Commit graph

114 commits

Author SHA1 Message Date
Prakash Mortha
596c88f460 i2c: Restore i2c_smbus_process_call function
Restore the i2c_smbus_process_call() as one driver (for the
Micronas MAP5401) will need it soon.

[JD: Update documentation accordingly.]

Signed-off-by: Prakash Mortha <pmortha@escient.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-10-14 17:30:06 +02:00
David Brownell
a10f9e7caf i2c: Do earlier driver model init
Move I2C driver model init earlier in the boot sequence.

This avoids oopsing in statically linked systems when some
subsystems register I2C drivers in subsys_initcall() code,
but those subsystems are linked (and initialized) before I2C.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-10-14 17:30:06 +02:00
David Brownell
1d0b19c9a0 i2c: Guard against oopses from bad init sequences
Guard I2C against oopsing because of init sequence problems, by
verifying that i2c_init() has been called before calling any
routines that rely on that initialization.  This specific test
just requires that bus_register(&i2c_bus_type) was called.

Examples of this kind of oopsing come from subystems and drivers
which register I2C drivers in their subsys_initcall code but
which are statically linked before I2C by drivers/Makefile.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-10-14 17:30:05 +02:00
Jean Delvare
4329cf8613 i2c: Prevent log spam on some DVB adapters
Some DVB adapters do not support the special I2C transaction that we
use for probing purposes. There's no point in logging this event, as
there's nothing the user can do and in general there is no actual
problem. So, degrade one of these messages to a debug message, and
move the other one around so that it is only printed on bogus drivers.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Uwe Bugla <uwe.bugla@gmx.de>
2008-08-28 08:33:23 +02:00
Marc Pignat
ee35425c8e i2c: Fix device_init_wakeup place
device_init_wakeup must be called after device_register.

Signed-off-by: Marc Pignat <marc.pignat@hevs.ch>
Acked-by: David Brownell <david-b@pacbell.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-08-28 08:33:22 +02:00
Jean Delvare
c1159f9e89 i2c: Check for address business before creating clients
We check for address business in i2c_probe_address(),
i2c_detect_address() and i2c_new_probed_device(), but this isn't
sufficient. Drivers can call i2c_attach_client() and
i2c_new_device() on any address, so we must check the address there
as well.

This fixes bug #11239:
http://bugzilla.kernel.org/show_bug.cgi?id=11239

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-08-10 22:56:16 +02:00
Hans Verkuil
b25b791b13 i2c: Fix NULL pointer dereference in i2c_new_probed_device
Fix a NULL pointer dereference that happened when calling
i2c_new_probed_device on one of the addresses for which we use byte
reads instead of quick write for detection purpose (that is: 0x30-0x37
and 0x50-0x5f).

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-08-10 22:56:15 +02:00
Greg Kroah-Hartman
93562b5376 Driver Core: add ability for class_for_each_device to start in middle of list
This mirrors the functionality that driver_for_each_device has as well.

We add a start variable, and all callers of the function are fixed up at
the same time.

The block layer will be using this new functionality in a follow-on
patch.


Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-07-21 21:54:47 -07:00
Jean Delvare
bd4bc3dbde i2c: Clear i2c_adapter.dev on adapter removal
Clear i2c_adapter.dev on adapter removal. This makes it possible to
re-add the adapter at a later point, which some drivers
(i2c-amd756-s4882, i2c-nforce2-s4985) actually do.

This fixes a bug reported by John Stultz here:
  http://lkml.org/lkml/2008/7/15/720
and by Ingo Molar there:
  http://lkml.org/lkml/2008/7/16/78

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
2008-07-16 19:30:05 +02:00
Jean Delvare
4735c98f84 i2c: Add detection capability to new-style drivers
Add a mechanism to let new-style i2c drivers optionally autodetect
devices they would support on selected buses and ask i2c-core to
instantiate them. This is a replacement for legacy i2c drivers, much
cleaner.

Where drivers had to implement both a legacy i2c_driver and a
new-style i2c_driver so far, this mechanism makes it possible to get
rid of the legacy i2c_driver and implement both enumerated and
detected device support with just one (new-style) i2c_driver.

