linux-toradex.git/drivers/w1/w1.c, branch v3.11

w1: add family based automatic module loading

2013-06-03T21:09:14+00:00

This patch allows the 1-wire bus to autoload the corresponding module
for each slave being attached.
This works similar to bluetooth protocols.

Signed-off-by: Alexander Stein 
Signed-off-by: Greg Kroah-Hartman

w1: fix oops when w1_search is called from netlink connector

2013-03-12T23:20:46+00:00

On Sat, Mar 02, 2013 at 10:45:10AM +0100, Sven Geggus wrote:
> This is the bad commit I found doing git bisect:
> 04f482faf50535229a5a5c8d629cf963899f857c is the first bad commit
> commit 04f482faf50535229a5a5c8d629cf963899f857c
> Author: Patrick McHardy 
> Date:   Mon Mar 28 08:39:36 2011 +0000

Good job. I was too lazy to bisect for bad commit;)

Reading the code I found problematic kthread_should_stop call from netlink
connector which causes the oops. After applying a patch, I've been testing
owfs+w1 setup for nearly two days and it seems to work very reliable (no
hangs, no memleaks etc).
More detailed description and possible fix is given below:

Function w1_search can be called from either kthread or netlink callback.
While the former works fine, the latter causes oops due to kthread_should_stop
invocation.

This patch adds a check if w1_search is serving netlink command, skipping
kthread_should_stop invocation if so.

Signed-off-by: Marcin Jurkowski 
Acked-by: Evgeniy Polyakov 
Cc: Josh Boyer 
Tested-by: Sven Geggus 
Signed-off-by: Greg Kroah-Hartman 
Cc: stable  # 3.0+

w1: remove CONFIG_HOTPLUG ifdefs

2012-11-21T20:42:25+00:00

Remove conditional code based on CONFIG_HOTPLUG being false.  It's
always on now in preparation of it going away as an option.

Signed-off-by: Bill Pemberton 
Cc: Evgeniy Polyakov 
Signed-off-by: Greg Kroah-Hartman

W1: split master mutex to avoid deadlocks.

2012-06-13T23:38:40+00:00

The 'mutex' in struct w1_master is use for two very different
purposes.

Firstly it protects various data structures such as the list of all
slaves.

Secondly it protects the w1 buss against concurrent accesses.

This can lead to deadlocks when the ->probe code called while adding a
slave needs to talk on the bus, as is the case for power_supply
devices.
ds2780 and ds2781 drivers contain a work around to track which
process hold the lock simply to avoid this deadlock.  bq27000 doesn't
have that work around and so deadlocks.

There are other possible deadlocks involving sysfs.
When removing a device the sysfs s_active lock is held, so the lock
that protects the slave list must take precedence over s_active.
However when access power_supply attributes via sysfs, the s_active
lock must take precedence over the lock that protects accesses to
the bus.

So to avoid deadlocks between w1 slaves and sysfs, these must be
two separate locks.  Making them separate means that the work around
in ds2780 and ds2781 can be removed.

So this patch:
 - adds a new mutex: "bus_mutex" which serialises access to the bus.
 - takes in mutex in w1_search and ds1wm_search while they access
   the bus for searching.  The mutex is dropped before calling the
   callback which adds the slave.
 - changes all slaves to use bus_mutex instead of mutex to
   protect access to the bus
 - removes w1_ds2790_io_nolock and w1_ds2781_io_nolock, and the
   related code from drivers/power/ds278[01]_battery.c which
   calls them.

Signed-off-by: NeilBrown 
Acked-by: Evgeniy Polyakov 
Signed-off-by: Greg Kroah-Hartman

Revert "w1: introduce a slave mutex for serializing IO"

2012-06-13T23:33:54+00:00

This reverts commit 59d4467be405316916a4087d5b02d99196eeef04.

Turns out it was the wrong version, will apply the correct version after
this.

Reported-by: NeilBrown 
Cc: Evgeniy Polyakov 
Cc: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

w1: cleanup w1_uevent

2012-06-12T22:27:32+00:00

There were some return statements around in the w1_uevent, used goto
to cleanup those return statements with the help of err variable,
and also removed a semi colon at the end of the w1_uevent's closing
brace.

Signed-off-by: Devendra Naga 
Acked-by: Evgeniy Polyakov 
Signed-off-by: Greg Kroah-Hartman

w1: introduce a slave mutex for serializing IO

2012-06-12T22:27:32+00:00

w1 devices need a mutex to serial IO.  Most use master->mutex.
However that is used for other purposes and they can conflict.

In particular master->mutex is held while w1_attach_slave_device is
called.

For bq27000, this registers a 'powersupply' device which tries to read the
current status.  The attempt to read will cause a deadlock on
master->mutex.

So create a new per-slave mutex and use that for serializing IO for
bq27000.

Signed-off-by: NeilBrown 
Cc: Evgeniy Polyakov 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

w1: fix slave driver registration error message

2012-04-09T22:05:47+00:00

W1 core prints "Failed to register master driver" if error happens
on registering SLAVE driver. Fix it.

Signed-off-by: Dmitry Artamonow 
Acked-by: Evgeniy Polyakov 
Signed-off-by: Greg Kroah-Hartman

w1: add fast search for single slave bus

2011-12-10T03:19:18+00:00

This enables a much more efficient way of device searching. It uses the
1-wire read-rom operation which allows the direct reading of the slave
address. BUT this works only with exactly one slave on the bus.

Signed-off-by: Hubert Feurstein 
Acked-by: Evgeniy Polyakov 

index c374978..9761950 100644
Signed-off-by: Greg Kroah-Hartman

MAINTAINERS: Evgeniy has moved

2011-08-25T23:25:33+00:00

Signed-off-by: Evgeniy Polyakov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds