NAME

       patm — device driver for IDT77252 based ATM interfaces (ProSum and IDT)

SYNOPSIS

       device patm
       device utopia
       device atm

       options NATM
       options LIBMBPOOL

DESCRIPTION

       The  patm  device driver supports ATM cards based on the IDT77252 chip.  It has been tested with ProSum's
       ProATM-155 cards and with IDT's evaluation boards.  The driver interfaces  with  the  natm(4)  framework,
       netgraph(4)  and  HARP.   It provides only PVC services.  Signalling, ATMARP, ILMI and other higher layer
       protocols are implemented using netgraph(4) or HARP.

       For configuring the card for IP see natmip(4).

       The driver supports UBR, CBR, VBR and ABR traffic.  Supported AALs are: AAL0 (cell  payloads),  AAL5  and
       raw  AAL.   The  driver  supports  opening  of VCI/VPI 0/0 in RX, raw AAL-mode.  This VC will receive all
       incoming cells (even those with non-zero GFC fields and VPI/VCI values outside the  allowed  range)  that
       are not claimed by other open connections.  This may be used for monitoring purposes.

       The following sysctls are recognized by the driver additionally to those handled by utopia(4):

       hw.atm.patmN.istats
               Returns a list of uint32_t statistic counters with internal driver statistics.

       hw.atm.patmN.eeprom
               This is a read-only variable containing the contents of the on-board EEPROM device.

       hw.atm.patmN.lbuf_max
               This  puts  an upper limit on the number of large receive buffers the driver will allocate.  This
               is a read-only variable that can be set via a loader(8) tunable.

       hw.atm.patmN.tx_maxmaps
               This is the upper limit of transmission DMA maps the driver will allocate.  This is read-only but
               may be set via a loader(8) tunable.

       hw.atm.patmN.debug
               (Only if debugging enabled.)  These are debugging flags.  See  src/sys/dev/patm/if_patmvar.h  for
               the possible flags.  This may be initialized via a loader(8) tunable.

       hw.atm.patmN.regs
               (Only if debugging enabled.)  Returns the current values of the card's registers.

       hw.atm.patmN.tsq
               Returns the transmit status queue.

       When loaded, the driver initializes several variables from loader(8) tunables:

       hw.patmN.lbuf_max
               This initializes the corresponding sysctl(8) variable and defines an upper limit on the number of
               large receive buffers (mbuf clusters).

       hw.patmN.tx_maxmaps
               This  initializes  the corresponding sysctl(8) variable and is the maximum number of DMA maps for
               transmission that the driver will allocated.

       hw.patmN.debug
               (Only if debugging enabled.)  Initializes the debugging flags.

       The driver supports the media options sdh, noscramb and unassigned (see utopia(4)) when  the  card  is  a
       155MBit  card.   Both  PMC-Sierra S/UNI and IDT77155 PHY chips are supported for these cards.  For 25MBit
       cards the IDT77105 is supported.

DIAGNOSTICS

       patm1: <NICStAR (77222/77252) ATM adapter> port 0xc000-0xc0ff mem 0xf8000000-0xf83fffff,0xf4000000-0xf4000fff irq 11 at device 8.0 on pci2
       patm1: IDT77252 155MBit interface; idt77252 Rev. G; IDT77155 PHY
       patm1: 128K x 32 SRAM; 4096 connections

SEE ALSO

       natm(4), natmip(4), utopia(4)

ACKNOWLEDGEMENTS

       Thanks to Christian Bucari from ProSum for lending two of these cards to enable the development  of  this
       driver.  Thanks also for answering my questions.

AUTHORS

       Harti Brandt <harti@FreeBSD.org>

CAVEATS

       The  card  fails  to generate an interrupt if a cell is received in AAL0 mode that has the MSB of the PTI
       field cleared.  Therefore cells will be delivered on the next receive interrupt which can  happen  either
       when the receive status queue is full, or a cell with the last bit of the PTI set is received.

       Although the card supports AAL3/4 the driver does not.

       The  rate  tables used by this driver are not the tables recommended by IDT (they are wrong anyway).  The
       driver's tables are slightly more aggressive than IDT's.  That means, that the actual cell  rate  can  be
       slightly  higher than the specified.  This is in contrast to the IDT tables where cell rates 5% less than
       the allowed one have been observed.  This can be changed by changing the  program  that  generates  these
       tables, found in /usr/src/sys/dev/patm/genrtab, and regenerating them.

       The  reported media for the 155MBit cards will always be OC3/MM, because there is no (known to me) way to
       figure out the actual medium.  The medium should really be coded in the EEPROM by the manufacturer.

       The Tx cell counter in the utopia statistics is wrong, because the chip uses idle cells for  spacing  and
       the  PHY counts these cells.  While there is a configuration option for the chip to switch of these cells
       and, according to the documentation, this should not influence cell spacing, it does, so the driver  lets
       the chip generate idle cells.

Debian                                            July 15, 2003                                          PATM(4)