[PATCH v7 1/3] usb: Add Xen pvUSB protocol description

Juergen Gross
2021-11-23T13:20:58Z

Add the definition of pvUSB protocol used between the pvUSB frontend in
a Xen domU and the pvUSB backend in a Xen driver domain (usually Dom0).

This header was originally provided by Fujitsu for Xen based on Linux
2.6.18.

Changes are:
- adapt to Linux kernel style guide
- use Xen namespace
- add lots of comments
- don't use kernel internal defines

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
include/xen/interface/io/usbif.h | 405 +++++++++++++++++++++++++++++++
1 file changed, 405 insertions(+)
create mode 100644 include/xen/interface/io/usbif.h

diff --git a/include/xen/interface/io/usbif.h b/include/xen/interface/io/usbif.h
new file mode 100644
index 000000000000..a70e0b93178b
--- /dev/null
+++ b/include/xen/interface/io/usbif.h
@@ -0,0 +1,405 @@
+/* SPDX-License-Identifier: MIT */
+
+/*
+ * usbif.h
+ *
+ * USB I/O interface for Xen guest OSes.
+ *
+ * Copyright (C) 2009, FUJITSU LABORATORIES LTD.
+ * Author: Noboru Iwamatsu <n_iwamatsu@jp.fujitsu.com>
+ */
+
+#ifndef __XEN_PUBLIC_IO_USBIF_H__
+#define __XEN_PUBLIC_IO_USBIF_H__
+
+#include "ring.h"
+#include "../grant_table.h"
+
+/*
+ * Detailed Interface Description
+ * ==============================
+ * The pvUSB interface is using a split driver design: a frontend driver in
+ * the guest and a backend driver in a driver domain (normally dom0) having
+ * access to the physical USB device(s) being passed to the guest.
+ *
+ * The frontend and backend drivers use XenStore to initiate the connection
+ * between them, the I/O activity is handled via two shared ring pages and an
+ * event channel. As the interface between frontend and backend is at the USB
+ * host connector level, multiple (up to 31) physical USB devices can be
+ * handled by a single connection.
+ *
+ * The Xen pvUSB device name is "qusb", so the frontend's XenStore entries are
+ * to be found under "device/qusb", while the backend's XenStore entries are
+ * under "backend/<guest-dom-id>/qusb".
+ *
+ * When a new pvUSB connection is established, the frontend needs to setup the
+ * two shared ring pages for communication and the event channel. The ring
+ * pages need to be made available to the backend via the grant table
+ * interface.
+ *
+ * One of the shared ring pages is used by the backend to inform the frontend
+ * about USB device plug events (device to be added or removed). This is the
+ * "conn-ring".
+ *
+ * The other ring page is used for USB I/O communication (requests and
+ * responses). This is the "urb-ring".
+ *
+ * Feature and Parameter Negotiation
+ * =================================
+ * The two halves of a Xen pvUSB driver utilize nodes within the XenStore to
+ * communicate capabilities and to negotiate operating parameters. This
+ * section enumerates these nodes which reside in the respective front and
+ * backend portions of the XenStore, following the XenBus convention.
+ *
+ * Any specified default value is in effect if the corresponding XenBus node
+ * is not present in the XenStore.
+ *
+ * XenStore nodes in sections marked "PRIVATE" are solely for use by the
+ * driver side whose XenBus tree contains them.
+ *
+ *****************************************************************************
+ * Backend XenBus Nodes
+ *****************************************************************************
+ *
+ *------------------ Backend Device Identification (PRIVATE) ------------------
+ *
+ * num-ports
+ * Values: unsigned [1...31]
+ *
+ * Number of ports for this (virtual) USB host connector.
+ *
+ * usb-ver
+ * Values: unsigned [1...2]
+ *
+ * USB version of this host connector: 1 = USB 1.1, 2 = USB 2.0.
+ *
+ * port/[1...31]
+ * Values: string
+ *
+ * Physical USB device connected to the given port, e.g. "3-1.5".
+ *
+ *****************************************************************************
+ * Frontend XenBus Nodes
+ *****************************************************************************
+ *
+ *----------------------- Request Transport Parameters -----------------------
+ *
+ * event-channel
+ * Values: unsigned
+ *
+ * The identifier of the Xen event channel used to signal activity
+ * in the ring buffer.
