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Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 EST.

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).
81	
82	
83	Non-Transparent Bridge (NTB) Driver
84	===================================
85	
86	An NTB driver is provided for the switchtec hardware in switchtec_ntb.
87	Currently, it only supports switches configured with exactly 2
88	partitions. It also requires the following configuration settings:
89	
90	* Both partitions must be able to access each other's GAS spaces.
91	  Thus, the bits in the GAS Access Vector under Management Settings
92	  must be set to support this.
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