Here is a quick conversion guide for these drivers, step by step:

* Delete the legacy driver definition, registration and removal.
  Delete the attach_adapter and detach_client methods of the legacy
  driver.

* Change the prototype of the legacy detect function from
    static int foo_detect(struct i2c_adapter *adapter, int address, int kind);
  to
    static int foo_detect(struct i2c_client *client, int kind,
    			  struct i2c_board_info *info);

* Set the new-style driver detect callback to this new function, and
  set its address_data to &addr_data (addr_data is generally provided
  by I2C_CLIENT_INSMOD.)

* Add the appropriate class to the new-style driver. This is
  typically the class the legacy attach_adapter method was checking
  for. Class checking is now mandatory (done by i2c-core.) See
  <linux/i2c.h> for the list of available classes.

* Remove the i2c_client allocation and freeing from the detect
  function. A pre-allocated client is now handed to you by i2c-core,
  and is freed automatically.

* Make the detect function fill the type field of the i2c_board_info
  structure it was passed as a parameter, and return 0, on success. If
  the detection fails, return -ENODEV.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:36 +02:00
Jean Delvare
8508159e2f i2c: Call client_unregister for new-style devices too
We call adapter->client_register for both legacy and new-style i2c
devices, however we only call adapter->client_unregister for legacy
drivers. This doesn't make much sense. Usually, drivers will undo
in client_unregister what they did in client_register, so we should
call neither or both for every given i2c device.

In order to ease the transition from legacy to new-style devices, it
seems preferable to actually call both.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: David Brownell <david-b@pacbell.net>
2008-07-14 22:38:36 +02:00
Jon Smirl
e9ca9eb9d7 i2c: Export the i2c_bus_type symbol
Export the root of the i2c bus so that PowerPC device tree code can
iterate over devices on the i2c bus.

Signed-off-by: Jon Smirl <jonsmirl@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:35 +02:00
Jean Delvare
e0457442fd i2c: Simplify i2c_device_probe
i2c_driver.id_table is mandatory now, so we can simplify
i2c_device_probe() a bit.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:30 +02:00
Jean Delvare
f7050bd716 i2c: Simplify i2c_del_driver()
i2c_del_driver() can be simplified a bit.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:26 +02:00
Matthias Kaehlcke
6a03cd9311 i2c: Use list_for_each_entry_safe
Use list_for_each_entry_safe() in i2c_del_adapter() and i2c_del_driver().

Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:26 +02:00
David Brownell
6ea438ec8d i2c: i2c_use_client() defends against NULL
Defend the i2c refcount calls against NULL pointers, as is important
(and conventional) for such calls.  Note that none of the current
callers of i2c_use_client() use its return value.

[JD: I hate this but apparently all the other subsystems do it so...]

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:24 +02:00
David Brownell
a1cdedac63 i2c: Kerneldoc for most I/O calls
Provide kerneldoc for most of the I2C and SMBus I/O calls.  Add a
comment summarizing some fault reporting issues which affect the
ability to provide clean fault reports through I2C master transfer
calls.  (Making it hard to precisely specify their return values...)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:24 +02:00
Jean Delvare
67c2e66571 i2c: Delete unused function i2c_smbus_write_quick
Function i2c_smbus_write_quick has no users left, so we can delete it.

Also update the list of these helper functions which are gone but
could be added back if needed.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:23 +02:00
David Brownell
24a5bb7b18 i2c-core: Return -Errno, not -1
More updates to the I2C stack's fault reporting:  make the core stop
returning "-1" (usually "-EPERM") for all faults.  Instead, pass lower
level fault code up the stack, or return some appropriate errno.

This patch happens to touch almost exclusively SMBus calls.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:23 +02:00
Jean Delvare
75415490d6 i2c-core: Remove needless include
i2c-core doesn't use seq files, so doesn't need to include
<linux/seq_file.h>.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:22 +02:00
Dave Young
7f101a9786 i2c: Use class_for_each_device
Use class_for_each_device for iteration.

