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, 14 insertions, 0 deletions

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 1a32d96774b4..4301e96c417b 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -404,6 +404,20 @@ config USB_G_SERIAL
           which includes instructions and a "driver info file" needed to
           make MS-Windows work with this driver.
 
+config USB_MIDI_GADGET
+        tristate "MIDI Gadget (EXPERIMENTAL)"
+        depends on SND && EXPERIMENTAL
+        select SND_RAWMIDI
+        help
+          The MIDI Gadget acts as a USB Audio device, with one MIDI
+          input and one MIDI output. These MIDI jacks appear as
+          a sound "card" in the ALSA sound system. Other MIDI
+          connections can then be made on the gadget system, using
+          ALSA's aconnect utility etc.
+
+          Say "y" to link the driver statically, or "m" to build a
+          dynamically linked module called "g_midi".
+
 
 # put drivers that need isochronous transfer support (for audio
 # or video class gadget drivers), or specific hardware, here.