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ALTERA_SDCARD(4)	    Kernel Interfaces Manual	      ALTERA_SDCARD(4)

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 Univer-
       sity 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 sup-
       ported 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.  Per-
       haps 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	inser-
       tion/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  appropri-
       ate  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 attach-
       ments will be required.

FreeBSD	14.3			August 18, 2012		      ALTERA_SDCARD(4)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=altera_sdcard&sektion=4&manpath=FreeBSD+14.3-RELEASE+and+Ports>

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