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path: root/net/dsa/dsa.c
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2017-10-01net: dsa: change dsa_ptr for a dsa_portVivien Didelot
With DSA, a master net device (CPU facing interface) has a dsa_ptr pointer to which hangs a dsa_switch_tree. This is not correct because a master interface is wired to a dedicated switch port, and because we can theoretically have several master interfaces pointing to several CPU ports of the same switch fabric. Change the master interface's dsa_ptr for the CPU dsa_port pointer. This is a step towards supporting multiple CPU ports. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-09-19net: dsa: move master ethtool codeVivien Didelot
DSA overrides the master device ethtool ops, so that it can inject stats from its dedicated switch CPU port as well. The related code is currently split in dsa.c and slave.c, but it only scopes the master net device. Move it to a new master.c DSA core file. This file will be later extented with master net device specific code. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-09-19net: dsa: remove copy of master ethtool_opsVivien Didelot
There is no need to store a copy of the master ethtool ops, storing the original pointer in DSA and the new one in the master netdev itself is enough. In the meantime, set orig_ethtool_ops to NULL when restoring the master ethtool ops and check the presence of the master original ethtool ops as well as its needed functions before calling them. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-21dsa: remove unused net_device arg from handlersFlorian Westphal
compile tested only, but saw no warnings/errors with allmodconfig build. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-07net: dsa: Add support for learning FDB through notificationArkadi Sharshevsky
Add support for learning FDB through notification. The driver defers the hardware update via ordered work queue. In case of a successful FDB add a notification is sent back to bridge. In case of hw FDB del failure the static FDB will be deleted from the bridge, thus, the interface is moved to down state in order to indicate inconsistent situation. Signed-off-by: Arkadi Sharshevsky <arkadis@mellanox.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-07net: dsa: remove useless args of dsa_cpu_dsa_setupVivien Didelot
dsa_cpu_dsa_setup currently takes 4 arguments but they are all available from the dsa_port argument. Remove all others. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-06net: dsa: User per-cpu 64-bit statisticsFlorian Fainelli
During testing with a background iperf pushing 1Gbit/sec worth of traffic and having both ifconfig and ethtool collect statistics, we could see quite frequent deadlocks. Convert the often accessed DSA slave network devices statistics to per-cpu 64-bit statistics to remove these deadlocks and provide fast efficient statistics updates. Fixes: f613ed665bb3 ("net: dsa: Add support for 64-bit statistics") Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-02net: dsa: Add support for 64-bit statisticsFlorian Fainelli
DSA slave network devices maintain a pair of bytes and packets counters for each directions, but these are not 64-bit capable. Re-use pcpu_sw_netstats which contains exactly what we need for that purpose and update the code path to report 64-bit capable statistics. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-19net: dsa: unexport dsa_is_port_initializedVivien Didelot
The dsa_is_port_initialized helper is only used by dsa_switch_resume and dsa_switch_suspend, if CONFIG_PM_SLEEP is enabled. Make it static to dsa.c. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-13net: dsa: Relocate master ethtool operationsFlorian Fainelli
Relocate master_ethtool_ops and master_orig_ethtool_ops into struct dsa_port in order to be both consistent, and make things self contained within the dsa_port structure. This is a preliminary change to supporting multiple CPU port interfaces. Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-13net: dsa: Remove master_netdev and use dst->cpu_dp->netdevFlorian Fainelli
In preparation for supporting multiple CPU ports, remove dst->master_netdev and ds->master_netdev and replace them with only one instance of the common object we have for a port: struct dsa_port::netdev. ds->master_netdev is currently write only and would be helpful in the case where we have two switches, both with CPU ports, and also connected within each other, which the multi-CPU port patch series would address. While at it, introduce a helper function used in net/dsa/slave.c to immediately get a reference on the master network device called dsa_master_netdev(). Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-06Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller
Just some simple overlapping changes in marvell PHY driver and the DSA core code. Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-04net: dsa: Pass dsa_port reference to ethtool setup/restoreFlorian Fainelli
