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Diffstat (limited to 'include/linux/surface_aggregator/serial_hub.h')
| -rw-r--r-- | include/linux/surface_aggregator/serial_hub.h | 672 |
1 files changed, 672 insertions, 0 deletions
diff --git a/include/linux/surface_aggregator/serial_hub.h b/include/linux/surface_aggregator/serial_hub.h new file mode 100644 index 000000000000..64276fbfa1d5 --- /dev/null +++ b/include/linux/surface_aggregator/serial_hub.h @@ -0,0 +1,672 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Surface Serial Hub (SSH) protocol and communication interface. + * + * Lower-level communication layers and SSH protocol definitions for the + * Surface System Aggregator Module (SSAM). Provides the interface for basic + * packet- and request-based communication with the SSAM EC via SSH. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#ifndef _LINUX_SURFACE_AGGREGATOR_SERIAL_HUB_H +#define _LINUX_SURFACE_AGGREGATOR_SERIAL_HUB_H + +#include <linux/crc-ccitt.h> +#include <linux/kref.h> +#include <linux/ktime.h> +#include <linux/list.h> +#include <linux/types.h> + + +/* -- Data structures for SAM-over-SSH communication. ----------------------- */ + +/** + * enum ssh_frame_type - Frame types for SSH frames. + * + * @SSH_FRAME_TYPE_DATA_SEQ: + * Indicates a data frame, followed by a payload with the length specified + * in the ``struct ssh_frame.len`` field. This frame is sequenced, meaning + * that an ACK is required. + * + * @SSH_FRAME_TYPE_DATA_NSQ: + * Same as %SSH_FRAME_TYPE_DATA_SEQ, but unsequenced, meaning that the + * message does not have to be ACKed. + * + * @SSH_FRAME_TYPE_ACK: + * Indicates an ACK message. + * + * @SSH_FRAME_TYPE_NAK: + * Indicates an error response for previously sent frame. In general, this + * means that the frame and/or payload is malformed, e.g. a CRC is wrong. + * For command-type payloads, this can also mean that the command is + * invalid. + */ +enum ssh_frame_type { + SSH_FRAME_TYPE_DATA_SEQ = 0x80, + SSH_FRAME_TYPE_DATA_NSQ = 0x00, + SSH_FRAME_TYPE_ACK = 0x40, + SSH_FRAME_TYPE_NAK = 0x04, +}; + +/** + * struct ssh_frame - SSH communication frame. + * @type: The type of the frame. See &enum ssh_frame_type. + * @len: The length of the frame payload directly following the CRC for this + * frame. Does not include the final CRC for that payload. + * @seq: The sequence number for this message/exchange. + */ +struct ssh_frame { + u8 type; + __le16 len; + u8 seq; +} __packed; + +static_assert(sizeof(struct ssh_frame) == 4); + +/* + * SSH_FRAME_MAX_PAYLOAD_SIZE - Maximum SSH frame payload length in bytes. + * + * This is the physical maximum length of the protocol. Implementations may + * set a more constrained limit. + */ +#define SSH_FRAME_MAX_PAYLOAD_SIZE U16_MAX + +/** + * enum ssh_payload_type - Type indicator for the SSH payload. + * @SSH_PLD_TYPE_CMD: The payload is a command structure with optional command + * payload. + */ +enum ssh_payload_type { + SSH_PLD_TYPE_CMD = 0x80, +}; + +/** + * struct ssh_command - Payload of a command-type frame. + * @type: The type of the payload. See &enum ssh_payload_type. Should be + * SSH_PLD_TYPE_CMD for this struct. + * @tc: Command target category. + * @tid_out: Output target ID. Should be zero if this an incoming (EC to host) + * message. + * @tid_in: Input target ID. Should be zero if this is an outgoing (host to + * EC) message. + * @iid: Instance ID. + * @rqid: Request ID. Used to match requests with responses and differentiate + * between responses and events. + * @cid: Command ID. + */ +struct ssh_command { + u8 type; + u8 tc; + u8 tid_out; + u8 tid_in; + u8 iid; + __le16 rqid; + u8 cid; +} __packed; + +static_assert(sizeof(struct ssh_command) == 8); + +/* + * SSH_COMMAND_MAX_PAYLOAD_SIZE - Maximum SSH command payload length in bytes. + * + * This is the physical maximum length of the protocol. Implementations may + * set a more constrained limit. + */ +#define SSH_COMMAND_MAX_PAYLOAD_SIZE \ + (SSH_FRAME_MAX_PAYLOAD_SIZE - sizeof(struct ssh_command)) + +/* + * SSH_MSG_LEN_BASE - Base-length of a SSH message. + * + * This is the minimum number of bytes required to form a message. The actual + * message length is SSH_MSG_LEN_BASE plus the length of the frame payload. + */ +#define SSH_MSG_LEN_BASE (sizeof(struct ssh_frame) + 3ull * sizeof(u16)) + +/* + * SSH_MSG_LEN_CTRL - Length of a SSH control message. + * + * This is the length of a SSH control message, which is equal to a SSH + * message without any payload. + */ +#define SSH_MSG_LEN_CTRL SSH_MSG_LEN_BASE + +/** + * SSH_MESSAGE_LENGTH() - Compute length of SSH message. + * @payload_size: Length of the payload inside the SSH frame. + * + * Return: Returns the length of a SSH message with payload of specified size. + */ +#define SSH_MESSAGE_LENGTH(payload_size) (SSH_MSG_LEN_BASE + (payload_size)) + +/** + * SSH_COMMAND_MESSAGE_LENGTH() - Compute length of SSH command message. + * @payload_size: Length of the command payload. + * + * Return: Returns the length of a SSH command message with command payload of + * specified size. + */ +#define SSH_COMMAND_MESSAGE_LENGTH(payload_size) \ + SSH_MESSAGE_LENGTH(sizeof(struct ssh_command) + (payload_size)) + +/** + * SSH_MSGOFFSET_FRAME() - Compute offset in SSH message to specified field in + * frame. + * @field: The field for which the offset should be computed. + * + * Return: Returns the offset of the specified &struct ssh_frame field in the + * raw SSH message data as. Takes SYN bytes (u16) preceding the frame into + * account. + */ +#define SSH_MSGOFFSET_FRAME(field) \ + (sizeof(u16) + offsetof(struct ssh_frame, field)) + +/** + * SSH_MSGOFFSET_COMMAND() - Compute offset in SSH message to specified field + * in command. + * @field: The field for which the offset should be computed. + * + * Return: Returns the offset of the specified &struct ssh_command field in + * the raw SSH message data. Takes SYN bytes (u16) preceding the frame and the + * frame CRC (u16) between frame and command into account. + */ +#define SSH_MSGOFFSET_COMMAND(field) \ + (2ull * sizeof(u16) + sizeof(struct ssh_frame) \ + + offsetof(struct ssh_command, field)) + +/* + * SSH_MSG_SYN - SSH message synchronization (SYN) bytes as u16. + */ +#define SSH_MSG_SYN ((u16)0x55aa) + +/** + * ssh_crc() - Compute CRC for SSH messages. + * @buf: The pointer pointing to the data for which the CRC should be computed. + * @len: The length of the data for which the CRC should be computed. + * + * Return: Returns the CRC computed on the provided data, as used for SSH + * messages. + */ +static inline u16 ssh_crc(const u8 *buf, size_t len) +{ + return crc_ccitt_false(0xffff, buf, len); +} + +/* + * SSH_NUM_EVENTS - The number of reserved event IDs. + * + * The number of reserved event IDs, used for registering an SSH event + * handler. Valid event IDs are numbers below or equal to this value, with + * exception of zero, which is not an event ID. Thus, this is also the + * absolute maximum number of event handlers that can be registered. + */ +#define SSH_NUM_EVENTS 34 + +/* + * SSH_NUM_TARGETS - The number of communication targets used in the protocol. + */ +#define SSH_NUM_TARGETS 2 + +/** + * ssh_rqid_next_valid() - Return the next valid request ID. + * @rqid: The current request ID. + * + * Return: Returns the next valid request ID, following the current request ID + * provided to this function. This function skips any request IDs reserved for + * events. + */ +static inline u16 