Internal API Documentation

Packet Transport Layer

struct sshp_buf

Parser buffer for SSH messages.

Definition

struct sshp_buf {
  u8 *ptr;
  size_t len;
  size_t cap;
};

Members

ptr

Pointer to the beginning of the buffer.

len

Number of bytes used in the buffer.

cap

Maximum capacity of the buffer.

void sshp_buf_init(struct sshp_buf *buf, u8 *ptr, size_t cap)

Initialize a SSH parser buffer.

Parameters

struct sshp_buf *buf

The buffer to initialize.

u8 *ptr

The memory backing the buffer.

size_t cap

The length of the memory backing the buffer, i.e. its capacity.

Description

Initializes the buffer with the given memory as backing and set its used length to zero.

int sshp_buf_alloc(struct sshp_buf *buf, size_t cap, gfp_t flags)

Allocate and initialize a SSH parser buffer.

Parameters

struct sshp_buf *buf

The buffer to initialize/allocate to.

size_t cap

The desired capacity of the buffer.

gfp_t flags

The flags used for allocating the memory.

Description

Allocates cap bytes and initializes the provided buffer struct with the allocated memory.

Return

Returns zero on success and -ENOMEM if allocation failed.

void sshp_buf_free(struct sshp_buf *buf)

Free a SSH parser buffer.

Parameters

struct sshp_buf *buf

The buffer to free.

Description

Frees a SSH parser buffer by freeing the memory backing it and then resetting its pointer to NULL and length and capacity to zero. Intended to free a buffer previously allocated with sshp_buf_alloc().

void sshp_buf_drop(struct sshp_buf *buf, size_t n)

Drop data from the beginning of the buffer.

Parameters

struct sshp_buf *buf

The buffer to drop data from.

size_t n

The number of bytes to drop.

Description

Drops the first n bytes from the buffer. Re-aligns any remaining data to the beginning of the buffer.

size_t sshp_buf_read_from_fifo(struct sshp_buf *buf, struct kfifo *fifo)

Transfer data from a fifo to the buffer.

Parameters

struct sshp_buf *buf

The buffer to write the data into.

struct kfifo *fifo

The fifo to read the data from.

Description

Transfers the data contained in the fifo to the buffer, removing it from the fifo. This function will try to transfer as much data as possible, limited either by the remaining space in the buffer or by the number of bytes available in the fifo.

Return

Returns the number of bytes transferred.

void sshp_buf_span_from(struct sshp_buf *buf, size_t offset, struct ssam_span *span)

Initialize a span from the given buffer and offset.

Parameters

struct sshp_buf *buf

The buffer to create the span from.

size_t offset

The offset in the buffer at which the span should start.

struct ssam_span *span

The span to initialize (output).

Description

Initializes the provided span to point to the memory at the given offset in the buffer, with the length of the span being capped by the number of bytes used in the buffer after the offset (i.e. bytes remaining after the offset).

Warning: This function does not validate that offset is less than or equal to the number of bytes used in the buffer or the buffer capacity. This must be guaranteed by the caller.

bool sshp_validate_crc(const struct ssam_span *src, const u8 *crc)

Validate a CRC in raw message data.

Parameters

const struct ssam_span *src

The span of data over which the CRC should be computed.

const u8 *crc

The pointer to the expected u16 CRC value.

Description

Computes the CRC of the provided data span (src), compares it to the CRC stored at the given address (crc), and returns the result of this comparison, i.e. true if equal. This function is intended to run on raw input/message data.

Return

Returns true if the computed CRC matches the stored CRC, false otherwise.

bool sshp_starts_with_syn(const struct ssam_span *src)

Check if the given data starts with SSH SYN bytes.

Parameters

const struct ssam_span *src

The data span to check the start of.

bool sshp_find_syn(const struct ssam_span *src, struct ssam_span *rem)

Find SSH SYN bytes in the given data span.

Parameters

const struct ssam_span *src

The data span to search in.

struct ssam_span *rem

The span (output) indicating the remaining data, starting with SSH SYN bytes, if found.

Description

Search for SSH SYN bytes in the given source span. If found, set the rem span to the remaining data, starting with the first SYN bytes and capped by the source span length, and return true. This function does not copy any data, but rather only sets pointers to the respective start addresses and length values.

If no SSH SYN bytes could be found, set the rem span to the zero-length span at the end of the source span and return false.

If partial SSH SYN bytes could be found at the end of the source span, set the rem span to cover these partial SYN bytes, capped by the end of the source span, and return false. This function should then be re-run once more data is available.

Return

Returns true if a complete SSH SYN sequence could be found, false otherwise.

int sshp_parse_frame(const struct device *dev, const struct ssam_span *source, struct ssh_frame **frame, struct ssam_span *payload, size_t maxlen)

Parse SSH frame.

Parameters

const struct device *dev

The device used for logging.

const struct ssam_span *source

The source to parse from.

struct ssh_frame **frame

The parsed frame (output).

struct ssam_span *payload

The parsed payload (output).

size_t maxlen

The maximum supported message length.

Description

Parses and validates a SSH frame, including its payload, from the given source. Sets the provided frame pointer to the start of the frame and writes the limits of the frame payload to the provided payload span pointer.

This function does not copy any data, but rather only validates the message data and sets pointers (and length values) to indicate the respective parts.

If no complete SSH frame could be found, the frame pointer will be set to the NULL pointer and the payload span will be set to the null span (start pointer NULL, size zero).

Return

Returns zero on success or if the frame is incomplete, -ENOMSG if the start of the message is invalid, -EBADMSG if any (frame-header or payload) CRC is invalid, or -EMSGSIZE if the SSH message is bigger than the maximum message length specified in the maxlen parameter.

int sshp_parse_command(const struct device *dev, const struct ssam_span *source, struct ssh_command **command, struct ssam_span *command_data)

Parse SSH command frame payload.

Parameters

const struct device *dev

The device used for logging.

const struct ssam_span *source

The source to parse from.

struct ssh_command **command

The parsed command (output).

struct ssam_span *command_data

The parsed command data/payload (output).

Description

Parses and validates a SSH command frame payload. Sets the command pointer to the command header and the command_data span to the command data (i.e. payload of the command). This will result in a zero-length span if the command does not have any associated data/payload. This function does not check the frame-payload-type field, which should be checked by the caller before calling this function.

The source parameter should be the complete frame payload, e.g. returned by the sshp_parse_frame() command.

This function does not copy any data, but rather only validates the frame payload data and sets pointers (and length values) to indicate the respective parts.

Return

Returns zero on success or -ENOMSG if source does not represent a valid command-type frame payload, i.e. is too short.

struct msgbuf

Buffer struct to construct SSH messages.

Definition

struct msgbuf {
  u8 *begin;
  u8 *end;
  u8 *ptr;
};

Members

begin

Pointer to the beginning of the allocated buffer space.

end

Pointer to the end (one past last element) of the allocated buffer space.

ptr

Pointer to the first free element in the buffer.

void msgb_init(struct msgbuf *msgb, u8 *ptr, size_t cap)

Initialize the given message buffer struct.

Parameters

struct msgbuf *msgb

The buffer struct to initialize

u8 *ptr

Pointer to the underlying memory by which the buffer will be backed.

size_t cap

Size of the underlying memory.

Description

Initialize the given message buffer struct using the provided memory as backing.

size_t msgb_bytes_used(const struct msgbuf *msgb)

Return the current number of bytes used in the buffer.

Parameters

const struct msgbuf *msgb

The message buffer.

void msgb_push_u16(struct msgbuf *msgb, u16 value)

Push a u16 value to the buffer.

Parameters

struct msgbuf *msgb

The message buffer.

u16 value

The value to push to the buffer.

void msgb_push_syn(struct msgbuf *msgb)

Push SSH SYN bytes to the buffer.

Parameters

struct msgbuf *msgb

The message buffer.

void msgb_push_buf(struct msgbuf *msgb, const u8 *buf, size_t len)

Push raw data to the buffer.

