Commit Graph

4 Commits

Author SHA1 Message Date
Greg Kroah-Hartman 94c9e6d665 w1: slaves: w1_ds2423: convert to use w1_family_ops.groups
This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.

Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-22 11:05:43 -07:00
Alexander Stein 8d7bda5188 w1: add family based automatic module loading
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 <alexander.stein@informatik.tu-chemnitz.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-06-03 14:09:14 -07:00
NeilBrown b02f8bede2 W1: split master mutex to avoid deadlocks.
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 <neilb@suse.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-06-13 16:38:40 -07:00
Mika Laitio 17fecb5582 w1: DS2423 counter driver and documentation
This is a 1-wire/w1 DS2423 slave driver for reading the values from all 4
counters available DS2423 devices by using standard w1_slave file.  In
ds2423 the counters are tied to ram pages 12-15 in and each of those
ram-pages.  Each of these counter values (and asoociated ram page values)
are represented as a own line in w1_slave file.  Driver has been tested on
mips and x86.

usage example:
cat /sys/bus/w1/devices/1d-00000009b964/w1_slave

00 02 00 00 00 00 00 00 00 6d 38 00 ff ff 00 00 fe ff 00 00 ff ff 00 00 ff
ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2
00 02 00 00 00 00 00 00 00 e0 1f 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff
ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2
00 5a 0e 5f 18 00 00 00 00 0b 28 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff
ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=408882778
00 05 00 00 00 00 00 00 00 8d 39 ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff crc=YES c=5

Patch includes also the documentation.

[randy.dunlap@oracle.com: fix ds2423 build, needs to select CRC16]
Signed-off-by: Mika Laitio <lamikr@pilppa.org>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-13 08:03:22 -08:00