ssh_rqid_next_valid(u16 rqid) +{ + return rqid > 0 ? rqid + 1u : rqid + SSH_NUM_EVENTS + 1u; +} + +/** + * ssh_rqid_to_event() - Convert request ID to its corresponding event ID. + * @rqid: The request ID to convert. + */ +static inline u16 ssh_rqid_to_event(u16 rqid) +{ + return rqid - 1u; +} + +/** + * ssh_rqid_is_event() - Check if given request ID is a valid event ID. + * @rqid: The request ID to check. + */ +static inline bool ssh_rqid_is_event(u16 rqid) +{ + return ssh_rqid_to_event(rqid) < SSH_NUM_EVENTS; +} + +/** + * ssh_tc_to_rqid() - Convert target category to its corresponding request ID. + * @tc: The target category to convert. + */ +static inline u16 ssh_tc_to_rqid(u8 tc) +{ + return tc; +} + +/** + * ssh_tid_to_index() - Convert target ID to its corresponding target index. + * @tid: The target ID to convert. + */ +static inline u8 ssh_tid_to_index(u8 tid) +{ + return tid - 1u; +} + +/** + * ssh_tid_is_valid() - Check if target ID is valid/supported. + * @tid: The target ID to check. + */ +static inline bool ssh_tid_is_valid(u8 tid) +{ + return ssh_tid_to_index(tid) < SSH_NUM_TARGETS; +} + +/** + * struct ssam_span - Reference to a buffer region. + * @ptr: Pointer to the buffer region. + * @len: Length of the buffer region. + * + * A reference to a (non-owned) buffer segment, consisting of pointer and + * length. Use of this struct indicates non-owned data, i.e. data of which the + * life-time is managed (i.e. it is allocated/freed) via another pointer. + */ +struct ssam_span { + u8 *ptr; + size_t len; +}; + +/* + * Known SSH/EC target categories. + * + * List of currently known target category values; "Known" as in we know they + * exist and are valid on at least some device/model. Detailed functionality + * or the full category name is only known for some of these categories and + * is detailed in the respective comment below. + * + * These values and abbreviations have been extracted from strings inside the + * Windows driver. + */ +enum ssam_ssh_tc { + /* Category 0x00 is invalid for EC use. */ + SSAM_SSH_TC_SAM = 0x01, /* Generic system functionality, real-time clock. */ + SSAM_SSH_TC_BAT = 0x02, /* Battery/power subsystem. */ + SSAM_SSH_TC_TMP = 0x03, /* Thermal subsystem. */ + SSAM_SSH_TC_PMC = 0x04, + SSAM_SSH_TC_FAN = 0x05, + SSAM_SSH_TC_PoM = 0x06, + SSAM_SSH_TC_DBG = 0x07, + SSAM_SSH_TC_KBD = 0x08, /* Legacy keyboard (Laptop 1/2). */ + SSAM_SSH_TC_FWU = 0x09, + SSAM_SSH_TC_UNI = 0x0a, + SSAM_SSH_TC_LPC = 0x0b, + SSAM_SSH_TC_TCL = 0x0c, + SSAM_SSH_TC_SFL = 0x0d, + SSAM_SSH_TC_KIP = 0x0e, + SSAM_SSH_TC_EXT = 0x0f, + SSAM_SSH_TC_BLD = 0x10, + SSAM_SSH_TC_BAS = 0x11, /* Detachment system (Surface Book 2/3). */ + SSAM_SSH_TC_SEN = 0x12, + SSAM_SSH_TC_SRQ = 0x13, + SSAM_SSH_TC_MCU = 0x14, + SSAM_SSH_TC_HID = 0x15, /* Generic HID input subsystem. */ + SSAM_SSH_TC_TCH = 0x16, + SSAM_SSH_TC_BKL = 0x17, + SSAM_SSH_TC_TAM = 0x18, + SSAM_SSH_TC_ACC = 0x19, + SSAM_SSH_TC_UFI = 0x1a, + SSAM_SSH_TC_USC = 0x1b, + SSAM_SSH_TC_PEN = 0x1c, + SSAM_SSH_TC_VID = 0x1d, + SSAM_SSH_TC_AUD = 0x1e, + SSAM_SSH_TC_SMC = 0x1f, + SSAM_SSH_TC_KPD = 0x20, + SSAM_SSH_TC_REG = 0x21, /* Extended event registry. */ +}; + + +/* -- Packet transport layer (ptl). ----------------------------------------- */ + +/** + * enum ssh_packet_base_priority - Base priorities for &struct ssh_packet. + * @SSH_PACKET_PRIORITY_FLUSH: Base priority for flush packets. + * @SSH_PACKET_PRIORITY_DATA: Base priority for normal data packets. + * @SSH_PACKET_PRIORITY_NAK: Base priority for NAK packets. + * @SSH_PACKET_PRIORITY_ACK: Base priority for ACK packets. + */ +enum ssh_packet_base_priority { + SSH_PACKET_PRIORITY_FLUSH = 0, /* same as DATA to sequence flush */ + SSH_PACKET_PRIORITY_DATA = 0, + SSH_PACKET_PRIORITY_NAK = 1, + SSH_PACKET_PRIORITY_ACK = 2, +}; + +/* + * Same as SSH_PACKET_PRIORITY() below, only with actual values. + */ +#define __SSH_PACKET_PRIORITY(base, try) \ + (((base) << 4) | ((try) & 0x0f)) + +/** + * SSH_PACKET_PRIORITY() - Compute packet priority from base priority and + * number of tries. + * @base: The base priority as suffix of &enum ssh_packet_base_priority, e.g. + * ``FLUSH``, ``DATA``, ``ACK``, or ``NAK``. + * @try: The number of tries (must be less than 16). + * + * Compute the combined packet priority. The combined priority is dominated by + * the base priority, whereas the number of (re-)tries decides the precedence + * of packets with the same base priority, giving higher priority to packets + * that already have more tries. + * + * Return: Returns the computed priority as value fitting inside a &u8. A + * higher number means a higher priority. + */ +#define SSH_PACKET_PRIORITY(base, try) \ + __SSH_PACKET_PRIORITY(SSH_PACKET_PRIORITY_##base, (try)) + +/** + * ssh_packet_priority_get_try() - Get number of tries from packet priority. + * @priority: The packet priority. + * + * Return: Returns the number of tries encoded in the specified packet + * priority. + */ +static inline u8 ssh_packet_priority_get_try(u8 priority) +{ + return priority & 0x0f; +} + +/** + * ssh_packet_priority_get_base - Get base priority from packet priority. + * @priority: The packet priority. + * + * Return: Returns the base priority encoded in the given packet priority. + */ +static inline u8 ssh_packet_priority_get_base(u8 priority) +{ + return (priority & 0xf0) >> 4; +} + +enum ssh_packet_flags { + /* state flags */ + SSH_PACKET_SF_LOCKED_BIT, + SSH_PACKET_SF_QUEUED_BIT, + SSH_PACKET_SF_PENDING_BIT, + SSH_PACKET_SF_TRANSMITTING_BIT, + SSH_PACKET_SF_TRANSMITTED_BIT, + SSH_PACKET_SF_ACKED_BIT, + SSH_PACKET_SF_CANCELED_BIT, + SSH_PACKET_SF_COMPLETED_BIT, + + /* type flags */ + SSH_PACKET_TY_FLUSH_BIT, + SSH_PACKET_TY_SEQUENCED_BIT, + SSH_PACKET_TY_BLOCKING_BIT, + + /* mask for state flags */ + SSH_PACKET_FLAGS_SF_MASK = + BIT(SSH_PACKET_SF_LOCKED_BIT) + | BIT(SSH_PACKET_SF_QUEUED_BIT) + | BIT(SSH_PACKET_SF_PENDING_BIT) + | BIT(SSH_PACKET_SF_TRANSMITTING_BIT) + | BIT(SSH_PACKET_SF_TRANSMITTED_BIT) + | BIT(SSH_PACKET_SF_ACKED_BIT) + | BIT(SSH_PACKET_SF_CANCELED_BIT) + | BIT(SSH_PACKET_SF_COMPLETED_BIT), + + /* mask for type flags */ + SSH_PACKET_FLAGS_TY_MASK = + BIT(SSH_PACKET_TY_FLUSH_BIT) + | BIT(SSH_PACKET_TY_SEQUENCED_BIT) + | BIT(SSH_PACKET_TY_BLOCKING_BIT), +}; + +struct ssh_ptl; +struct ssh_packet; + +/** + * struct ssh_packet_ops - Callback operations for a SSH packet. + * @release: Function called when the packet reference count reaches zero. + * This callback must be relied upon to ensure that the packet has + * left the transport system(s). + * @complete: Function called when the packet is completed, either with + * success or failure. In case of failure, the reason for the + * failure is indicated by the value of the provided status code + * argument. This value will be zero in case of success. Note that + * a call to this callback does not guarantee that the packet is + * not in use by the transport system any more. + */ +struct ssh_packet_ops { + void (*release)(struct ssh_packet *p); + void (*complete)(struct ssh_packet *p, int status); +}; + +/** + * struct ssh_packet - SSH transport packet. + * @ptl: Pointer to the packet transport layer. May be %NULL if the packet + * (or enclosing request) has not been submitted yet. + * @refcnt: Reference count of the packet. + * @priority: Priority of the packet. Must be computed via + * SSH_PACKET_PRIORITY(). Must only be accessed while holding the + * queue lock after first submission. + * @data: Raw message