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: NNeilBrown <neilb@suse.de>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If multiple threads try, they trip over each other badly.
Signed-off-by: NNeilBrown <neilb@suse.de>
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The function is never used so remove it to avoid bit-rot.
It can trivially be re-added if there is ever a need.
Signed-off-by: NNeilBrown <neilb@suse.de>
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

As recent change means that we now dereference 'dev' before testing
for NULL.

That means either the change was wrong, or the test isn't needed.
As this function is only called from one driver (bq27x000_battery) and
it always passed a non-NULL dev, it seems good to assume that the
test isn't needed.

So remove it.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NNeilBrown <neilb@suse.de>
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

w1_bq27000 adds a bq27000-battery platform device but does not provide
platform data for it. This causes the bq27x00 driver to dereference a NULL
pointer.
So provide the appropriate platform data.  This requires modifying
w1_bq27000_read so that it find the w1 device as the parent of the bq device.

Also there is no point exporting w1_bq27000_read as nothing else uses it
or could use it.  So make it static.

Finally, as there is no way to track how many batteries have been found, and
we will probably only find one, use an id number of '-1' to assert that this
is a unique instance.
Signed-off-by: NNeilBrown <neilb@suse.de>
Tested-by: NThomas Weber <weber@corscience.de>
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Provide the BQ27000 slave interface driver.

Signed-off-by: Madhusudhan Chikkature<madhu.cr@ti.com>
Acked-by: NEvgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>