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The initial version of the DSA driver only supported a single switch
chip per network interface, while DSA-capable switch chips can be
interconnected to form a tree of switch chips. This patch adds support
for multiple switch chips on a network interface.
An example topology for a 16-port device with an embedded CPU is as
follows:
+-----+ +--------+ +--------+
| |eth0 10| switch |9 10| switch |
| CPU +----------+ +-------+ |
| | | chip 0 | | chip 1 |
+-----+ +---++---+ +---++---+
|| ||
|| ||
||1000baseT ||1000baseT
||ports 1-8 ||ports 9-16
This requires a couple of interdependent changes in the DSA layer:
- The dsa platform driver data needs to be extended: there is still
only one netdevice per DSA driver instance (eth0 in the example
above), but each of the switch chips in the tree needs its own
mii_bus device pointer, MII management bus address, and port name
array. (include/net/dsa.h) The existing in-tree dsa users need
some small changes to deal with this. (arch/arm)
- The DSA and Ethertype DSA tagging modules need to be extended to
use the DSA device ID field on receive and demultiplex the packet
accordingly, and fill in the DSA device ID field on transmit
according to which switch chip the packet is heading to.
(net/dsa/tag_{dsa,edsa}.c)
- The concept of "CPU port", which is the switch chip port that the
CPU is connected to (port 10 on switch chip 0 in the example), needs
to be extended with the concept of "upstream port", which is the
port on the switch chip that will bring us one hop closer to the CPU
(port 10 for both switch chips in the example above).
- The dsa platform data needs to specify which ports on which switch
chips are links to other switch chips, so that we can enable DSA
tagging mode on them. (For inter-switch links, we always use
non-EtherType DSA tagging, since it has lower overhead. The CPU
link uses dsa or edsa tagging depending on what the 'root' switch
chip supports.) This is done by specifying "dsa" for the given
port in the port array.
- The dsa platform data needs to be extended with information on via
which port to reach any given switch chip from any given switch chip.
This info is specified via the per-switch chip data struct ->rtable[]
array, which gives the nexthop ports for each of the other switches
in the tree.
For the example topology above, the dsa platform data would look
something like this:
static struct dsa_chip_data sw[2] = {
{
.mii_bus = &foo,
.sw_addr = 1,
.port_names[0] = "p1",
.port_names[1] = "p2",
.port_names[2] = "p3",
.port_names[3] = "p4",
.port_names[4] = "p5",
.port_names[5] = "p6",
.port_names[6] = "p7",
.port_names[7] = "p8",
.port_names[9] = "dsa",
.port_names[10] = "cpu",
.rtable = (s8 []){ -1, 9, },
}, {
.mii_bus = &foo,
.sw_addr = 2,
.port_names[0] = "p9",
.port_names[1] = "p10",
.port_names[2] = "p11",
.port_names[3] = "p12",
.port_names[4] = "p13",
.port_names[5] = "p14",
.port_names[6] = "p15",
.port_names[7] = "p16",
.port_names[10] = "dsa",
.rtable = (s8 []){ 10, -1, },
},
},
static struct dsa_platform_data pd = {
.netdev = &foo,
.nr_switches = 2,
.sw = sw,
};
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Tested-by: Gary Thomas <gary@mlbassoc.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Distributed Switch Architecture is a protocol for managing hardware
switch chips. It consists of a set of MII management registers and
commands to configure the switch, and an ethernet header format to
signal which of the ports of the switch a packet was received from
or is intended to be sent to.
The switches that this driver supports are typically embedded in
access points and routers, and a typical setup with a DSA switch
looks something like this:
+-----------+ +-----------+
| | RGMII | |
| +-------+ +------ 1000baseT MDI ("WAN")
| | | 6-port +------ 1000baseT MDI ("LAN1")
| CPU | | ethernet +------ 1000baseT MDI ("LAN2")
| |MIImgmt| switch +------ 1000baseT MDI ("LAN3")
| +-------+ w/5 PHYs +------ 1000baseT MDI ("LAN4")
| | | |
+-----------+ +-----------+
The switch driver presents each port on the switch as a separate
network interface to Linux, polls the switch to maintain software
link state of those ports, forwards MII management interface
accesses to those network interfaces (e.g. as done by ethtool) to
the switch, and exposes the switch's hardware statistics counters
via the appropriate Linux kernel interfaces.
This initial patch supports the MII management interface register
layout of the Marvell 88E6123, 88E6161 and 88E6165 switch chips, and
supports the "Ethertype DSA" packet tagging format.
(There is no officially registered ethertype for the Ethertype DSA
packet format, so we just grab a random one. The ethertype to use
is programmed into the switch, and the switch driver uses the value
of ETH_P_EDSA for this, so this define can be changed at any time in
the future if the one we chose is allocated to another protocol or
if Ethertype DSA gets its own officially registered ethertype, and
everything will continue to work.)
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Tested-by: Nicolas Pitre <nico@marvell.com>
Tested-by: Byron Bradley <byron.bbradley@gmail.com>
Tested-by: Tim Ellis <tim.ellis@mac.com>
Tested-by: Peter van Valderen <linux@ddcrew.com>
Tested-by: Dirk Teurlings <dirk@upexia.nl>
Signed-off-by: David S. Miller <davem@davemloft.net>
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