$ lspci -vvnn | grep -A9 Network
04:00.0 Network controller [0280]: Broadcom Corporation BCM4356 802.11ac Wireless Network Adapter [14e4:43ec] (rev 02)
    Subsystem: Lenovo Device [17aa:0777]
    Control: I/O- Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
    Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
    Interrupt: pin A routed to IRQ 18
    Region 0: Memory at f1400000 (64-bit, non-prefetchable) [size=32K]
    Region 2: Memory at f1000000 (64-bit, non-prefetchable) [size=4M]
    Capabilities: <access denied>


$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 15.10
Release:    15.10
Codename:   wily

$ uname -a
Linux gimly 4.2.0-30-generic #35-Ubuntu SMP Fri Feb 19 13:52:26 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

sudo apt-get purge bcmwl-kernel-source
sudo modprobe -r brcmfmac

sudo modprobe brcmfmac

sudo apt-mark hold linux-firmware