bionic (4) altera_sdcard.4freebsd.gz

Provided by: freebsd-manpages_11.1-3_all bug

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.