An i2c bus can be divided into segments which can be selectively connected
and disconnected from the main bus. This is usually done to enable using
multiple slave devices having the same address, by isolating the devices
onto separate bus segments, only one of which is connected to the main bus
at once.
There are several types of i2c bus muxes, which break down into two general
categories...
- Muxes which are themselves i2c slaves. These devices respond to i2c
commands on their upstream bus, and based on those commands, connect
various downstream buses to the upstream. In newbus terms, they are both
a child of an iicbus and the parent of one or more iicbus instances.
- Muxes which are not i2c devices themselves. Such devices are part of the
i2c bus electrically, but in newbus terms their parent is some other
bus. The association with the upstream bus must be established by
separate metadata (such as FDT data).
In both cases, the mux driver has one or more iicbus child instances
representing the downstream buses. The mux driver implements the iicbus_if
interface, as if it were an iichb host bridge/i2c controller driver. It
services the IO requests sent to it by forwarding them to the iicbus
instance representing the upstream bus, after electrically connecting the
upstream bus to the downstream bus that hosts the i2c slave device which
made the IO request.
The net effect is automatic mux switching which is transparent to slaves on
the downstream buses. They just do i2c IO they way they normally do, and the
bus is electrically connected for the duration of the IO and then idled when
it is complete.
The existing iicbus_if callback() method is enhanced so that the parameter
passed to it can be a struct which contains a device_t for the requesting
bus and slave devices. This change is done by adding a flag that indicates
the extra values are present, and making the flags field the first field of
a new args struct. If the flag is set, the iichb or mux driver can recast
the pointer-to-flags into a pointer-to-struct and access the extra
fields. Thus abi compatibility with older drivers is retained (but a mux
cannot exist on the bus with the older iicbus driver in use.)
A new set of core support routines exists in iicbus.c. This code will help
implement mux drivers for any type of mux hardware by supplying all the
boilerplate code that forwards IO requests upstream. It also has code for
parsing metadata and instantiating the child iicbus instances based on it.
Two new hardware mux drivers are added. The ltc430x driver supports the
LTC4305/4306 mux chips which are controlled via i2c commands. The
iic_gpiomux driver supports any mux hardware which is controlled by
manipulating the state of one or more gpio pins. Test Plan
Tested locally using a variety of mux'd bus configurations involving both
ltc4305 and a homebrew gpio-controlled mux. Tested configurations included
cascaded muxes (unlikely in the real world, but useful to prove that 'it all
just works' in terms of the automatic switching and upstream forwarding of
IO requests).
- Drop mention of _LP64. FreeBSD's source generally uses __LP64__
instead of _LP64, and the relevant macros are better covered in the
"Predefined Macros" section.
- Fix a noun/verb disagreement.
Reviewed by: emaste
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D22975
- Add missing .Pp after the end of some lists so that there is a blank
line before the subsequent paragraph.
- Use a more typical '-tag' bullet list of the make variable descriptions
at the end. This adds separation between bullets and is the formatting
typically used in manpages for this sort of list.
r355588 Fix WITHOUT_CLANG build
r355646 Revert r354348
r355943 add LDNS build knob dependency on OPENSSL
r356111 Use LLVM as default toolchain for all PowerPC targets
To be used when like rmlocks, except when sleeping for readers needs to be
allowed. See the manpage for more information.
Reviewed by: kib (previous version)
Differential Revision: https://reviews.freebsd.org/D22823
This enables LLVM as the default compiler for powerpc, powerpc64, and
powerpcspe, as well as LLD as the default linker for powerpc64.
LLD is not yet ready for prime time for powerpc and powerpcspe, but work is
continuing on it.
Submitted by: alfredo.junior_eldorado.org.br
Relnotes: YES
Differential Revision: https://reviews.freebsd.org/D20378
srandom(9) is meaningless on SMP systems or any system with, say,
interrupts. One could never rely on random(9) to produce a reproducible
sequence of outputs on the basis of a specific srandom() seed because the
global state was shared by all kernel contexts. As such, removing it is
literally indistinguishable to random(9) consumers (as compared with
retaining it).
Mark random(9) as deprecated and slated for quick removal. This is not to
say we intend to remove all fast, non-cryptographic PRNG(s) in the kernel.
It/they just won't be random(9), as it exists today, in either name or
implementation.
Before random(9) is removed, a replacement will be provided and in-tree
consumers will be converted.
Note that despite the name, the random(9) interface does not bear any
resemblance to random(3). Instead, it is the same crummy 1988 Park-Miller
LCG used in libc rand(3).
_sleep(9), wakeup(9), sleepqueue(9), et al do not dereference or modify the
channel pointers provided in any way; they are merely used as intptrs into a
dictionary structure to match waiters with wakers. Correctly annotate this
such that _sleep() and wakeup() may be used on const pointers without
invoking ugly patterns like __DECONST(). Plumb const through all of the
underlying sleepqueue bits.
No functional change.
Reviewed by: rlibby
Discussed with: kib, markj
Differential Revision: https://reviews.freebsd.org/D22914
off the stack, initialized to default values, and then filled in with
driver-specific values, all without having to worry about the numerous
other fields in the tag. The resulting template is then passed into
busdma and the normal opaque tag object created. See the man page for
details on how to initialize a template.
Templates do not support tag filters. Filters have been broken for many
years, and only existed for an ancient make/model of hardware that had a
quirky DMA engine. Instead of breaking the ABI/API and changing the
arugment signature of bus_dma_tag_create() to remove the filter arguments,
templates allow us to ignore them, and also significantly reduce the
complexity of creating and managing tags.
