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| -rw-r--r-- | Documentation/switchtec.txt | 53 | ||||
| -rw-r--r-- | MAINTAINERS | 1 |
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diff --git a/Documentation/switchtec.txt b/Documentation/switchtec.txt new file mode 100644 index 000000000000..4bced4c78446 --- /dev/null +++ b/Documentation/switchtec.txt @@ -0,0 +1,53 @@ +======================== +Linux Switchtec Support +======================== + +Microsemi's "Switchtec" line of PCI switch devices is already +supported by the kernel with standard PCI switch drivers. However, the +Switchtec device advertises a special management endpoint which +enables some additional functionality. This includes: + +* Packet and Byte Counters +* Firmware Upgrades +* Event and Error logs +* Querying port link status +* Custom user firmware commands + +The switchtec kernel module implements this functionality. + + +Interface +========= + +The primary means of communicating with the Switchtec management firmware is +through the Memory-mapped Remote Procedure Call (MRPC) interface. +Commands are submitted to the interface with a 4-byte command +identifier and up to 1KB of command specific data. The firmware will +respond with a 4 bytes return code and up to 1KB of command specific +data. The interface only processes a single command at a time. + + +Userspace Interface +=================== + +The MRPC interface will be exposed to userspace through a simple char +device: /dev/switchtec#, one for each management endpoint in the system. + +The char device has the following semantics: + +* A write must consist of at least 4 bytes and no more than 1028 bytes. + The first four bytes will be interpreted as the command to run and + the remainder will be used as the input data. A write will send the + command to the firmware to begin processing. + +* Each write must be followed by exactly one read. Any double write will + produce an error and any read that doesn't follow a write will + produce an error. + +* A read will block until the firmware completes the command and return + the four bytes of status plus up to 1024 bytes of output data. (The + length will be specified by the size parameter of the read call -- + reading less than 4 bytes will produce an error. + +* The poll call will also be supported for userspace applications that + need to do other things while waiting for the command to complete. diff --git a/MAINTAINERS b/MAINTAINERS index 16bd75d30ac1..5bc3b7c7e0d9 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9661,6 +9661,7 @@ M: Stephen Bates <stephen.bates@microsemi.com> M: Logan Gunthorpe <logang@deltatee.com> L: linux-pci@vger.kernel.org S: Maintained +F: Documentation/switchtec.txt F: drivers/pci/switch/switchtec* PCI DRIVER FOR NVIDIA TEGRA |