Teach vr(4) to use bus_dma(9) and major overhauling to handle link

Teach vr(4) to use bus_dma(9) and major overhauling to handle link
state change and reliable error recovery.
 o Moved vr_softc structure and relevant macros to header file.
 o Use PCIR_BAR macro to get BARs.
 o Implemented suspend/resume methods.
 o Implemented automatic Tx threshold configuration which will be
   activated when it suffers from Tx underrun. Also Tx underrun
   will try to restart only Tx path and resort to previous
   full-reset(both Rx/Tx) operation if restarting Tx path have failed.
 o Removed old bit-banging MII interface. Rhine provides simple and
   efficient MII interface. While I'm here show PHY address and PHY
   register number when its read/write operation was failed.
 o Define VR_MII_TIMEOUT constant and use it in MII access routines.
 o Always honor link up/down state reported by mii layers. The link
   state information is used in vr_start() to determine whether we
   got a valid link.
 o Removed vr_setcfg() which is now handled in vr_link_task(), link
   state taskqueue handler. When mii layer reports link state changes
   the taskqueue handler reprograms MAC to reflect negotiated duplex
   settings. Flow-control changes are not handled yet and it should
   be revisited when mii layer knows the notion of flow-control.
 o Added a new sysctl interface to get statistics of an instance of
   the driver.(sysctl dev.vr.0.stats=1)
 o Chip name was renamed to reflect the official name of the chips
   described in VIA Rhine I/II/III datasheet.
	REV_ID_3065_A -> REV_ID_VT6102_A
	REV_ID_3065_B -> REV_ID_VT6102_B
	REV_ID_3065_C -> REV_ID_VT6102_C
	REV_ID_3106_J -> REV_ID_VT6105_A0
	REV_ID_3106_S -> REV_ID_VT6105M_A0
   The following chip revisions were added.
	#define REV_ID_VT6105_B0	0x83
	#define REV_ID_VT6105_LOM	0x8A
	#define REV_ID_VT6107_A0	0x8C
	#define REV_ID_VT6107_A1	0x8D
	#define REV_ID_VT6105M_B1	0x94
 o Always show chip revision number in device attach. This shall help
   identifying revision specific issues.
 o Check whether EEPROM reloading is complete by inspecting the state
   of VR_EECSR_LOAD bit. This bit is self-cleared after the EEPROM
   reloading. Previously vr(4) blindly spins for 200us which may/may
   not enough to complete the EEPROM reload.
 o Removed if_mtu setup. It's done in ether_ifattach().
 o Use our own callout to drive watchdog timer.
 o In vr_attach disable further interrupts after reset. For VT6102 or
   newer hardwares, diable MII state change interrupt as well because
   mii state handling is done by mii layer.
 o Add more sane register initialization for VT6102 or newer chips.
    - Have NIC report error instead of retrying forever.
    - Let hardware detect MII coding error.
    - Enable MODE10T mode.
    - Enable memory-read-multiple for VT6107.
 o PHY address for VT6105 or newer chips is located at fixed address 1.
   For older chips the PHY address is stored in VR_PHYADDR register.
   Armed with these information, there is no need to re-read
   VR_PHYADDR register in miibus handler to get PHY address. This
   saves one register access cycle for each MII access.
 o Don't reprogram VR_PHYADDR register whenever access to a register
   located at a PHY address is made. Rhine fmaily allows reprogramming
   PHY address location via VR_PHYADDR register depending on
   VR_MIISTAT_PHYOPT bit of VR_MIISTAT register. This used to lead
   numerous phantom PHYs attached to miibus during phy probe phase and
   driver used to limit allowable PHY address in mii register accessors
   for certain chip revisions. This removes one more register access
   cycle for each MII access.
 o Correctly set VLAN header length.
 o bus_dma(9) conversion.
    - Limit DMA access to be in range of 32bit address space. Hardware
      doesn't support DAC.
    - Apply descriptor ring alignment requirements(16 bytes alignment)
    - Apply Rx buffer address alignment requirements(4 bytes alignment)
    - Apply Tx buffer address alignment requirements(4 bytes alignment)
      for Rhine I chip. Rhine II or III has no Tx buffer address
      alignment restrictions, though.
    - Reduce number of allowable number of DMA segments to 8.
    - Removed the atomic(9) used in descriptor ownership managements
      as it's job of bus_dmamap_sync(9).
    With these change vr(4) should work on all platforms.
 o Rhine uses two separated 8bits command registers to control Tx/Rx
   MAC. So don't access it as a single 16bit register.
 o For non-strict alignment architectures vr(4) no longer require
   time-consuming copy operation for received frames to align IP
   header. This greatly improves Rx performance on i386/amd64
   platforms. However the alignment is still necessary for
   strict-alignment platforms(e.g. sparc64). The alignment is handled
   in new fuction vr_fixup_rx().
 o vr_rxeof() now rejects multiple-segmented(fragmented) frames as
   vr(4) is not ready to handle this situation. Datasheet said nothing
   about the reason when/why it happens.
 o In vr_newbuf() don't set VR_RXSTAT_FIRSTFRAG/VR_RXSTAT_LASTFRAG
   bits as it's set by hardware.
 o Don't pass checksum offload information to upper layer for
   fragmented frames. The hardware assisted checksum is valid only
   when the frame is non-fragmented IP frames. Also mark the checksum
   is valid for corrupted frames such that upper layers doesn't need
   to recompute the checksum with software routine.
 o Removed vr_rxeoc(). RxDMA doesn't seem to need to be idle before
   sending VR_CMD_RX_GO command. Previously it used to stop RxDMA
   first which in turn resulted in long delays in Rx error recovery.
 o Rewrote Tx completion handler.
