NAME

       altera_sdcard — driver for the Altera University Program Secure Data Card IP Core

SYNOPSIS

       device altera_sdcard

       In /boot/device.hints:
       hint.altera_sdcardc.0.at="nexus0"
       hint.altera_sdcardc.0.maddr=0x7f008000
       hint.altera_sdcardc.0.msize=0x400

DESCRIPTION

       The  altera_sdcard  device driver provides support for the Altera University Program Secure Data Card (SD
       Card) IP Core device.  A controller device, altera_sdcardcX, will  be  attached  during  boot.   Inserted
       disks are presented as disk(9) devices, altera_sdcardX, corresponding to the controller number.

HARDWARE

       The  current  version of the altera_sdcard driver supports the SD Card IP core as described in the August
       2011 version of Altera's documentation.  The core supports only cards up to 2G (CSD 0); larger cards,  or
       cards  using  newer  CSD  versions, will not be detected.  The IP core has two key limitations: a lack of
       interrupt support, requiring timer-driven polling to detect I/O completion, and support for  only  single
       512-byte  block read and write operations at a time.  The combined effect of those two limits is that the
       system clock rate, HZ, must be set to at least 200 in order to accomplish the maximum 100KB/s  data  rate
       supported by the IP core.

SEE ALSO

       disk(9)

       Altera   University  Program  Secure  Data  Card  IP  Core,  Altera  Corporation  -  University  Program,
       ftp://ftp.altera.com/up/pub/Altera_Material/11.0/University_Program_IP_Cores/Memory/SD_Card_Interface_for_SoPC_Builder.pdf,
       August 2011.

HISTORY

       The altera_sdcard device driver first appeared in FreeBSD 10.0.

AUTHORS

       The altera_sdcard device driver and this  manual  page  were  developed  by  SRI  International  and  the
       University  of  Cambridge  Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237) (“CTSRD”), as
       part of the DARPA CRASH research programme.  This device driver was written by Robert N. M. Watson.

BUGS

       altera_sdcard contains a number of work-arounds for IP core bugs.  Perhaps most critically, altera_sdcard
       ignores the CRC error bit returned in the RR1 register, which appears to be unexpectedly set  by  the  IP
       core.

       altera_sdcard  uses  fixed  polling  intervals  are  used  for  card insertion/removal and I/O completion
       detection; an adaptive strategy might improve performance by reducing the latency to detecting  completed
       I/O.   However,  in  our experiments, using polling rates greater than 200 times a second did not improve
       performance.

       altera_sdcard supports only a nexus bus attachment, which is appropriate for system-on-chip  busses  such
       as  Altera's  Avalon  bus.   If  the  IP  core is configured off of another bus type, then additional bus
       attachments will be required.

Debian                                           August 18, 2012                                ALTERA_SDCARD(4)