Merge branch 'Thunderbolt-networking'

Mika Westerberg says:

====================
Thunderbolt networking

In addition of tunneling PCIe, Display Port and USB traffic, Thunderbolt
allows connecting two hosts (domains) over a Thunderbolt cable. It is
possible to tunnel arbitrary data packets over such connection using
high-speed DMA rings available in the Thunderbolt host controller.

In order to discover Thunderbolt services the other host supports, there is
a software protocol running on top of the automatically configured control
channel (ring 0). This protocol is called XDomain discovery protocol and it
uses XDomain properties to describe the host (domain) and the services it
supports.

Once both sides have agreed what services are supported they can enable
high-speed DMA rings to transfer data over the cable.

This series adds support for the XDomain protocol so that we expose each
remote connection as Thunderbolt XDomain device and each service as
Thunderbolt service device. On top of that we create an API that allows
writing drivers for these services and finally we provide an example
Thunderbolt service driver that creates virtual ethernet inferface that
allows tunneling networking packets over Thunderbolt cable. The API could
be used for creating other future Thunderbolt services, such as tunneling
SCSI over Thunderbolt, for example.

The XDomain protocol and networking support is also available in macOS and
Windows so this makes it possible to connect Linux to macOS and Windows as
well.

The patches are based on previous Thunderbolt networking patch series by
Amir Levy and Michael Jamet, that can be found here:

  https://lwn.net/Articles/705998/

The main difference to that patch series is that we have the XDomain
protocol running in the kernel now so there is no need for a separate
userspace daemon.

Note this does not affect the existing functionality, so security levels
and NVM firmware upgrade continue to work as before (with the small
exception that now sysfs also shows the XDomain connections and services in
addition to normal Thunderbolt devices). It is also possible to connect up
to 5 Thunderbolt devices and then another host, and the network driver
works exactly the same.

This is third version of the patch series. The previous versions can be
be found here:

  v2: https://lkml.org/lkml/2017/9/25/225
  v1: https://lwn.net/Articles/734019/

Changes from the v2:

  * Add comment regarding calculation of interrupt throttling value
  * Add UUIDs as strings in comments on top of each declaration
  * Add a patch removing __packed from existing ICM messages. They are all
    32-bit aligned and should pack fine without the __packed.
  * Move adding MAINTAINERS entries to a separate patches
  * Added Michael and Yehezkel to be maintainers of the network driver
  * Remove __packed from the new ICM messages. They should pack fine as
    well without it.
  * Call register_netdev() after all other initialization is done in the
    network driver.
  * Use build_skb() instead of copying. We allocate order 1 page here to
    leave room for SKB shared info required by build_skb(). However, we do
    not leave room for full NET_SKB_PAD because the NHI hardware does not
    cope well if a frame crosses 4kB boundary. According comments in
    __build_skb() that should still be fine.
  * Added Reviewed-by tag from Andy.

Changes from the v1:

  * Add include/linux/thunderbolt.h to MAINTAINERS
  * Correct Linux version and date of new sysfs entries in
    Documentation/ABI/testing/sysfs-bus-thunderbolt
  * Move network driver from drivers/thunderbolt/net.c to
    drivers/net/thunderbolt.c and update it to follow coding style in
    drivers/net/*.
  * Add MAINTAINERS entry for the network driver
  * Minor cleanups

In case someone wants to try this out, the last patch adds documentation
how the networking driver can be used. In short, if you connect Linux to a
macOS or Windows, everything is done automatically (as those systems have
the networking service enabled by default). For Linux to Linux connection
one host needs to load the networking driver first (so that the other side
can locate the networking service and load the corresponding driver).
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 640 insertions, 0 deletions

diff --git a/include/linux/byteorder/generic.h b/include/linux/byteorder/generic.h
index 89f67c1c3160..805d16654459 100644
--- a/include/linux/byteorder/generic.h
+++ b/include/linux/byteorder/generic.h
@@ -170,4 +170,20 @@ static inline void be64_add_cpu(__be64 *var, u64 val)
 	*var = cpu_to_be64(be64_to_cpu(*var) + val);
 }
 