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-07-14 22:38:19 +02:00
Jean Delvare
eb8a790809 i2c: Kill the old driver matching scheme
Remove the old driver_name/type scheme for i2c driver matching. Only the
standard aliasing model will be used from now on.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-05-18 20:49:41 +02:00
Jean Delvare
60b129d7bf i2c: Match dummy devices by type
As the old driver_name/type matching scheme is going away soon, change
the dummy device mechanism to use the new matching scheme.

This has the downside that dummy i2c clients can no longer choose
their name, they'll all appear as "dummy" in sysfs and in log
messages. I don't think it is a problem in practice though, as there
is little reason to use these i2c clients to log messages.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-05-11 20:37:06 +02:00
Jean Delvare
d2653e9273 i2c: Add support for device alias names
Based on earlier work by Jon Smirl and Jochen Friedrich.

This patch allows new-style i2c chip drivers to have alias names using
the official kernel aliasing system and MODULE_DEVICE_TABLE(). At this
point, the old i2c driver binding scheme (driver_name/type) is still
supported.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Jochen Friedrich <jochen@scram.de>
Cc: Jon Smirl <jonsmirl@gmail.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
2008-04-29 23:11:39 +02:00
Harvey Harrison
08882d2093 i2c: Replace remaining __FUNCTION__ occurrences
__FUNCTION__ is gcc-specific, use __func__.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-04-22 22:16:47 +02:00
Matthew Wilcox
6188e10d38 Convert asm/semaphore.h users to linux/semaphore.h
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
2008-04-18 22:22:54 -04:00
Randy Dunlap
8c07e46f39 i2c: Fix docbook problem
Sometimes kernel-doc and xmlto conspire to create output that is invalid
and causes problems.  Until I know a real/better solution, change the
source code that causes this.

If anyone has better fixes or can just explain what is happening here,
that would be great.

xmlto: input does not validate (status 1)
mmotm-2008-0314-1449/Documentation/DocBook/kernel-api.xml:71468: parser error : Opening and ending tag mismatch: programlisting line 71464 and para
   </para><para>
          ^
mmotm-2008-0314-1449/Documentation/DocBook/kernel-api.xml:71480: parser error : Opening and ending tag mismatch: para line 71473 and programlisting
</programlisting></informalexample>
                 ^
make[1]: *** [Documentation/DocBook/kernel-api.html] Error 1

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-03-23 20:28:20 +01:00
Hans Verkuil
50c3304a5e i2c: Keep client->driver and client->dev.driver in sync
Ensure that client->driver is set to NULL if the probe() returns an
error (this keeps client->driver and client->dev.driver in sync).

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-03-12 14:15:00 +01:00
David Brownell
e9f1373b64 i2c: Add i2c_new_dummy() utility
This adds a i2c_new_dummy() primitive to help work with devices
that consume multiple addresses, which include many I2C eeproms
and at least one RTC.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-01-27 18:14:52 +01:00
Jean Delvare
0b987dcd3a i2c: Drop legacy locking in i2c_new_probed_device
It is no longer required to hold adapter->clist_lock to call
i2c_check_addr.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: David Brownell <david-b@pacbell.net>
2008-01-27 18:14:52 +01:00
Jean Delvare
9ddced16bb i2c: Limit locking scope in i2c_detach_client
We only need to hold adapter->clist_lock when we touch the client list.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-01-27 18:14:51 +01:00
David Brownell
86ec5ec872 i2c-remove-redundant-i2c_client-list.patch
This goes on top of the patch removing most i2c_adapter.clients usage,
updating i2c_attach_client:

 - Don't call device_register() while holding clist_lock.  This
   removes a self-deadlock when on the i2c_driver.probe() path,
   for drivers that need to attach new devices (e.g. dummies).

 - Remove a redundant address check.  The driver model core does
   this as a consequence of guaranteeing unique names.

 - Move the "device registered" diagnostic so that it never lies;
   previously, on error paths it would falsely report success.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-01-27 18:14:51 +01:00
David Brownell
9b766b814d i2c: Stop using the redundant client list
The i2c_adapter.clients list of i2c_client nodes duplicates driver
model state.  This patch starts removing that list, letting us remove
most existing users of those i2c-core lists.