Parameters

struct msgbuf *msgb

The message buffer.

const u8 *buf

The data to push to the buffer.

size_t len

The length of the data to push to the buffer.

void msgb_push_crc(struct msgbuf *msgb, const u8 *buf, size_t len)

Compute CRC and push it to the buffer.

Parameters

struct msgbuf *msgb

The message buffer.

const u8 *buf

The data for which the CRC should be computed.

size_t len

The length of the data for which the CRC should be computed.

void msgb_push_frame(struct msgbuf *msgb, u8 ty, u16 len, u8 seq)

Push a SSH message frame header to the buffer.

Parameters

struct msgbuf *msgb

The message buffer

u8 ty

The type of the frame.

u16 len

The length of the payload of the frame.

u8 seq

The sequence ID of the frame/packet.

void msgb_push_ack(struct msgbuf *msgb, u8 seq)

Push a SSH ACK frame to the buffer.

Parameters

struct msgbuf *msgb

The message buffer

u8 seq

The sequence ID of the frame/packet to be ACKed.

void msgb_push_nak(struct msgbuf *msgb)

Push a SSH NAK frame to the buffer.

Parameters

struct msgbuf *msgb

The message buffer

void msgb_push_cmd(struct msgbuf *msgb, u8 seq, u16 rqid, const struct ssam_request *rqst)

Push a SSH command frame with payload to the buffer.

Parameters

struct msgbuf *msgb

The message buffer.

u8 seq

The sequence ID (SEQ) of the frame/packet.

u16 rqid

The request ID (RQID) of the request contained in the frame.

const struct ssam_request *rqst

The request to wrap in the frame.

enum ssh_ptl_state_flags

State-flags for struct ssh_ptl.

Constants

SSH_PTL_SF_SHUTDOWN_BIT

Indicates that the packet transport layer has been shut down or is being shut down and should not accept any new packets/data.

struct ssh_ptl_ops

Callback operations for packet transport layer.

Definition

struct ssh_ptl_ops {
  void (*data_received)(struct ssh_ptl *p, const struct ssam_span *data);
};

Members

data_received

Function called when a data-packet has been received. Both, the packet layer on which the packet has been received and the packet’s payload data are provided to this function.

struct ssh_ptl

SSH packet transport layer.

Definition

struct ssh_ptl {
  struct serdev_device *serdev;
  unsigned long state;
  struct {
    spinlock_t lock;
    struct list_head head;
  } queue;
  struct {
    spinlock_t lock;
    struct list_head head;
    atomic_t count;
  } pending;
  struct {
    atomic_t running;
    struct task_struct *thread;
    struct completion thread_cplt_tx;
    struct completion thread_cplt_pkt;
    struct wait_queue_head packet_wq;
  } tx;
  struct {
    struct task_struct *thread;
    struct wait_queue_head wq;
    struct kfifo fifo;
    struct sshp_buf buf;
    struct {
      u16 seqs[8];
      u16 offset;
    } blocked;
  } rx;
  struct {
    spinlock_t lock;
    ktime_t timeout;
    ktime_t expires;
    struct delayed_work reaper;
  } rtx_timeout;
  struct ssh_ptl_ops ops;
};

Members

serdev

Serial device providing the underlying data transport.

state

State(-flags) of the transport layer.

queue

Packet submission queue.

queue.lock

Lock for modifying the packet submission queue.

queue.head

List-head of the packet submission queue.

pending

Set/list of pending packets.

pending.lock

Lock for modifying the pending set.

pending.head

List-head of the pending set/list.

pending.count

Number of currently pending packets.

tx

Transmitter subsystem.

tx.running

Flag indicating (desired) transmitter thread state.

tx.thread

Transmitter thread.

tx.thread_cplt_tx

Completion for transmitter thread waiting on transfer.

tx.thread_cplt_pkt

Completion for transmitter thread waiting on packets.

tx.packet_wq

Waitqueue-head for packet transmit completion.

rx

Receiver subsystem.

rx.thread

Receiver thread.

rx.wq

Waitqueue-head for receiver thread.

rx.fifo

Buffer for receiving data/pushing data to receiver thread.

rx.buf

Buffer for evaluating data on receiver thread.

rx.blocked

List of recent/blocked sequence IDs to detect retransmission.

rx.blocked.seqs

Array of blocked sequence IDs.

rx.blocked.offset

Offset indicating where a new ID should be inserted.

rtx_timeout

Retransmission timeout subsystem.

rtx_timeout.lock

Lock for modifying the retransmission timeout reaper.

rtx_timeout.timeout

Timeout interval for retransmission.

rtx_timeout.expires

Time specifying when the reaper work is next scheduled.

rtx_timeout.reaper

Work performing timeout checks and subsequent actions.

ops

Packet layer operations.

struct device *ssh_ptl_get_device(struct ssh_ptl *ptl)

Get device associated with packet transport layer.

Parameters

struct ssh_ptl *ptl

The packet transport layer.

Return

Returns the device on which the given packet transport layer builds upon.

void ssh_ptl_tx_wakeup_transfer(struct ssh_ptl *ptl)

Wake up packet transmitter thread for transfer.

Parameters

struct ssh_ptl *ptl

The packet transport layer.

Description

Wakes up the packet transmitter thread, notifying it that the underlying transport has more space for data to be transmitted. If the packet transport layer has been shut down, calls to this function will be ignored.

bool ssh_ptl_should_drop_ack_packet(void)

Error injection hook to drop ACK packets.

Parameters

void

no arguments

Description

Useful to test detection and handling of automated re-transmits by the EC. Specifically of packets that the EC considers not-ACKed but the driver already considers ACKed (due to dropped ACK). In this case, the EC re-transmits the packet-to-be-ACKed and the driver should detect it as duplicate/already handled. Note that the driver should still send an ACK for the re-transmitted packet.

bool ssh_ptl_should_drop_nak_packet(void)

Error injection hook to drop NAK packets.

Parameters

void

no arguments

Description

Useful to test/force automated (timeout-based) re-transmit by the EC. Specifically, packets that have not reached the driver completely/with valid checksums. Only useful in combination with receival of (injected) bad data.

bool ssh_ptl_should_drop_dsq_packet(void)

Error injection hook to drop sequenced data packet.

Parameters

void

no arguments

Description

Useful to test re-transmit timeout of the driver. If the data packet has not been ACKed after a certain time, the driver should re-transmit the packet up to limited number of times defined in SSH_PTL_MAX_PACKET_TRIES.

int ssh_ptl_should_fail_write(void)

Error injection hook to make serdev_device_write() fail.

Parameters

void

no arguments

Description

Hook to simulate errors in serdev_device_write when transmitting packets.

bool ssh_ptl_should_corrupt_tx_data(void)

Error injection hook to simulate invalid data being sent to the EC.

Parameters

void

no arguments

Description

Hook to simulate corrupt/invalid data being sent from host (driver) to EC. Causes the packet data to be actively corrupted by overwriting it with pre-defined values, such that it becomes invalid, causing the EC to respond with a NAK packet. Useful to test handling of NAK packets received by the driver.

bool ssh_ptl_should_corrupt_rx_syn(void)

Error injection hook to simulate invalid data being sent by the EC.

Parameters

void

no arguments

Description

Hook to simulate invalid SYN bytes, i.e. an invalid start of messages and test handling thereof in the driver.

bool ssh_ptl_should_corrupt_rx_data(void)

Error injection hook to simulate invalid data being sent by the EC.

Parameters

void

no arguments

Description

Hook to simulate invalid data/checksum of the message frame and test handling thereof in the driver.

void ssh_packet_init(struct ssh_packet *packet, unsigned long type, u8 priority, const struct ssh_packet_ops *ops)

Initialize SSH packet.

Parameters

struct ssh_packet *packet

The packet to initialize.

unsigned long type

Type-flags of the packet.

u8 priority

Priority of the packet. See SSH_PACKET_PRIORITY() for details.

const struct ssh_packet_ops *ops

Packet operations.

