Adding Thunderbolt(TM) networking documentation. Signed-off-by: Amir Levy <amir.jer.levy@xxxxxxxxx> Signed-off-by: Michael Jamet <michael.jamet@xxxxxxxxx> --- Documentation/00-INDEX | 2 + Documentation/thunderbolt.txt | 135 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 137 insertions(+) create mode 100644 Documentation/thunderbolt.txt diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index cd077ca..d9b0e30 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -439,6 +439,8 @@ this_cpu_ops.txt - List rationale behind and the way to use this_cpu operations. thermal/ - directory with information on managing thermal issues (CPU/temp) +thunderbolt.txt + - Thunderbolt(TM) Networking driver description. trace/ - directory with info on tracing technologies within linux unaligned-memory-access.txt diff --git a/Documentation/thunderbolt.txt b/Documentation/thunderbolt.txt new file mode 100644 index 0000000..e4185b3 --- /dev/null +++ b/Documentation/thunderbolt.txt @@ -0,0 +1,135 @@ +Intel Thunderbolt(TM) Linux driver +================================== + +Copyright(c) 2013 - 2016 Intel Corporation. + +Contact Information: +Intel Thunderbolt mailing list <thunderbolt-software@xxxxxxxxxxxx> +Edited by Michael Jamet <michael.jamet@xxxxxxxxx> + +Overview +======== + +Thunderbolt(TM) Networking mode is introduced with this driver. +This kernel code creates an ethernet device utilized in computer to computer +communication over a Thunderbolt cable. +This driver has been added on the top of the existing thunderbolt driver +for systems with firwmare (FW) based Thunderbolt controllers supporting +Thunderbolt Networking. + +Files +===== + +- icm_nhi.c/h: These files allow communication with the FW (a.k.a ICM) based controller. + In addition, they create an interface for netlink communication with + a user space daemon. + +- net.c/net.h: These files implement the 'eth' interface for the Thunderbolt(TM) + networking. + +Interface to user space +======================= + +The interface to the user space module is implemented through a Generic Netlink. +In order to be accessed by the user space module, both kernel and user space +modules have to register with the same GENL_NAME. In our case, this is +simply "thunderbolt". +The registration is done at driver initialization time for all instances of +the Thunderbolt controllers. +The communication is then carried through pre-defined Thunderbolt messages. +Each specific message has a callback function that is called when +the related message is received. + +The messages are defined as follows: +* NHI_CMD_UNSPEC: Not used. +* NHI_CMD_SUBSCRIBE: Subscription request from daemon to driver to open the + communication channel. +* NHI_CMD_UNSUBSCRIBE: Request from daemon to driver to unsubscribe + to close communication channel. +* NHI_CMD_QUERY_INFORMATION: Request information from the driver such as + driver version, FW version offset, number of ports in the controller + and DMA port. +* NHI_CMD_MSG_TO_ICM: Message from user space module to FW. +* NHI_CMD_MSG_FROM_ICM: Response from FW to user space module. +* NHI_CMD_MAILBOX: Message that uses mailbox mechanism such as FW policy + changes or disconnect path. +* NHI_CMD_APPROVE_TBT_NETWORKING: Request from user space + module to FW to establish path. +* NHI_CMD_ICM_IN_SAFE_MODE: Indication that the FW has entered safe mode. + +Communication with ICM (Firmware) +================================= + +The communication with ICM is principally achieved through +a DMA mechanism on Ring 0. +The driver allocates a shared memory that is physically mapped onto +the DMA physical space at Ring 0. + +Interrupts +========== + +Thunderbolt relies on MSI-X interrupts. +The MSI-X vector is allocated as follows: +ICM + - Tx: MSI-X vector index 0 + - Rx: MSI-X vector index 1 + +Port 0 + - Tx: MSI-X vector index 2 + - Rx: MSI-X vector index 3 + +Port 1 + - Tx: MSI-X vector index 4 + - Rx: MSI-X vector index 5 + +ICM interrupts are used for communication with ICM only. +Port 0 and Port 1 interrupts are used for Thunderbolt Networking +communications. +In case MSI-X is not available, the driver requests to enable MSI only. + +Mutexes, semaphores and spinlocks +================================= + +The driver should be able to operate in an environment where hardware +is asynchronously accessed by multiple entities such as netlink, +multiple controllers etc. + +* send_sem: This semaphore enforces unique sender (one sender at a time) + to avoid wrong impairing with responses. FW may process one message + at the time. +* d0_exit_send_mutex: This mutex protects D0 exit (D3) situation + to avoid continuing to send messages to FW. +* d0_exit_mailbox_mutex: This mutex protects D0 exit (D3) situation to + avoid continuing to send commands to mailbox. +* mailbox_mutex: This mutex enforces unique sender (one sender at a time) + for the mailbox command. + A mutex is sufficient since the mailbox mechanism uses a polling mechanism + to get the command response. +* lock: This spinlock protects from simultaneous changes during + disable/enable interrupts. +* state_lock: This mutex comes to protect changes during net device state + changes and net_device operations. +* controllers_list_rwsem: This read/write sempahore syncs the access to + the controllers list when there are multiple controllers in the system. + +FW path enablement +================== + +In order to SW to communicate with the FW, the driver needs to send to FW +the PDF driver ready command and receive response from FW. +The driver ready command PDF value is 12 and the response is 13. +Once the exchange is completed, the user space module should be able to send +messages through the driver to the FW and FW starts to send notifications +about HW/FW events. + +Information +=========== + +Mailing list: + thunderbolt-software@xxxxxxxxxxxx + Register at: https://lists.01.org/mailman/listinfo/thunderbolt-software + Archives at: https://lists.01.org/pipermail/thunderbolt-software/ + +For additional information about Thunderbolt technology visit: + https://01.org/thunderbolt-sw + https://thunderbolttechnology.net/ -- 1.9.1 --------------------------------------------------------------------- Intel Israel (74) Limited This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). 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