 * The core I2C code now iterates over the driver model's list instead
   of the i2c-internal one in some places where it's safe:
      - Passing a command/ioctl to each client, a mechanims
        used almost exclusively by DVB adapters;
      - Device address checking, in both i2c-core and i2c-dev.

 * Provide i2c_verify_client() to use with driver model iterators.

 * Flag the relevant i2c_adapter and i2c_client fields as deprecated,
   to help prevent new users from appearing.

For the moment the list needs to stick around, since some issues show
up when deleting devices created by legacy I2C drivers.  (They don't
follow standard driver model rules.  Removing those devices can cause
self-deadlocks.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-01-27 18:14:51 +01:00
Mike Rapoport
cea443a81c i2c: Support i2c_transfer in atomic contexts
Allow i2c_transfer to be called in contexts where sleeping is not allowed.
It is the reponsability of the caller to ensure that the underlying i2c bus
driver will not sleep either.

Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-01-27 18:14:50 +01:00
Jean Delvare
caada32afe i2c: Rename main mutex
Rename the main mutex in i2c-core from core_lists to core_lock. This
makes more sense now that the redundant lists are gone.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-01-27 18:14:49 +01:00
Jean Delvare
026526f5af i2c: Drop redundant i2c_driver.list
i2c_driver.list is superfluous, this list duplicates the one
maintained by the driver core. Drop it.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
2008-01-27 18:14:49 +01:00
Jean Delvare
87c6c22945 i2c: Drop redundant i2c_adapter.list
i2c_adapter.list is superfluous, this list duplicates the one
maintained by the driver core. Drop it.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
2008-01-27 18:14:48 +01:00
Jean Delvare
e48d33193d i2c: Change prototypes of refcounting functions
Use more standard prototypes for i2c_use_client() and
i2c_release_client(). The former now returns a pointer to the client,
and the latter no longer returns anything. This matches what all other
subsystems do.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: David Brownell <david-b@pacbell.net>
2008-01-27 18:14:48 +01:00
Jean Delvare
bdc511f438 i2c: Use the driver model reference counting
Don't implement our own reference counting mechanism for i2c clients
when the driver model already has one.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: David Brownell <david-b@pacbell.net>
2008-01-27 18:14:48 +01:00
Mark M. Hoffman
bfb6df24fa i2c: Constify client address data
This patch allows much of the I2C client address data to move from initdata
into text.
    
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-01-27 18:14:46 +01:00
Jean Delvare
5e31c2bd3c i2c: Make i2c_check_addr static
i2c_check_addr is only used inside i2c-core now, so we can make it
static and stop exporting it. Thanks to David Brownell for noticing.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2007-11-15 19:24:02 +01:00
Jan Engelhardt
96de0e252c Convert files to UTF-8 and some cleanups
* Convert files to UTF-8.

  * Also correct some people's names
    (one example is Eißfeldt, which was found in a source file.
    Given that the author used an ß at all in a source file
    indicates that the real name has in fact a 'ß' and not an 'ss',
    which is commonly used as a substitute for 'ß' when limited to
    7bit.)

  * Correct town names (Goettingen -> Göttingen)

  * Update Eberhard Mönkeberg's address (http://lkml.org/lkml/2007/1/8/313)

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
2007-10-19 23:21:04 +02:00
David Brownell
53be795934 i2c: Remove i2c_algorithm.algo_control()
This removes:

 - An effectively unused hook:  i2c_algorithm.algo_control.

 - The i2c_control() call, used only by i2c-dev to call that
   unused hook or set two barely supported adapter params.

   (That param setting moves into i2c-dev.c ... still iffy
   due to lack of locking, but no other changes.)

As shown by diffstat, this is a net code shrink.  It also reduces the
complexity of the I2C adapter and /dev interfaces.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2007-10-13 23:56:32 +02:00
David Brownell
a64ec07d3d i2c: Document struct i2c_msg
Clarify use of the I2C_M_* flags by highlighting the fact that
most of them depend on I2C_FUNC_PROTOCOL_MANGLING.

Also provide kerneldoc for i2c_smbus_read_block_data() and also
for "struct i2c_msg".