Description

Initializes the given SSH packet. Sets the transmission buffer pointer to NULL and the transmission buffer length to zero. For data-type packets, this buffer has to be set separately via ssh_packet_set_data() before submission, and must contain a valid SSH message, i.e. frame with optional payload of any type.

int ssh_ctrl_packet_cache_init(void)

Initialize the control packet cache.

Parameters

void

no arguments

void ssh_ctrl_packet_cache_destroy(void)

Deinitialize the control packet cache.

Parameters

void

no arguments

int ssh_ctrl_packet_alloc(struct ssh_packet **packet, struct ssam_span *buffer, gfp_t flags)

Allocate packet from control packet cache.

Parameters

struct ssh_packet **packet

Where the pointer to the newly allocated packet should be stored.

struct ssam_span *buffer

The buffer corresponding to this packet.

gfp_t flags

Flags used for allocation.

Description

Allocates a packet and corresponding transport buffer from the control packet cache. Sets the packet’s buffer reference to the allocated buffer. The packet must be freed via ssh_ctrl_packet_free(), which will also free the corresponding buffer. The corresponding buffer must not be freed separately. Intended to be used with ssh_ptl_ctrl_packet_ops as packet operations.

Return

Returns zero on success, -ENOMEM if the allocation failed.

void ssh_ctrl_packet_free(struct ssh_packet *p)

Free packet allocated from control packet cache.

Parameters

struct ssh_packet *p

The packet to free.

void ssh_ptl_tx_wakeup_packet(struct ssh_ptl *ptl)

Wake up packet transmitter thread for new packet.

Parameters

struct ssh_ptl *ptl

The packet transport layer.

Description

Wakes up the packet transmitter thread, notifying it that a new packet has arrived and is ready for transfer. If the packet transport layer has been shut down, calls to this function will be ignored.

int ssh_ptl_tx_start(struct ssh_ptl *ptl)

Start packet transmitter thread.

Parameters

struct ssh_ptl *ptl

The packet transport layer.

Return

Returns zero on success, a negative error code on failure.

int ssh_ptl_tx_stop(struct ssh_ptl *ptl)

Stop packet transmitter thread.

Parameters

struct ssh_ptl *ptl

The packet transport layer.

Return

Returns zero on success, a negative error code on failure.

int ssh_ptl_submit(struct ssh_ptl *ptl, struct ssh_packet *p)

Submit a packet to the transport layer.

Parameters

struct ssh_ptl *ptl

The packet transport layer to submit the packet to.

struct ssh_packet *p

The packet to submit.

Description

Submits a new packet to the transport layer, queuing it to be sent. This function should not be used for re-submission.

Return

Returns zero on success, -EINVAL if a packet field is invalid or the packet has been canceled prior to submission, -EALREADY if the packet has already been submitted, or -ESHUTDOWN if the packet transport layer has been shut down.

void ssh_ptl_cancel(struct ssh_packet *p)

Cancel a packet.

Parameters

struct ssh_packet *p

The packet to cancel.

Description

Cancels a packet. There are no guarantees on when completion and release callbacks will be called. This may occur during execution of this function or may occur at any point later.

Note that it is not guaranteed that the packet will actually be canceled if the packet is concurrently completed by another process. The only guarantee of this function is that the packet will be completed (with success, failure, or cancellation) and released from the transport layer in a reasonable time-frame.

May be called before the packet has been submitted, in which case any later packet submission fails.

int ssh_ptl_rx_start(struct ssh_ptl *ptl)

Start packet transport layer receiver thread.

Parameters

struct ssh_ptl *ptl

The packet transport layer.

Return

Returns zero on success, a negative error code on failure.

int ssh_ptl_rx_stop(struct ssh_ptl *ptl)

Stop packet transport layer receiver thread.

Parameters

struct ssh_ptl *ptl

The packet transport layer.

Return

Returns zero on success, a negative error code on failure.

int ssh_ptl_rx_rcvbuf(struct ssh_ptl *ptl, const u8 *buf, size_t n)

Push data from lower-layer transport to the packet layer.

Parameters

struct ssh_ptl *ptl

The packet transport layer.

const u8 *buf

Pointer to the data to push to the layer.

size_t n

Size of the data to push to the layer, in bytes.

Description

Pushes data from a lower-layer transport to the receiver fifo buffer of the packet layer and notifies the receiver thread. Calls to this function are ignored once the packet layer has been shut down.

Return

Returns the number of bytes transferred (positive or zero) on success. Returns -ESHUTDOWN if the packet layer has been shut down.

void ssh_ptl_shutdown(struct ssh_ptl *ptl)

Shut down the packet transport layer.

Parameters

struct ssh_ptl *ptl

The packet transport layer.

Description

Shuts down the packet transport layer, removing and canceling all queued and pending packets. Packets canceled by this operation will be completed with -ESHUTDOWN as status. Receiver and transmitter threads will be stopped.

As a result of this function, the transport layer will be marked as shut down. Submission of packets after the transport layer has been shut down will fail with -ESHUTDOWN.

int ssh_ptl_init(struct ssh_ptl *ptl, struct serdev_device *serdev, struct ssh_ptl_ops *ops)

Initialize packet transport layer.

Parameters

struct ssh_ptl *ptl

The packet transport layer to initialize.

struct serdev_device *serdev

The underlying serial device, i.e. the lower-level transport.

struct ssh_ptl_ops *ops

Packet layer operations.

Description

Initializes the given packet transport layer. Transmitter and receiver threads must be started separately via ssh_ptl_tx_start() and ssh_ptl_rx_start(), after the packet-layer has been initialized and the lower-level transport layer has been set up.

Return

Returns zero on success and a nonzero error code on failure.

void ssh_ptl_destroy(struct ssh_ptl *ptl)

Deinitialize packet transport layer.

Parameters

struct ssh_ptl *ptl

The packet transport layer to deinitialize.

Description

Deinitializes the given packet transport layer and frees resources associated with it. If receiver and/or transmitter threads have been started, the layer must first be shut down via ssh_ptl_shutdown() before this function can be called.

Request Transport Layer

enum ssh_rtl_state_flags

State-flags for struct ssh_rtl.

Constants

SSH_RTL_SF_SHUTDOWN_BIT

Indicates that the request transport layer has been shut down or is being shut down and should not accept any new requests.

struct ssh_rtl_ops

Callback operations for request transport layer.

Definition

struct ssh_rtl_ops {
  void (*handle_event)(struct ssh_rtl *rtl, const struct ssh_command *cmd, const struct ssam_span *data);
};

Members

handle_event

Function called when a SSH event has been received. The specified function takes the request layer, received command struct, and corresponding payload as arguments. If the event has no payload, the payload span is empty (not NULL).

struct ssh_rtl

SSH request transport layer.

Definition

struct ssh_rtl {
  struct ssh_ptl ptl;
  unsigned long state;
  struct {
    spinlock_t lock;
    struct list_head head;
  } queue;
  struct {
    spinlock_t lock;
    struct list_head head;
    atomic_t count;
  } pending;
  struct {
    struct work_struct work;
  } tx;
  struct {
    spinlock_t lock;
    ktime_t timeout;
    ktime_t expires;
    struct delayed_work reaper;
  } rtx_timeout;
  struct ssh_rtl_ops ops;
};

Members

ptl

Underlying packet transport layer.

state

State(-flags) of the transport layer.

queue

Request submission queue.

queue.lock

Lock for modifying the request submission queue.

queue.head

List-head of the request submission queue.

pending

Set/list of pending requests.

pending.lock

Lock for modifying the request set.

pending.head

List-head of the pending set/list.

pending.count

Number of currently pending requests.

tx

Transmitter subsystem.

tx.work

Transmitter work item.

rtx_timeout

Retransmission timeout subsystem.

rtx_timeout.lock

Lock for modifying the retransmission timeout reaper.

rtx_timeout.timeout

Timeout interval for retransmission.

rtx_timeout.expires

Time specifying when the reaper work is next scheduled.

rtx_timeout.reaper

Work performing timeout checks and subsequent actions.

ops

Request layer operations.

struct device *ssh_rtl_get_device(struct ssh_rtl *rtl)

Get device associated with request transport layer.