data. + * @data.len: Length of the raw message data. + * @data.ptr: Pointer to the raw message data buffer. + * @state: State and type flags describing current packet state (dynamic) + * and type (static). See &enum ssh_packet_flags for possible + * options. + * @timestamp: Timestamp specifying when the latest transmission of a + * currently pending packet has been started. May be %KTIME_MAX + * before or in-between transmission attempts. Used for the packet + * timeout implementation. Must only be accessed while holding the + * pending lock after first submission. + * @queue_node: The list node for the packet queue. + * @pending_node: The list node for the set of pending packets. + * @ops: Packet operations. + */ +struct ssh_packet { + struct ssh_ptl *ptl; + struct kref refcnt; + + u8 priority; + + struct { + size_t len; + u8 *ptr; + } data; + + unsigned long state; + ktime_t timestamp; + + struct list_head queue_node; + struct list_head pending_node; + + const struct ssh_packet_ops *ops; +}; + +struct ssh_packet *ssh_packet_get(struct ssh_packet *p); +void ssh_packet_put(struct ssh_packet *p); + +/** + * ssh_packet_set_data() - Set raw message data of packet. + * @p: The packet for which the message data should be set. + * @ptr: Pointer to the memory holding the message data. + * @len: Length of the message data. + * + * Sets the raw message data buffer of the packet to the provided memory. The + * memory is not copied. Instead, the caller is responsible for management + * (i.e. allocation and deallocation) of the memory. The caller must ensure + * that the provided memory is valid and contains a valid SSH message, + * starting from the time of submission of the packet until the ``release`` + * callback has been called. During this time, the memory may not be altered + * in any way. + */ +static inline void ssh_packet_set_data(struct ssh_packet *p, u8 *ptr, size_t len) +{ + p->data.ptr = ptr; + p->data.len = len; +} + + +/* -- Request transport layer (rtl). ---------------------------------------- */ + +enum ssh_request_flags { + /* state flags */ + SSH_REQUEST_SF_LOCKED_BIT, + SSH_REQUEST_SF_QUEUED_BIT, + SSH_REQUEST_SF_PENDING_BIT, + SSH_REQUEST_SF_TRANSMITTING_BIT, + SSH_REQUEST_SF_TRANSMITTED_BIT, + SSH_REQUEST_SF_RSPRCVD_BIT, + SSH_REQUEST_SF_CANCELED_BIT, + SSH_REQUEST_SF_COMPLETED_BIT, + + /* type flags */ + SSH_REQUEST_TY_FLUSH_BIT, + SSH_REQUEST_TY_HAS_RESPONSE_BIT, + + /* mask for state flags */ + SSH_REQUEST_FLAGS_SF_MASK = + BIT(SSH_REQUEST_SF_LOCKED_BIT) + | BIT(SSH_REQUEST_SF_QUEUED_BIT) + | BIT(SSH_REQUEST_SF_PENDING_BIT) + | BIT(SSH_REQUEST_SF_TRANSMITTING_BIT) + | BIT(SSH_REQUEST_SF_TRANSMITTED_BIT) + | BIT(SSH_REQUEST_SF_RSPRCVD_BIT) + | BIT(SSH_REQUEST_SF_CANCELED_BIT) + | BIT(SSH_REQUEST_SF_COMPLETED_BIT), + + /* mask for type flags */ + SSH_REQUEST_FLAGS_TY_MASK = + BIT(SSH_REQUEST_TY_FLUSH_BIT) + | BIT(SSH_REQUEST_TY_HAS_RESPONSE_BIT), +}; + +struct ssh_rtl; +struct ssh_request; + +/** + * struct ssh_request_ops - Callback operations for a SSH request. + * @release: Function called when the request's reference count reaches zero. + * This callback must be relied upon to ensure that the request has + * left the transport systems (both, packet an request systems). + * @complete: Function called when the request is completed, either with + * success or failure. The command data for the request response + * is provided via the &struct ssh_command parameter (``cmd``), + * the command payload of the request response via the &struct + * ssh_span parameter (``data``). + * + * If the request does not have any response or has not been + * completed with success, both ``cmd`` and ``data`` parameters will + * be NULL. If the request response does not have any command + * payload, the ``data`` span will be an empty (zero-length) span. + * + * In case of failure, the reason for the failure is indicated by + * the value of the provided status code argument (``status``). This + * value will be zero in case of success and a regular errno + * otherwise. + * + * Note that a call to this callback does not guarantee that the + * request is not in use by the transport systems any more. + */ +struct ssh_request_ops { + void (*release)(struct ssh_request *rqst); + void (*complete)(struct ssh_request *rqst, + const struct ssh_command *cmd, + const struct ssam_span *data, int status); +}; + +/** + * struct ssh_request - SSH transport request. + * @packet: The underlying SSH transport packet. + * @node: List node for the request queue and pending set. + * @state: State and type flags describing current request state (dynamic) + * and type (static). See &enum ssh_request_flags for possible + * options. + * @timestamp: Timestamp specifying when we start waiting on the response of + * the request. This is set once the underlying packet has been + * completed and may be %KTIME_MAX before that, or when the request + * does not expect a response. Used for the request timeout + * implementation. + * @ops: Request Operations. + */ +struct ssh_request { + struct ssh_packet packet; + struct list_head node; + + unsigned long state; + ktime_t timestamp; + + const struct ssh_request_ops *ops; +}; + +/** + * to_ssh_request() - Cast a SSH packet to its enclosing SSH request. + * @p: The packet to cast. + * + * Casts the given &struct ssh_packet to its enclosing &struct ssh_request. + * The caller is responsible for making sure that the packet is actually + * wrapped in a &struct ssh_request. + * + * Return: Returns the &struct ssh_request wrapping the provided packet. + */ +static inline struct ssh_request *to_ssh_request(struct ssh_packet *p) +{ + return container_of(p, struct ssh_request, packet); +} + +/** + * ssh_request_get() - Increment reference count of request. + * @r: The request to increment the reference count of. + * + * Increments the reference count of the given request by incrementing the + * reference count of the underlying &struct ssh_packet, enclosed in it. + * + * See also ssh_request_put(), ssh_packet_get(). + * + * Return: Returns the request provided as input. + */ +static inline struct ssh_request *ssh_request_get(struct ssh_request *r) +{ + return r ? to_ssh_request(ssh_packet_get(&r->packet)) : NULL; +} + +/** + * ssh_request_put() - Decrement reference count of request. + * @r: The request to decrement the reference count of. + * + * Decrements the reference count of the given request by decrementing the + * reference count of the underlying &struct ssh_packet, enclosed in it. If + * the reference count reaches zero, the ``release`` callback specified in the + * request's &struct ssh_request_ops, i.e. ``r->ops->release``, will be + * called. + * + * See also ssh_request_get(), ssh_packet_put(). + */ +static inline void ssh_request_put(struct ssh_request *r) +{ + if (r) + ssh_packet_put(&r->packet); +} + +/** + * ssh_request_set_data() - Set raw message data of request. + * @r: The request for which the message data should be set. + * @ptr: Pointer to the memory holding the message data. + * @len: Length of the message data. + * + * Sets the raw message data buffer of the underlying packet to the specified + * buffer. Does not copy the actual message data, just sets the buffer pointer + * and length. Refer to ssh_packet_set_data() for more details. + */ +static inline void ssh_request_set_data(struct ssh_request *r, u8 *ptr, size_t len) +{ + ssh_packet_set_data(&r->packet, ptr, len); +} + +#endif /* _LINUX_SURFACE_AGGREGATOR_SERIAL_HUB_H */ |