LXR linux/Documentation/switchtec.txt

   1========================
   2Linux Switchtec Support
   3========================
   4
   5Microsemi's "Switchtec" line of PCI switch devices is already
   6supported by the kernel with standard PCI switch drivers. However, the
   7Switchtec device advertises a special management endpoint which
   8enables some additional functionality. This includes:
   9
  10* Packet and Byte Counters
  11* Firmware Upgrades
  12* Event and Error logs
  13* Querying port link status
  14* Custom user firmware commands
  15
  16The switchtec kernel module implements this functionality.
  17
  18
  19Interface
  20=========
  21
  22The primary means of communicating with the Switchtec management firmware is
  23through the Memory-mapped Remote Procedure Call (MRPC) interface.
  24Commands are submitted to the interface with a 4-byte command
  25identifier and up to 1KB of command specific data. The firmware will
  26respond with a 4-byte return code and up to 1KB of command-specific
  27data. The interface only processes a single command at a time.
  28
  29
  30Userspace Interface
  31===================
  32
  33The MRPC interface will be exposed to userspace through a simple char
  34device: /dev/switchtec#, one for each management endpoint in the system.
  35
  36The char device has the following semantics:
  37
  38* A write must consist of at least 4 bytes and no more than 1028 bytes.
  39  The first 4 bytes will be interpreted as the Command ID and the
  40  remainder will be used as the input data. A write will send the
  41  command to the firmware to begin processing.
  42
  43* Each write must be followed by exactly one read. Any double write will
  44  produce an error and any read that doesn't follow a write will
  45  produce an error.
  46
  47* A read will block until the firmware completes the command and return
  48  the 4-byte Command Return Value plus up to 1024 bytes of output
  49  data. (The length will be specified by the size parameter of the read
  50  call -- reading less than 4 bytes will produce an error.)
  51
  52* The poll call will also be supported for userspace applications that
  53  need to do other things while waiting for the command to complete.
  54
  55The following IOCTLs are also supported by the device:
  56
  57* SWITCHTEC_IOCTL_FLASH_INFO - Retrieve firmware length and number
  58  of partitions in the device.
  59
  60* SWITCHTEC_IOCTL_FLASH_PART_INFO - Retrieve address and lengeth for
  61  any specified partition in flash.
  62
  63* SWITCHTEC_IOCTL_EVENT_SUMMARY - Read a structure of bitmaps
  64  indicating all uncleared events.
  65
  66* SWITCHTEC_IOCTL_EVENT_CTL - Get the current count, clear and set flags
  67  for any event. This ioctl takes in a switchtec_ioctl_event_ctl struct
  68  with the event_id, index and flags set (index being the partition or PFF
  69  number for non-global events). It returns whether the event has
  70  occurred, the number of times and any event specific data. The flags
  71  can be used to clear the count or enable and disable actions to
  72  happen when the event occurs.
  73  By using the SWITCHTEC_IOCTL_EVENT_FLAG_EN_POLL flag,
  74  you can set an event to trigger a poll command to return with
  75  POLLPRI. In this way, userspace can wait for events to occur.
  76
  77* SWITCHTEC_IOCTL_PFF_TO_PORT and SWITCHTEC_IOCTL_PORT_TO_PFF convert
  78  between PCI Function Framework number (used by the event system)
  79  and Switchtec Logic Port ID and Partition number (which is more
  80  user friendly).
  81
  82
  83Non-Transparent Bridge (NTB) Driver
  84===================================
  85
  86An NTB hardware driver is provided for the Switchtec hardware in
  87ntb_hw_switchtec. Currently, it only supports switches configured with
  88exactly 2 NT partitions and zero or more non-NT partitions. It also requires
  89the following configuration settings:
  90
  91* Both NT partitions must be able to access each other's GAS spaces.
  92  Thus, the bits in the GAS Access Vector under Management Settings
  93  must be set to support this.
  94* Kernel configuration MUST include support for NTB (CONFIG_NTB needs
  95  to be set)
  96
  97NT EP BAR 2 will be dynamically configured as a Direct Window, and
  98the configuration file does not need to configure it explicitly.
  99
 100Please refer to Documentation/ntb.txt in Linux source tree for an overall
 101understanding of the Linux NTB stack. ntb_hw_switchtec works as an NTB
 102Hardware Driver in this stack.
 103