Parameters

struct ssh_rtl *rtl

The request transport layer.

Return

Returns the device on which the given request transport layer builds upon.

struct ssh_rtl *ssh_request_rtl(struct ssh_request *rqst)

Get request transport layer associated with request.

Parameters

struct ssh_request *rqst

The request to get the request transport layer reference for.

Return

Returns the struct ssh_rtl associated with the given SSH request.

bool ssh_rtl_should_drop_response(void)

Error injection hook to drop request responses.

Parameters

void

no arguments

Description

Useful to cause request transmission timeouts in the driver by dropping the response to a request.

int ssh_rtl_submit(struct ssh_rtl *rtl, struct ssh_request *rqst)

Submit a request to the transport layer.

Parameters

struct ssh_rtl *rtl

The request transport layer.

struct ssh_request *rqst

The request to submit.

Description

Submits a request to the transport layer. A single request may not be submitted multiple times without reinitializing it.

Return

Returns zero on success, -EINVAL if the request type is invalid or the request has been canceled prior to submission, -EALREADY if the request has already been submitted, or -ESHUTDOWN in case the request transport layer has been shut down.

bool ssh_rtl_cancel(struct ssh_request *rqst, bool pending)

Cancel request.

Parameters

struct ssh_request *rqst

The request to cancel.

bool pending

Whether to also cancel pending requests.

Description

Cancels the given request. If pending is false, this will not cancel pending requests, i.e. requests that have already been submitted to the packet layer but not been completed yet. If pending is true, this will cancel the given request regardless of the state it is in.

If the request has been canceled by calling this function, both completion and release callbacks of the request will be executed in a reasonable time-frame. This may happen during execution of this function, however, there is no guarantee for this. For example, a request currently transmitting will be canceled/completed only after transmission has completed, and the respective callbacks will be executed on the transmitter thread, which may happen during, but also some time after execution of the cancel function.

Return

Returns true if the given request has been canceled or completed, either by this function or prior to calling this function, false otherwise. If pending is true, this function will always return true.

int ssh_request_init(struct ssh_request *rqst, enum ssam_request_flags flags, const struct ssh_request_ops *ops)

Initialize SSH request.

Parameters

struct ssh_request *rqst

The request to initialize.

enum ssam_request_flags flags

Request flags, determining the type of the request.

const struct ssh_request_ops *ops

Request operations.

Description

Initializes the given SSH request and underlying packet. Sets the message buffer pointer to NULL and the message buffer length to zero. This buffer has to be set separately via ssh_request_set_data() before submission and must contain a valid SSH request message.

Return

Returns zero on success or -EINVAL if the given flags are invalid.

int ssh_rtl_init(struct ssh_rtl *rtl, struct serdev_device *serdev, const struct ssh_rtl_ops *ops)

Initialize request transport layer.

Parameters

struct ssh_rtl *rtl

The request transport layer to initialize.

struct serdev_device *serdev

The underlying serial device, i.e. the lower-level transport.

const struct ssh_rtl_ops *ops

Request transport layer operations.

Description

Initializes the given request transport layer and associated packet transport layer. Transmitter and receiver threads must be started separately via ssh_rtl_start(), after the request-layer has been initialized and the lower-level serial device layer has been set up.

Return

Returns zero on success and a nonzero error code on failure.

void ssh_rtl_destroy(struct ssh_rtl *rtl)

Deinitialize request transport layer.

Parameters

struct ssh_rtl *rtl

The request transport layer to deinitialize.

Description

Deinitializes the given request transport layer and frees resources associated with it. If receiver and/or transmitter threads have been started, the layer must first be shut down via ssh_rtl_shutdown() before this function can be called.

int ssh_rtl_start(struct ssh_rtl *rtl)

Start request transmitter and receiver.

Parameters

struct ssh_rtl *rtl

The request transport layer.

Return

Returns zero on success, a negative error code on failure.

int ssh_rtl_flush(struct ssh_rtl *rtl, unsigned long timeout)

Flush the request transport layer.

Parameters

struct ssh_rtl *rtl

request transport layer

unsigned long timeout

timeout for the flush operation in jiffies

Description

Queue a special flush request and wait for its completion. This request will be completed after all other currently queued and pending requests have been completed. Instead of a normal data packet, this request submits a special flush packet, meaning that upon completion, also the underlying packet transport layer has been flushed.

Flushing the request layer guarantees that all previously submitted requests have been fully completed before this call returns. Additionally, flushing blocks execution of all later submitted requests until the flush has been completed.

If the caller ensures that no new requests are submitted after a call to this function, the request transport layer is guaranteed to have no remaining requests when this call returns. The same guarantee does not hold for the packet layer, on which control packets may still be queued after this call.

Return

Returns zero on success, -ETIMEDOUT if the flush timed out and has been canceled as a result of the timeout, or -ESHUTDOWN if the packet and/or request transport layer has been shut down before this call. May also return -EINTR if the underlying packet transmission has been interrupted.

void ssh_rtl_shutdown(struct ssh_rtl *rtl)

Shut down request transport layer.

Parameters

struct ssh_rtl *rtl

The request transport layer.

Description

Shuts down the request transport layer, removing and canceling all queued and pending requests. Requests canceled by this operation will be completed with -ESHUTDOWN as status. Receiver and transmitter threads will be stopped, the lower-level packet layer will be shutdown.

As a result of this function, the transport layer will be marked as shut down. Submission of requests after the transport layer has been shut down will fail with -ESHUTDOWN.

Controller

struct ssh_seq_counter

Safe counter for SSH sequence IDs.

Definition

struct ssh_seq_counter {
  u8 value;
};

Members

value

The current counter value.

struct ssh_rqid_counter

Safe counter for SSH request IDs.

Definition

struct ssh_rqid_counter {
  u16 value;
};

Members

value

The current counter value.

struct ssam_nf_head

Notifier head for SSAM events.

Definition

struct ssam_nf_head {
  struct srcu_struct srcu;
  struct list_head head;
};

Members

srcu

The SRCU struct for synchronization.

head

List-head for notifier blocks registered under this head.

struct ssam_nf

Notifier callback- and activation-registry for SSAM events.

Definition

struct ssam_nf {
  struct mutex lock;
  struct rb_root refcount;
  struct ssam_nf_head head[SSH_NUM_EVENTS];
};

Members

lock

Lock guarding (de-)registration of notifier blocks. Note: This lock does not need to be held for notifier calls, only registration and deregistration.

refcount

The root of the RB-tree used for reference-counting enabled events/notifications.

head

The list of notifier heads for event/notification callbacks.

struct ssam_event_item

Struct for event queuing and completion.

Definition

struct ssam_event_item {
  struct list_head node;
  u16 rqid;
  struct {
    void (*free)(struct ssam_event_item *event);
  } ops;
  struct ssam_event event;
};

Members

node

The node in the queue.

rqid

The request ID of the event.

ops

Instance specific functions.

ops.free

Callback for freeing this event item.

event

Actual event data.

struct ssam_event_queue

Queue for completing received events.

Definition

struct ssam_event_queue {
  struct ssam_cplt *cplt;
  spinlock_t lock;
  struct list_head head;
  struct work_struct work;
};

Members

cplt

Reference to the completion system on which this queue is active.

lock

The lock for any operation on the queue.

head

The list-head of the queue.

work

The struct work_struct performing completion work for this queue.

struct ssam_event_target

Set of queues for a single SSH target ID.

Definition

struct ssam_event_target {
  struct ssam_event_queue queue[SSH_NUM_EVENTS];
};

Members

queue

The array of queues, one queue per event ID.

struct ssam_cplt

SSAM event/async request completion system.

Definition

struct ssam_cplt {
  struct device *dev;
  struct workqueue_struct *wq;
  struct {
    struct ssam_event_target target[SSH_NUM_TARGETS];
    struct ssam_nf notif;
  } event;
};

Members

dev

The device with which this system is associated. Only used for logging.

wq

The struct workqueue_struct on which all completion work items are queued.

event

Event completion management.

event.target

Array of struct ssam_event_target, one for each target.

event.notif

Notifier callbacks and event activation reference counting.

enum ssam_controller_state

State values for struct ssam_controller.