+static inline void cpu_to_be32_array(__be32 *dst, const u32 *src, size_t len)
+{
+	int i;
+
+	for (i = 0; i < len; i++)
+		dst[i] = cpu_to_be32(src[i]);
+}
+
+static inline void be32_to_cpu_array(u32 *dst, const __be32 *src, size_t len)
+{
+	int i;
+
+	for (i = 0; i < len; i++)
+		dst[i] = be32_to_cpu(src[i]);
+}
+
 #endif /* _LINUX_BYTEORDER_GENERIC_H */
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 694cebb50f72..7625c3b81f84 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -683,5 +683,31 @@ struct fsl_mc_device_id {
 	const char obj_type[16];
 };
 
+/**
+ * struct tb_service_id - Thunderbolt service identifiers
+ * @match_flags: Flags used to match the structure
+ * @protocol_key: Protocol key the service supports
+ * @protocol_id: Protocol id the service supports
+ * @protocol_version: Version of the protocol
+ * @protocol_revision: Revision of the protocol software
+ * @driver_data: Driver specific data
+ *
+ * Thunderbolt XDomain services are exposed as devices where each device
+ * carries the protocol information the service supports. Thunderbolt
+ * XDomain service drivers match against that information.
+ */
+struct tb_service_id {
+	__u32 match_flags;
+	char protocol_key[8 + 1];
+	__u32 protocol_id;
+	__u32 protocol_version;
+	__u32 protocol_revision;
+	kernel_ulong_t driver_data;
+};
+
+#define TBSVC_MATCH_PROTOCOL_KEY	0x0001
+#define TBSVC_MATCH_PROTOCOL_ID		0x0002
+#define TBSVC_MATCH_PROTOCOL_VERSION	0x0004
+#define TBSVC_MATCH_PROTOCOL_REVISION	0x0008
 
