0], b, 0);
+			break;
+		case STATE_2PARAM_1:
+			port->data[1] = b;
+			port->state = STATE_2PARAM_2;
+			break;
+		case STATE_2PARAM_2:
+			if (port->data[0] < 0xf0) {
+				p0 |= port->data[0] >> 4;
+				port->state = STATE_2PARAM_1;
+			} else {
+				p0 |= 0x03;
+				port->state = STATE_UNKNOWN;
+			}
+			gmidi_transmit_packet(req,
+				p0, port->data[0], port->data[1], b);
+			break;
+		case STATE_SYSEX_0:
+			port->data[0] = b;
+			port->state = STATE_SYSEX_1;
+			break;
+		case STATE_SYSEX_1:
+			port->data[1] = b;
+			port->state = STATE_SYSEX_2;
+			break;
+		case STATE_SYSEX_2:
+			gmidi_transmit_packet(req,
+				p0 | 0x04, port->data[0], port->data[1], b);
+			port->state = STATE_SYSEX_0;
+			break;
+		}
+	}
+}
+
+static void gmidi_transmit(struct gmidi_device* dev, struct usb_request* req)
+{
+	struct usb_ep* ep = dev->in_ep;
+	struct gmidi_in_port* port = &dev->in_port;
+
+	if (!ep) {
+		return;
+	}
+	if (!req) {
+		req = alloc_ep_req(ep, buflen);
+	}
+	if (!req) {
+		ERROR(dev, "gmidi_transmit: alloc_ep_request failed\n");
+		return;
+	}
+	req->length = 0;
+	req->complete = gmidi_complete;
+
+	if (port->active) {
+		while (req->length + 3 < buflen) {
+			uint8_t b;
+			if (snd_rawmidi_transmit(dev->in_substream, &b, 1)
+				!= 1)
+			{
+				port->active = 0;
+				break;
+			}
+			gmidi_transmit_byte(req, port, b);
+		}
+	}
+	if (req->length > 0) {
+		usb_ep_queue(ep, req, GFP_ATOMIC);
+	} else {
+		free_ep_req(ep, req);
+	}
+}
+
+static void gmidi_in_tasklet(unsigned long data)
+{
+	struct gmidi_device* dev = (struct gmidi_device*)data;
+
+	gmidi_transmit(dev, NULL);
+}
+
+static int gmidi_in_open(struct snd_rawmidi_substream *substream)
+{
+	struct gmidi_device* dev = substream->rmidi->private_data;
+
+	VDBG(dev, "gmidi_in_open\n");
+	dev->in_substream = substream;
+	dev->in_port.state = STATE_UNKNOWN;
+	return 0;
+}
+
+static int gmidi_in_close(struct snd_rawmidi_substream *substream)
+{
+	VDBG(dev, "gmidi_in_close\n");
+	return 0;
+}
+
+static void gmidi_in_trigger(struct snd_rawmidi_substream *substream, int up)
+{
+	struct gmidi_device* dev = substream->rmidi->private_data;
+
+	VDBG(dev, "gmidi_in_trigger %d\n", up);
+	dev->in_port.active = up;
+	if (up) {
+		tasklet_hi_schedule(&dev->tasklet);
+	}
+}
+
+static int gmidi_out_open(struct snd_rawmidi_substream *substream)
+{
+	struct gmidi_device* dev = substream->rmidi->private_data;
+
+	VDBG(dev, "gmidi_out_open\n");
+	dev->out_substream = substream;
+	return 0;
+}
+
+static int gmidi_out_close(struct snd_rawmidi_substream *substream)
+{
+	VDBG(dev, "gmidi_out_close\n");
+	return 0;
+}
+
+static void gmidi_out_trigger(struct snd_rawmidi_substream *substream, int up)
+{
+	struct gmidi_device* dev = substream->rmidi->private_data;
+
+	VDBG(dev, "gmidi_out_trigger %d\n", up);
+	if (up) {
+		set_bit(substream->number, &dev->out_triggered);
+	} else {
+		clear_bit(substream->number, &dev->out_triggered);
+	}
+}
+
+static struct snd_rawmidi_ops gmidi_in_ops = {
+	.open = gmidi_in_open,
+	.close = gmidi_in_close,
+	.trigger = gmidi_in_trigger,
+};
+
+static struct snd_rawmidi_ops gmidi_out_ops = {
