USB: export <linux/usb_gadgetfs> as <linux/usb/gadgetfs.h>

Make sure gadgetfs userspace interface is properly exported:

 - Move <linux/usb_gadgetfs.h> to <linux/usb/gadgetfs.h>;
 - Export it using Kbuild;
 - Add an #include guard;
 - Correct some internal documentation;
 - Update struct layout so it's the same on 32/64 bit kernels.

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

2 files changed, 82 insertions, 0 deletions

diff --git a/include/linux/usb/Kbuild b/include/linux/usb/Kbuild
index 43f160cfe003..6ce42bf9f743 100644
--- a/include/linux/usb/Kbuild
+++ b/include/linux/usb/Kbuild
@@ -1,5 +1,6 @@
 unifdef-y += audio.h
 unifdef-y += cdc.h
 unifdef-y += ch9.h
+unifdef-y += gadgetfs.h
 unifdef-y += midi.h
 
diff --git a/include/linux/usb/gadgetfs.h b/include/linux/usb/gadgetfs.h
new file mode 100644
index 000000000000..e8654c338729
--- /dev/null
+++ b/include/linux/usb/gadgetfs.h
@@ -0,0 +1,81 @@
+#ifndef __LINUX_USB_GADGETFS_H
+#define __LINUX_USB_GADGETFS_H
+
+#include <asm/types.h>
+#include <asm/ioctl.h>
+
+#include <linux/usb/ch9.h>
+
+/*
+ * Filesystem based user-mode API to USB Gadget controller hardware
+ *
+ * Other than ep0 operations, most things are done by read() and write()
+ * on endpoint files found in one directory.  They are configured by
+ * writing descriptors, and then may be used for normal stream style
+ * i/o requests.  When ep0 is configured, the device can enumerate;
+ * when it's closed, the device disconnects from usb.  Operations on
+ * ep0 require ioctl() operations.
+ *
+ * Configuration and device descriptors get written to /dev/gadget/$CHIP,
+ * which may then be used to read usb_gadgetfs_event structs.  The driver
+ * may activate endpoints as it handles SET_CONFIGURATION setup events,
+ * or earlier; writing endpoint descriptors to /dev/gadget/$ENDPOINT
+ * then performing data transfers by reading or writing.
+ */
+
+/*
+ * Events are delivered on the ep0 file descriptor, when the user mode driver
+ * reads from this file descriptor after writing the descriptors.  Don't
+ * stop polling this descriptor.
+ */
+
+enum usb_gadgetfs_event_type {
+        GADGETFS_NOP = 0,
+
+        GADGETFS_CONNECT,
+        GADGETFS_DISCONNECT,
+        GADGETFS_SETUP,
+        GADGETFS_SUSPEND,
+        // and likely more !
+};
+
+/* NOTE:  this structure must stay the same size and layout on
+ * both 32-bit and 64-bit kernels.
+ */
+struct usb_gadgetfs_event {
+        union {
+                // NOP, DISCONNECT, SUSPEND: nothing
+                // ... some hardware can't report disconnection
+
+                // CONNECT: just the speed
+                enum usb_device_speed   speed;
+
+                // SETUP: packet; DATA phase i/o precedes next event
+                // (setup.bmRequestType & USB_DIR_IN) flags direction
+                // ... includes SET_CONFIGURATION, SET_INTERFACE
+                struct usb_ctrlrequest  setup;
+        } u;
+        enum usb_gadgetfs_event_type    type;
+};
+
+
+/* endpoint ioctls */
+
+/* IN transfers may be reported to the gadget driver as complete
+ *      when the fifo is loaded, before the host reads the data;
+ * OUT transfers may be reported to the host's "client" driver as
+ *      complete when they're sitting in the FIFO unread.
+ * THIS returns how many bytes are "unclaimed" in the endpoint fifo
+ * (needed for precise fault handling, when the hardware allows it)
+ */
+#define GADGETFS_FIFO_STATUS    _IO('g',1)
+
+/* discards any unclaimed data in the fifo. */
+#define GADGETFS_FIFO_FLUSH     _IO('g',2)
+
+/* resets endpoint halt+toggle; used to implement set_interface.
+ * some hardware (like pxa2xx) can't support this.
+ */
+#define GADGETFS_CLEAR_HALT     _IO('g',3)
+
+#endif /* __LINUX_USB_GADGETFS_H */