    - Always check VR_TXSTAT_OWN bit in status word prior to
      inspecting other status bits in the status word.
    - Collision counter updates were corrected as VT3071 or newer
      ones use different bits to notify collisions.
    - Unlike other chip revisions, VT86C100A uses different bit to
      indicate Tx underrun. For VT3071 or newer ones, check both
      VR_TXSTAT_TBUFF and VR_TXSTAT_UDF bits to see whether Tx
      underrun was happend. In case of Tx underrun requeue the failed
      frame and restart stalled Tx SM. Also double Tx DMA threshold
      size on each failure to mitigate future Tx underruns.
    - Disarm watchdog timer only if we have no queued packets,
      otherwise don't touch watchdog timer.
 o Rewrote interrupt handler.
    - status word in Tx/Rx descriptors indicates more detailed error
      state required to recover from the specific error. There is no
      need to rely on interrupt status word to recover from Tx/Rx
      error except PCI bus error. Other event notifications like
      statistics counter overflows or link state events will be
      handled in main interrupt handler.
    - Don't touch VR_IMR register if we are in suspend mode. Touching
      the register may hang the hardware if we are in suspended state.
      Previously it seems that touching VR_IMR register in interrupt
      handler was to work-around panic occurred in system shutdown
      stage on SMP systems. I think that work-around would hide
      root-cause of the panic and I couldn't reproduce the panic
      with multiple attempts on my box.
 o While padding space to meet minimum frame size, zero the pad data
   in order to avoid possibly leaking sensitive data.
 o Rewrote vr_start_locked().
    - Don't try to queue packets if number of available Tx descriptors
      are short than that of required one.
 o Don't reinitialize hardware whenever media configuration is
   changed. Media/link state changes are reported from mii layer if
   this happens and vr_link_task() will perform necessary changes.
 o Don't reinitialize hardware if only PROMISC bit was changed. Just
   toggle the PROMISC bit in hardware is sufficient to reflect the
   request.
 o Rearrganed the IFCAP_POLLING/IFCAP_HWCSUM handling in vr_ioctl().
 o Generate Tx completion interrupts for every VR_TX_INTR_THRESH-th
   frames. This reduces Tx completion interrupts under heavy network
   loads.
 o Since vr(4) doesn't request Tx interrupts for every queued frames,
   reclaim any pending descriptors not handled in Tx completion
   handler before actually firing up watchdog timeouts.
 o Added vr_tx_stop()/vr_rx_stop() to wait for the end of active
   TxDMA/RxDMA cycles(draining). These routines are used in vr_stop()
   to ensure sane state of MAC before releasing allocated Tx/Rx
   buffers. vr_link_task() also takes advantage of these functions to
   get to idle state prior to restarting Tx/Rx.
 o Added vr_tx_start()/vr_rx_start() to restart Rx/Tx. By separating
   Rx operation from Tx operation vr(4) no longer need to full-reset
   the hardware in case of Tx/Rx error recovery.
 o Implemented WOL.
 o Added VT6105M specific register definitions. VT6105M has the
   following hardware capabilities.
    - Tx/Rx IP/TCP/UDP checksum offload.
    - VLAN hardware tag insertion/extraction. Due to lack of information
       for getting extracted VLAN tag in Rx path, VLAN hardware support
       was not implemented yet.
    - CAM(Content Addressable Memory) based 32 entry perfect multicast/
      VLAN filtering.
    - 8 priority queues.
 o Implemented CAM based 32 entry perfect multicast filtering for
   VT6105M. If number of multicast entry is greater than 32, vr(4)
   uses traditional hash based filtering.
 o Reflect real Tx/Rx descriptor structure. Previously vr(4) used to
   embed other driver (private) data into these structure. This type
   of embedding make it hard to work on LP64 systems.
 o Removed unused vr_mii_frame structure and MII bit-baning
   definitions.
 o Added new PCI configuration registers that controls mii operation
   and mode selection.
 o Reduced number of Tx/Rx descriptors to 128 from 256. From my
   testing, increasing number of descriptors above than 64 didn't help
   increasing performance at all. Experimentations show 128 Rx
   descriptors seems to help a lot reducing Rx FIFO overruns under
   high system loads. It seems the poor Tx performance of Rhine
   hardwares comes from the limitation of hardware. You wouldn't
   satuarte the link with vr(4) no matter how fast CPU/large number of
   descriptors are used.
 o Added vr_statistics structure to hold various counter values.

No regression was reported but one variant of Rhine III(VT6105M)
found on RouterBOARD 44 does not work yet(Reported by Milan Obuch).
I hope this would be resolved in near future.

I'd like to say big thanks to Mike Tancsa who kindly donated a Rhine
hardware to me. Without his enthusiastic testing and feedbacks
overhauling vr(4) never have been possible. Also thanks to Masayuki
Murayama who provided some good comments on the hardware's internals.
This driver is result of combined effort of many users who provided
many feedbacks so I'd like to say special thanks to them.

Hardware donated by:	Mike Tancsa (mike AT sentex dot net)
Reviewed by:		remko (initial version)
Tested by:		Mike Tancsa(x86), JoaoBR ( joao AT matik DOT com DOT br )
			Marcin Wisnicki ( mwisnicki+freebsd AT gmail DOT com )
			Stefan Ehmann ( shoesoft AT gmx DOT net )
			Florian Smeets ( flo AT kasimir DOT com )
			Phil Oleson ( oz AT nixil DOT net )
			Larry Baird ( lab AT gta DOT com )
			Milan Obuch ( freebsd-current AT dino DOT sk )
			remko (initial version)