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.Dd February 28, 2013
.Dt DEVCFG 4
.Os
.Sh NAME
.Nm devcfg
.Nd Zynq PL device config interface
.Sh SYNOPSIS
.Cd device devcfg
.Sh DESCRIPTION
The special file
.Pa /dev/devcfg
can be used to configure the PL (FPGA) section of the Xilinx Zynq-7000.
.Pp
On the first write to the character device at file offset 0, the
.Nm
driver
asserts the top-level PL reset signals, disables the PS-PL level shifters,
and clears the PL configuration.
Write data is sent to the PCAP (processor configuration access port).
When the PL asserts the DONE signal, the devcfg driver will enable the level
shifters and release the top-level PL reset signals.
.Pp
The PL (FPGA) can be configured by writing the bitstream to the character
device like this:
.Bd -literal -offset indent
cat design.bit.bin > /dev/devcfg
.Ed
.Pp
The file should not be confused with the .bit file output by the FPGA
design tools.
It is the binary form of the configuration bitstream.
The Xilinx
.Ic promgen
tool can do the conversion:
.Bd -literal -offset indent
promgen -b -w -p bin -data_width 32 -u 0 design.bit -o design.bit.bin
.Ed
.Sh SYSCTL VARIABLES
The
.Nm
driver provides the following
.Xr sysctl 8
variables:
.Bl -tag -width 4n
.It Va hw.fpga.pl_done
.Pp
This variable always reflects the status of the PL's DONE signal.
A 1 means the PL section has been properly programmed.
.It Va hw.fpga.en_level_shifters
.Pp
This variable controls if the PS-PL level shifters are enabled after the
PL section has been reconfigured.
This variable is 1 by default but setting it to 0 allows the PL section to be
programmed with configurations that do not interface to the PS section of the
part.
Changing this value has no effect on the level shifters until the next device
reconfiguration.
.El
.Sh FILES
.Bl -tag -width 12n
.It Pa /dev/devcfg
Character device for the
.Nm
driver.
.El
.Sh SEE ALSO
Zynq-7000 SoC Technical Reference Manual (Xilinx doc UG585)
.Sh AUTHORS
Thomas Skibo