Constants

SSAM_CONTROLLER_UNINITIALIZED

The controller has not been initialized yet or has been deinitialized.

SSAM_CONTROLLER_INITIALIZED

The controller is initialized, but has not been started yet.

SSAM_CONTROLLER_STARTED

The controller has been started and is ready to use.

SSAM_CONTROLLER_STOPPED

The controller has been stopped.

SSAM_CONTROLLER_SUSPENDED

The controller has been suspended.

struct ssam_controller_caps

Controller device capabilities.

Definition

struct ssam_controller_caps {
  u32 ssh_power_profile;
  u32 ssh_buffer_size;
  u32 screen_on_sleep_idle_timeout;
  u32 screen_off_sleep_idle_timeout;
  u32 d3_closes_handle:1;
};

Members

ssh_power_profile

SSH power profile.

ssh_buffer_size

SSH driver UART buffer size.

screen_on_sleep_idle_timeout

SAM UART screen-on sleep idle timeout.

screen_off_sleep_idle_timeout

SAM UART screen-off sleep idle timeout.

d3_closes_handle

SAM closes UART handle in D3.

Description

Controller and SSH device capabilities found in ACPI.

struct ssam_controller

SSAM controller device.

Definition

struct ssam_controller {
  struct kref kref;
  struct rw_semaphore lock;
  enum ssam_controller_state state;
  struct ssh_rtl rtl;
  struct ssam_cplt cplt;
  struct {
    struct ssh_seq_counter seq;
    struct ssh_rqid_counter rqid;
  } counter;
  struct {
    int num;
    bool wakeup_enabled;
  } irq;
  struct ssam_controller_caps caps;
};

Members

kref

Reference count of the controller.

lock

Main lock for the controller, used to guard state changes.

state

Controller state.

rtl

Request transport layer for SSH I/O.

cplt

Completion system for SSH/SSAM events and asynchronous requests.

counter

Safe SSH message ID counters.

counter.seq

Sequence ID counter.

counter.rqid

Request ID counter.

irq

Wakeup IRQ resources.

irq.num

The wakeup IRQ number.

irq.wakeup_enabled

Whether wakeup by IRQ is enabled during suspend.

caps

The controller device capabilities.

int ssam_controller_receive_buf(struct ssam_controller *ctrl, const unsigned char *buf, size_t n)

Provide input-data to the controller.

Parameters

struct ssam_controller *ctrl

The controller.

const unsigned char *buf

The input buffer.

size_t n

The number of bytes in the input buffer.

Description

Provide input data to be evaluated by the controller, which has been received via the lower-level transport.

Return

Returns the number of bytes consumed, or, if the packet transport layer of the controller has been shut down, -ESHUTDOWN.

void ssam_controller_write_wakeup(struct ssam_controller *ctrl)

Notify the controller that the underlying device has space available for data to be written.

Parameters

struct ssam_controller *ctrl

The controller.

void ssh_seq_reset(struct ssh_seq_counter *c)

Reset/initialize sequence ID counter.

Parameters

struct ssh_seq_counter *c

The counter to reset.

u8 ssh_seq_next(struct ssh_seq_counter *c)

Get next sequence ID.

Parameters

struct ssh_seq_counter *c

The counter providing the sequence IDs.

Return

Returns the next sequence ID of the counter.

void ssh_rqid_reset(struct ssh_rqid_counter *c)

Reset/initialize request ID counter.

Parameters

struct ssh_rqid_counter *c

The counter to reset.

u16 ssh_rqid_next(struct ssh_rqid_counter *c)

Get next request ID.

Parameters

struct ssh_rqid_counter *c

The counter providing the request IDs.

Return

Returns the next request ID of the counter, skipping any reserved request IDs.

bool ssam_event_matches_notifier(const struct ssam_event_notifier *n, const struct ssam_event *event)

Test if an event matches a notifier.

Parameters

const struct ssam_event_notifier *n

The event notifier to test against.

const struct ssam_event *event

The event to test.

Return

Returns true if the given event matches the given notifier according to the rules set in the notifier’s event mask, false otherwise.

int ssam_nfblk_call_chain(struct ssam_nf_head *nh, struct ssam_event *event)

Call event notifier callbacks of the given chain.

Parameters

struct ssam_nf_head *nh

The notifier head for which the notifier callbacks should be called.

struct ssam_event *event

The event data provided to the callbacks.

Description

Call all registered notifier callbacks in order of their priority until either no notifier is left or a notifier returns a value with the SSAM_NOTIF_STOP bit set. Note that this bit is automatically set via ssam_notifier_from_errno() on any non-zero error value.

Return

Returns the notifier status value, which contains the notifier status bits (SSAM_NOTIF_HANDLED and SSAM_NOTIF_STOP) as well as a potential error value returned from the last executed notifier callback. Use ssam_notifier_to_errno() to convert this value to the original error value.

int ssam_nfblk_insert(struct ssam_nf_head *nh, struct ssam_notifier_block *nb)

Insert a new notifier block into the given notifier list.

Parameters

struct ssam_nf_head *nh

The notifier head into which the block should be inserted.

struct ssam_notifier_block *nb

The notifier block to add.

Note

This function must be synchronized by the caller with respect to other insert, find, and/or remove calls by holding struct ssam_nf.lock.

Return

Returns zero on success, -EEXIST if the notifier block has already been registered.

bool ssam_nfblk_find(struct ssam_nf_head *nh, struct ssam_notifier_block *nb)

Check if a notifier block is registered on the given notifier head. list.

Parameters

struct ssam_nf_head *nh

The notifier head on which to search.

struct ssam_notifier_block *nb

The notifier block to search for.

Note

This function must be synchronized by the caller with respect to other insert, find, and/or remove calls by holding struct ssam_nf.lock.

Return

Returns true if the given notifier block is registered on the given notifier head, false otherwise.

void ssam_nfblk_remove(struct ssam_notifier_block *nb)

Remove a notifier block from its notifier list.

Parameters

struct ssam_notifier_block *nb

The notifier block to be removed.

Note

This function must be synchronized by the caller with respect to other insert, find, and/or remove calls by holding struct ssam_nf.lock. Furthermore, the caller _must_ ensure SRCU synchronization by calling synchronize_srcu() with nh->srcu after leaving the critical section, to ensure that the removed notifier block is not in use any more.

int ssam_nf_head_init(struct ssam_nf_head *nh)

Initialize the given notifier head.

Parameters

struct ssam_nf_head *nh

The notifier head to initialize.

void ssam_nf_head_destroy(struct ssam_nf_head *nh)

Deinitialize the given notifier head.

Parameters

struct ssam_nf_head *nh

The notifier head to deinitialize.

struct ssam_nf_refcount_key

Key used for event activation reference counting.

Definition

struct ssam_nf_refcount_key {
  struct ssam_event_registry reg;
  struct ssam_event_id id;
};

Members

reg

The registry via which the event is enabled/disabled.

id

The ID uniquely describing the event.

struct ssam_nf_refcount_entry

RB-tree entry for reference counting event activations.

Definition

struct ssam_nf_refcount_entry {
  struct rb_node node;
  struct ssam_nf_refcount_key key;
  int refcount;
  u8 flags;
};

Members

node

The node of this entry in the rb-tree.

key

The key of the event.

refcount

The reference-count of the event.

flags

The flags used when enabling the event.

struct ssam_nf_refcount_entry *ssam_nf_refcount_inc(struct ssam_nf *nf, struct ssam_event_registry reg, struct ssam_event_id id)

Increment reference-/activation-count of the given event.

Parameters

struct ssam_nf *nf

The notifier system reference.

struct ssam_event_registry reg

The registry used to enable/disable the event.

struct ssam_event_id id

The event ID.

