On architectures where long is more then 32 bits, modifying a 32-bit field
with set_bit (and other atomic bit operations) may cause bytes following
the field to by modified.
Because the endianness of the bits within a field is the native endianness
of the CPU[1], on big-endian machines, bit number zero is in the last byte
of the field.
Therefore, `set_bit(0, ptr)' on a 64-bit big-endian machine is roughly
equivalent to `((char *)ptr)[7] |= 1', and since w1 driver uses a 32-bit
field for holding the flags, this causes bytes beyond the field to be
modified.
[1] From Documentation/atomic_ops.txt:
Native atomic bit operations are defined to operate on objects
aligned to the size of an "unsigned long" C data type, and are
least of that size. The endianness of the bits within each
"unsigned long" are the native endianness of the cpu.
Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
This reverts commit 59d4467be4.
Turns out it was the wrong version, will apply the correct version after
this.
Reported-by: NeilBrown <neilb@suse.de>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 <neilb@suse.de>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reorganize so the netlink connector one wire search command will update
the kernel list of detected slave devices. Otherwise, a newly detected
device is unusable because unless it's in the kernel list of known devices
any commands will result in ENODEV status.
Signed-off-by: David Fries <David@Fries.net>
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>
The first patch adds generic functionnality to w1_io for Resume Command
[A5h] lots of slaves support. I found it useful for multi-commands/reset
workflows with the same slave on a multi-slave bus.
This DS2408 w1 slave driver is not complete for all the features of the
chip, but its sufficient if you use it as a simple IO expander. Enjoy!
The ds1wm had Kconfig dependencies towards ARM && HAVE_CLK. I took them
out since I was using the ds1wm on an x86_64 platform (ds1wm in a FPGA
through pcie) and found them irrelevant.
The clock freq/divisors at the top of ds1wm.c did not have the MSB set to
1. This bit is CLK_EN which turns the whole prescaler and dividers on.
The driver never mentionned this bit either, so I just included this bit
right in the table entries. I also took the liberty to add a couple of
entries to the table. The spec doesn't explicitely mentions these
possibilities but the description and examination of the core shows the
prescalers & dividers can be used for more than the table explicitely
shows. The table I enlarged still doesn't cover all possibilities, but
it's a good start.
I also made a few tweaks to a couple of the read and write algorithms
which made sense while I had my head very deep in the ds1wm documentation.
We stressed it a lot with 10+ slaves on the bus, many ds2408, ds2431 and
ds2433 at the same time doing extensive interaction. It proved quite
stable in our production environment.
This patch:
Add generic functionnality to w1_io for Resume Command [A5h] lots of
slaves support.
Signed-off-by: Jean-François Dagenais <dagenaisj@sonatest.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
Cc: Matt Reimer <mreimer@vpop.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Writes and returns sampled data back to userspace.
Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Export the w1_read_8 function for use of drivers. The OMAP HDQ
driver(drivers/w1/masters/omap_hdq.c) uses this function.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Madhusudhan Chikkature<madhu.cr@ti.com>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixed data reading bug by replacing binary attribute with device one.
Switching the sysfs read from bin_attribute to device_attribute. The data
is far under PAGE_SIZE so the binary interface isn't required. As the
device_attribute interface will make one call to w1_therm_read per file
open and buffer, the result is, the following problems go away.
buffer overflow:
Execute a short read on w1_slave and w1_therm_read_bin would still
return the full string size worth of data clobbering the user space
buffer when it returned. Switching to device_attribute avoids the
buffer overflow problems. With the snprintf formatted output dealing
with short reads without doing a conversion per read would have
been difficult.
bad behavior:
`cat w1_slave` would cause two temperature conversions to take place.
Previously the code assumed W1_SLAVE_DATA_SIZE would be returned with
each read. It would not return 0 unless the offset was less
than W1_SLAVE_DATA_SIZE. The result was the first read did a
temperature conversion, filled the buffer and returned, the
offset in the second read would be less than
W1_SLAVE_DATA_SIZE and also fill the buffer and return, the
third read would finnally have a big enough offset to return 0
and cause cat to stop. Now w1_therm_read will be called at
most once per open.
Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a strong pullup option to the w1 system. This supplies extra power
for parasite powered devices. There is a w1_master_pullup sysfs entry and
enable_pullup module parameter to enable or disable the strong pullup.
The one wire bus requires at a minimum one wire and ground. The common
wire is used for sending and receiving data as well as supplying power to
devices that are parasite powered of which temperature sensors can be one
example. The bus must be idle and left high while a temperature
conversion is in progress, in addition the normal pullup resister on
larger networks or even higher temperatures might not supply enough power.
The pullup resister can't provide too much pullup current, because
devices need to pull the bus down to write a value. This enables the
strong pullup for supported hardware, which can supply more current when
requested. Unsupported hardware will just delay with the bus high.
