Documentation/switchtec.txt

   1 ========================
   2 Linux Switchtec Support
   3 ========================
   4
   5 Microsemi's "Switchtec" line of PCI switch devices is already
   6 supported by the kernel with standard PCI switch drivers. However, the
   7 Switchtec device advertises a special management endpoint which
   8 enables 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
  16 The switchtec kernel module implements this functionality.
  17
  18
  19 Interface
  20 =========
  21
  22 The primary means of communicating with the Switchtec management firmware is
  23 through the Memory-mapped Remote Procedure Call (MRPC) interface.
  24 Commands are submitted to the interface with a 4-byte command
  25 identifier and up to 1KB of command specific data. The firmware will
  26 respond with a 4 bytes return code and up to 1KB of command specific
  27 data. The interface only processes a single command at a time.
  28
  29
  30 Userspace Interface
  31 ===================
  32
  33 The MRPC interface will be exposed to userspace through a simple char
  34 device: /dev/switchtec#, one for each management endpoint in the system.
  35
  36 The 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 four bytes will be interpreted as the command to run and
  40   the 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 four bytes of status plus up to 1024 bytes of output data. (The
  49   length will be specified by the size parameter of the read call --
  50   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
  55 The 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).