thunderbolt: Add support for XDomain discovery protocol

When two hosts are connected over a Thunderbolt cable, there is a
protocol they can use to communicate capabilities supported by the host.
The discovery protocol uses automatically configured control channel
(ring 0) and is build on top of request/response transactions using
special XDomain primitives provided by the Thunderbolt base protocol.

The capabilities consists of a root directory block of basic properties
used for identification of the host, and then there can be zero or more
directories each describing a Thunderbolt service and its capabilities.

Once both sides have discovered what is supported the two hosts can
setup high-speed DMA paths and transfer data to the other side using
whatever protocol was agreed based on the properties. The software
protocol used to communicate which DMA paths to enable is service
specific.

This patch adds support for the XDomain discovery protocol to the
Thunderbolt bus. We model each remote host connection as a Linux XDomain
device. For each Thunderbolt service found supported on the XDomain
device, we create Linux Thunderbolt service device which Thunderbolt
service drivers can then bind to based on the protocol identification
information retrieved from the property directory describing the
service.

This code is based on the work done by Amir Levy and Michael Jamet.

Signed-off-by: Michael Jamet <michael.jamet@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 268 insertions, 0 deletions

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
index 43b8d1e09341..18c0e3d5e85c 100644
--- a/include/linux/thunderbolt.h
+++ b/include/linux/thunderbolt.h
@@ -17,6 +17,7 @@
 #include <linux/device.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/mod_devicetable.h>
 #include <linux/uuid.h>
 
 enum tb_cfg_pkg_type {
@@ -77,6 +78,8 @@ struct tb {
 };
 
 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
 
@@ -155,4 +158,243 @@ struct tb_property *tb_property_get_next(struct tb_property_dir *dir,
 	     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);
+}
+
 #endif /* THUNDERBOLT_H_ */