 #endif /* LINUX_MOD_DEVICETABLE_H */
diff --git a/include/linux/thunderbolt.h b/include/linux/thunderbolt.h
new file mode 100644
index 000000000000..7b69853188b1
--- /dev/null
+++ b/include/linux/thunderbolt.h
@@ -0,0 +1,598 @@
+/*
+ * Thunderbolt service API
+ *
+ * Copyright (C) 2014 Andreas Noever <andreas.noever@gmail.com>
+ * Copyright (C) 2017, Intel Corporation
+ * Authors: Michael Jamet <michael.jamet@intel.com>
+ *          Mika Westerberg <mika.westerberg@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef THUNDERBOLT_H_
+#define THUNDERBOLT_H_
+
+#include <linux/device.h>
+#include <linux/idr.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/mod_devicetable.h>
+#include <linux/pci.h>
+#include <linux/uuid.h>
+#include <linux/workqueue.h>
+
+enum tb_cfg_pkg_type {
+	TB_CFG_PKG_READ = 1,
+	TB_CFG_PKG_WRITE = 2,
+	TB_CFG_PKG_ERROR = 3,
+	TB_CFG_PKG_NOTIFY_ACK = 4,
+	TB_CFG_PKG_EVENT = 5,
+	TB_CFG_PKG_XDOMAIN_REQ = 6,
+	TB_CFG_PKG_XDOMAIN_RESP = 7,
+	TB_CFG_PKG_OVERRIDE = 8,
+	TB_CFG_PKG_RESET = 9,
+	TB_CFG_PKG_ICM_EVENT = 10,
+	TB_CFG_PKG_ICM_CMD = 11,
+	TB_CFG_PKG_ICM_RESP = 12,
+	TB_CFG_PKG_PREPARE_TO_SLEEP = 13,
+};
+
+/**
+ * enum tb_security_level - Thunderbolt security level
+ * @TB_SECURITY_NONE: No security, legacy mode
+ * @TB_SECURITY_USER: User approval required at minimum
+ * @TB_SECURITY_SECURE: One time saved key required at minimum
+ * @TB_SECURITY_DPONLY: Only tunnel Display port (and USB)
+ */
+enum tb_security_level {
+	TB_SECURITY_NONE,
+	TB_SECURITY_USER,
+	TB_SECURITY_SECURE,
+	TB_SECURITY_DPONLY,
+};
+
+/**
+ * struct tb - main thunderbolt bus structure
+ * @dev: Domain device
+ * @lock: Big lock. Must be held when accessing any struct
+ *	  tb_switch / struct tb_port.
+ * @nhi: Pointer to the NHI structure
+ * @ctl: Control channel for this domain
+ * @wq: Ordered workqueue for all domain specific work
+ * @root_switch: Root switch of this domain
+ * @cm_ops: Connection manager specific operations vector
+ * @index: Linux assigned domain number
+ * @security_level: Current security level
+ * @privdata: Private connection manager specific data
+ */
+struct tb {
+	struct device dev;
+	struct mutex lock;
+	struct tb_nhi *nhi;
+	struct tb_ctl *ctl;
+	struct workqueue_struct *wq;
+	struct tb_switch *root_switch;
+	const struct tb_cm_ops *cm_ops;
+	int index;
+	enum tb_security_level security_level;
+	unsigned long privdata[0];
+};
+
+extern struct bus_type tb_bus_type;
+extern struct device_type tb_service_type;
+extern struct device_type tb_xdomain_type;
+
+#define TB_LINKS_PER_PHY_PORT	2
+
+static inline unsigned int tb_phy_port_from_link(unsigned int link)
+{
+	return (link - 1) / TB_LINKS_PER_PHY_PORT;
+}
+
+/**
+ * struct tb_property_dir - XDomain property directory
+ * @uuid: Directory UUID or %NULL if root directory
+ * @properties: List of properties in this directory
+ *
+ * User needs to provide serialization if needed.
+ */
+struct tb_property_dir {
+	const uuid_t *uuid;
+	struct list_head properties;
+};
+
+enum tb_property_type {
+	TB_PROPERTY_TYPE_UNKNOWN = 0x00,
+	TB_PROPERTY_TYPE_DIRECTORY = 0x44,
+	TB_PROPERTY_TYPE_DATA = 0x64,
+	TB_PROPERTY_TYPE_TEXT = 0x74,
+	TB_PROPERTY_TYPE_VALUE = 0x76,
+};
+
+#define TB_PROPERTY_KEY_SIZE	8
+
+/**
+ * struct tb_property - XDomain property
+ * @list: Used to link properties together in a directory
+ * @key: Key for the property (always terminated).
+ * @type: Type of the property
+ * @length: Length of the property data in dwords
+ * @value: Property value
+ *
+ * Users use @type to determine which field in @value is filled.
+ */
+struct tb_property {
+	struct list_head list;
+	char key[TB_PROPERTY_KEY_SIZE + 1];
+	enum tb_property_type type;
+	size_t length;
+	union {
+		struct tb_property_dir *dir;
+		u8 *data;
+		char *text;
+		u32 immediate;
+	} value;
+};
+
+struct tb_property_dir *tb_property_parse_dir(const u32 *block,
+					      size_t block_len);