Reviewed by: imp, kib
Differential Revision: https://reviews.freebsd.org/D22906
- Don't allow an unprivileged user to set the stride. [1]
- Only set the stride under the softc lock.
- Rename the internal fields to accurately reflect their use. Keep
ro_bkt to avoid changing the user API.
- Simplify the implementation. The port index is just sc_seq / stride.
- Document rr_limit in ifconfig.8.
Reported by: Ilja Van Sprundel <ivansprundel@ioactive.com> [1]
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D22857
There are probably bits that are still wrong, but this fixes some
things at least:
- Add named arguments to the functions in crypto(9).
- Add missing algorithms.
- Don't mention arguments that don't exist in crypto_register.
- Add CIOGSESSION2.
- Remove CIOCNFSESSION.
- Clarify some stale language that assumed an fd had only one sesson.
- Note that you have to use CRIOGET and add a note in BUGS lamenting
that one has to use CRIOGET.
- Various other cleanups.
Reviewed by: cem (earlier version)
MFC after: 2 weeks
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D22784
than "/compat/linux". Useful when you have several compat directories
with different Linux versions and you don't want to clash with files
installed by linux-c7 packages.
Reviewed by: bcr (manpages)
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D22574
Document the common practices around copyrights with "all rights reserved" in
them as new copyright notices get added.
It's an open question qhether to point people at the fact that since the Berne
convention was ratified, All rights reserved is largely obsolete.
https://en.wikipedia.org/wiki/All_rights_reserved#Obsolescence has the
details. The committer's guide will be revised shortly, and it's likely that's a
better place for this discussion. If not, I'll add a blurb here.
Reviewed by: jhb@, brooks@
Differential Review: https://reviews.freebsd.org/D22800
Contractions cause problems for translators, so s/aren't/are not/ in the one
place this slipped through.
While here, noticed I commited with the date I did the work, not today's
date. Fix that too.
Noticed by: bjk@
Delay the attachment of children, when requested, until after interrutps are
running. This is often needed to allow children to run transactions on i2c or
spi busses. It's a common enough idiom that it will be useful to have its own
wrapper.
Reviewed by: ian
Differential Revision: https://reviews.freebsd.org/D21465
s/BIT_NAND/BIT_ANDNOT/, and for CPU and DOMAINSET too. The actual
implementation is "and not" (or "but not"), i.e. A but not B.
Fortunately this does appear to be what all existing callers want.
Don't supply a NAND (not (A and B)) operation at this time.
Discussed with: jeff
Reviewed by: cem
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D22791
r355436 moved mitigation sysctls to machdep.mitigations but did not
rationalize the sense of the invidual knobs. Clarify that the old
names remain the canonical way to set these mitigations.
Backwards compatibility will be maintained for the original names
(e.g. hw.ibrs_disable), but not from the interim names
(e.g. machdep.mitigations.ibrs.disable).
Sponsored by: The FreeBSD Foundation
This typedef is the same as timeout_t except that it is in the callout
namespace and header.
Use this typedef in various places of the callout implementation that
were either using the raw type or timeout_t.
While here, add <sys/callout.h> to the manpage.
Reviewed by: kib, imp
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D22751
The datasheets for these chips claim the maximum is 921,600, but testing
shows these two higher rates also work (but no rates above 921,600 other
than these two work; these represent dividing the base buad clock by 3 and 2
respectively).
The current vnode layout is not smp-friendly by having frequently read data
avoidably sharing cachelines with very frequently modified fields. In
particular v_iflag inspected for VI_DOOMED can be found in the same line with
v_usecount. Instead make it available in the same cacheline as the v_op, v_data
and v_type which all get read all the time.
v_type is avoidably 4 bytes while the necessary data will easily fit in 1.
Shrinking it frees up 3 bytes, 2 of which get used here to introduce a new
flag field with a new value: VIRF_DOOMED.
Reviewed by: kib, jeff
Differential Revision: https://reviews.freebsd.org/D22715
o Remove All Rights Reserved from my notices
o imp@FreeBSD.org everywhere
o regularize punctiation, eliminate date ranges
o Make sure that it's clear that I don't claim All Rights reserved by listing
All Rights Reserved on same line as other copyright holders (but not
me). Other such holders are also listed last where it's clear.
This makes it possible to retrieve per-connection statistical
information such as the receive window size, RTT, or goodput,
using a newly added TCP_STATS getsockopt(3) option, and extract
them using the stats_voistat_fetch(3) API.
See the net/tcprtt port for an example consumer of this API.
Compared to the existing TCP_INFO system, the main differences
are that this mechanism is easy to extend without breaking ABI,
and provides statistical information instead of raw "snapshots"
of values at a given point in time. stats(3) is more generic
and can be used in both userland and the kernel.
Reviewed by: thj
Tested by: thj
Obtained from: Netflix
Relnotes: yes
Sponsored by: Klara Inc, Netflix
Differential Revision: https://reviews.freebsd.org/D20655
FDT bindings document for gpio-i2c devices.
Using the gpio_pin_* functions to acquire/release/manipulate gpio pins
removes the constraint that both gpio pins must belong to the same gpio
controller/bank, and that the gpioiic instance must be a child of gpiobus.
Removing those constraints allows the driver to be fully compatible with
the modern dts bindings for a gpio bitbanged i2c bus.
For hinted attachment, the two gpio pins still must be on the same gpiobus,
and the device instance must be a child of that bus. This preserves
compatibility for existing installations that have use gpioiic(4) with hints.