+	.open = gmidi_out_open,
+	.close = gmidi_out_close,
+	.trigger = gmidi_out_trigger
+};
+
+/* register as a sound "card" */
+static int gmidi_register_card(struct gmidi_device *dev)
+{
+	struct snd_card *card;
+	struct snd_rawmidi *rmidi;
+	int err;
+	int out_ports = 1;
+	int in_ports = 1;
+	static struct snd_device_ops ops = {
+		.dev_free = gmidi_snd_free,
+	};
+
+	card = snd_card_new(index, id, THIS_MODULE, 0);
+	if (!card) {
+		ERROR(dev, "snd_card_new failed\n");
+		err = -ENOMEM;
+		goto fail;
+	}
+	dev->card = card;
+
+	err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, dev, &ops);
+	if (err < 0) {
+		ERROR(dev, "snd_device_new failed: error %d\n", err);
+		goto fail;
+	}
+
+	strcpy(card->driver, longname);
+	strcpy(card->longname, longname);
+	strcpy(card->shortname, shortname);
+
+	/* Set up rawmidi */
+	dev->in_port.dev = dev;
+	dev->in_port.active = 0;
+	snd_component_add(card, "MIDI");
+	err = snd_rawmidi_new(card, "USB MIDI Gadget", 0,
+			      out_ports, in_ports, &rmidi);
+	if (err < 0) {
+		ERROR(dev, "snd_rawmidi_new failed: error %d\n", err);
+		goto fail;
+	}
+	dev->rmidi = rmidi;
+	strcpy(rmidi->name, card->shortname);
+	rmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
+			    SNDRV_RAWMIDI_INFO_INPUT |
+			    SNDRV_RAWMIDI_INFO_DUPLEX;
+	rmidi->private_data = dev;
+
+	/* Yes, rawmidi OUTPUT = USB IN, and rawmidi INPUT = USB OUT.
+	   It's an upside-down world being a gadget. */
+	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &gmidi_in_ops);
+	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &gmidi_out_ops);
+
+	snd_card_set_dev(card, &dev->gadget->dev);
+
+	/* register it - we're ready to go */
+	err = snd_card_register(card);
+	if (err < 0) {
+		ERROR(dev, "snd_card_register failed\n");
+		goto fail;
+	}
+
+	VDBG(dev, "gmidi_register_card finished ok\n");
+	return 0;
+
+fail:
+	if (dev->card) {
+		snd_card_free(dev->card);
+		dev->card = NULL;
+	}
+	return err;
+}
+
+/*
+ * Creates an output endpoint, and initializes output ports.
+ */
+static int __devinit gmidi_bind(struct usb_gadget *gadget)
+{
+	struct gmidi_device *dev;
+	struct usb_ep *in_ep, *out_ep;
+	int gcnum, err = 0;
+
+	/* support optional vendor/distro customization */
+	if (idVendor) {
+		if (!idProduct) {
+			printk(KERN_ERR "idVendor needs idProduct!\n");
+			return -ENODEV;
+		}
+		device_desc.idVendor = cpu_to_le16(idVendor);
+		device_desc.idProduct = cpu_to_le16(idProduct);
+		if (bcdDevice) {
+			device_desc.bcdDevice = cpu_to_le16(bcdDevice);
+		}
+	}
+	if (iManufacturer) {
+		strlcpy(manufacturer, iManufacturer, sizeof(manufacturer));
+	} else {
+		snprintf(manufacturer, sizeof(manufacturer), "%s %s with %s",
+			system_utsname.sysname, system_utsname.release,
+			gadget->name);
+	}
+	if (iProduct) {
+		strlcpy(product_desc, iProduct, sizeof(product_desc));
+	}
+	if (iSerialNumber) {
+		device_desc.iSerialNumber = STRING_SERIAL,
+		strlcpy(serial_number, iSerialNumber, sizeof(serial_number));
+	}
+
+	/* Bulk-only drivers like this one SHOULD be able to
+	 * autoconfigure on any sane usb controller driver,
+	 * but there may also be important quirks to address.