+ssize_t tb_property_format_dir(const struct tb_property_dir *dir, u32 *block,
+			       size_t block_len);
+struct tb_property_dir *tb_property_create_dir(const uuid_t *uuid);
+void tb_property_free_dir(struct tb_property_dir *dir);
+int tb_property_add_immediate(struct tb_property_dir *parent, const char *key,
+			      u32 value);
+int tb_property_add_data(struct tb_property_dir *parent, const char *key,
+			 const void *buf, size_t buflen);
+int tb_property_add_text(struct tb_property_dir *parent, const char *key,
+			 const char *text);
+int tb_property_add_dir(struct tb_property_dir *parent, const char *key,
+			struct tb_property_dir *dir);
+void tb_property_remove(struct tb_property *tb_property);
+struct tb_property *tb_property_find(struct tb_property_dir *dir,
+			const char *key, enum tb_property_type type);
+struct tb_property *tb_property_get_next(struct tb_property_dir *dir,
+					 struct tb_property *prev);
+
+#define tb_property_for_each(dir, property)			\
+	for (property = tb_property_get_next(dir, NULL);	\
+	     property;						\
+	     property = tb_property_get_next(dir, property))
+
+int tb_register_property_dir(const char *key, struct tb_property_dir *dir);
+void tb_unregister_property_dir(const char *key, struct tb_property_dir *dir);
+
+/**
+ * struct tb_xdomain - Cross-domain (XDomain) connection
+ * @dev: XDomain device
+ * @tb: Pointer to the domain
+ * @remote_uuid: UUID of the remote domain (host)
+ * @local_uuid: Cached local UUID
+ * @route: Route string the other domain can be reached
+ * @vendor: Vendor ID of the remote domain
+ * @device: Device ID of the demote domain
+ * @lock: Lock to serialize access to the following fields of this structure
+ * @vendor_name: Name of the vendor (or %NULL if not known)
+ * @device_name: Name of the device (or %NULL if not known)
+ * @is_unplugged: The XDomain is unplugged
+ * @resume: The XDomain is being resumed
+ * @transmit_path: HopID which the remote end expects us to transmit
+ * @transmit_ring: Local ring (hop) where outgoing packets are pushed
+ * @receive_path: HopID which we expect the remote end to transmit
+ * @receive_ring: Local ring (hop) where incoming packets arrive
+ * @service_ids: Used to generate IDs for the services
+ * @properties: Properties exported by the remote domain
+ * @property_block_gen: Generation of @properties
+ * @properties_lock: Lock protecting @properties.
+ * @get_properties_work: Work used to get remote domain properties
+ * @properties_retries: Number of times left to read properties
+ * @properties_changed_work: Work used to notify the remote domain that
+ *			     our properties have changed
+ * @properties_changed_retries: Number of times left to send properties
+ *				changed notification
+ * @link: Root switch link the remote domain is connected (ICM only)
+ * @depth: Depth in the chain the remote domain is connected (ICM only)
+ *
+ * This structure represents connection across two domains (hosts).
+ * Each XDomain contains zero or more services which are exposed as
+ * &struct tb_service objects.
+ *
+ * Service drivers may access this structure if they need to enumerate
+ * non-standard properties but they need hold @lock when doing so
+ * because properties can be changed asynchronously in response to
+ * changes in the remote domain.
+ */
+struct tb_xdomain {
+	struct device dev;
+	struct tb *tb;
+	uuid_t *remote_uuid;
+	const uuid_t *local_uuid;
+	u64 route;
+	u16 vendor;
+	u16 device;
+	struct mutex lock;
+	const char *vendor_name;
+	const char *device_name;
+	bool is_unplugged;
+	bool resume;
+	u16 transmit_path;
+	u16 transmit_ring;
+	u16 receive_path;
+	u16 receive_ring;
+	struct ida service_ids;
+	struct tb_property_dir *properties;
+	u32 property_block_gen;
+	struct delayed_work get_properties_work;
+	int properties_retries;
+	struct delayed_work properties_changed_work;
+	int properties_changed_retries;
+	u8 link;
+	u8 depth;
+};
+
+int tb_xdomain_enable_paths(struct tb_xdomain *xd, u16 transmit_path,
+			    u16 transmit_ring, u16 receive_path,
+			    u16 receive_ring);
+int tb_xdomain_disable_paths(struct tb_xdomain *xd);
+struct tb_xdomain *tb_xdomain_find_by_uuid(struct tb *tb, const uuid_t *uuid);
+
+static inline struct tb_xdomain *
+tb_xdomain_find_by_uuid_locked(struct tb *tb, const uuid_t *uuid)
+{
+	struct tb_xdomain *xd;
+
+	mutex_lock(&tb->lock);
+	xd = tb_xdomain_find_by_uuid(tb, uuid);
+	mutex_unlock(&tb->lock);
+
+	return xd;
+}
+
+static inline struct tb_xdomain *tb_xdomain_get(struct tb_xdomain *xd)
+{
+	if (xd)
+		get_device(&xd->dev);
+	return xd;
+}
+
+static inline void tb_xdomain_put(struct tb_xdomain *xd)
+{
+	if (xd)
+		put_device(&xd->dev);
+}
+
+static inline bool tb_is_xdomain(const struct device *dev)
+{
+	return dev->type == &tb_xdomain_type;
+}
+
+static inline struct tb_xdomain *tb_to_xdomain(struct device *dev)
+{
+	if (tb_is_xdomain(dev))
+		return container_of(dev, struct tb_xdomain, dev);
+	return NULL;
+}
+
+int tb_xdomain_response(struct tb_xdomain *xd, const void *response,
+			size_t size, enum tb_cfg_pkg_type type);
+int tb_xdomain_request(struct tb_xdomain *xd, const void *request,
+		       size_t request_size, enum tb_cfg_pkg_type request_type,
+		       void *response, size_t response_size,
+		       enum tb_cfg_pkg_type response_type,
+		       unsigned int timeout_msec);
+
+/**
+ * tb_protocol_handler - Protocol specific handler
+ * @uuid: XDomain messages with this UUID are dispatched to this handler
+ * @callback: Callback called with the XDomain message. Returning %1
+ *	      here tells the XDomain core that the message was handled
+ *	      by this handler and should not be forwared to other
+ *	      handlers.
+ * @data: Data passed with the callback
+ * @list: Handlers are linked using this
+ *
+ * Thunderbolt services can hook into incoming XDomain requests by
+ * registering protocol handler. Only limitation is that the XDomain
+ * discovery protocol UUID cannot be registered since it is handled by
+ * the core XDomain code.
+ *
+ * The @callback must check that the message is really directed to the
+ * service the driver implements.
+ */
+struct tb_protocol_handler {
+	const uuid_t *uuid;
+	int (*callback)(const void *buf, size_t size, void *data);
+	void *data;
+	struct list_head list;
+};
+
+int tb_register_protocol_handler(struct tb_protocol_handler *handler);
+void tb_unregister_protocol_handler(struct tb_protocol_handler *handler);
+
+/**
+ * struct tb_service - Thunderbolt service
+ * @dev: XDomain device
+ * @id: ID of the service (shown in sysfs)
+ * @key: Protocol key from the properties directory
+ * @prtcid: Protocol ID from the properties directory
+ * @prtcvers: Protocol version from the properties directory
+ * @prtcrevs: Protocol software revision from the properties directory
+ * @prtcstns: Protocol settings mask from the properties directory
+ *
+ * Each domain exposes set of services it supports as collection of
+ * properties. For each service there will be one corresponding
+ * &struct tb_service. Service drivers are bound to these.
+ */
+struct tb_service {
+	struct device dev;
+	int id;
+	const char *key;
+	u32 prtcid;
+	u32 prtcvers;
+	u32 prtcrevs;
+	u32 prtcstns;
+};
+
+static inline struct tb_service *tb_service_get(struct tb_service *svc)
+{
+	if (svc)
+		get_device(&svc->dev);
+	return svc;
+}
+
+static inline void tb_service_put(struct tb_service *svc)
+{
+	if (svc)
+		put_device(&svc->dev);
+}
+
+static inline bool tb_is_service(const struct device *dev)
+{
+	return dev->type == &tb_service_type;
+}
+
+static inline struct tb_service *tb_to_service(struct device *dev)
+{
+	if (tb_is_service(dev))
+		return container_of(dev, struct tb_service, dev);
+	return NULL;
+}
+
+/**
+ * tb_service_driver - Thunderbolt service driver
+ * @driver: Driver structure
