linux/usb/gadgetfs.h

0001 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
0002 /*
0003  * Filesystem based user-mode API to USB Gadget controller hardware
0004  *
0005  * Other than ep0 operations, most things are done by read() and write()
0006  * on endpoint files found in one directory.  They are configured by
0007  * writing descriptors, and then may be used for normal stream style
0008  * i/o requests.  When ep0 is configured, the device can enumerate;
0009  * when it's closed, the device disconnects from usb.  Operations on
0010  * ep0 require ioctl() operations.
0011  *
0012  * Configuration and device descriptors get written to /dev/gadget/$CHIP,
0013  * which may then be used to read usb_gadgetfs_event structs.  The driver
0014  * may activate endpoints as it handles SET_CONFIGURATION setup events,
0015  * or earlier; writing endpoint descriptors to /dev/gadget/$ENDPOINT
0016  * then performing data transfers by reading or writing.
0017  */
0018
0019 #ifndef __LINUX_USB_GADGETFS_H
0020 #define __LINUX_USB_GADGETFS_H
0021
0022 #include <linux/types.h>
0023 #include <linux/ioctl.h>
0024
0025 #include <linux/usb/ch9.h>
0026
0027 /*
0028  * Events are delivered on the ep0 file descriptor, when the user mode driver
0029  * reads from this file descriptor after writing the descriptors.  Don't
0030  * stop polling this descriptor.
0031  */
0032
0033 enum usb_gadgetfs_event_type {
0034     GADGETFS_NOP = 0,
0035
0036     GADGETFS_CONNECT,
0037     GADGETFS_DISCONNECT,
0038     GADGETFS_SETUP,
0039     GADGETFS_SUSPEND,
0040     /* and likely more ! */
0041 };
0042
0043 /* NOTE:  this structure must stay the same size and layout on
0044  * both 32-bit and 64-bit kernels.
0045  */
0046 struct usb_gadgetfs_event {
0047     union {
0048         /* NOP, DISCONNECT, SUSPEND: nothing
0049          * ... some hardware can't report disconnection
0050          */
0051
0052         /* CONNECT: just the speed */
0053         enum usb_device_speed   speed;
0054
0055         /* SETUP: packet; DATA phase i/o precedes next event
0056          *(setup.bmRequestType & USB_DIR_IN) flags direction
0057          * ... includes SET_CONFIGURATION, SET_INTERFACE
0058          */
0059         struct usb_ctrlrequest  setup;
0060     } u;
0061     enum usb_gadgetfs_event_type    type;
0062 };
0063
0064
0065 /* The 'g' code is also used by printer gadget ioctl requests.
0066  * Don't add any colliding codes to either driver, and keep
0067  * them in unique ranges (size 0x20 for now).
0068  */
0069
0070 /* endpoint ioctls */
0071
0072 /* IN transfers may be reported to the gadget driver as complete
0073  *  when the fifo is loaded, before the host reads the data;
0074  * OUT transfers may be reported to the host's "client" driver as
0075  *  complete when they're sitting in the FIFO unread.
0076  * THIS returns how many bytes are "unclaimed" in the endpoint fifo
0077  * (needed for precise fault handling, when the hardware allows it)
0078  */
0079 #define GADGETFS_FIFO_STATUS    _IO('g', 1)
0080
0081 /* discards any unclaimed data in the fifo. */
0082 #define GADGETFS_FIFO_FLUSH _IO('g', 2)
0083
0084 /* resets endpoint halt+toggle; used to implement set_interface.
0085  * some hardware (like pxa2xx) can't support this.
0086  */
0087 #define GADGETFS_CLEAR_HALT _IO('g', 3)
0088
0089 #endif /* __LINUX_USB_GADGETFS_H */