22 Aug, 2018
1 commit
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Pull i2c updates from Wolfram Sang:
- the core has now a lockless variant of i2c_smbus_xfer. Some open
coded versions of this got removed in drivers. This also enables
proper SCCB support in regmap.- locking got a more precise naming. i2c_{un}lock_adapter() had to go,
and we know use i2c_lock_bus() consistently with flags like
I2C_LOCK_ROOT_ADAPTER and I2C_LOCK_SEGMENT to avoid ambiguity.- the gpio fault injector got a new delicate testcase
- the bus recovery procedure got fixed to handle the new testcase
correctly- a new quirk flag for controllers not able to handle zero length
messages together with driver updates to use it- new drivers: FSI bus attached I2C masters, GENI I2C controller, Owl
family S900- and a good set of driver improvements and bugfixes
* 'i2c/for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (77 commits)
i2c: rcar: implement STOP and REP_START according to docs
i2c: rcar: refactor private flags
i2c: core: ACPI: Make acpi_gsb_i2c_read_bytes() check i2c_transfer return value
i2c: core: ACPI: Properly set status byte to 0 for multi-byte writes
dt-bindings: i2c: rcar: Add r8a774a1 support
dt-bindings: i2c: sh_mobile: Add r8a774a1 support
i2c: imx: Simplify stopped state tracking
i2c: imx: Fix race condition in dma read
i2c: pasemi: remove hardcoded bus numbers on smbus
i2c: designware: Add SPDX license tag
i2c: designware: Convert to use struct i2c_timings
i2c: core: Parse SDA hold time from firmware
i2c: designware-pcidrv: Mark expected switch fall-through
i2c: amd8111: Mark expected switch fall-through
i2c: sh_mobile: use core to detect 'no zero length read' quirk
i2c: xlr: use core to detect 'no zero length' quirk
i2c: rcar: use core to detect 'no zero length' quirk
i2c: stu300: use core to detect 'no zero length' quirk
i2c: pmcmsp: use core to detect 'no zero length' quirk
i2c: mxs: use core to detect 'no zero length' quirk
...
25 Jul, 2018
1 commit
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If an i2c topology has instances of nested muxes, then a lockdep splat
is produced when when i2c_parent_lock_bus() is called. Here is an
example:============================================
WARNING: possible recursive locking detected
--------------------------------------------
insmod/68159 is trying to acquire lock:
(i2c_register_adapter#2){+.+.}, at: i2c_parent_lock_bus+0x32/0x50 [i2c_mux]but task is already holding lock:
(i2c_register_adapter#2){+.+.}, at: i2c_parent_lock_bus+0x32/0x50 [i2c_mux]other info that might help us debug this:
Possible unsafe locking scenario:CPU0
----
lock(i2c_register_adapter#2);
lock(i2c_register_adapter#2);*** DEADLOCK ***
May be due to missing lock nesting notation
1 lock held by insmod/68159:
#0: (i2c_register_adapter#2){+.+.}, at: i2c_parent_lock_bus+0x32/0x50 [i2c_mux]stack backtrace:
CPU: 13 PID: 68159 Comm: insmod Tainted: G O
Call Trace:
dump_stack+0x67/0x98
__lock_acquire+0x162e/0x1780
lock_acquire+0xba/0x200
rt_mutex_lock+0x44/0x60
i2c_parent_lock_bus+0x32/0x50 [i2c_mux]
i2c_parent_lock_bus+0x3e/0x50 [i2c_mux]
i2c_smbus_xfer+0xf0/0x700
i2c_smbus_read_byte+0x42/0x70
my2c_init+0xa2/0x1000 [my2c]
do_one_initcall+0x51/0x192
do_init_module+0x62/0x216
load_module+0x20f9/0x2b50
SYSC_init_module+0x19a/0x1c0
SyS_init_module+0xe/0x10
do_syscall_64+0x6c/0x1a0
entry_SYSCALL_64_after_hwframe+0x42/0xb7Reported-by: John Sperbeck
Tested-by: John Sperbeck
Signed-off-by: Peter Rosin
Signed-off-by: Peter Zijlstra (Intel)
Cc: Davidlohr Bueso
Cc: Deepa Dinamani
Cc: Greg Kroah-Hartman
Cc: Linus Torvalds
Cc: Peter Chang
Cc: Peter Zijlstra
Cc: Philippe Ombredanne
Cc: Thomas Gleixner
Cc: Will Deacon
Cc: Wolfram Sang
Link: http://lkml.kernel.org/r/20180720083914.1950-3-peda@axentia.se
Signed-off-by: Ingo Molnar
04 Jul, 2018
1 commit
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Calling the __i2c_smbus_xfer wrapper in __i2c_mux_smbus_xfer provides
retries and thus makes the parent-locked case consistent with the both
mux-locked (i2c_mux_smbus_xfer) and the I2C transfer cases.Signed-off-by: Peter Rosin
Signed-off-by: Wolfram Sang
24 May, 2018
1 commit
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Trivial, but still: the failed symlink is not *for* the channel but a
link *to* the channel.Signed-off-by: Wolfram Sang
Signed-off-by: Peter Rosin
16 May, 2017
1 commit
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As is, a failure message is printed unconditionally, which is confusing.
