There is no point in implementing a detect callback for the MAX6875, as
this device can't be detected. It was there solely to handle "force"
module parameters to instantiate devices, but now we have a better sysfs
interface that can do the same.

So we can get rid of the ugly module parameters and the detect callback.
This basically divides the binary module size by 2.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Acked-by: NWolfram Sang <w.sang@pengutronix.de>
Acked-by: NBen Gardner <gardner.ben@gmail.com>

This driver only reads the user EEPROM of that chip, so we can move it
to the eeprom-directory in order to further clean up (and later remove)
drivers/i2c/chips.

The Kconfig text was updated to match the current functionality,
dropping the meanwhile obsoleted parts.

Defconfigs have been adapted.
Signed-off-by: NWolfram Sang <w.sang@pengutronix.de>
Acked-by: NBen Gardner <gardner.ben@gmail.com>
Signed-off-by: NJean Delvare <khali@linux-fr.org>

The new-style max6875 driver implements the optional detect() callback
to cover the use cases of the legacy driver. I'm curious if anyone
really needs this though, so it might be removed in the feature.
Signed-off-by: NJean Delvare <khali@linux-fr.org>

Clean up old i2c chip drivers:
* Name the i2c_client "client" instead of "new_client".
* Drop useless initializations to 0.
Signed-off-by: NJean Delvare <khali@linux-fr.org>

i2c-core takes care of the possible corruption of 24RF08 chips for
quite some times, so device devices no longer need to do it. And they
really should not, as applying the prevention twice voids it.

I thought that I had fixed all drivers long ago but apparently I had
missed that one.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Cc: Ben Gardner <bgardner@wabtec.com>

Signed-off-by: NJean Delvare <khali@linux-fr.org>

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: NJean Delvare <khali@linux-fr.org>

Well, first of all, I don't want to change so many files either.

What I do:
Adding a new parameter "struct bin_attribute *" in the
.read/.write methods for the sysfs binary attributes.

In fact, only the four lines change in fs/sysfs/bin.c and
include/linux/sysfs.h do the real work.
But I have to update all the files that use binary attributes
to make them compatible with the new .read and .write methods.
I'm not sure if I missed any. :(

Why I do this:
For a sysfs attribute, we can get a pointer pointing to the
struct attribute in the .show/.store method,
while we can't do this for the binary attributes.
I don't know why this is different, but this does make it not
so handy to use the binary attributes as the regular ones.
So I think this patch is reasonable. :)

Who benefits from it:
The patch that exposes ACPI tables in sysfs
requires such an improvement.
All the table binary attributes share the same .read method.
Parameter "struct bin_attribute *" is used to get
the table signature and instance number which are used to
distinguish different ACPI table binary attributes.

Without this parameter, we need to offer different .read methods
for different ACPI table binary attributes.
This is impossible as there are various ACPI tables on different
platforms, and we don't know what they are until they are loaded.
Signed-off-by: NZhang Rui <rui.zhang@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

sysfs is now completely out of driver/module lifetime game.  After
deletion, a sysfs node doesn't access anything outside sysfs proper,
so there's no reason to hold onto the attribute owners.  Note that
often the wrong modules were accounted for as owners leading to
accessing removed modules.

This patch kills now unnecessary attribute->owner.  Note that with
this change, userland holding a sysfs node does not prevent the
backing module from being unloaded.

For more info regarding lifetime rule cleanup, please read the
following message.

  http://article.gmane.org/gmane.linux.kernel/510293

(tweaked by Greg to not delete the field just yet, to make it easier to
merge things properly.)
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

i2c: __must_check fixes (chip drivers)

Check for error on sysfs file creation.
Delete sysfs files on device removal.

The approach taken for the most complex case (pcf8591) is similar to
what Mark M. Hoffman proposed for hardware monitoring chip drivers.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Cc: Ben Gardner <bgardner@wabtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

semaphore to mutex conversion.

the conversion was generated via scripts, and the result was validated
automatically via a script as well.

build tested.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Now that i2c_add_driver() doesn't need the module owner to be set by
hand, we can delete it from the drivers.  This patch catches all of the
drivers that I found in the current tree (if a driver sets the .owner by
hand, it's not a problem, just not needed.)
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
Cc: Jean Delvare <khali@linux-fr.org>

We should use the i2c_driver.driver's .name and .owner fields
instead of the i2c_driver's ones.

