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Commit dc0a2c7b authored by Alessandro Rubini's avatar Alessandro Rubini
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zio.h and doc: introduce ZIO_CSET_TYPE_RAW 

Signed-off-by: Alessandro Rubini's avatarAlessandro Rubini <rubini@gnudd.com>
Acked-by: 's avatarFederico Vaga <federico.vaga@gmail.com>
parent aa9fc46f
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doc/zio-manual.in
View file @ dc0a2c7b
......@@ -34,7 +34,7 @@
@comment %**end of header
@setchapternewpage off
@set update-month January 2013
@set update-month January 2014
@finalout
@c #################################################################
@titlepage
......@@ -1927,6 +1927,7 @@ or used by the developer are:
@cindex ZIO_CSET_TYPE_DIGITAL
@cindex ZIO_CSET_TYPE_ANALOG
@cindex ZIO_CSET_TYPE_TIME
@cindex ZIO_CSET_TYPE_RAW
@cindex ZIO_CSET_SELF_TIMED
@cindex ZIO_DIR_INPUT
@cindex ZIO_DIR_OUTPUT
......@@ -1934,7 +1935,8 @@ or used by the developer are:
A few flags, the most important being the type of cset:
@code{ZIO_CSET_TYPE_DIGITAL},
@code{ZIO_CSET_TYPE_ANALOG} or @code{ZIO_CSET_TYPE_TIME} (other types
@code{ZIO_CSET_TYPE_ANALOG}, @code{ZIO_CSET_TYPE_TIME}
or @code{ZIO_CSET_TYPE_RAW} (other types
may be added in the future, we reserved for 8 of them), OR'd with
@t{ZIO_DIR_INPUT} or @t{ZIO_DIR_OUTPUT}. Then, if you set
@t{ZIO_CSET_SELF_TIMED} for an input cset, the trigger will be
......@@ -1967,6 +1969,46 @@ or used by the developer are:
@end table
@c --------------------------------------------------------------------------
@node The Cset Types
@subsection The Cset Types
@cindex ZIO_CSET_TYPE_DIGITAL
@cindex ZIO_CSET_TYPE_ANALOG
@cindex ZIO_CSET_TYPE_TIME
@cindex ZIO_CSET_TYPE_RAW
ZIO was born as a transport for analog and digital I/O, supporting
driver-independent applications, like monitoring and
diagnostics. Thus, each cset had to claim to eithe be
@t{ZIO_CSET_TYPE_DIGITAL} or @t{ZIO_CSET_TYPE_ANALOG}. For digital
I/O, each bit in the sample represents an input or output line, for
analog, each sample represents a single value. In both situations,
the @i{nbits} field repsents the actual data width.
Our use case, however, included the requirement to acquire
high-precision time stamps for the raising edge of input pulses, or
produce high-precision pulses. Those applications are called TDC and
DTC (time to digital converter, and the reverse). TDC devices have
been used measuring the speed of neutrinos, for example.
Thus, @t{ZIO_CSET_TYPE_TIME} represents channel sets that input or
output a data-less event, using the timestamp field of the control
structure. Two software-only examples are @t{zio-fake-dtc} and
@t{zio-irq-tdc}, part of this package.
Sometimes, however, expecially for fast operations, users may prever
to avoid using a standard representation for their data, using the ZIO
transport to carry opaque data instead. By using @t{ZIO_CSET_TYPE_RAW}
developers can prevent generic applications from trying to make sense
of the data block.
Typically, a @t{RAW} input sample is the snapshot of a set of machine
registers when some event happened. Converting the registers to
well-laid-out ZIO attributes, or calibrated analog values may be
unfeasible; by passing @t{TYPE_RAW} data blocks developers can achieve
better perfomance figures while still leveraging on a consistent
framework.
@c --------------------------------------------------------------------------
@node The Channel
@subsection The Channel
......
include/linux/zio.h
View file @ dc0a2c7b
......@@ -206,6 +206,7 @@ enum zio_cset_flags {
ZIO_CSET_TYPE_DIGITAL = 0x00,
ZIO_CSET_TYPE_ANALOG = 0x10,
ZIO_CSET_TYPE_TIME = 0x20,
ZIO_CSET_TYPE_RAW = 0x30,
ZIO_CSET_CHAN_TEMPLATE = 0x80, /* 1 if channels from template */
ZIO_CSET_SELF_TIMED = 0x100, /* for trigger use (see docs) */
ZIO_CSET_CHAN_INTERLEAVE= 0x200, /* 1 if cset can interleave */
......
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