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2007-10-13 23:56:31 +02:00
Adrian Bunk
83eaaed0d0 i2c-core: Make some code static
After the i2c-isa removal some code can become static.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2007-10-13 23:56:30 +02:00
David Brownell
3bbb835d4c i2c: New-style devices can support driver model wakeup flags
We need to be able to flag I2C devices, such as RTCs, which can issue wake
events (usually through IRQ lines).  This adds an i2c_board_info.flags bit,
and uses it to initialize the i2c device node.  (And shrinks a few lines
that were overly long.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2007-10-13 23:56:29 +02:00
Kay Sievers
7eff2e7a8b Driver core: change add_uevent_var to use a struct
This changes the uevent buffer functions to use a struct instead of a
long list of parameters. It does no longer require the caller to do the
proper buffer termination and size accounting, which is currently wrong
in some places. It fixes a known bug where parts of the uevent
environment are overwritten because of wrong index calculations.

Many thanks to Mathieu Desnoyers for finding bugs and improving the
error handling.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12 14:51:01 -07:00
Linus Torvalds
40b42f1ebf Merge branch 'release' of git://lm-sensors.org/kernel/mhoffman/hwmon-2.6
* 'release' of git://lm-sensors.org/kernel/mhoffman/hwmon-2.6: (44 commits)
  i2c: Delete the i2c-isa pseudo bus driver
  hwmon: refuse to load abituguru driver on non-Abit boards
  hwmon: fix Abit Uguru3 driver detection on some motherboards
  hwmon/w83627ehf: Be quiet when no chip is found
  hwmon/w83627ehf: No need to initialize fan_min
  hwmon/w83627ehf: Export the thermal sensor types
  hwmon/w83627ehf: Enable VBAT monitoring
  hwmon/w83627ehf: Add support for the VID inputs
  hwmon/w83627ehf: Fix timing issues
  hwmon/w83627ehf: Add error messages for two error cases
  hwmon/w83627ehf: Convert to a platform driver
  hwmon/w83627ehf: Update the Kconfig entry
  make coretemp_device_remove() static
  hwmon: Add LM93 support
  hwmon: Improve the pwmN_enable documentation
  hwmon/smsc47b397: Don't report missing fans as spinning at 82 RPM
  hwmon: Add support for newer uGuru's
  hwmon/f71805f: Add temperature-tracking fan control mode
  hwmon/w83627ehf: Preserve speed reading when changing fan min
  hwmon: fix detection of abituguru volt inputs
  ...

Manual fixup of trivial conflict in MAINTAINERS file
2007-07-19 14:24:57 -07:00
Jean Delvare
e24b8cb4fa i2c: Delete the i2c-isa pseudo bus driver
There are no users of i2c-isa left, so we can finally get rid of it.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2007-07-19 14:25:20 -04:00
Jean Delvare
4b2643d7d9 i2c: Fix the i2c_smbus_read_i2c_block_data() prototype
Let the drivers specify how many bytes they want to read with
i2c_smbus_read_i2c_block_data(). So far, the block count was
hard-coded to I2C_SMBUS_BLOCK_MAX (32), which did not make much sense.
Many driver authors complained about this before, and I believe it's
about time to fix it. Right now, authors have to do technically stupid
things, such as individual byte reads or full-fledged I2C messaging,
to work around the problem. We do not want to encourage that.

I even found that some bus drivers (e.g. i2c-amd8111) already
implemented I2C block read the "right" way, that is, they didn't
follow the old, broken standard. The fact that it was never noticed
before just shows how little i2c_smbus_read_i2c_block_data() was used,
which isn't that surprising given how broken its prototype was so far.

There are some obvious compatiblity considerations:
* This changes the i2c_smbus_read_i2c_block_data() prototype. Users
  outside the kernel tree will notice at compilation time, and will
  have to update their code.
* User-space has access to i2c_smbus_xfer() directly using i2c-dev, so
  the changed expectations would affect tools such as i2cdump. In order
  to preserve binary compatibility, we give I2C_SMBUS_I2C_BLOCK_DATA
  a new numeric value, and define I2C_SMBUS_I2C_BLOCK_BROKEN with the
  old numeric value. When i2c-dev receives a transaction with the
  old value, it can convert it to the new format on the fly.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2007-07-12 14:12:29 +02:00