mirror of
https://github.com/torvalds/linux.git
synced 2024-11-18 10:01:43 +00:00
fb513f60ea
The ntb_hw_switchtec driver has requirements on kernel configuration so add these notes to the documentation and also clean up a few other sentences in the documentation. Signed-off-by: Wesley Yung <wesley.yung@microchip.com> Signed-off-by: Kelvin Cao <kelvin.cao@microchip.com> Signed-off-by: Wesley Sheng <wesley.sheng@microchip.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
103 lines
4.0 KiB
Plaintext
103 lines
4.0 KiB
Plaintext
========================
|
|
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-byte 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 4 bytes will be interpreted as the Command ID 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 4-byte Command Return Value 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.
|
|
|
|
The following IOCTLs are also supported by the device:
|
|
|
|
* SWITCHTEC_IOCTL_FLASH_INFO - Retrieve firmware length and number
|
|
of partitions in the device.
|
|
|
|
* SWITCHTEC_IOCTL_FLASH_PART_INFO - Retrieve address and lengeth for
|
|
any specified partition in flash.
|
|
|
|
* SWITCHTEC_IOCTL_EVENT_SUMMARY - Read a structure of bitmaps
|
|
indicating all uncleared events.
|
|
|
|
* SWITCHTEC_IOCTL_EVENT_CTL - Get the current count, clear and set flags
|
|
for any event. This ioctl takes in a switchtec_ioctl_event_ctl struct
|
|
with the event_id, index and flags set (index being the partition or PFF
|
|
number for non-global events). It returns whether the event has
|
|
occurred, the number of times and any event specific data. The flags
|
|
can be used to clear the count or enable and disable actions to
|
|
happen when the event occurs.
|
|
By using the SWITCHTEC_IOCTL_EVENT_FLAG_EN_POLL flag,
|
|
you can set an event to trigger a poll command to return with
|
|
POLLPRI. In this way, userspace can wait for events to occur.
|
|
|
|
* SWITCHTEC_IOCTL_PFF_TO_PORT and SWITCHTEC_IOCTL_PORT_TO_PFF convert
|
|
between PCI Function Framework number (used by the event system)
|
|
and Switchtec Logic Port ID and Partition number (which is more
|
|
user friendly).
|
|
|
|
|
|
Non-Transparent Bridge (NTB) Driver
|
|
===================================
|
|
|
|
An NTB hardware driver is provided for the Switchtec hardware in
|
|
ntb_hw_switchtec. Currently, it only supports switches configured with
|
|
exactly 2 NT partitions and zero or more non-NT partitions. It also requires
|
|
the following configuration settings:
|
|
|
|
* Both NT partitions must be able to access each other's GAS spaces.
|
|
Thus, the bits in the GAS Access Vector under Management Settings
|
|
must be set to support this.
|
|
* Kernel configuration MUST include support for NTB (CONFIG_NTB needs
|
|
to be set)
|
|
|
|
NT EP BAR 2 will be dynamically configured as a Direct Window, and
|
|
the configuration file does not need to configure it explicitly.
|
|
|
|
Please refer to Documentation/ntb.txt in Linux source tree for an overall
|
|
understanding of the Linux NTB stack. ntb_hw_switchtec works as an NTB
|
|
Hardware Driver in this stack.
|