Description

Increments the reference-/activation-count associated with the specified event type/ID, allocating a new entry for this event ID if necessary. A newly allocated entry will have a refcount of one.

Note

nf->lock must be held when calling this function.

Return

Returns the refcount entry on success. Returns an error pointer with -ENOSPC if there have already been INT_MAX events of the specified ID and type registered, or -ENOMEM if the entry could not be allocated.

struct ssam_nf_refcount_entry *ssam_nf_refcount_dec(struct ssam_nf *nf, struct ssam_event_registry reg, struct ssam_event_id id)

Decrement reference-/activation-count of the given event.

Parameters

struct ssam_nf *nf

The notifier system reference.

struct ssam_event_registry reg

The registry used to enable/disable the event.

struct ssam_event_id id

The event ID.

Description

Decrements the reference-/activation-count of the specified event, returning its entry. If the returned entry has a refcount of zero, the caller is responsible for freeing it using kfree().

Note

nf->lock must be held when calling this function.

Return

Returns the refcount entry on success or NULL if the entry has not been found.

bool ssam_nf_refcount_empty(struct ssam_nf *nf)

Test if the notification system has any enabled/active events.

Parameters

struct ssam_nf *nf

The notification system.

void ssam_nf_call(struct ssam_nf *nf, struct device *dev, u16 rqid, struct ssam_event *event)

Call notification callbacks for the provided event.

Parameters

struct ssam_nf *nf

The notifier system

struct device *dev

The associated device, only used for logging.

u16 rqid

The request ID of the event.

struct ssam_event *event

The event provided to the callbacks.

Description

Execute registered callbacks in order of their priority until either no callback is left or a callback returns a value with the SSAM_NOTIF_STOP bit set. Note that this bit is set automatically when converting non-zero error values via ssam_notifier_from_errno() to notifier values.

Also note that any callback that could handle an event should return a value with bit SSAM_NOTIF_HANDLED set, indicating that the event does not go unhandled/ignored. In case no registered callback could handle an event, this function will emit a warning.

In case a callback failed, this function will emit an error message.

int ssam_nf_init(struct ssam_nf *nf)

Initialize the notifier system.

Parameters

struct ssam_nf *nf

The notifier system to initialize.

void ssam_nf_destroy(struct ssam_nf *nf)

Deinitialize the notifier system.

Parameters

struct ssam_nf *nf

The notifier system to deinitialize.

int ssam_event_item_cache_init(void)

Initialize the event item cache.

Parameters

void

no arguments

void ssam_event_item_cache_destroy(void)

Deinitialize the event item cache.

Parameters

void

no arguments

void ssam_event_item_free(struct ssam_event_item *item)

Free the provided event item.

Parameters

struct ssam_event_item *item

The event item to free.

struct ssam_event_item *ssam_event_item_alloc(size_t len, gfp_t flags)

Allocate an event item with the given payload size.

Parameters

size_t len

The event payload length.

gfp_t flags

The flags used for allocation.

Description

Allocate an event item with the given payload size, preferring allocation from the event item cache if the payload is small enough (i.e. smaller than SSAM_EVENT_ITEM_CACHE_PAYLOAD_LEN). Sets the item operations and payload length values. The item free callback (ops.free) should not be overwritten after this call.

Return

Returns the newly allocated event item.

void ssam_event_queue_push(struct ssam_event_queue *q, struct ssam_event_item *item)

Push an event item to the event queue.

Parameters

struct ssam_event_queue *q

The event queue.

struct ssam_event_item *item

The item to add.

struct ssam_event_item *ssam_event_queue_pop(struct ssam_event_queue *q)

Pop the next event item from the event queue.

Parameters

struct ssam_event_queue *q

The event queue.

Description

Returns and removes the next event item from the queue. Returns NULL If there is no event item left.

bool ssam_event_queue_is_empty(struct ssam_event_queue *q)

Check if the event queue is empty.

Parameters

struct ssam_event_queue *q

The event queue.

struct ssam_event_queue *ssam_cplt_get_event_queue(struct ssam_cplt *cplt, u8 tid, u16 rqid)

Get the event queue for the given parameters.

Parameters

struct ssam_cplt *cplt

The completion system on which to look for the queue.

u8 tid

The target ID of the queue.

u16 rqid

The request ID representing the event ID for which to get the queue.

Return

Returns the event queue corresponding to the event type described by the given parameters. If the request ID does not represent an event, this function returns NULL. If the target ID is not supported, this function will fall back to the default target ID (tid = 1).

bool ssam_cplt_submit(struct ssam_cplt *cplt, struct work_struct *work)

Submit a work item to the completion system workqueue.

Parameters

struct ssam_cplt *cplt

The completion system.

struct work_struct *work

The work item to submit.

int ssam_cplt_submit_event(struct ssam_cplt *cplt, struct ssam_event_item *item)

Submit an event to the completion system.

Parameters

struct ssam_cplt *cplt

The completion system.

struct ssam_event_item *item

The event item to submit.

Description

Submits the event to the completion system by queuing it on the event item queue and queuing the respective event queue work item on the completion workqueue, which will eventually complete the event.

Return

Returns zero on success, -EINVAL if there is no event queue that can handle the given event item.

void ssam_cplt_flush(struct ssam_cplt *cplt)

Flush the completion system.

Parameters

struct ssam_cplt *cplt

The completion system.

Description

Flush the completion system by waiting until all currently submitted work items have been completed.

This operation is only intended to, during normal operation prior to shutdown, try to complete most events and requests to get them out of the system while the system is still fully operational. It does not aim to provide any guarantee that all of them have been handled.

Note

This function does not guarantee that all events will have been handled once this call terminates. In case of a larger number of to-be-completed events, the event queue work function may re-schedule its work item, which this flush operation will ignore.

void ssam_event_queue_init(struct ssam_cplt *cplt, struct ssam_event_queue *evq)

Initialize an event queue.

Parameters

struct ssam_cplt *cplt

The completion system on which the queue resides.

struct ssam_event_queue *evq

The event queue to initialize.

int ssam_cplt_init(struct ssam_cplt *cplt, struct device *dev)

Initialize completion system.

Parameters

struct ssam_cplt *cplt

The completion system to initialize.

struct device *dev

The device used for logging.

void ssam_cplt_destroy(struct ssam_cplt *cplt)

Deinitialize the completion system.

Parameters

struct ssam_cplt *cplt

The completion system to deinitialize.

Description

Deinitialize the given completion system and ensure that all pending, i.e. yet-to-be-completed, event items and requests have been handled.

void ssam_controller_lock(struct ssam_controller *c)

Acquire the main controller lock.

Parameters

struct ssam_controller *c

The controller to lock.

Description

This lock must be held for any state transitions, including transition to suspend/resumed states and during shutdown. See ssam_controller_statelock() for more details on controller locking.

See ssam_controller_unlock() for the corresponding unlock function.

int ssam_controller_caps_load_from_acpi(acpi_handle handle, struct ssam_controller_caps *caps)

Load controller capabilities from ACPI _DSM.

Parameters

acpi_handle handle

The handle of the ACPI controller/SSH device.

struct ssam_controller_caps *caps

Where to store the capabilities in.

Description

Initializes the given controller capabilities with default values, then checks and, if the respective _DSM functions are available, loads the actual capabilities from the _DSM.

Return

Returns zero on success, a negative error code on failure.

int ssam_controller_init(struct ssam_controller *ctrl, struct serdev_device *serdev)

Initialize SSAM controller.

Parameters

struct ssam_controller *ctrl

The controller to initialize.

struct serdev_device *serdev

The serial device representing the underlying data transport.

Description

Initializes the given controller. Does neither start receiver nor transmitter threads. After this call, the controller has to be hooked up to the serdev core separately via struct serdev_device_ops, relaying calls to ssam_controller_receive_buf() and ssam_controller_write_wakeup(). Once the controller has been hooked up, transmitter and receiver threads may be started via ssam_controller_start(). These setup steps need to be completed before controller can be used for requests.

int ssam_controller_start(struct ssam_controller *ctrl)

Start the receiver and transmitter threads of the controller.

