iio: temp: maxim_thermocouple: Fix alignment for DMA safety

____cacheline_aligned is an insufficient guarantee for non-coherent DMA
on platforms with 128 byte cachelines above L1. Switch to the updated
IIO_DMA_MINALIGN definition

Fixes: 1f25ca11d84a ("iio: temperature: add support for Maxim thermocouple chips")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Matt Ranostay <mranostay@gmail.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-93-jic23@kernel.org

iio: temperature: maxim_thermocouple: Switch from of headers to mod_devicetable.h

There is nothing directly using of specific interfaces in this driver,
so lets not include the headers.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220202205328.57837-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: remove explicit IIO device parent assignment

This patch applies the semantic patch:
@@
expression I, P, SP;
@@
I = devm_iio_device_alloc(P, SP);
...
- I->dev.parent = P;

It updates 302 files and does 307 deletions.
This semantic patch also removes some comments like
'/* Establish that the iio_dev is a child of the i2c device */'

But this is is only done in case where the block is left empty.

The patch does not seem to cover all cases. It looks like in some cases a
different variable is used in some cases to assign the parent, but it
points to the same reference.
In other cases, the block covered by ... may be just too big to be covered
by the semantic patch.

However, this looks pretty good as well, as it does cover a big bulk of the
drivers that should remove the parent assignment.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: maxim_thermocouple: add thermocouple_type sysfs attribute

We added a sysfs ABI for getting/setting the type of a thermocouple. This
driver supports chips that support specific fixed thermocouple types; we
cannot set it, but still we can add this sysfs attribute in RO mode to
read-back the thermocouple type.

This driver supports actually several chips:
- max6675
- max31855[k/j/n/s/t/e/r]asa family

Max6675 supports only K-type thermocouples, so we can just report that.

Each chip in max31855 family supports just one specific thermocouple type
(in the obvious way: i.e. max31855jasa supports J-type). This driver did
accept a generic SPI ID and OF compatible "max31855" which does not give
any clue about which chip is really involved (and unfortunately it seems
we have no way to detect it).

This patch introduces a new set of, more specific, SPI IDs and OF
compatible strings to better match the chip type.

The old, generic, "max31855" binding is kept for compatibility reasons, but
this patch aims to deprecate it, so, should we hit it, a warning is spit.
In such case the reported thermocouple type in sysfs is '?', because we
have no way to know.

Regarding the implementation: the thermocouple type information is stored
in the driver private data and I've kept only two maxim_thermocouple_chip
types in order to avoid a lot of duplications (seven chip types with just
a different thermocouple type).

RFT because I have no real HW to test this.

Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Patrick Havelange <patrick.havelange@essensium.com>
Cc: Matt Weber <matthew.weber@rockwellcollins.com>
Cc: Matt Ranostay <matt.ranostay@konsulko.com>
Cc: Chuhong Yuan <hslester96@gmail.com>
Cc: Daniel Gomez <dagmcr@gmail.com>
Cc: linux-iio@vger.kernel.org
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: temp: maxim thermocouple: Drop unneeded semi colon.

Identified by coccinelle

CHECK drivers/iio/temperature/maxim_thermocouple.c
drivers/iio/temperature/maxim_thermocouple.c:197:3-4: Unneeded semicolon

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>

iio: maxim_thermocouple: Use device-managed APIs

Use device-managed APIs to simplify the code.
The remove functions are redundant now and can
be deleted.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: temperature: maxim_thermocouple: declare missing of table

Add missing <of_device_id> table for SPI driver relying on SPI
device match since compatible is in a DT binding or in a DTS.

Before this patch:
modinfo drivers/iio/temperature/maxim_thermocouple.ko | grep alias
alias: spi:max31855
alias: spi:max6675

After this patch:
modinfo drivers/iio/temperature/maxim_thermocouple.ko | grep alias
alias: spi:max31855
alias: spi:max6675
alias: of:N*T*Cmaxim,max31855C*
alias: of:N*T*Cmaxim,max31855
alias: of:N*T*Cmaxim,max6675C*
alias: of:N*T*Cmaxim,max6675

Reported-by: Javier Martinez Canillas <javier@dowhile0.org>
Signed-off-by: Daniel Gomez <dagmcr@gmail.com>
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Revert "iio: temperature: maxim_thermocouple: add MAX31856 part"

This reverts commit 535fba29b3e1afef4ba201b3c69a6992583ec0bd.

