I2C slave controller must be powered and active all the time when I2C
slave backend is registered in order to let master address and
communicate with us.

Now if the controller is runtime PM capable it will be suspended after
probe and cannot ever respond to the master or generate interrupts.

Fix this by resuming the controller when I2C slave backend is registered
and let it suspend after unregistering.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

I guess pm_runtime_put_noidle() call in i2c_dw_probe_slave() was copied
by accident from similar master mode adapter registration code. It is
unbalanced due missing pm_runtime_get_noresume() but harmless since it
doesn't decrease dev->power.usage_count below zero.

In theory we can hit similar needless runtime suspend/resume cycle
during slave mode adapter registration that was happening when
registering the master mode adapter. See commit cd998ded5c12 ("i2c:
designware: Prevent runtime suspend during adapter registration").

However, since we are slave, we can consider it as a wrong configuration
if we have other slaves attached under this adapter and can omit the
pm_runtime_get_noresume()/pm_runtime_put_noidle() calls for simplicity.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Before I skipped null checks when the master is in the STOP state; this
fixes that.

Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Fixes: f327c686d3ba ("i2c: aspeed: added driver for Aspeed I2C")

Use api pair of request_mem_region and release_mem_region
instead of release_resource.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev <vasilyev@ispras.ru>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

I2C drivers were required to have an I2C device ID table even if were for
devices that would only be registered using a specific firmware interface
(e.g: OF or ACPI).

But commit da10c06a044b ("i2c: Make I2C ID tables non-mandatory for DT'ed
devices") changed the I2C core to relax the requirement and allow drivers
to avoid defining this table.

Unfortunately it only took into account drivers for OF-only devices and
forgot about ACPI-only ones, and this was fixed by commit c64ffff7a9d1
("i2c: core: Allow empty id_table in ACPI case as well").

But the latter didn't update the original comment, so it doesn't reflect
what the code does now.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Code sets bit DW_IC_CON_SPEED_FAST (0x4) always when configuring the slave
mode. This results incorrect register value DW_IC_CON_SPEED_HIGH (0x6)
when OR'ed together with DW_IC_CON_SPEED_STD (0x2).

Remove this and let the code set the speed mode bits according to clock
frequency or default to fast mode.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

When i2c-designware is initialized in slave mode the
i2c-designware-slave.c: i2c_dw_irq_handler_slave() can hit a NULL
pointer dereference when I2C slave backend is not registered but code is
accessing the struct dw_i2c_dev.slave without testing is it NULL.

We might get spurious interrupts from other devices or from IRQ core
during unloading the driver when CONFIG_DEBUG_SHIRQ is set. Existing
check for enable and IRQ status is not enough since device can be power
gated and those bits may read 1.

Fix this by handling the interrupt only when also struct dw_i2c_dev.slave
is set.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

The commit 8503ff166504 ("i2c: designware: Avoid unnecessary resuming
during system suspend"), may suggest to the PM core to try out the so
called direct_complete path for system sleep. In this path, the PM core
treats a runtime suspended device as it's already in a proper low power
state for system sleep, which makes it skip calling the system sleep
callbacks for the device, except for the ->prepare() and the ->complete()
callbacks.

However, the PM core may unset the direct_complete flag for a parent
device, in case its child device are being system suspended before. In this
scenario, the PM core invokes the system sleep callbacks, no matter if the
device is runtime suspended or not.

Particularly in cases of an existing i2c slave device, the above path is
triggered, which breaks the assumption that the i2c device is always
runtime resumed whenever the dw_i2c_plat_suspend() is being called.

More precisely, dw_i2c_plat_suspend() calls clk_core_disable() and
clk_core_unprepare(), for an already disabled/unprepared clock, leading to
a splat in the log about clocks calls being wrongly balanced and breaking
system sleep.

To still allow the direct_complete path in cases when it's possible, but
also to keep the fix simple, let's runtime resume the i2c device in the
->suspend() callback, before continuing to put the device into low power
state.

Note, in cases when the i2c device is attached to the ACPI PM domain, this
problem doesn't occur, because ACPI's ->suspend() callback, assigned to
acpi_subsys_suspend(), already calls pm_runtime_resume() for the device.

It should also be noted that this change does not fix commit 8503ff166504
("i2c: designware: Avoid unnecessary resuming during system suspend").
Because for the non-ACPI case, the system sleep support was already broken
prior that point.

Cc: <stable@vger.kernel.org> # v4.4+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: John Stultz <john.stultz@linaro.org>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Allow i2c-versatile to be enabled for ARM MPS platforms.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>