And noisy.Fixes: 8d4d159f25a7 ("i2c: mux: provide more info on failure in i2c_mux_add_adapter")
Signed-off-by: Peter Rosin
03 Apr, 2017
1 commit
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No callers then need to report any further info, thus reducing both the
amount of code and the log noise.Reviewed-by: Wolfram Sang
Signed-off-by: Peter Rosin
03 Mar, 2017
1 commit
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Refcount of of_node is increased with of_node_get() in i2c_mux_add_adapter().
It must be decreased with of_node_put() in i2c_mux_del_adapters().Cc: stable@vger.kernel.org
Signed-off-by: Qi Hou
Reviewed-by: Zhang Xiao
Signed-off-by: Peter Rosin
31 Aug, 2016
1 commit
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This makes it trivial to constify them, so do that.
Signed-off-by: Peter Rosin
Acked-by: Daniel Vetter
Signed-off-by: Wolfram Sang
26 Aug, 2016
3 commits
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Signed-off-by: Wolfram Sang
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Backwards compatibility is preserved; the subnodes are in practice
optional.However, the mux core needs to know what subnode it should examine, so add
a couple of new flags for i2c_mux_alloc for this purpose.The rule is that if the mux core finds a 'reg' property in the appropriate
subnode, e.g. if 'reg' exists in the 'i2c-mux' subnode, then the mux core
will assume that this is an old style entry and not an i2c-mux subnode
(correspondingly for arbitrators and gates with 'i2c-arb' and 'i2c-gate').Reviewed-by: Wolfram Sang
Signed-off-by: Peter Rosin -
This unifies usage with i2c_lock_bus and i2c_unlock_bus, and paves the
way for the next patch which looks a bit saner with this preparatory
work taken care of beforehand.Signed-off-by: Peter Rosin
Signed-off-by: Wolfram Sang
05 May, 2016
2 commits
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With a i2c topology like the following
GPIO ---| ------ BAT1
| v /
I2C -----+----------+---- MUX
| \
EEPROM ------ BAT2there is a locking problem with the GPIO controller since it is a client
on the same i2c bus that it muxes. Transfers to the mux clients (e.g. BAT1)
will lock the whole i2c bus prior to attempting to switch the mux to the
correct i2c segment. In the above case, the GPIO device is an I/O expander
with an i2c interface, and since the GPIO subsystem knows nothing (and
rightfully so) about the lockless needs of the i2c mux code, this results
in a deadlock when the GPIO driver issues i2c transfers to modify the
mux.So, observing that while it is needed to have the i2c bus locked during the
actual MUX update in order to avoid random garbage on the slave side, it
is not strictly a must to have it locked over the whole sequence of a full
select-transfer-deselect mux client operation. The mux itself needs to be
locked, so transfers to clients behind the mux are serialized, and the mux
needs to be stable during all i2c traffic (otherwise individual mux slave
segments might see garbage, or worse).Introduce this new locking concept as "mux-locked" muxes, and call the
pre-existing mux locking scheme "parent-locked".Modify the i2c mux locking so that muxes that are "mux-locked" locks only
the muxes on the parent adapter instead of the whole i2c bus when there is
a transfer to the slave side of the mux. This lock serializes transfers to
the slave side of the muxes on the parent adapter.Add code to i2c-mux-gpio and i2c-mux-pinctrl that checks if all involved
gpio/pinctrl devices have a parent that is an i2c adapter in the same
adapter tree that is muxed, and request a "mux-locked mux" if that is the
case.Modify the select-transfer-deselect code for "mux-locked" muxes so
that each of the select-transfer-deselect ops locks the mux parent
adapter individually.Signed-off-by: Peter Rosin
Signed-off-by: Wolfram Sang -
Instead of checking for i2c parent adapters for every lock/unlock, simply
override the locking for muxes to always lock/unlock the parent adapter
directly.Signed-off-by: Peter Rosin
Signed-off-by: Wolfram Sang
22 Apr, 2016
2 commits
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All i2c mux users are using an explicit i2c mux core, drop support
for implicit i2c mux cores.Signed-off-by: Peter Rosin
Signed-off-by: Wolfram Sang -
All i2c-muxes have a parent adapter and one or many child
adapters. A mux also has some means of selection. Previously,
this was stored per child adapter, but it is only needed
to keep track of this per mux.Add an i2c mux core, that keeps track of this consistently.