This patch updates the miscellaneaous i2c chip drivers.
Signed-off-by: NLaurent Riffard <laurent.riffard@free.fr>
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Just about every i2c chip driver sets the I2C_DF_NOTIFY flag, so we
can simply make it the default and drop the flag. If any driver really
doesn't want to be notified when i2c adapters are added, that driver
can simply omit to set .attach_adapter. This approach is also more
robust as it prevents accidental NULL pointer dereferences.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Use kzalloc instead of kmalloc+memset in all remaining i2c bus and
chip drivers.
Signed-off-by: NDeepak Saxena <dsaxena@plexity.net>
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The 24RF08 corruption would better be prevented at i2c-core level than
at chip driver level, for several reasons:
* The second quick write should happen as soon as possible after the
  first one, so as to limit the risk that another command is issued on
  the bus inbetween, causing the corruption.
* As a matter of fact, the protection code at driver level was reworked
  at least three times already, which proves how hard it is to get it
  right there, while it's straightforward at i2c-core level.
* It's easy to add a new driver that would need the protection, and
  forget to add it. This did happen already.
* As additional probing addresses can be passed to most i2c chip drivers
  as module parameters, virtually every i2c chip driver would need the
  protection if we want to be really safe.
* Why duplicate code when we can easily avoid it?
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The only thing left in i2c-sensor.h are module parameter definition
macros. It's only an extension of what i2c.h offers, and this extension
is not sensors-specific. As a matter of fact, a few non-sensors drivers
use them. So we better merge them in i2c.h, and get rid of i2c-sensor.h
altogether.
Signed-off-by: NJean Delvare <khali@linux-fr>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

i2c_probe and i2c_detect now do the exact same thing and operate on
the same data structure, so we can have everyone call i2c_probe.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

We could refactor the error message 34 different i2c drivers print if
i2c_detach_client() fails in this function itself. Saves quite a few
lines of code. Documentation is updated to reflect that change.

Note that this patch should be applied after Rudolf Marek's w83792d
patches.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Kill normal_isa in header files, documentation and all chip drivers, as
it is no more used.

normal_i2c could be renamed to normal, but I decided not to do so at the
moment, so as to limit the number of changes. This might be done later
as part of the i2c_probe/i2c_detect merge.
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Remove an unused local variable and change the subclient name.
Signed-off-by: NBen Gardner <bgardner@wabtec.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Move the inline function kobj_to_i2c_client() from max6875.c to i2c.h.
Signed-off-by: NBen Gardner <bgardner@wabtec.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This is an update to the max6875 driver.
It no longer does any detection, so the address must be forced on module load.
It only makes available the user EEPROM (read-only).

This patch is based off 2.6.13-rc2-mm2.
Signed-off-by: NBen Gardner <bgardner@wabtec.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The 24RF08 corruption prevention in the eeprom and max6875 drivers wasn't
complete. For one thing, the additional quick write should happen as soon
as possible and unconditionally, while both drivers had error paths before.
For another, when a given chip is forced, the core does not emit a quick
write, so a second quick write would cause the corruption rather than
prevent it.

I plan to move the corruption prevention in the core in the long run, so
that individual drivers don't have to care anymore. But I need to merge
i2c_probe and i2c_detect before I do (work in progress).
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

After a careful code analysis on the new max6875 driver
(drivers/i2c/chips/max6875.c), I have come to the conclusion that this
driver may cause EEPROM corruptions if used on random systems.

The EEPROM part of the MAX6875 chip is accessed using rather uncommon
I2C sequences. What is seen by the MAX6875 as reads can be seen by a
standard EEPROM (24C02) as writes. If you check the detection method
used by the driver, you'll find that the first SMBus command it will
send on the bus is i2c_smbus_write_byte_data(client, 0x80, 0x40). For
the MAX6875 it makes an internal pointer point to a specific offset of
the EEPROM waiting for a subsequent read command, so it's not an actual
data write operation, but for a standard EEPROM, this instead means
writing value 0x40 to offset 0x80. Blame Philips and Intel for the
obscure protocol.

Since the MAX6875 and the standard, common 24C02 EEPROMs share two I2C
addresses (0x50 and 0x52), loading the max6875 driver on a system with
standard EEPROMs at either address will trigger a write on these
EEPROMs, which will lead to their corruption if they happen not to be
write protected. This kind of EEPROMs can be found on memory modules
(SPD), ethernet adapters (MAC address), laptops (proprietary data) and
displays (EDID/DDC). Most of these are hopefully write-protected, but
not all of them.

For this reason, I would recommend that the max6875 driver be
neutralized, in a way that nobody can corrupt his/her EEPROMs by just
loading the driver. This means either deleting the driver completely, or
not listing any default address for it. I'd like this to be done before
2.6.13-rc1 is released.

Additionally, the max6875 driver lacks the 24RF08 corruption preventer
present in the eeprom driver, which means that loading this driver in a
system with such a chip would corrupt it as well.

Here is a proposed quick patch addressing the issue, although I wouldn't
mind a complete removal if it makes everyone feel safer. I think Ben
has plans to replace this driver by a much simplified one anyway.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch adds support for the MAX6875/MAX6874 chips.
Signed-off-by: NBen Gardner <bgardner@wabtec.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>