The Lenovo Miix2 8 DSDT contains an i2c clk / bus speed of 1700000 Hz
for one if its devices, which is not supported.

This is the second DSDT to show up with an unsupported clk in a short
time, remove the hardcoded fix for DSDTs with a 1 MiHz clock and simply
always round down the clk to the nearest supported value.

Reported-by: russianneuromancer@ya.ru
Fixes: 682c6c2188 ("i2c: designware: Some broken DSTDs use 1MiHz ...")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Compare the number of bytes actually seen on the wire to the byte
count field returned by the slave device.

Previously we just overwrote the byte count returned by the slave
with the real byte count and let the caller figure out if the
message was sane.

Signed-off-by: Stephen Douthit <stephend@adiengineering.com>
Tested-by: Dan Priamo <danp@adiengineering.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org

According to Table 15-14 of the C2000 EDS (Intel doc #510524) the
rx data pointed to by the descriptor dptr contains the byte count.

desc->rxbytes reports all bytes read on the wire, including the
"byte count" byte.  So if a device sends 4 bytes in response to a
block read, on the wire and in the DMA buffer we see:

count data1 data2 data3 data4
 0x04  0xde  0xad  0xbe  0xef

That's what we want to return in data->block to the next level.

Instead we were actually prefixing that with desc->rxbytes:

bad
count count data1 data2 data3 data4
 0x05  0x04  0xde  0xad  0xbe  0xef

This was discovered while developing a BMC solution relying on the
ipmi_ssif.c driver which was trying to interpret the bogus length
field as part of the IPMI response.

Signed-off-by: Stephen Douthit <stephend@adiengineering.com>
Tested-by: Dan Priamo <danp@adiengineering.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org

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>