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>

2 files changed, 165 insertions, 0 deletions

diff --git a/include/linux/usb/audio.h b/include/linux/usb/audio.h
new file mode 100644
index 000000000000..6bd235994dc2
--- /dev/null
+++ b/include/linux/usb/audio.h
@@ -0,0 +1,53 @@
+/*
+ * <linux/usb/audio.h> -- USB Audio definitions.
+ *
+ * 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 file holds USB constants and structures defined
+ * by the USB Device Class Definition for Audio Devices.
+ * Comments below reference relevant sections of that document:
+ *
+ * http://www.usb.org/developers/devclass_docs/audio10.pdf
+ */
+
+#ifndef __LINUX_USB_AUDIO_H
+#define __LINUX_USB_AUDIO_H
+
+#include <linux/types.h>
+
+/* A.2 Audio Interface Subclass Codes */
+#define USB_SUBCLASS_AUDIOCONTROL       0x01
+#define USB_SUBCLASS_AUDIOSTREAMING     0x02
+#define USB_SUBCLASS_MIDISTREAMING      0x03
+
+/* 4.3.2  Class-Specific AC Interface Descriptor */
+struct usb_ac_header_descriptor {
+        __u8  bLength;                  // 8+n
+        __u8  bDescriptorType;          // USB_DT_CS_INTERFACE
+        __u8  bDescriptorSubtype;       // USB_MS_HEADER
+        __le16 bcdADC;                  // 0x0100
+        __le16 wTotalLength;            // includes Unit and Terminal desc.
+        __u8  bInCollection;            // n
+        __u8  baInterfaceNr[];          // [n]
+} __attribute__ ((packed));
+
+#define USB_DT_AC_HEADER_SIZE(n)        (8+(n))
+
+/* As above, but more useful for defining your own descriptors: */
+#define DECLARE_USB_AC_HEADER_DESCRIPTOR(n)                     \
+struct usb_ac_header_descriptor_##n {                           \
+        __u8  bLength;                                          \
+        __u8  bDescriptorType;                                  \
+        __u8  bDescriptorSubtype;                               \
+        __le16 bcdADC;                                          \
+        __le16 wTotalLength;                                    \
+        __u8  bInCollection;                                    \
+        __u8  baInterfaceNr[n];                                 \
+} __attribute__ ((packed))
+
+#endif
diff --git a/include/linux/usb/midi.h b/include/linux/usb/midi.h
new file mode 100644
index 000000000000..11a97d5ffd34
--- /dev/null
+++ b/include/linux/usb/midi.h
@@ -0,0 +1,112 @@
+/*
+ * <linux/usb/midi.h> -- USB MIDI definitions.
+ *
+ * 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 file holds USB constants and structures defined
+ * by the USB Device Class Definition for MIDI Devices.
+ * Comments below reference relevant sections of that document:
+ *
+ * http://www.usb.org/developers/devclass_docs/midi10.pdf
+ */
+
+#ifndef __LINUX_USB_MIDI_H
+#define __LINUX_USB_MIDI_H
+
+#include <linux/types.h>
+
+/* A.1  MS Class-Specific Interface Descriptor Subtypes */
+#define USB_MS_HEADER           0x01
+#define USB_MS_MIDI_IN_JACK     0x02
+#define USB_MS_MIDI_OUT_JACK    0x03
+#define USB_MS_ELEMENT          0x04
+
+/* A.2  MS Class-Specific Endpoint Descriptor Subtypes */
+#define USB_MS_GENERAL          0x01
+
+/* A.3  MS MIDI IN and OUT Jack Types */
+#define USB_MS_EMBEDDED         0x01
+#define USB_MS_EXTERNAL         0x02
+
+/* 6.1.2.1  Class-Specific MS Interface Header Descriptor */
+struct usb_ms_header_descriptor {
+        __u8  bLength;
+        __u8  bDescriptorType;
+        __u8  bDescriptorSubtype;
+        __le16 bcdMSC;
+        __le16 wTotalLength;
+} __attribute__ ((packed));
+
+#define USB_DT_MS_HEADER_SIZE   7
+
+/* 6.1.2.2  MIDI IN Jack Descriptor */
+struct usb_midi_in_jack_descriptor {
+        __u8  bLength;
+        __u8  bDescriptorType;          // USB_DT_CS_INTERFACE
+        __u8  bDescriptorSubtype;       // USB_MS_MIDI_IN_JACK
+        __u8  bJackType;                // USB_MS_EMBEDDED/EXTERNAL
+        __u8  bJackID;
+        __u8  iJack;
+} __attribute__ ((packed));
+
+#define USB_DT_MIDI_IN_SIZE     6
+
+struct usb_midi_source_pin {
+        __u8  baSourceID;
+        __u8  baSourcePin;
+} __attribute__ ((packed));
+
+/* 6.1.2.3  MIDI OUT Jack Descriptor */
+struct usb_midi_out_jack_descriptor {
+        __u8  bLength;
+        __u8  bDescriptorType;          // USB_DT_CS_INTERFACE
+        __u8  bDescriptorSubtype;       // USB_MS_MIDI_OUT_JACK
+        __u8  bJackType;                // USB_MS_EMBEDDED/EXTERNAL
+        __u8  bJackID;
+        __u8  bNrInputPins;             // p
+        struct usb_midi_source_pin pins[]; // [p]
+        /*__u8  iJack;  -- ommitted due to variable-sized pins[] */
+} __attribute__ ((packed));
+
+#define USB_DT_MIDI_OUT_SIZE(p) (7 + 2 * (p))
+
+/* As above, but more useful for defining your own descriptors: */
+#define DECLARE_USB_MIDI_OUT_JACK_DESCRIPTOR(p)                 \
+struct usb_midi_out_jack_descriptor_##p {                       \
+        __u8  bLength;                                          \
+        __u8  bDescriptorType;                                  \
+        __u8  bDescriptorSubtype;                               \
+        __u8  bJackType;                                        \
+        __u8  bJackID;                                          \
+        __u8  bNrInputPins;                                     \
+        struct usb_midi_source_pin pins[p];                     \
+        __u8  iJack;                                            \
+} __attribute__ ((packed))
+
+/* 6.2.2  Class-Specific MS Bulk Data Endpoint Descriptor */
+struct usb_ms_endpoint_descriptor {
+        __u8  bLength;                  // 4+n
+        __u8  bDescriptorType;          // USB_DT_CS_ENDPOINT
+        __u8  bDescriptorSubtype;       // USB_MS_GENERAL
+        __u8  bNumEmbMIDIJack;          // n
+        __u8  baAssocJackID[];          // [n]
+} __attribute__ ((packed));
+
+#define USB_DT_MS_ENDPOINT_SIZE(n)      (4 + (n))
+
+/* As above, but more useful for defining your own descriptors: */
+#define DECLARE_USB_MS_ENDPOINT_DESCRIPTOR(n)                   \
+struct usb_ms_endpoint_descriptor_##n {                         \
+        __u8  bLength;                                          \
+        __u8  bDescriptorType;                                  \
+        __u8  bDescriptorSubtype;                               \
+        __u8  bNumEmbMIDIJack;                                  \
+        __u8  baAssocJackID[n];                                 \
+} __attribute__ ((packed))
+
+#endif