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FMC DEL 1ns 4cha - Software
Commit 07d7c65f authored by Alessandro Rubini's avatar Alessandro Rubini
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doc: documented input config and minor changes

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doc/fine-delay.in
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......@@ -35,7 +35,7 @@
@setchapternewpage off
@set update-month April 2012
@set update-month May 2012
@finalout
......@@ -350,9 +350,9 @@ directory is @i{/sys/bus/zio/devices/zio-fd-0200}:
@smallexample
spusa# ls -Ff /sys/bus/zio/devices/zio-fd-0200/
./ enable utc-l power/ fd-ch2/
../ resolution-bits coarse driver@ fd-ch3/
uevent version host-time fd-input/ fd-ch4/
name utc-h subsystem@ fd-ch1/
../ resolution-bits coarse driver fd-ch3/
uevent version command fd-input/ fd-ch4/
name utc-h subsystem fd-ch1/
@end smallexample
@c ==========================================================================
......@@ -475,6 +475,7 @@ attributes}, which you can look at using @code{zio-dump} or
* Input Device Attributes::
* Reading with zio-dump::
* Reading with fd-raw-input::
* Configuring the Input Channel::
* Generating Bursts by Software::
@end menu
......@@ -494,9 +495,12 @@ is defined in @i{fine-delay.h} for libraries/applications to use them:
FD_ATTR_TDC_SEQ,
FD_ATTR_TDC_CHAN,
FD_ATTR_TDC_FLAGS,
FD_ATTR_TDC_OFFSET,
};
#define FD_ATTR_TDCF_ENABLE 1
#define FD_ATTR_TDCF_TERM 2
/* Names have been chosen so that 0 is the default at load time */
#define FD_TDCF_DISABLE_INPUT 1
#define FD_TDCF_DISABLE_TSTAMP 2
#define FD_TDCF_TERM_50 4
@end example
The attributes are also visibile in @i{/sys}, in the directory
......@@ -504,16 +508,21 @@ describing the cset:
@smallexample
spusa# ls -Ff /sys/bus/zio/devices/zio-fd-0200/fd-input/
./ enable utc-l chan chan0/
../ current_trigger coarse flags
uevent current_buffer frac power/
name utc-h seq trigger/
./ enable utc-l chan trigger/
../ current_trigger coarse flags chan0/
uevent current_buffer frac offset
name utc-h seq power/
@end smallexample
Note, however, that the values in those files don't change to reflect
the values last retrieved, to avoid wasting CPU power. If it is
considered useful, copying over the acquired attributes where
@i{sysfs} can read them is pretty trivial.
The timestamp-related values in this file reflect the last stamp that
has been enqueued to user space (this may be the next event to be
read by the actual reading process). The @i{offset} attribute
is the stamping offset, in picoseconds, for the TDC channe.
The @i{flags} attribute can be used to change three configuration
bits, defined by the respective macros. Please note that the default
at module load time is zero, so some of the flags bits are inverted
over the hardware counterpart.
@c --------------------------------------------------------------------------
@node Reading with zio-dump
......@@ -588,6 +597,15 @@ The tool reports lost events using the sequence number (attribute number
/dev/zio/zio-fd-0200-0-0-ctrl: 1958.412804184 (delta 0.000009376)
@end smallexample
@c --------------------------------------------------------------------------
@node Configuring the Input Channel
@subsection Configuring the Input Channel
There is no support in @i{tools/} to change channel configuration.
The user is expected to write values in the @i{flags} file directly.
For example, to enable the termination resistors, write 4 to the
@i{flags} file in @i{sysfs}.
@c --------------------------------------------------------------------------
@node Generating Bursts by Software
@subsection Generating Bursts by Software
......@@ -678,12 +696,8 @@ Tomasz, is as follows. It covers all device features we need to export:
@end smallexample
This API doesn't support multiple boards but is still a useful reference
for the feature-set we need.
While it does everything that's needed for testing, I see some
issues with it and would like to offer something different.
This is a list of issues I find and that must be discussed before the
code is finalized with the final public API:
for the feature-set we need. The next sections describe the new library,
that is part of this package and relies on the kernel driver.
@c ==========================================================================
@node Initialization and Cleanup
......@@ -774,9 +788,44 @@ to validate the library works as expected:
1335974946.493415600
@end smallexample
@c ==========================================================================
@node Input Configuration
@section Input Configuration
To configure the input channel for a board, the library offers the
following function and macros:
@table @code
@item int fdelay_set_config_tdc(struct fdelay_board *b, int flags);
@itemx int fdelay_get_config_tdc(struct fdelay_board *b);
The function configures a few options in the input channel.
The @i{flags} argument is a bitmask of the following three
values (note that 0 is the default at initialization time).
The function returns -1 with @code{EINVAL} if the @i{flags}
argument includes undefined bits.
@item FD_TDCF_DISABLE_INPUT
@itemx FD_TDCF_DISABLE_TSTAMP
@itemx FD_TDCF_TERM_50
The first bit disables the input channel, the second disables
acquisition of timestamps, and the last enables the 50-ohm
termination on the input channel.
@end table
The example program @i{fdelay-term} demonstrates use of the function.
It just enables or disables the 50-ohm resistor. The effect is
usually verifiable by hooking a scope to the input signal:
@c ##########################################################################
@node Known bugs and missing features
@chapter Known bugs and missing features
@node Known Bugs and Missing Features
@chapter Known Bugs and Missing Features
This package is still work in progress, and unfortunately the same
applies to the packages it depends on. The current package set (i.e.,
......@@ -787,7 +836,6 @@ the following known issues exposed by @i{fine-delay}:
@item The auto-loading of @i{spec} submodules is not really working:
the @i{modprobe} command will be stuck sleeping if you try to use it.
Run `@code{insmod spec-fine-delay}'' (or @i{modprobe} by hand instead.
@end itemize
This is the list of known bugs and missing features over what hardware
......@@ -795,10 +843,11 @@ allows:
@itemize @bullet
@item There is no support for White Rabbit at this time.
@item Output support is missing. It simply is not there at this point.
@item We need interrupt support. The input is performed with a kernel timer.
Also, we need an in-driver buffer for input samples.
@item The driver should re-measure temperature every 30s, to keep
the output delay calibrated.
......@@ -813,10 +862,18 @@ cards. Reading the magic number from an SPEC that is not programmed
(or likely that is programmed with a different gateware) may lock up
the host computer.
@end itemize
Other less important issues may be dealt with over time, but are not
urgent as I write this:
@item The driver should register its own ZIO trigger, or use the new
attribute for ``greedy-input'' offered in new versions of ZIO
(thank you Federico).
@item We may implement commands to flush the input queue and reset the
input sequence number.
@end itemize
......
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