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 <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Dustin Byford <dustin@cumulusnetworks.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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 <alexander.sverdlin@nokia.com>
Tested-by: Łukasz Gemborowski <lukasz.gemborowski@nokia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
Fixes: b7f6258402 ("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 <lukasz.gemborowski@nokia.com>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
Fixes: b7f6258402 ("i2c: add quirk checks to core")
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 <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Fixes: c9449affad
Cc: stable@kernel.org
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-8
Signed-off-by: Gerlando Falauto <gerlando.falauto@keymile.com>
[wsa: simplified sysfs-usage and fixed format string usage]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Martin Belanger <martin.belanger@cyaninc.com>
Acked-by: Danielle Costantino <danielle.costantino@gmail.com>
The current implementation creates muxed i2c-<n> busses as immediate
children of their i2c-<n> 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 <wsa@the-dreams.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
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 <eliedebrauwer@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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 <wsa@the-dreams.de>
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 <lars@metafoo.de>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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 <lars@metafoo.de>
Acked-by: Ben Hutchings <bhutchings@solarflare.com>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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 <khali@linux-fr.org>
Cc: Peter Korsgaard <peter.korsgaard@barco.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Michael Lawnick <ml.lawnick@gmx.de>
Cc: Rodolfo Giometti <giometti@linux.it>
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 <david.daney@cavium.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Tested-by: Lars-Peter Clausen <lars@metafoo.de>
[wsa: removed superfluous ret-variable and fixed a typo in a comment]
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
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 <david.daney@cavium.com>
Tested-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
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 <khali@linux-fr.org>
Acked-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Add multiplexed bus core support. I2C multiplexer and switches
like pca954x get instantiated as new adapters per port.
Signed-off-by: Michael Lawnick <ml.lawnick@gmx.de>
Acked-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Dustin Byford