Parameters

struct ssam_controller *ctrl

The controller.

Note

When this function is called, the controller should be properly hooked up to the serdev core via struct serdev_device_ops. Please refer to ssam_controller_init() for more details on controller initialization.

Description

This function must be called with the main controller lock held (i.e. by calling ssam_controller_lock()).

void ssam_controller_shutdown(struct ssam_controller *ctrl)

Shut down the controller.

Parameters

struct ssam_controller *ctrl

The controller.

Description

Shuts down the controller by flushing all pending requests and stopping the transmitter and receiver threads. All requests submitted after this call will fail with -ESHUTDOWN. While it is discouraged to do so, this function is safe to use in parallel with ongoing request submission.

In the course of this shutdown procedure, all currently registered notifiers will be unregistered. It is, however, strongly recommended to not rely on this behavior, and instead the party registering the notifier should unregister it before the controller gets shut down, e.g. via the SSAM bus which guarantees client devices to be removed before a shutdown.

Note that events may still be pending after this call, but, due to the notifiers being unregistered, these events will be dropped when the controller is subsequently destroyed via ssam_controller_destroy().

This function must be called with the main controller lock held (i.e. by calling ssam_controller_lock()).

void ssam_controller_destroy(struct ssam_controller *ctrl)

Destroy the controller and free its resources.

Parameters

struct ssam_controller *ctrl

The controller.

Description

Ensures that all resources associated with the controller get freed. This function should only be called after the controller has been stopped via ssam_controller_shutdown(). In general, this function should not be called directly. The only valid place to call this function directly is during initialization, before the controller has been fully initialized and passed to other processes. This function is called automatically when the reference count of the controller reaches zero.

This function must be called with the main controller lock held (i.e. by calling ssam_controller_lock()).

int ssam_controller_suspend(struct ssam_controller *ctrl)

Suspend the controller.

Parameters

struct ssam_controller *ctrl

The controller to suspend.

Description

Marks the controller as suspended. Note that display-off and D0-exit notifications have to be sent manually before transitioning the controller into the suspended state via this function.

See ssam_controller_resume() for the corresponding resume function.

Return

Returns -EINVAL if the controller is currently not in the “started” state.

int ssam_controller_resume(struct ssam_controller *ctrl)

Resume the controller from suspend.

Parameters

struct ssam_controller *ctrl

The controller to resume.

Description

Resume the controller from the suspended state it was put into via ssam_controller_suspend(). This function does not issue display-on and D0-entry notifications. If required, those have to be sent manually after this call.

Return

Returns -EINVAL if the controller is currently not suspended.

struct ssh_notification_params

Command payload to enable/disable SSH notifications.

Definition

struct ssh_notification_params {
  u8 target_category;
  u8 flags;
  __le16 request_id;
  u8 instance_id;
};

Members

target_category

The target category for which notifications should be enabled/disabled.

flags

Flags determining how notifications are being sent.

request_id

The request ID that is used to send these notifications.

instance_id

The specific instance in the given target category for which notifications should be enabled.

int ssam_ssh_event_enable(struct ssam_controller *ctrl, struct ssam_event_registry reg, struct ssam_event_id id, u8 flags)

Enable SSH event.

Parameters

struct ssam_controller *ctrl

The controller for which to enable the event.

struct ssam_event_registry reg

The event registry describing what request to use for enabling and disabling the event.

struct ssam_event_id id

The event identifier.

u8 flags

The event flags.

Description

Enables the specified event on the EC. This function does not manage reference counting of enabled events and is basically only a wrapper for the raw EC request. If the specified event is already enabled, the EC will ignore this request.

Return

Returns the status of the executed SAM request (zero on success and negative on direct failure) or -EPROTO if the request response indicates a failure.

int ssam_ssh_event_disable(struct ssam_controller *ctrl, struct ssam_event_registry reg, struct ssam_event_id id, u8 flags)

Disable SSH event.

Parameters

struct ssam_controller *ctrl

The controller for which to disable the event.

struct ssam_event_registry reg

The event registry describing what request to use for enabling and disabling the event (must be same as used when enabling the event).

struct ssam_event_id id

The event identifier.

u8 flags

The event flags (likely ignored for disabling of events).

Description

Disables the specified event on the EC. This function does not manage reference counting of enabled events and is basically only a wrapper for the raw EC request. If the specified event is already disabled, the EC will ignore this request.

Return

Returns the status of the executed SAM request (zero on success and negative on direct failure) or -EPROTO if the request response indicates a failure.

int ssam_get_firmware_version(struct ssam_controller *ctrl, u32 *version)

Get the SAM/EC firmware version.

Parameters

struct ssam_controller *ctrl

The controller.

u32 *version

Where to store the version number.

Return

Returns zero on success or the status of the executed SAM request if that request failed.

int ssam_ctrl_notif_display_off(struct ssam_controller *ctrl)

Notify EC that the display has been turned off.

Parameters

struct ssam_controller *ctrl

The controller.

Description

Notify the EC that the display has been turned off and the driver may enter a lower-power state. This will prevent events from being sent directly. Rather, the EC signals an event by pulling the wakeup GPIO high for as long as there are pending events. The events then need to be manually released, one by one, via the GPIO callback request. All pending events accumulated during this state can also be released by issuing the display-on notification, e.g. via ssam_ctrl_notif_display_on(), which will also reset the GPIO.

On some devices, specifically ones with an integrated keyboard, the keyboard backlight will be turned off by this call.

This function will only send the display-off notification command if display notifications are supported by the EC. Currently all known devices support these notifications.

Use ssam_ctrl_notif_display_on() to reverse the effects of this function.

Return

Returns zero on success or if no request has been executed, the status of the executed SAM request if that request failed, or -EPROTO if an unexpected response has been received.

int ssam_ctrl_notif_display_on(struct ssam_controller *ctrl)

Notify EC that the display has been turned on.

Parameters

struct ssam_controller *ctrl

The controller.

Description

Notify the EC that the display has been turned back on and the driver has exited its lower-power state. This notification is the counterpart to the display-off notification sent via ssam_ctrl_notif_display_off() and will reverse its effects, including resetting events to their default behavior.

This function will only send the display-on notification command if display notifications are supported by the EC. Currently all known devices support these notifications.

See ssam_ctrl_notif_display_off() for more details.

Return

Returns zero on success or if no request has been executed, the status of the executed SAM request if that request failed, or -EPROTO if an unexpected response has been received.

int ssam_ctrl_notif_d0_exit(struct ssam_controller *ctrl)

Notify EC that the driver/device exits the D0 power state.

Parameters

struct ssam_controller *ctrl

The controller

Description

Notifies the EC that the driver prepares to exit the D0 power state in favor of a lower-power state. Exact effects of this function related to the EC are currently unknown.

This function will only send the D0-exit notification command if D0-state notifications are supported by the EC. Only newer Surface generations support these notifications.

Use ssam_ctrl_notif_d0_entry() to reverse the effects of this function.

Return

Returns zero on success or if no request has been executed, the status of the executed SAM request if that request failed, or -EPROTO if an unexpected response has been received.

int ssam_ctrl_notif_d0_entry(struct ssam_controller *ctrl)

Notify EC that the driver/device enters the D0 power state.

Parameters

struct ssam_controller *ctrl

The controller

Description

Notifies the EC that the driver has exited a lower-power state and entered the D0 power state. Exact effects of this function related to the EC are currently unknown.

This function will only send the D0-entry notification command if D0-state notifications are supported by the EC. Only newer Surface generations support these notifications.

See ssam_ctrl_notif_d0_exit() for more details.

Return

Returns zero on success or if no request has been executed, the status of the executed SAM request if that request failed, or -EPROTO if an unexpected response has been received.

int ssam_notifier_disable_registered(struct ssam_controller *ctrl)

Disable events for all registered notifiers.

Parameters

struct ssam_controller *ctrl

The controller for which to disable the notifiers/events.

Description

Disables events for all currently registered notifiers. In case of an error (EC command failing), all previously disabled events will be restored and the error code returned.