Seems the submitter (er me, hang head in shame) didn't look at the datasheet
enough to see that the registers are quite different.

This needs to be reverted because a) would never work b) to open it be added
to a Maxim RTDs (Resistance Temperature Detectors) under development by author

Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: add SPDX identifier for various drivers

Add GPLv2+ SPDX identifier and update email for author's drivers.

Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio:temperature: drop assignment of iio_info.driver_module

The equivalent of this is now done via macro magic when
the relevant register call is made. The actual structure
elements will shortly go away.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>

iio: temperature: maxim_thermocouple: add MAX31856 part

MAX31856 is register equivalent to the MAX31855 but suppports J, N, R,
S, T, E and B type thermocouples in addition to K-type.

Data conversion for the various types happens transparently to the driver
via probe type detection, and a LUT on the sensor.

Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: maxim_thermocouple: Set parent device

Initialize the parent of the IIO device to the device that registered it.
This makes sure that the IIO device appears the right level in the device
hierarchy.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: maxim_thermocouple: detect invalid storage size in read()

As found by gcc -Wmaybe-uninitialized, having a storage_bytes value other
than 2 or 4 will result in undefined behavior:

drivers/iio/temperature/maxim_thermocouple.c: In function 'maxim_thermocouple_read':
drivers/iio/temperature/maxim_thermocouple.c:141:5: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This probably cannot happen, but returning -EINVAL here is appropriate
and makes gcc happy and the code more robust.

Fixes: 231147ee77f3 ("iio: maxim_thermocouple: Align 16 bit big endian value of raw reads")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
(cherry picked from commit 32cb7d27e65df9daa7cee8f1fdf7b259f214bee2)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

iio: maxim_thermocouple: detect invalid storage size in read()

As found by gcc -Wmaybe-uninitialized, having a storage_bytes value other
than 2 or 4 will result in undefined behavior:

drivers/iio/temperature/maxim_thermocouple.c: In function 'maxim_thermocouple_read':
drivers/iio/temperature/maxim_thermocouple.c:141:5: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This probably cannot happen, but returning -EINVAL here is appropriate
and makes gcc happy and the code more robust.

Fixes: 231147ee77f3 ("iio: maxim_thermocouple: Align 16 bit big endian value of raw reads")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: maxim_thermocouple: Align 16 bit big endian value of raw reads

Driver was reporting invalid raw read values for MAX6675 on big
endian architectures. MAX6675 buffered mode is not affected, nor
is the MAX31855.

The driver was losing a 2 byte read value when it used a 32 bit
integer buffer to store a 16 bit big endian value. Use big endian
types to properly align buffers on big endian architectures.

Fixes following sparse endianness warnings:
warning: cast to restricted __be16
warning: cast to restricted __be32
Fixes checkpatch issue:
CHECK: No space is necessary after a cast

Signed-off-by: sayli karnik <karniksayli1995@gmail.com>
Fixes: 1f25ca11d84a ("iio: temperature: add support for Maxim
thermocouple chips")
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: temperature: fix non static symbol warnings

Fixes the following sparse warnings:

drivers/iio/temperature/maxim_thermocouple.c:35:28: warning:
symbol 'max6675_channels' was not declared. Should it be static?
drivers/iio/temperature/maxim_thermocouple.c:52:28: warning:
symbol 'max31855_channels' was not declared. Should it be static?
drivers/iio/temperature/maxim_thermocouple.c:98:38: warning:
symbol 'maxim_thermocouple_chips' was not declared. Should it be static?

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-By: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: temperature: add support for Maxim thermocouple chips

Add initial driver support for MAX6675, and MAX31855 thermocouple chips.

Cc: Marek Vasut <marex@denx.de>
Cc: Matt Porter <mporter@konsulko.com>
Signed-off-by: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>