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author | Jiri Pirko <jiri@resnulli.us> | 2014-11-28 14:34:17 +0100 |
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committer | David S. Miller <davem@davemloft.net> | 2014-12-02 20:01:20 -0800 |
commit | 007f790c8276271de26416f90d55561bcc96588a (patch) | |
tree | 03a55b7897402e9daa8af64ea2c81d5236f77367 /Documentation/networking/switchdev.txt | |
parent | 02637fce3e0103ba086b9c33b6d529e69460e4b6 (diff) | |
download | linux-007f790c8276271de26416f90d55561bcc96588a.tar.gz linux-007f790c8276271de26416f90d55561bcc96588a.tar.bz2 linux-007f790c8276271de26416f90d55561bcc96588a.zip |
net: introduce generic switch devices support
The goal of this is to provide a possibility to support various switch
chips. Drivers should implement relevant ndos to do so. Now there is
only one ndo defined:
- for getting physical switch id is in place.
Note that user can use random port netdevice to access the switch.
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Reviewed-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Andy Gospodarek <gospo@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking/switchdev.txt')
-rw-r--r-- | Documentation/networking/switchdev.txt | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/Documentation/networking/switchdev.txt b/Documentation/networking/switchdev.txt new file mode 100644 index 000000000000..f981a9295a39 --- /dev/null +++ b/Documentation/networking/switchdev.txt @@ -0,0 +1,59 @@ +Switch (and switch-ish) device drivers HOWTO +=========================== + +Please note that the word "switch" is here used in very generic meaning. +This include devices supporting L2/L3 but also various flow offloading chips, +including switches embedded into SR-IOV NICs. + +Lets describe a topology a bit. Imagine the following example: + + +----------------------------+ +---------------+ + | SOME switch chip | | CPU | + +----------------------------+ +---------------+ + port1 port2 port3 port4 MNGMNT | PCI-E | + | | | | | +---------------+ + PHY PHY | | | | NIC0 NIC1 + | | | | | | + | | +- PCI-E -+ | | + | +------- MII -------+ | + +------------- MII ------------+ + +In this example, there are two independent lines between the switch silicon +and CPU. NIC0 and NIC1 drivers are not aware of a switch presence. They are +separate from the switch driver. SOME switch chip is by managed by a driver +via PCI-E device MNGMNT. Note that MNGMNT device, NIC0 and NIC1 may be +connected to some other type of bus. + +Now, for the previous example show the representation in kernel: + + +----------------------------+ +---------------+ + | SOME switch chip | | CPU | + +----------------------------+ +---------------+ + sw0p0 sw0p1 sw0p2 sw0p3 MNGMNT | PCI-E | + | | | | | +---------------+ + PHY PHY | | | | eth0 eth1 + | | | | | | + | | +- PCI-E -+ | | + | +------- MII -------+ | + +------------- MII ------------+ + +Lets call the example switch driver for SOME switch chip "SOMEswitch". This +driver takes care of PCI-E device MNGMNT. There is a netdevice instance sw0pX +created for each port of a switch. These netdevices are instances +of "SOMEswitch" driver. sw0pX netdevices serve as a "representation" +of the switch chip. eth0 and eth1 are instances of some other existing driver. + +The only difference of the switch-port netdevice from the ordinary netdevice +is that is implements couple more NDOs: + + ndo_switch_parent_id_get - This returns the same ID for two port netdevices + of the same physical switch chip. This is + mandatory to be implemented by all switch drivers + and serves the caller for recognition of a port + netdevice. + ndo_switch_parent_* - Functions that serve for a manipulation of the switch + chip itself (it can be though of as a "parent" of the + port, therefore the name). They are not port-specific. + Caller might use arbitrary port netdevice of the same + switch and it will make no difference. + ndo_switch_port_* - Functions that serve for a port-specific manipulation. |