We do not need to have a reference to a dsa_switch, instead we should pass a reference to a CPU dsa_port, change that. This is a preliminary change to better support multiple CPU ports. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-02net: dsa: Move dsa_switch_{suspend,resume} out of legacy.cFlorian Fainelli
dsa_switch_suspend() and dsa_switch_resume() are functions that belong in net/dsa/dsa.c and are not part of the legacy platform support code. Fixes: a6a71f19fe5e ("net: dsa: isolate legacy code") Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-31dsa: add support for Microchip KSZ tail taggingWoojung Huh
Adding support for the Microchip KSZ switch family tail tagging. Reviewed-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Woojung Huh <Woojung.Huh@microchip.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-18net: dsa: include dsa.h only onceVivien Didelot
The public include/net/dsa.h file is meant for DSA drivers, while all DSA core files share a common private header net/dsa/dsa_priv.h file. Ensure that dsa_priv.h is the only DSA core file to include net/dsa.h, and add a new line to separate absolute and relative headers at the same time. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-17net: dsa: Sort DSA tagging protocol driversAndrew Lunn
With more tag protocols being added, regain some order by sorting the entries in various places. Signed-off-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-20net: dsa: add support for the SMSC-LAN9303 tagging formatJuergen Beisert
To define the outgoing port and to discover the incoming port a regular VLAN tag is used by the LAN9303. But its VID meaning is 'special'. This tag handler/filter depends on some hardware features which must be enabled in the device to provide and make use of this special VLAN tag to control the destination and the source of an ethernet packet. Signed-off-by: Juergen Borleis <jbe@pengutronix.de> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-17net: dsa: isolate legacy codeVivien Didelot
This patch moves as is the legacy DSA code from dsa.c to legacy.c, except the few shared symbols which remain in dsa.c. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-08net: dsa: Factor bottom tag receive functionsFlorian Fainelli
All DSA tag receive functions do strictly the same thing after they have located the originating source port from their tag specific protocol: - push ETH_HLEN bytes - set pkt_type to PACKET_HOST - call eth_type_trans() - bump up counters - call netif_receive_skb() Factor all of that into dsa_switch_rcv(). This also makes us return a pointer to a sk_buff, which makes us symetric with the xmit function. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-08net: dsa: Move skb_unshare() to dsa_switch_rcv()Florian Fainelli
All DSA tag receive functions need to unshare the skb before mangling it, move this to the generic dsa_switch_rcv() function which will allow us to make the tag receive function return their mangled skb without caring about freeing a NULL skb. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-07net-next: dsa: add Mediatek tag RX/TX handlerSean Wang
Add the support for the 4-bytes tag for DSA port distinguishing inserted allowing receiving and transmitting the packet via the particular port. The tag is being added after the source MAC address in the ethernet header. Signed-off-by: Sean Wang <sean.wang@mediatek.com> Signed-off-by: Landen Chao <Landen.Chao@mediatek.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-28net: break include loop netdevice.h, dsa.h, devlink.hAndrew Lunn
There is an include loop between netdevice.h, dsa.h, devlink.h because of NETDEV_ALIGN, making it impossible to use devlink structures in dsa.h. Break this loop by taking dsa.h out of netdevice.h, add a forward declaration of dsa_switch_tree and netdev_set_default_ethtool_ops() function, which is what netdevice.h requires. No longer having dsa.h in netdevice.h means the includes in dsa.h no longer get included. This breaks a few other files which depend on these includes. Add these directly in the affected file. Signed-off-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-07net: dsa: Rename and export dev_to_net_device()Florian Fainelli
In preparation for using this function in net/dsa/dsa2.c, rename the function to make its scope DSA specific, and export it. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-06net: dsa: add switch notifierVivien Didelot
Add a notifier block per DSA switch, registered against a notifier head in the switch fabric they belong to. This infrastructure will allow to propagate fabric-wide events such as port bridging, VLAN configuration, etc. If a DSA switch driver cares about cross-chip configuration, such events can be caught. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-06net: dsa: move netdevice notifier registrationVivien Didelot
Move the netdevice notifier block register code in slave.c and provide helpers for dsa.c to register and unregister it. At the same time, check for errors since (un)register_netdevice_notifier may fail. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-29net: dsa: use ds->num_ports when possibleVivien Didelot
The dsa_switch structure contains the number of ports. Use it where the structure is valid instead of the DSA_MAX_PORTS value. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-29net: dsa: variable number of portsVivien Didelot
Change the ports[DSA_MAX_PORTS] array of the dsa_switch structure for a zero-length array, allocated at the same time as the dsa_switch structure itself. A dsa_switch_alloc() helper is provided for that. This commit brings no functional change yet since we pass DSA_MAX_PORTS as the number of ports for the moment. Future patches can update the DSA drivers separately to support dynamic number of ports. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-26net: dsa: Make most functions take a dsa_port argumentFlorian Fainelli
In preparation for allowing platform data, and therefore no valid device_node pointer, make most DSA functions takes a pointer to a dsa_port structure whenever possible. While at it, introduce a dsa_port_is_valid() helper function which checks whether port->dn is NULL or not at the moment. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-24net: dsa: Fix inverted test for multiple CPU interfaceAndrew Lunn
Remove the wrong !, otherwise we get false positives about having multiple CPU interfaces. Fixes: b22de490869d ("net: dsa: store CPU switch structure in the tree") Signed-off-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-20net: dsa: Remove hwmon supportAndrew Lunn
Only the Marvell mv88e6xxx DSA driver made use of the HWMON support in DSA. The temperature sensor registers are actually in the embedded PHYs, and the PHY driver now supports it. So remove all HWMON support from DSA and drivers. Signed-off-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-18net: dsa: use cpu_switch instead of ds[0]Vivien Didelot
Now that the DSA Ethernet switches are true Linux devices, the CPU switch is not necessarily the first one. If its address is higher than the second switch on the same MDIO bus, its index will be 1, not 0. Avoid any confusion by using dst->cpu_switch instead of dst->ds[0]. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-18net: dsa: store CPU switch structure in the treeVivien Didelot
Store a dsa_switch pointer to the CPU switch in the tree instead of only its index. This avoids the need to initialize it to -1. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-09net: dsa: Make dsa_switch_ops constFlorian Fainelli
Now that we have properly encapsulated and made drivers utilize exported functions, we can switch dsa_switch_ops to be a annotated with const. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-09net: dsa: Encapsulate legacy switch drivers into dsa_switch_driverFlorian Fainelli
In preparation for making struct dsa_switch_ops const, encapsulate it within a dsa_switch_driver which has a list pointer and a pointer to dsa_switch_ops. This allows us to take the list_head pointer out of dsa_switch_ops, which is written to by {un,}register_switch_driver. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-07net: dsa: move HWMON support to its own fileVivien Didelot
Isolate the HWMON support in DSA in its own file. Currently only the legacy DSA code is concerned. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-06net: dsa: remove version stringVivien Didelot
The dsa_driver_version string is irrelevant and has not been bumped since its introduction about 9 years ago. Kill it. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-04net: dsa: remove out label in dsa_switch_setup_oneVivien Didelot
The "out" label in dsa_switch_setup_one() is useless, thus remove it. Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-29of_mdio: add helper to deregister fixed-link PHYsJohan Hovold
Add helper to deregister fixed-link PHYs registered using of_phy_register_fixed_link(). Convert the two drivers that care to deregister their fixed-link PHYs to use the new helper, but note that most drivers currently fail to do so. Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-27net: dsa: fix fixed-link-phy device leaksJohan Hovold
Make sure to drop the reference taken by of_phy_find_device() when registering and deregistering the fixed-link PHY-device. Fixes: 39b0c705195e ("net: dsa: Allow configuration of CPU & DSA port speeds/duplex") Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-20net-next: dsa: make the set_addr() operation optionalJohn Crispin
Only 1 of the 3 drivers currently has a set_addr() operation. Make the set_addr() callback optional to reduce the amount of empty stubs inside the drivers. Signed-off-by: John Crispin <john@phrozen.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-16net-next: dsa: add Qualcomm tag RX/TX handlerJohn Crispin
Add support for the 2-bytes Qualcomm tag that gigabit switches such as the QCA8337/N might insert when receiving packets, or that we need to insert while targeting specific switch ports. The tag is inserted directly behind the ethernet header. Reviewed-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: John Crispin <john@phrozen.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-24net: dsa: rename switch operations structureVivien Didelot
Now that the dsa_switch_driver structure contains only function pointers as it is supposed to, rename it to the more appropriate dsa_switch_ops, uniformly to any other operations structure in the kernel. No functional changes here, basically just the result of something like: s/dsa_switch_driver *drv/dsa_switch_ops *ops/g However keep the {un,}register_switch_driver functions and their dsa_switch_drivers list as is, since they represent the -- likely to be deprecated soon -- legacy DSA registration framework. In the meantime, also fix the following checks from checkpatch.pl to make it happy with this patch: CHECK: Comparison to NULL could be written "!ops" #403: FILE: net/dsa/dsa.c:470: + if (ops == NULL) { CHECK: Comparison to NULL could be written "ds->ops->get_strings" #773: FILE: net/dsa/slave.c:697: + if (ds->ops->get_strings != NULL) CHECK: Comparison to NULL could be written "ds->ops->get_ethtool_stats" #824: FILE: net/dsa/slave.c:785: + if (ds->ops->get_ethtool_stats != NULL) CHECK: Comparison to NULL could be written "ds->ops->get_sset_count" #835: FILE: net/dsa/slave.c:798: + if (ds->ops->get_sset_count != NULL) total: 0 errors, 0 warnings, 4 checks, 784 lines checked Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Acked-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-22net: dsa: Allow the DSA driver to indicate the tag protocolAndrew Lunn
DSA drivers may drive different families of switches which need different tag protocol. Rather than hard code the tag protocol in the driver structure, have a callback for the DSA core to call. Signed-off-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-19net: dsa: bcm_sf2: Make it a real platform device driverFlorian Fainelli
The Broadcom Starfighter 2 switch driver should be a proper platform driver, now that the DSA code has been updated to allow that, register a switch device, feed it with the proper configuration data coming from Device Tree and register our switch device with DSA. The bulk of the changes consist in moving what bcm_sf2_sw_setup() did into the platform driver probe function. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-19net: dsa: Export suspend/resume functionsFlorian Fainelli
In preparation for allowing switch drivers to implement system-wide suspend/resume functions, export dsa_switch_suspend and dsa_switch_resume() such that these are callable from the appropriate driver specific suspend/resume functions. Reviewed-by: Andrew Lunn <andrew@lunn.ch> Tested-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-07-08net: dsa: initialize the routing tableVivien Didelot
The routing table of every switch in a tree is currently initialized to all zeros. This is an issue since 0 is a valid port number. Add a DSA_RTABLE_NONE=-1 constant to initialize the signed values of the routing table pointing to other switches. This fixes the device mapping of the mv88e6xxx driver where the port pointing to the switch itself and to non-existent switches was wrongly configured to be 0. It is now set to the expected 0xf value. Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-08net: dsa: Initialize CPU port ethtool ops per treeFlorian Fainelli
Now that we can properly support multiple distinct trees in the system, using a global variable: dsa_cpu_port_ethtool_ops is getting clobbered as soon as the second switch tree gets probed, and we don't want that. We need to move this to be dynamically allocated, and since we can't really be comparing addresses anymore to determine first time initialization versus any other times, just move this to dsa.c and dsa2.c where the remainder of the dst/ds initialization happens. The operations teardown restores the master netdev's ethtool_ops to its original ethtool_ops pointer (typically within the Ethernet driver) Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-04net: dsa: Add new binding implementationAndrew Lunn
The existing DSA binding has a number of limitations and problems. The main problem is that it cannot represent a switch as a linux device, hanging off some bus. It is limited to one CPU port. The DSA platform device is artificial, and does not really represent hardware. Implement a new binding which can be embedded into any type of node on a bus to represent one switch device, and its links to other switches. Signed-off-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-04net: dsa: Make mdio bus optionalAndrew Lunn
The switch may want to instantiate its own MDIO bus. Only do it centrally if the switch has not already created one, and the read op is implemented. Signed-off-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>