+ * @probe: Called when the driver is probed
+ * @remove: Called when the driver is removed (optional)
+ * @shutdown: Called at shutdown time to stop the service (optional)
+ * @id_table: Table of service identifiers the driver supports
+ */
+struct tb_service_driver {
+	struct device_driver driver;
+	int (*probe)(struct tb_service *svc, const struct tb_service_id *id);
+	void (*remove)(struct tb_service *svc);
+	void (*shutdown)(struct tb_service *svc);
+	const struct tb_service_id *id_table;
+};
+
+#define TB_SERVICE(key, id)				\
+	.match_flags = TBSVC_MATCH_PROTOCOL_KEY |	\
+		       TBSVC_MATCH_PROTOCOL_ID,		\
+	.protocol_key = (key),				\
+	.protocol_id = (id)
+
+int tb_register_service_driver(struct tb_service_driver *drv);
+void tb_unregister_service_driver(struct tb_service_driver *drv);
+
+static inline void *tb_service_get_drvdata(const struct tb_service *svc)
+{
+	return dev_get_drvdata(&svc->dev);
+}
+
+static inline void tb_service_set_drvdata(struct tb_service *svc, void *data)
+{
+	dev_set_drvdata(&svc->dev, data);
+}
+
+static inline struct tb_xdomain *tb_service_parent(struct tb_service *svc)
+{
+	return tb_to_xdomain(svc->dev.parent);
+}
+
+/**
+ * struct tb_nhi - thunderbolt native host interface
+ * @lock: Must be held during ring creation/destruction. Is acquired by
+ *	  interrupt_work when dispatching interrupts to individual rings.
+ * @pdev: Pointer to the PCI device
+ * @iobase: MMIO space of the NHI
+ * @tx_rings: All Tx rings available on this host controller
+ * @rx_rings: All Rx rings available on this host controller
+ * @msix_ida: Used to allocate MSI-X vectors for rings
+ * @going_away: The host controller device is about to disappear so when
+ *		this flag is set, avoid touching the hardware anymore.
+ * @interrupt_work: Work scheduled to handle ring interrupt when no
+ *		    MSI-X is used.
+ * @hop_count: Number of rings (end point hops) supported by NHI.
+ */
+struct tb_nhi {
+	spinlock_t lock;
+	struct pci_dev *pdev;
+	void __iomem *iobase;
+	struct tb_ring **tx_rings;
+	struct tb_ring **rx_rings;
+	struct ida msix_ida;
+	bool going_away;
+	struct work_struct interrupt_work;
+	u32 hop_count;
+};
+
+/**
+ * struct tb_ring - thunderbolt TX or RX ring associated with a NHI
+ * @lock: Lock serializing actions to this ring. Must be acquired after
+ *	  nhi->lock.
+ * @nhi: Pointer to the native host controller interface
+ * @size: Size of the ring
+ * @hop: Hop (DMA channel) associated with this ring
+ * @head: Head of the ring (write next descriptor here)
+ * @tail: Tail of the ring (complete next descriptor here)
+ * @descriptors: Allocated descriptors for this ring
+ * @queue: Queue holding frames to be transferred over this ring
+ * @in_flight: Queue holding frames that are currently in flight
+ * @work: Interrupt work structure
+ * @is_tx: Is the ring Tx or Rx
+ * @running: Is the ring running
+ * @irq: MSI-X irq number if the ring uses MSI-X. %0 otherwise.
+ * @vector: MSI-X vector number the ring uses (only set if @irq is > 0)
+ * @flags: Ring specific flags
+ * @sof_mask: Bit mask used to detect start of frame PDF
+ * @eof_mask: Bit mask used to detect end of frame PDF
+ * @start_poll: Called when ring interrupt is triggered to start
+ *		polling. Passing %NULL keeps the ring in interrupt mode.
+ * @poll_data: Data passed to @start_poll
+ */
+struct tb_ring {
+	spinlock_t lock;
+	struct tb_nhi *nhi;
+	int size;
+	int hop;
+	int head;
+	int tail;
+	struct ring_desc *descriptors;
+	dma_addr_t descriptors_dma;
+	struct list_head queue;
+	struct list_head in_flight;
+	struct work_struct work;
+	bool is_tx:1;
+	bool running:1;
+	int irq;
+	u8 vector;
+	unsigned int flags;
+	u16 sof_mask;
+	u16 eof_mask;
+	void (*start_poll)(void *data);
+	void *poll_data;
+};
+
+/* Leave ring interrupt enabled on suspend */
+#define RING_FLAG_NO_SUSPEND	BIT(0)
+/* Configure the ring to be in frame mode */