+	 */
+	usb_ep_autoconfig_reset(gadget);
+	in_ep = usb_ep_autoconfig(gadget, &bulk_in_desc);
+	if (!in_ep) {
+autoconf_fail:
+		printk(KERN_ERR "%s: can't autoconfigure on %s\n",
+			shortname, gadget->name);
+		return -ENODEV;
+	}
+	EP_IN_NAME = in_ep->name;
+	in_ep->driver_data = in_ep;	/* claim */
+
+	out_ep = usb_ep_autoconfig(gadget, &bulk_out_desc);
+	if (!out_ep) {
+		goto autoconf_fail;
+	}
+	EP_OUT_NAME = out_ep->name;
+	out_ep->driver_data = out_ep;	/* claim */
+
+	gcnum = usb_gadget_controller_number(gadget);
+	if (gcnum >= 0) {
+		device_desc.bcdDevice = cpu_to_le16(0x0200 + gcnum);
+	} else {
+		/* gmidi is so simple (no altsettings) that
+		 * it SHOULD NOT have problems with bulk-capable hardware.
+		 * so warn about unrecognized controllers, don't panic.
+		 */
+		printk(KERN_WARNING "%s: controller '%s' not recognized\n",
+			shortname, gadget->name);
+		device_desc.bcdDevice = __constant_cpu_to_le16(0x9999);
+	}
+
+
+	/* ok, we made sense of the hardware ... */
+	dev = kzalloc(sizeof(*dev), SLAB_KERNEL);
+	if (!dev) {
+		return -ENOMEM;
+	}
+	spin_lock_init(&dev->lock);
+	dev->gadget = gadget;
+	dev->in_ep = in_ep;
+	dev->out_ep = out_ep;
+	set_gadget_data(gadget, dev);
+	tasklet_init(&dev->tasklet, gmidi_in_tasklet, (unsigned long)dev);
+
+	/* preallocate control response and buffer */
+	dev->req = usb_ep_alloc_request(gadget->ep0, GFP_KERNEL);
+	if (!dev->req) {
+		err = -ENOMEM;
+		goto fail;
+	}
+	dev->req->buf = usb_ep_alloc_buffer(gadget->ep0, USB_BUFSIZ,
+				&dev->req->dma, GFP_KERNEL);
+	if (!dev->req->buf) {
+		err = -ENOMEM;
+		goto fail;
+	}
+
+	dev->req->complete = gmidi_setup_complete;
+
+	device_desc.bMaxPacketSize0 = gadget->ep0->maxpacket;
+
+	gadget->ep0->driver_data = dev;
+
+	INFO(dev, "%s, version: " DRIVER_VERSION "\n", longname);
+	INFO(dev, "using %s, OUT %s IN %s\n", gadget->name,
+		EP_OUT_NAME, EP_IN_NAME);
+
+	/* register as an ALSA sound card */
+	err = gmidi_register_card(dev);
+	if (err < 0) {
+		goto fail;
+	}
+
+	VDBG(dev, "gmidi_bind finished ok\n");
+	return 0;
+
+fail:
+	gmidi_unbind(gadget);
+	return err;
+}
+
+
+static void gmidi_suspend(struct usb_gadget *gadget)
+{
+	struct gmidi_device *dev = get_gadget_data(gadget);
+
+	if (gadget->speed == USB_SPEED_UNKNOWN) {
+		return;
+	}
+
+	DBG(dev, "suspend\n");
+}
+
+static void gmidi_resume(struct usb_gadget *gadget)
+{
+	struct gmidi_device *dev = get_gadget_data(gadget);
+
+	DBG(dev, "resume\n");
+}
+
+
+static struct usb_gadget_driver gmidi_driver = {
+	.speed		= USB_SPEED_FULL,
+	.function	= (char *)longname,
+	.bind		= gmidi_bind,
+	.unbind		= __exit_p(gmidi_unbind),
+
+	.setup		= gmidi_setup,
+	.disconnect	= gmidi_disconnect,
+
+	.suspend	= gmidi_suspend,
+	.resume		= gmidi_resume,
+
+	.driver 	= {
+		.name		= (char *)shortname,
+		.owner		= THIS_MODULE,
+	},
+};
+
+static int __init gmidi_init(void)
+{
+	return usb_gadget_register_driver(&gmidi_driver);
+}
+module_init(gmidi_init);
+
+static void __exit gmidi_cleanup(void)
+{
+	usb_gadget_unregister_driver(&gmidi_driver);
+}
+module_exit(gmidi_cleanup);
+