class Fusb302Protocol
Defined at line 117 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.h
FUSB302-specific implementation of the USB PD Protocol Layer.
The FUSB302 hardware can take on some aspects of the PD Protocol Layer. This
class is responsible for a complete implementation, while delegating some
parts to hardware.
Receiving messages works as follows:
* The hardware control logic is responsible for calling DrainReceiveFifo()
when the hardware signals that its receive FIFO is not empty.
* The USB PD implementation uses HasUnreadMessage() and FirstUnreadMessage()
to process received messages. MarkMessageAsRead() must be called after a
message is processed, before transmitting any reply to the message.
* The hardware control logic is responsible for calling
DidTransmitHardwareGeneratedGoodCrc() when the hardware signals that it
generated and transmitted a GoodCRC reply for a received PD packet.
Transmitting messages works as follows:
* next_transmitted_message_id() produces the MessageID to be used in the
usb_pd::Header constructor for a usb_pd::Message.
* Transmit() drives the hardware to transmit a usb_pd::Message over the PD
connection.
* DrainReceiveFifo(), documented in the reception section above, tracks
the USB PD connection partner's acknowledgement of Transmit() messages.
* The hardware control logic is responsible for calling
DidTimeoutWaitingForGoodCrc() when a message transmitted via Transmit()
is not acknowledged (via GoodCRC) by the other side of the USB PD
connection within the time mandated by the USB PD specification.
The implementation supports 3 integration models with a hardware-accelerated
GoodCRC generation module, which map to the 3 member variables of the
`GoodCrcGenerationMode` enum.
* kSoftware - MarkMessageAsRead() generates a GoodCRC packet for the returned
packet, and drives the hardware to transmit it
* kTracked - DidTransmitHardwareGeneratedGoodCrc() is called when the
hardware generates and transmits a GoodCRC packet; Transmit() queues its
argument for transmission if any previously received packet lacks a GoodCRC
reply; DidTransmitHardwareGeneratedGoodCrc() transmits any queued packet
* kAssumed - GoodCRC generation is completely ignored by the software
implementation
Public Methods
void Fusb302Protocol (GoodCrcGenerationMode good_crc_generation_mode, Fusb302Fifos & fifos)`fifos` must remain alive throughout the new instance's lifetime.
Defined at line 24 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.cc
zx::result<> MarkMessageAsRead ()Removes a message from the unread queue. Transmits a GoodCRC if neceesary.
`HasUnreadMessage()` must be true.
Returns an error if an I/O error occurred while transmitting a GoodCRC
acknowledging the read message.
Defined at line 34 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.cc
zx::result<> DrainReceiveFifo ()Reads any PD messages that may be pending in the Rx (receive) FIFO.
Returns an error if retrieving the PD message from the PHY layer encounters
an I/O error. Otherwise, performs PD Protocol Layer processing (mostly
MessageID validation), and updates (TBD: queue name).
Defined at line 67 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.cc
void Fusb302Protocol (const Fusb302Protocol & )Defined at line 122 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.h
Fusb302Protocol & operator= (const Fusb302Protocol & )Defined at line 123 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.h
void ~Fusb302Protocol ()Trivially destructible.
Defined at line 126 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.h
TransmissionState transmission_state ()See `TransmissionState` member comments.
Defined at line 129 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.h
bool HasUnreadMessage ()True if the unread queue is not empty.
All the messages in the unread queue must be processed and acknowledged via
`MarkMessageAsRead()` before `DrainReceiveFifo()` is called.
Defined at line 135 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.h
const usb_pd::Message & FirstUnreadMessage ()Returns the first message in the unread messages queue.
`HasUnreadMessage()` must be true.
Defined at line 140 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.h
usb_pd::MessageId next_transmitted_message_id ()Not meaningful while `transmission_state()` is `kPending`.
Defined at line 154 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.h
void SetGoodCrcTemplate (usb_pd::Header good_crc_template)The template will be used as-is (modulo MessageID) for GoodCRC messages.
Defined at line 180 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.h
zx::result<> Transmit (const usb_pd::Message & message)Transmits a PD message.
`message` must not be a GoodCRC. MarkMessageAsRead() dispatches any
necessary GoodCRC message internally.
`message`'s MessageID header field must equal
`next_transmitted_message_id()`.
Must not be called while `transmission_status()` is `kPending`. This is
because PD messages (with the excepton of GoodCRC) form a synchronous
stream that is blocked on the other side's GoodCRC acknowledgements.
Defined at line 188 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.cc
void FullReset ()PD protocol layer reset.
This method can be used when a new Type C connection is established, or
right before sending a Soft Reset message.
`DidReceiveSoftReset()` must be called instead of this method when a Soft
Reset message is received, because that situation requires different
initial values for MessageID counters.
Defined at line 211 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.cc
bool UsesHardwareAcceleratedGoodCrcNotifications ()If false, `DidTransmitHardwareGeneratedGoodCrc()` must never be called.
Defined at line 212 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.h
void DidReceiveSoftReset ()PD protocol layer reset, used after receiving a Soft Reset packet.
This must only be used for a soft reset initiated by a port partner
message. Incorrect use will result in incorrect initial MessageID values,
which will break future communication.
Defined at line 223 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.cc
void DidTimeoutWaitingForGoodCrc ()Hardware-side PD protocol layer says it gave up waiting for a GoodCRC.
This signal comes from the interrupt unit.
Defined at line 249 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.cc
void DidTransmitHardwareGeneratedGoodCrc ()Hardware-side PD protocol layer says it replied with a GoodCRC message.
This signal comes from the interrupt unit.
Defined at line 258 of file ../../src/devices/power/drivers/fusb302/fusb302-protocol.cc