+ *
+ * urb-ring-ref
+ * Values: unsigned
+ *
+ * The Xen grant reference granting permission for the backend to map
+ * the sole page in a single page sized ring buffer. This is the ring
+ * buffer for urb requests.
+ *
+ * conn-ring-ref
+ * Values: unsigned
+ *
+ * The Xen grant reference granting permission for the backend to map
+ * the sole page in a single page sized ring buffer. This is the ring
+ * buffer for connection/disconnection requests.
+ *
+ * protocol
+ * Values: string (XEN_IO_PROTO_ABI_*)
+ * Default Value: XEN_IO_PROTO_ABI_NATIVE
+ *
+ * The machine ABI rules governing the format of all ring request and
+ * response structures.
+ *
+ * Protocol Description
+ * ====================
+ *
+ *-------------------------- USB device plug events --------------------------
+ *
+ * USB device plug events are send via the "conn-ring" shared page. As only
+ * events are being sent, the respective requests from the frontend to the
+ * backend are just dummy ones.
+ * The events sent to the frontend have the following layout:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | portnum | speed | 4
+ * +----------------+----------------+----------------+----------------+
+ * id - uint16_t, event id (taken from the actual frontend dummy request)
+ * portnum - uint8_t, port number (1 ... 31)
+ * speed - uint8_t, device XENUSB_SPEED_*, XENUSB_SPEED_NONE == unplug
+ *
+ * The dummy request:
+ * 0 1 octet
+ * +----------------+----------------+
+ * | id | 2
+ * +----------------+----------------+
+ * id - uint16_t, guest supplied value (no need for being unique)
+ *
+ *-------------------------- USB I/O request ---------------------------------
+ *
+ * A single USB I/O request on the "urb-ring" has the following layout:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | nr_buffer_segs | 4
+ * +----------------+----------------+----------------+----------------+
+ * | pipe | 8
+ * +----------------+----------------+----------------+----------------+
+ * | transfer_flags | buffer_length | 12
+ * +----------------+----------------+----------------+----------------+
+ * | request type specific | 16
+ * | data | 20
+ * +----------------+----------------+----------------+----------------+
+ * | seg[0] | 24
+ * | data | 28
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | seg[XENUSB_MAX_SEGMENTS_PER_REQUEST - 1] | 144
+ * | data | 148
+ * +----------------+----------------+----------------+----------------+
+ * Bit field bit number 0 is always least significant bit, undefined bits must
+ * be zero.
+ * id - uint16_t, guest supplied value
+ * nr_buffer_segs - uint16_t, number of segment entries in seg[] array
+ * pipe - uint32_t, bit field with multiple information:
+ * bits 0-4: port request to send to
+ * bit 5: unlink request with specified id (cancel I/O) if set (see below)
+ * bit 7: direction (1 = read from device)
+ * bits 8-14: device number on port
+ * bits 15-18: endpoint of device
+ * bits 30-31: request type: 00 = isochronous, 01 = interrupt,
+ * 10 = control, 11 = bulk
+ * transfer_flags - uint16_t, bit field with processing flags:
+ * bit 0: less data than specified allowed
+ * buffer_length - uint16_t, total length of data
+ * request type specific data - 8 bytes, see below
+ * seg[] - array with 8 byte elements, see below
+ *
+ * Request type specific data for isochronous request:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | interval | start_frame | 4
+ * +----------------+----------------+----------------+----------------+
+ * | number_of_packets | nr_frame_desc_segs | 8
+ * +----------------+----------------+----------------+----------------+
+ * interval - uint16_t, time interval in msecs between frames
+ * start_frame - uint16_t, start frame number
+ * number_of_packets - uint16_t, number of packets to transfer
+ * nr_frame_desc_segs - uint16_t number of seg[] frame descriptors elements
+ *
+ * Request type specific data for interrupt request:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | interval | 0 | 4
+ * +----------------+----------------+----------------+----------------+
+ * | 0 | 8
+ * +----------------+----------------+----------------+----------------+
+ * interval - uint16_t, time in msecs until interruption
+ *