This function is intended to disable all events prior to hibernation entry. See ssam_notifier_restore_registered() to restore/re-enable all events disabled with this function.

Note that this function will not disable events for notifiers registered after calling this function. It should thus be made sure that no new notifiers are going to be added after this call and before the corresponding call to ssam_notifier_restore_registered().

Return

Returns zero on success. In case of failure returns the error code returned by the failed EC command to disable an event.

void ssam_notifier_restore_registered(struct ssam_controller *ctrl)

Restore/re-enable events for all registered notifiers.

Parameters

struct ssam_controller *ctrl

The controller for which to restore the notifiers/events.

Description

Restores/re-enables all events for which notifiers have been registered on the given controller. In case of a failure, the error is logged and the function continues to try and enable the remaining events.

This function is intended to restore/re-enable all registered events after hibernation. See ssam_notifier_disable_registered() for the counter part disabling the events and more details.

bool ssam_notifier_is_empty(struct ssam_controller *ctrl)

Check if there are any registered notifiers.

Parameters

struct ssam_controller *ctrl

The controller to check on.

Return

Returns true if there are currently no notifiers registered on the controller, false otherwise.

void ssam_notifier_unregister_all(struct ssam_controller *ctrl)

Unregister all currently registered notifiers.

Parameters

struct ssam_controller *ctrl

The controller to unregister the notifiers on.

Description

Unregisters all currently registered notifiers. This function is used to ensure that all notifiers will be unregistered and associated entries/resources freed when the controller is being shut down.

int ssam_irq_setup(struct ssam_controller *ctrl)

Set up SAM EC wakeup-GPIO interrupt.

Parameters

struct ssam_controller *ctrl

The controller for which the IRQ should be set up.

Description

Set up an IRQ for the wakeup-GPIO pin of the SAM EC. This IRQ can be used to wake the device from a low power state.

Note that this IRQ can only be triggered while the EC is in the display-off state. In this state, events are not sent to the host in the usual way. Instead the wakeup-GPIO gets pulled to “high” as long as there are pending events and these events need to be released one-by-one via the GPIO callback request, either until there are no events left and the GPIO is reset, or all at once by transitioning the EC out of the display-off state, which will also clear the GPIO.

Not all events, however, should trigger a full system wakeup. Instead the driver should, if necessary, inspect and forward each event to the corresponding subsystem, which in turn should decide if the system needs to be woken up. This logic has not been implemented yet, thus wakeup by this IRQ should be disabled by default to avoid spurious wake-ups, caused, for example, by the remaining battery percentage changing. Refer to comments in this function and comments in the corresponding IRQ handler for more details on how this should be implemented.

See also ssam_ctrl_notif_display_off() and ssam_ctrl_notif_display_off() for functions to transition the EC into and out of the display-off state as well as more details on it.

The IRQ is disabled by default and has to be enabled before it can wake up the device from suspend via ssam_irq_arm_for_wakeup(). On teardown, the IRQ should be freed via ssam_irq_free().

void ssam_irq_free(struct ssam_controller *ctrl)

Free SAM EC wakeup-GPIO interrupt.

Parameters

struct ssam_controller *ctrl

The controller for which the IRQ should be freed.

Description

Free the wakeup-GPIO IRQ previously set-up via ssam_irq_setup().

int ssam_irq_arm_for_wakeup(struct ssam_controller *ctrl)

Arm the EC IRQ for wakeup, if enabled.

Parameters

struct ssam_controller *ctrl

The controller for which the IRQ should be armed.

Description

Sets up the IRQ so that it can be used to wake the device. Specifically, this function enables the irq and then, if the device is allowed to wake up the system, calls enable_irq_wake(). See ssam_irq_disarm_wakeup() for the corresponding function to disable the IRQ.

This function is intended to arm the IRQ before entering S2idle suspend.

Note

calls to ssam_irq_arm_for_wakeup() and ssam_irq_disarm_wakeup() must be balanced.

void ssam_irq_disarm_wakeup(struct ssam_controller *ctrl)

Disarm the wakeup IRQ.

Parameters

struct ssam_controller *ctrl

The controller for which the IRQ should be disarmed.

Description

Disarm the IRQ previously set up for wake via ssam_irq_arm_for_wakeup().

This function is intended to disarm the IRQ after exiting S2idle suspend.

Note

calls to ssam_irq_arm_for_wakeup() and ssam_irq_disarm_wakeup() must be balanced.

Client Device Bus

bool ssam_device_id_compatible(const struct ssam_device_id *id, struct ssam_device_uid uid)

Check if a device ID matches a UID.

Parameters

const struct ssam_device_id *id

The device ID as potential match.

struct ssam_device_uid uid

The device UID matching against.

Description

Check if the given ID is a match for the given UID, i.e. if a device with the provided UID is compatible to the given ID following the match rules described in its ssam_device_id.match_flags member.

Return

Returns true if the given UID is compatible to the match rule described by the given ID, false otherwise.

bool ssam_device_id_is_null(const struct ssam_device_id *id)

Check if a device ID is null.

Parameters

const struct ssam_device_id *id

The device ID to check.

Description

Check if a given device ID is null, i.e. all zeros. Used to check for the end of MODULE_DEVICE_TABLE(ssam, ...) or similar lists.

Return

Returns true if the given ID represents a null ID, false otherwise.

void ssam_controller_remove_clients(struct ssam_controller *ctrl)

Remove SSAM client devices registered as direct children under the given controller.

Parameters

struct ssam_controller *ctrl

The controller to remove all direct clients for.

Description

Remove all SSAM client devices registered as direct children under the given controller. Note that this only accounts for direct children of the controller device. This does not take care of any client devices where the parent device has been manually set before calling ssam_device_add. Refer to ssam_device_add()/ssam_device_remove() for more details on those cases.

To avoid new devices being added in parallel to this call, the main controller lock (not statelock) must be held during this (and if necessary, any subsequent deinitialization) call.

int ssam_bus_register(void)

Register and set-up the SSAM client device bus.

Parameters

void

no arguments

void ssam_bus_unregister(void)

Unregister the SSAM client device bus.

Parameters

void

no arguments

Core

int ssam_try_set_controller(struct ssam_controller *ctrl)

Try to set the main controller reference.

Parameters

struct ssam_controller *ctrl

The controller to which the reference should point.

Description

Set the main controller reference to the given pointer if the reference hasn’t been set already.

Return

Returns zero on success or -EEXIST if the reference has already been set.

void ssam_clear_controller(void)

Remove/clear the main controller reference.

Parameters

void

no arguments

Description

Clears the main controller reference, i.e. sets it to NULL. This function should be called before the controller is shut down.

Trace Helpers

void ssam_trace_ptr_uid(const void *ptr, char *uid_str)

Convert the pointer to a non-pointer UID string.

Parameters

const void *ptr

The pointer to convert.

char *uid_str

A buffer of length SSAM_PTR_UID_LEN where the UID will be stored.

Description

Converts the given pointer into a UID string that is safe to be shared with userspace and logs, i.e. doesn’t give away the real memory location.

u16 ssam_trace_get_packet_seq(const struct ssh_packet *p)

Read the packet’s sequence ID.

Parameters

const struct ssh_packet *p

The packet.

Return

Returns the packet’s sequence ID (SEQ) field if present, or SSAM_SEQ_NOT_APPLICABLE if not (e.g. flush packet).

u32 ssam_trace_get_request_id(const struct ssh_packet *p)

Read the packet’s request ID.

Parameters

const struct ssh_packet *p

The packet.

Return

Returns the packet’s request ID (RQID) field if the packet represents a request with command data, or SSAM_RQID_NOT_APPLICABLE if not (e.g. flush request, control packet).

u32 ssam_trace_get_request_tc(const struct ssh_packet *p)

Read the packet’s request target category.

Parameters

const struct ssh_packet *p

The packet.

Return

Returns the packet’s request target category (TC) field if the packet represents a request with command data, or SSAM_TC_NOT_APPLICABLE if not (e.g. flush request, control packet).