The hardware USB 2490 one wire bus master has a bit on some commands which
will enable the strong pullup as soon as the command finishes executing.
To use strong pullup, call the new w1_next_pullup function to register the
duration. The next write command will call set_pullup before sending the
data, and reset the duration to zero once it returns.
Switched from simple_strtol to strict_strtol.
Signed-off-by: David Fries <david@fries.net>
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>
The w1_process thread's sleeping and termination has been modified.
msleep_interruptible was replaced by schedule_timeout and schedule to
allow for kthread_stop and wake_up_process to interrupt the sleep and the
unbounded sleeping when a bus search is disabled. The W1_MASTER_NEED_EXIT
and flags variable were removed as they were redundant with
kthread_should_stop and kthread_stop. If w1_process is sleeping,
requesting a search will immediately wake it up rather than waiting for
the end of msleep_interruptible previously.
Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
w1_control_thread was removed which would wake up every second and process
newly registered family codes and complete some final cleanup for a
removed master. Those routines were moved to the threads that were
previously requesting those operations. A new function
w1_reconnect_slaves takes care of reconnecting existing slave devices when
a new family code is registered or removed. The removal case was missing
and would cause a deadlock waiting for the family code reference count to
decrease, which will now happen. A problem with registering a family code
was fixed. A slave device would be unattached if it wasn't yet claimed,
then attached at the end of the list, two unclaimed slaves would cause an
infinite loop.
The struct w1_bus_master.search now takes a pointer to the struct
w1_master device to avoid searching for it, which would have caused a
lock ordering deadlock with the removal of w1_control_thread.
Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch contains the following possible cleanups:
- the following file did't #include the header with the prototypes for
it's global functions:
- w1_int.c
- #if 0 the following unused global function:
- w1_family.c: w1_family_get()
- make the following needlessly global functions static:
- w1_family.c: __w1_family_put()
- w1_io.c: w1_delay()
- w1_io.c: w1_touch_bit()
- w1_io.c: w1_read_8()
- remove the following unused EXPORT_SYMBOL's:
- w1_family.c: w1_family_put
- w1_family.c: w1_family_registered
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Nice cleanup spotted by Adrian Bunk, which was lost due to moving to the
completely new functionality.
Shame-shame-shame on me.
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Use mutexes instead of semaphores.
Patch tested on x86_64 and i386 with test bus master driver.
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
There are three types of messages between w1 core and userspace:
1. Events. They are generated each time new master or slave device found
either due to automatic or requested search.
2. Userspace commands. Includes read/write and search/alarm search comamnds.
3. Replies to userspace commands.
From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Special file in each w1 slave device's directory called "rw" is created
each time new slave and no appropriate w1 family is registered.
"rw" file supports read and write operations, which allows to perform
almost any kind of operations. Each logical operation is a transaction
in nature, which can contain several (two or one) low-level operations.
Let's see how one can read EEPROM context:
1. one must write control buffer, i.e. buffer containing command byte
and two byte address. At this step bus is reset and appropriate device
is selected using either W1_SKIP_ROM or W1_MATCH_ROM command.
Then provided control buffer is being written to the wire.
2. reading. This will issue reading eeprom response.
It is possible that between 1. and 2. w1 master thread will reset bus for
searching and slave device will be even removed, but in this case 0xff will
be read, since no device was selected.
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch removes old-style kernel thread initialization
and changes w1 to use kthread api.
It is based on Christoph Hellwig <hch@lst.de> work.
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch contains the following cleanups:
- make needlessly global code static
- declarations for global code belong into header files
- w1.c: #if 0 the unused struct w1_slave_device
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Patch is based on work from Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
I've created reconnect feature - if on start there are no registered families
all new devices will have defailt family, later when driver for appropriate
family is loaded, slaves, which were faound earlier, will still have defult
family instead of right one. Reconnect feature will force control thread to run
through all master devices and all slaves found and search for slaves with
default family id and try to reconnect them.
It does not store newly registered family and does not check only those slaves
which have reg_num.family the same as being registered one - all slaves with
default family are reconnected.
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Adds a sysfs entry (w1_master_search) that allows you to disable/enable
periodic searches.
Signed-off-by: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Adds the triplet w1 master method and changes w1_search() to use it.
Signed-off-by: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Removed some fields which are not required.
First step for writing operations.
Now only read and read name remain.
Patch depends on w1 cleanups patch.
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
- white space changes.
- list_for_each_entry/list_for_each_entry_safe and reverse changes.
- small coding style changes.
- removed redundant NULL checks.
- use attribute group and macros instead of direct device attributes.
Patch is havily based on work from Adrian Bunk and Dmitry Torokhov,
thanks guys.
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Michal Nazarewicz