+ * Request type specific data for control request:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | data of setup packet | 4
+ * | | 8
+ * +----------------+----------------+----------------+----------------+
+ *
+ * Request type specific data for bulk request:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | 0 | 4
+ * | 0 | 8
+ * +----------------+----------------+----------------+----------------+
+ *
+ * Request type specific data for unlink request:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | unlink_id | 0 | 4
+ * +----------------+----------------+----------------+----------------+
+ * | 0 | 8
+ * +----------------+----------------+----------------+----------------+
+ * unlink_id - uint16_t, request id of request to terminate
+ *
+ * seg[] array element layout:
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | gref | 4
+ * +----------------+----------------+----------------+----------------+
+ * | offset | length | 8
+ * +----------------+----------------+----------------+----------------+
+ * gref - uint32_t, grant reference of buffer page
+ * offset - uint16_t, offset of buffer start in page
+ * length - uint16_t, length of buffer in page
+ *
+ *-------------------------- USB I/O response --------------------------------
+ *
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | id | start_frame | 4
+ * +----------------+----------------+----------------+----------------+
+ * | status | 8
+ * +----------------+----------------+----------------+----------------+
+ * | actual_length | 12
+ * +----------------+----------------+----------------+----------------+
+ * | error_count | 16
+ * +----------------+----------------+----------------+----------------+
+ * id - uint16_t, id of the request this response belongs to
+ * start_frame - uint16_t, start_frame this response (iso requests only)
+ * status - int32_t, XENUSB_STATUS_* (non-iso requests)
+ * actual_length - uint32_t, actual size of data transferred
+ * error_count - uint32_t, number of errors (iso requests)
+ */
+
+enum xenusb_spec_version {
+ XENUSB_VER_UNKNOWN = 0,
+ XENUSB_VER_USB11,
+ XENUSB_VER_USB20,
+ XENUSB_VER_USB30, /* not supported yet */
+};
+
+/*
+ * USB pipe in xenusb_request
+ *
+ * - port number: bits 0-4
+ * (USB_MAXCHILDREN is 31)
+ *
+ * - operation flag: bit 5
+ * (0 = submit urb,
+ * 1 = unlink urb)
+ *
+ * - direction: bit 7
+ * (0 = Host-to-Device [Out]
+ * 1 = Device-to-Host [In])
+ *
+ * - device address: bits 8-14
+ *
+ * - endpoint: bits 15-18
+ *
+ * - pipe type: bits 30-31
+ * (00 = isochronous, 01 = interrupt,
+ * 10 = control, 11 = bulk)
+ */
+
+#define XENUSB_PIPE_PORT_MASK 0x0000001f
+#define XENUSB_PIPE_UNLINK 0x00000020
+#define XENUSB_PIPE_DIR 0x00000080
+#define XENUSB_PIPE_DEV_MASK 0x0000007f
+#define XENUSB_PIPE_DEV_SHIFT 8
+#define XENUSB_PIPE_EP_MASK 0x0000000f
+#define XENUSB_PIPE_EP_SHIFT 15
+#define XENUSB_PIPE_TYPE_MASK 0x00000003
+#define XENUSB_PIPE_TYPE_SHIFT 30
+#define XENUSB_PIPE_TYPE_ISOC 0
+#define XENUSB_PIPE_TYPE_INT 1
+#define XENUSB_PIPE_TYPE_CTRL 2
+#define XENUSB_PIPE_TYPE_BULK 3
+
+#define xenusb_pipeportnum(pipe) ((pipe) & XENUSB_PIPE_PORT_MASK)
+#define xenusb_setportnum_pipe(pipe, portnum) ((pipe) | (portnum))
+
+#define xenusb_pipeunlink(pipe) ((pipe) & XENUSB_PIPE_UNLINK)
+#define xenusb_pipesubmit(pipe) (!xenusb_pipeunlink(pipe))
+#define xenusb_setunlink_pipe(pipe) ((pipe) | XENUSB_PIPE_UNLINK)
+
+#define xenusb_pipein(pipe) ((pipe) & XENUSB_PIPE_DIR)
+#define xenusb_pipeout(pipe) (!xenusb_pipein(pipe))
+
+#define xenusb_pipedevice(pipe) \
+ (((pipe) >> XENUSB_PIPE_DEV_SHIFT) & XENUSB_PIPE_DEV_MASK)
+
+#define xenusb_pipeendpoint(pipe) \
+ (((pipe) >> XENUSB_PIPE_EP_SHIFT) & XENUSB_PIPE_EP_MASK)
+
+#define xenusb_pipetype(pipe) \
+ (((pipe) >> XENUSB_PIPE_TYPE_SHIFT) & XENUSB_PIPE_TYPE_MASK)
+#define xenusb_pipeisoc(pipe) (xenusb_pipetype(pipe) == XENUSB_PIPE_TYPE_ISOC)
+#define xenusb_pipeint(pipe) (xenusb_pipetype(pipe) == XENUSB_PIPE_TYPE_INT)
+#define xenusb_pipectrl(pipe) (xenusb_pipetype(pipe) == XENUSB_PIPE_TYPE_CTRL)
+#define xenusb_pipebulk(pipe) (xenusb_pipetype(pipe) == XENUSB_PIPE_TYPE_BULK)
+
+#define XENUSB_MAX_SEGMENTS_PER_REQUEST (16)
+#define XENUSB_MAX_PORTNR 31
+#define XENUSB_RING_SIZE 4096
+
+/*
+ * RING for transferring urbs.
