i2c: Remove redundant comparison in npcm_i2c_reg_slave

In the npcm_i2c_reg_slave() function, there was a redundant
comparison that checked if 'bus->slave' was null immediately after
assigning it the 'client' value. There were concerns about a
potential null dereference because of `client->adapter`, but
according to Wolfram Sang, "we trusted ourselves here" Therefore,
this comparison is unnecessary.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Rand Deeb <rand.sec96@gmail.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

i2c: npcm7xx: move to per-adapter debugfs directory

The I2C core now provides a per-adapter debugfs directory. Use it
instead of creating a custom one.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Fix callback completion ordering

Sometimes, our completions race with new master transfers and override
the bus->operation and bus->master_or_slave variables. This causes
transactions to timeout and kernel crashes less frequently.

To remedy this, we re-order all completions to the very end of the
function.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: William A. Kennington III <william@wkennington.com>
Reviewed-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

I2C: Explicitly include correct DT includes

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Alain Volmat <alain.volmat@foss.st.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Acked-by: Jochen Friedrich <jochen@scram.de>
Acked-by: Peter Rosin <peda@axentia.se>
Acked-by: Vadim Pasternak <vadimp@nvidia.com>
Reviewed-by: Asmaa Mnebhi <asnaa@nvidia.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: Chris Pringle <chris.pringle@phabrix.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Tali Perry <tali.perry@nuvoton.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Annotate register field definitions with longer names

To make the code easier to understand, add longer names to the
definitions of register fields. These longer names are based on source
code published by DELL/AESS for WPCM450, but should apply just as well
to NPCM7xx and NPCM8xx.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Group bank 0/1 registers together for readability

The unlabelled registers NPCM_I2CCTL4 to NPCM_I2CSCLHT overlap with the
bank 1 registers below, and they are accessed after selecting bank 0, so
they clearly belong to bank 0.

Move them together with the other bank 0 registers, and move the
unrelated definition of npcm_i2caddr down to keep the banked registers
in one piece.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Fix error handling in npcm_i2c_init()

A problem about i2c-npcm7xx create debugfs failed is triggered with the
following log given:

[ 173.827310] debugfs: Directory 'npcm_i2c' with parent '/' already present!

The reason is that npcm_i2c_init() returns platform_driver_register()
directly without checking its return value, if platform_driver_register()
failed, it returns without destroy the newly created debugfs, resulting
the debugfs of npcm_i2c can never be created later.

npcm_i2c_init()
debugfs_create_dir() # create debugfs directory
platform_driver_register()
driver_register()
bus_add_driver()
priv = kzalloc(...) # OOM happened
# return without destroy debugfs directory

Fix by removing debugfs when platform_driver_register() returns error.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Reviewed-by: Tali Perry <tali.perry@nuvoton.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm: Capitalize the one-line comment

Make the one-line comments capital in the driver to get the comment style
consistent.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm: Support NPCM845

Add NPCM8XX I2C support.
The NPCM8XX uses a similar i2c module as NPCM7XX.
The internal HW FIFO is larger in NPCM8XX.

Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Acked-by: Tomer Maimon <tmaimon77@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm: Correct slave role behavior

Correct the slave transaction logic to be compatible with the generic
slave backend driver.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm: Remove own slave addresses 2:10

NPCM can support up to 10 own slave addresses. In practice, only one
address is actually being used. In order to access addresses 2 and above,
need to switch register banks. The switch needs spinlock.
To avoid using spinlock for this useless feature removed support of SA >=
2. Also fix returned slave event enum.

Remove some comment since the bank selection is not required. The bank
selection is not required since the supported slave addresses are reduced.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Add check for platform_driver_register

As platform_driver_register() could fail, it should be better
to deal with the return value in order to maintain the code
consisitency.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Acked-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm: Handle spurious interrupts

On some platforms in rare cases (1 to 100,000 transactions),
the i2c gets a spurious interrupt which means that we enter an interrupt
but in the interrupt handler we don't find any status bit that points to
the reason we got this interrupt.