Also add some glue for users of the old interface, which will
create one implicit mux core per child adapter.Signed-off-by: Peter Rosin
Tested-by: Antti Palosaari
Tested-by: Crestez Dan Leonard
Signed-off-by: Wolfram Sang
21 Feb, 2016
1 commit
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I request this for drivers, so the core should adhere to sorted includes as
well.Signed-off-by: Wolfram Sang
25 Oct, 2015
1 commit
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Although I2C mux devices are easily enumerated using ACPI (_HID/_CID or
device property compatible string match), enumerating I2C client devices
connected through an I2C mux needs a little extra work.This change implements a method for describing an I2C device hierarchy that
includes mux devices by using an ACPI Device() for each mux channel along
with an _ADR to set the channel number for the device. See
Documentation/acpi/i2c-muxes.txt for a simple example.To make this work the ismt, i801, and designware pci/platform devs now
share an ACPI companion with their I2C adapter dev similar to how it's done
in OF. This is done on the assumption that power management functions will
not be called directly on the I2C dev that is sharing the ACPI node.Acked-by: Mika Westerberg
Tested-by: Mika Westerberg
Signed-off-by: Dustin Byford
Signed-off-by: Wolfram Sang
17 Jun, 2015
2 commits
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Newly introduced quirks infrastructure doesn't work for the devices behind
MUXes because MUX's master_xfer() calls parent's master_xfer() directly
without checking the quirks. Instead of duplicating check code in MUX just
call __i2c_transfer() instead. This has a side effect on tracing (messages
will appear on both MUX bus and parent bus), but maybe that's not bad at
the end.Signed-off-by: Alexander Sverdlin
Tested-by: Łukasz Gemborowski
Signed-off-by: Wolfram Sang
Cc: stable@kernel.org
Fixes: b7f625840267b1 ("i2c: add quirk checks to core") -
Inherit parent adapter quirks in MUX in case the devices on the multiplexed
buses are interested in the adapter limitations.Signed-off-by: Łukasz Gemborowski
Signed-off-by: Alexander Sverdlin
Signed-off-by: Wolfram Sang
Cc: stable@kernel.org
Fixes: b7f625840267b1 ("i2c: add quirk checks to core")
24 Apr, 2015
1 commit
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Those symlinks are created for the mux_dev, so we need to remove it from
there. Currently, it breaks for muxes where the mux_dev is not the device
of the parent adapter like this:[ 78.234644] WARNING: CPU: 0 PID: 365 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x5c/0x78()
[ 78.242438] sysfs: cannot create duplicate filename '/devices/platform/i2cbus@8/channel-0'Remove confusing comments while we are here.
Signed-off-by: Wolfram Sang
Signed-off-by: Wolfram Sang
Fixes: c9449affad2ae0
Cc: stable@kernel.org
18 Nov, 2014
2 commits
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This makes the topology clearer. For instance, by adding a pca9547
device with address 0x70 to bus i2c-0, you get:/sys/class/i2c-dev/i2c-0/device/0-0070/channel-0 -> i2c-1
...