+ */
+struct xenusb_request_segment {
+ grant_ref_t gref;
+ uint16_t offset;
+ uint16_t length;
+};
+
+struct xenusb_urb_request {
+ uint16_t id; /* request id */
+ uint16_t nr_buffer_segs; /* number of urb->transfer_buffer segments */
+
+ /* basic urb parameter */
+ uint32_t pipe;
+ uint16_t transfer_flags;
+#define XENUSB_SHORT_NOT_OK 0x0001
+ uint16_t buffer_length;
+ union {
+ uint8_t ctrl[8]; /* setup_packet (Ctrl) */
+
+ struct {
+ uint16_t interval; /* maximum (1024*8) in usb core */
+ uint16_t start_frame; /* start frame */
+ uint16_t number_of_packets; /* number of ISO packet */
+ uint16_t nr_frame_desc_segs; /* number of iso_frame_desc segments */
+ } isoc;
+
+ struct {
+ uint16_t interval; /* maximum (1024*8) in usb core */
+ uint16_t pad[3];
+ } intr;
+
+ struct {
+ uint16_t unlink_id; /* unlink request id */
+ uint16_t pad[3];
+ } unlink;
+
+ } u;
+
+ /* urb data segments */
+ struct xenusb_request_segment seg[XENUSB_MAX_SEGMENTS_PER_REQUEST];
+};
+
+struct xenusb_urb_response {
+ uint16_t id; /* request id */
+ uint16_t start_frame; /* start frame (ISO) */
+ int32_t status; /* status (non-ISO) */
+#define XENUSB_STATUS_OK 0
+#define XENUSB_STATUS_NODEV (-19)
+#define XENUSB_STATUS_INVAL (-22)
+#define XENUSB_STATUS_STALL (-32)
+#define XENUSB_STATUS_IOERROR (-71)
+#define XENUSB_STATUS_BABBLE (-75)
+#define XENUSB_STATUS_SHUTDOWN (-108)
+ int32_t actual_length; /* actual transfer length */
+ int32_t error_count; /* number of ISO errors */
+};
+
+DEFINE_RING_TYPES(xenusb_urb, struct xenusb_urb_request, struct xenusb_urb_response);
+#define XENUSB_URB_RING_SIZE __CONST_RING_SIZE(xenusb_urb, XENUSB_RING_SIZE)
+
+/*
+ * RING for notifying connect/disconnect events to frontend
+ */
+struct xenusb_conn_request {
+ uint16_t id;
+};
+
+struct xenusb_conn_response {
+ uint16_t id; /* request id */
+ uint8_t portnum; /* port number */
+ uint8_t speed; /* usb_device_speed */
+#define XENUSB_SPEED_NONE 0
+#define XENUSB_SPEED_LOW 1
+#define XENUSB_SPEED_FULL 2
+#define XENUSB_SPEED_HIGH 3
+};
+
+DEFINE_RING_TYPES(xenusb_conn, struct xenusb_conn_request, struct xenusb_conn_response);
+#define XENUSB_CONN_RING_SIZE __CONST_RING_SIZE(xenusb_conn, XENUSB_RING_SIZE)
+
+#endif /* __XEN_PUBLIC_IO_USBIF_H__ */
--
2.26.2