+#define RING_FLAG_FRAME		BIT(1)
+/* Enable end-to-end flow control */
+#define RING_FLAG_E2E		BIT(2)
+
+struct ring_frame;
+typedef void (*ring_cb)(struct tb_ring *, struct ring_frame *, bool canceled);
+
+/**
+ * enum ring_desc_flags - Flags for DMA ring descriptor
+ * %RING_DESC_ISOCH: Enable isonchronous DMA (Tx only)
+ * %RING_DESC_CRC_ERROR: In frame mode CRC check failed for the frame (Rx only)
+ * %RING_DESC_COMPLETED: Descriptor completed (set by NHI)
+ * %RING_DESC_POSTED: Always set this
+ * %RING_DESC_BUFFER_OVERRUN: RX buffer overrun
+ * %RING_DESC_INTERRUPT: Request an interrupt on completion
+ */
+enum ring_desc_flags {
+	RING_DESC_ISOCH = 0x1,
+	RING_DESC_CRC_ERROR = 0x1,
+	RING_DESC_COMPLETED = 0x2,
+	RING_DESC_POSTED = 0x4,
+	RING_DESC_BUFFER_OVERRUN = 0x04,
+	RING_DESC_INTERRUPT = 0x8,
+};
+
+/**
+ * struct ring_frame - For use with ring_rx/ring_tx
+ * @buffer_phy: DMA mapped address of the frame
+ * @callback: Callback called when the frame is finished (optional)
+ * @list: Frame is linked to a queue using this
+ * @size: Size of the frame in bytes (%0 means %4096)
+ * @flags: Flags for the frame (see &enum ring_desc_flags)
+ * @eof: End of frame protocol defined field
+ * @sof: Start of frame protocol defined field
+ */
+struct ring_frame {
+	dma_addr_t buffer_phy;
+	ring_cb callback;
+	struct list_head list;
+	u32 size:12;
+	u32 flags:12;
+	u32 eof:4;
+	u32 sof:4;
+};
+
+/* Minimum size for ring_rx */
+#define TB_FRAME_SIZE		0x100
+
+struct tb_ring *tb_ring_alloc_tx(struct tb_nhi *nhi, int hop, int size,
+				 unsigned int flags);
+struct tb_ring *tb_ring_alloc_rx(struct tb_nhi *nhi, int hop, int size,
+				 unsigned int flags, u16 sof_mask, u16 eof_mask,
+				 void (*start_poll)(void *), void *poll_data);
+void tb_ring_start(struct tb_ring *ring);
+void tb_ring_stop(struct tb_ring *ring);
+void tb_ring_free(struct tb_ring *ring);
+
+int __tb_ring_enqueue(struct tb_ring *ring, struct ring_frame *frame);
+
+/**
+ * tb_ring_rx() - enqueue a frame on an RX ring
+ * @ring: Ring to enqueue the frame
+ * @frame: Frame to enqueue
+ *
+ * @frame->buffer, @frame->buffer_phy have to be set. The buffer must
+ * contain at least %TB_FRAME_SIZE bytes.
+ *
+ * @frame->callback will be invoked with @frame->size, @frame->flags,
+ * @frame->eof, @frame->sof set once the frame has been received.
+ *
+ * If ring_stop() is called after the packet has been enqueued
+ * @frame->callback will be called with canceled set to true.
+ *
+ * Return: Returns %-ESHUTDOWN if ring_stop has been called. Zero otherwise.
+ */
+static inline int tb_ring_rx(struct tb_ring *ring, struct ring_frame *frame)
+{
+	WARN_ON(ring->is_tx);
+	return __tb_ring_enqueue(ring, frame);
+}
+
+/**
+ * tb_ring_tx() - enqueue a frame on an TX ring
+ * @ring: Ring the enqueue the frame
+ * @frame: Frame to enqueue
+ *
+ * @frame->buffer, @frame->buffer_phy, @frame->size, @frame->eof and
+ * @frame->sof have to be set.
+ *
+ * @frame->callback will be invoked with once the frame has been transmitted.
+ *
+ * If ring_stop() is called after the packet has been enqueued @frame->callback
+ * will be called with canceled set to true.
+ *
+ * Return: Returns %-ESHUTDOWN if ring_stop has been called. Zero otherwise.
+ */
+static inline int tb_ring_tx(struct tb_ring *ring, struct ring_frame *frame)
+{
+	WARN_ON(!ring->is_tx);
+	return __tb_ring_enqueue(ring, frame);
+}
+
+/* Used only when the ring is in polling mode */
+struct ring_frame *tb_ring_poll(struct tb_ring *ring);
+void tb_ring_poll_complete(struct tb_ring *ring);
+
+/**
+ * tb_ring_dma_device() - Return device used for DMA mapping
+ * @ring: Ring whose DMA device is retrieved
+ *
+ * Use this function when you are mapping DMA for buffers that are
+ * passed to the ring for sending/receiving.
+ */
+static inline struct device *tb_ring_dma_device(struct tb_ring *ring)
+{
+	return &ring->nhi->pdev->dev;
+}
+
+#endif /* THUNDERBOLT_H_ */