This may be a case of a rare HW issue or signal integrity issue that is
still under investigation.

In order to overcome this we are doing the following:
1. Disable incoming interrupts in master mode only when slave mode is not
enabled.
2. Clear end of busy (EOB) after every interrupt.
3. Clear other status bits (just in case since we found them cleared)
4. Return correct status during the interrupt that will finish the
transaction.

On next xmit transaction if the bus is still busy the master will issue a
recovery process before issuing the new transaction.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm: Correct register access width

The SMBnCTL3 register is 8-bit wide and the 32-bit access was always
incorrect, but simply didn't cause a visible error on the 32-bit machine.

On the 64-bit machine, the kernel message reports that ESR value is
0x96000021. Checking Arm Architecture Reference Manual Armv8 suggests that
it's the alignment fault.

SMBnCTL3's address is 0xE.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm: Add tx complete counter

tx_complete counter is used to indicate successful transaction count.
Similar counters for failed tx were previously added.

Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm: Fix timeout calculation

Use adap.timeout for timeout calculation instead of hard-coded
value of 35ms.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm: Remove unused variable clk_regmap

Remove unused variable clk_regmap.

Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm: Change the way of getting GCR regmap

Change the way of getting NPCM system manager reigster (GCR)
and still maintain the old mechanism as a fallback if getting
nuvoton,sys-mgr fails while working with the legacy devicetree
file.

Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Fix typos

The comments in this driver have a few typos. Let's fix them.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: tali.perry@nuvoton.com
Signed-off-by: Wolfram Sang <wsa@kernel.org>

Revert "Merge branch 'mctp-i2c-driver'"

This reverts commit 71812af7234f30362b43ccff33f93890ae4c0655, reversing
changes made to cc0be1ad686fb29a4d127948486f40b17fb34b50.

Wolfram Sang says:

Please revert. Besides the driver in net, it modifies the I2C core
code. This has not been acked by the I2C maintainer (in this case me).
So, please don't pull this in via the net tree. The question raised here
(extending SMBus calls to 255 byte) is complicated because we need ABI
backwards compatibility.

Link: https://lore.kernel.org/all/YZJ9H4eM%2FM7OXVN0@shikoro/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

i2c: npcm7xx: Allow 255 byte block SMBus transfers

255 byte support has been tested on a npcm750 board

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Reviewed-by: Tali Perry <tali.perry1@gmail.com>
Reviewed-by: Patrick Venture <venture@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

i2c: npcm7xx: Clear LAST bit after a failed transaction.

Due to a HW issue, in some scenarios the LAST bit might remain set.
This will cause an unexpected NACK after reading 16 bytes on the next
read.

Example: if user tries to read from a missing device, get a NACK,
then if the next command is a long read ( > 16 bytes),
the master will stop reading after 16 bytes.
To solve this, if a command fails, check if LAST bit is still
set. If it does, reset the module.

Fixes: 56a1485b102e (i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver)
Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Fix timeout calculation

timeout_usec value calculation was wrong, the calculated value
was in msec instead of usec.

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Reviewed-by: Avi Fishman <avifishman70@gmail.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Alex Qiu <xqiu@google.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: npcm_i2caddr[] can be static

Fixes: f54736925a4f ("i2c: npcm7xx: Add support for slave mode for Nuvoton")
Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Fix a couple of error codes in probe

The code here is accidentally returning IS_ERR() which is 1 but it
should be returning negative error codes with PTR_ERR().

Fixes: 56a1485b102e ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Remove unnecessary parentheses

Remove unnecessary parentheses around _bus_.

This issue was found with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Add support for slave mode for Nuvoton

Add support for slave mode for Nuvoton
NPCM BMC I2C controller driver.

Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver

Add Nuvoton NPCM BMC I2C controller driver.

Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>