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


     device patm
     device utopia
     device atm

     options NATM
     options LIBMBPOOL


     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

             Returns a list of uint32_t statistic counters with internal driver statistics.

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

             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.

             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.

             (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.

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

             Returns the transmit status queue.

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

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

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

             (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.


     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


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


     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.


     Harti Brandt <>


     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.