/sys/class/i2c-dev/i2c-0/device/0-0070/channel-7 -> i2c-8Signed-off-by: Gerlando Falauto
[wsa: simplified sysfs-usage and fixed format string usage]
Signed-off-by: Wolfram Sang
Acked-by: Martin Belanger
Acked-by: Danielle Costantino -
The current implementation creates muxed i2c- busses as immediate
children of their i2c- parent bus. In case of multiple muxes on one
bus, it is impossible to determine which muxed bus comes from which mux.It could be argued that the parent device should be changed from the
parent adapter to the mux device. This has pros and cons. To improve the
topology, simply add a "mux_device" symlink pointing to the actual
muxing device, so we can distinguish muxed busses. Doing it this way, we
don't break the ABI.Signed-off-by: Wolfram Sang
Tested-by: Guenter Roeck
13 Dec, 2013
1 commit
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If a muxed i2c bus gets created the default retry count and
timeout of the muxed bus is zero. Hence it it possible that you
end up with a situation where the parent controller sets a default
retry count and timeout which gets applied and used while the muxed
bus (using the same controller) has a default retry count of zero
and a default timeout of 1s (set in i2c_add_adapter()). This can be
solved by initializing the retry count and timeout of the muxed
bus with the values used by the the parent at creation time.Signed-off-by: Elie De Brauwer
Signed-off-by: Wolfram Sang
23 Aug, 2013
1 commit
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I2C of helpers used to live in of_i2c.c but experience (from SPI) shows
that it is much cleaner to have this in the core. This also removes a
circular dependency between the helpers and the core, and so we can
finally register child nodes in the core instead of doing this manually
in each driver. So, fix the drivers and documentation, too.Signed-off-by: Wolfram Sang
02 Apr, 2013
2 commits
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i2c_del_mux_adapter always returns 0 and none of it current users check its
return value anyway. It is also an essential requirement of the Linux device
driver model, that functions which may be called from a device's remove callback
to free resources provided by the device, are not allowed to fail. This is the
case for i2c_del_mux_adapter(), so make its return type void to make the
fact that it won't fail explicit.Signed-off-by: Lars-Peter Clausen
Reviewed-by: Jean Delvare
Signed-off-by: Wolfram Sang -
i2c_del_adapter() always returns 0. So all checks testing whether it will be
non zero will always evaluate to false and the conditional code is dead code.
This patch updates all callers of i2c_del_mux_adapter() to ignore the return
value and assume that it will always succeed (which it will). In a subsequent
patch the return type of i2c_del_adapter() will be made void.Signed-off-by: Lars-Peter Clausen
Acked-by: Ben Hutchings
Reviewed-by: Jean Delvare
Acked-by: Shawn Guo
Signed-off-by: Wolfram Sang
06 Oct, 2012
1 commit
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Let I2C bus segments behind multiplexers have a class. This allows for
device auto-detection on these segments. As long as parent segments
don't share the same class, it should be fine.I implemented support in drivers i2c-mux-gpio and i2c-mux-pca954x. I
left i2c-mux-pca9541 and i2c-mux-pinctrl alone for the moment as I
don't know if this feature makes sense for the use cases of these
drivers.Signed-off-by: Jean Delvare
Cc: Peter Korsgaard
Cc: David Daney
Cc: Michael Lawnick
Cc: Rodolfo Giometti
12 May, 2012
2 commits
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For 'normal' i2c bus drivers, we can call of_i2c_register_devices()
and have the device tree framework automatically populate the bus with
the devices specified in the device tree.This patch adds a common code to the i2c mux framework to have the mux
sub-busses be populated by the of_i2c_register_devices() too. If the
mux device has an of_node, we populate the sub-bus' of_node so that
the subsequent call to of_i2c_register_devices() will find the
corresponding devices.It seemed better to put this logic in i2c_add_mux_adapter() rather
than the individual mux drivers, as they will all probably want to do
the same thing.Signed-off-by: David Daney
Acked-by: Stephen Warren
Tested-by: Lars-Peter Clausen[wsa: removed superfluous ret-variable and fixed a typo in a comment]
Signed-off-by: Wolfram Sang -
And adjust all callers.
The new device parameter is used in the next patch to initialize the
mux's of_node so that its children may be automatically populated.Signed-off-by: David Daney
Tested-by: Lars-Peter Clausen
Signed-off-by: Wolfram Sang
16 Nov, 2010
1 commit
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It's about time to make it clear that i2c_adapter.id is deprecated.
Hopefully this will remind the last user to move over to a different
strategy.Signed-off-by: Jean Delvare
Acked-by: Jarod Wilson
Acked-by: Mauro Carvalho Chehab
Acked-by: Hans Verkuil
12 Aug, 2010
1 commit
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Add multiplexed bus core support. I2C multiplexer and switches
like pca954x get instantiated as new adapters per port.Signed-off-by: Michael Lawnick
Acked-by: Rodolfo Giometti
Signed-off-by: Jean Delvare
