The BYTECNT register holds the transfer size minus one.  Setting it to
the correct value removes the need for a dummy read/write at the end of
each transfer.  As zero-length transfers are not supported, do not
advertise I2C_FUNC_SMBUS_QUICK.

In other words, this patch makes the driver transfer the number of bytes
requested unless this is zero, which is not supported by the hardware
and is thus refused.
Signed-off-by: NMans Rullgard <mans@mansr.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Sigma Designs chips use a variant of this controller with the following
differences:

- The BUSY bit in the STATUS register is inverted
- Bit 8 of the CONFIG register must be set
- The controller can generate interrupts

This patch adds support for the first two of these.  It also calculates
and sets the correct clock divisor if a clk is provided.  The bus
frequency is optionally speficied in the device tree node.
Signed-off-by: NMans Rullgard <mans@mansr.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

There is code to divide by "bus_speed" some lines below.
To eliminate the possibility of division by zero, bail out if
"clock-frequency" is specified as zero.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

This input clock is used to generate the sampling clock for I2C bus.
If the clock rate is zero, there is something wrong with the clock
driver.  Bail out with the appropriate error message in such a case.
It would make it easier to find the root cause of failure.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

There is code to divide by "bus_speed" some lines below.
To eliminate the possibility of division by zero, bail out if
"clock-frequency" is specified as zero.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

This input clock is used to generate the sampling clock for I2C bus.
If the clock rate is zero, there is something wrong with the clock
driver.  Bail out with the appropriate error message in such a case.
It would make it easier to find the root cause of failure.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Switch to the new generic functions. Plain convert, no functionality
added yet.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

The probe function is a little bit messy, something here, something
there. Rework it so that there is some order: first init the private
structure, then the adapter, then do HW init. This also allows us to
remove the device argument of the clock calculation function, because it
now can be deduced from the private structure. Also, shorten some lines
where possible. This is a preparation for further refactoring.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Inspired from the i2c-rk3x driver (thanks guys!) but refactored and
extended. See built-in docs for further information.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Also, sort the properties alphabetically and make indentation
consistent. Wording largely taken from i2c-rk3x.txt, thanks guys!

Only "i2c-scl-internal-delay-ns" is new, the rest is used by two drivers
already and was documented in their driver binding documentation.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Add I2C slave provider using the generic slave interface.
Signed-off-by: NNiklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Allow the eg20t I2C driver to be built for MIPS platforms, in
preparation for use on the MIPS Boston board.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Set the I2C adapter devices of_node to that of the PCI device, such that
I2C clients may be instantiated via device tree.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

The hold field allows to configure the data hold time which can be set
with the help of the generic binding 'i2c-sda-hold-time-ns'. This
feature has been introduced with SAMA5D4 SoC family.
Signed-off-by: NLudovic Desroches <ludovic.desroches@atmel.com>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

smatch rightfully says:
drivers/i2c/busses/i2c-piix4.c:504 piix4_access warn: unused return: i = inb_p()
drivers/i2c/busses/i2c-piix4.c:537 piix4_access warn: unused return: i = inb_p()
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>
Tested-by: NChristian Fetzer <fetzer.ch@gmail.com>

For platform with auto restart support, between every transfer,
i2c controller will trigger an interrupt and SW need to handle
it to start new transfer. When doing write-then-read transfer,
instead of restart mechanism, using WRRD mode to have controller
send both transfer in one request to reduce latency.
Signed-off-by: NLiguo Zhang <liguo.zhang@mediatek.com>
Reviewed-by: NEddie Huang <eddie.huang@mediatek.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

The suspended flag is a flag holding the device's PM status.
The runtime framework does that for us.
Use pm_runtime_suspended call instead.
Signed-off-by: NShubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Currently the clocks are enabled at probe and disabled at remove.
Which keeps the clocks enabled even if no transaction is going on.
This patch enables the clocks at the start of transfer and disables
after it.

Also adapts to runtime pm.

converts dev pm to const to silence a checkpatch warning.
Signed-off-by: NShubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

This patch adds a i2c_check_quirks helper function to check the quirk flags
of an i2c adapter, in a similar way to i2c_check_functionality.
Signed-off-by: NNicola Corna <nicola@corna.info>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

As reported in the links given below. the BCM2835 has a hardware bug in
its i2c module which prevents a correct clock stretching. This patch
adds the I2C_AQ_NO_CLK_STRETCH quirk flag to i2c-bcm2835.
Signed-off-by: NNicola Corna <nicola@corna.info>
[wsa: put the links into the code as comments]
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Add I2C_AQ_NO_CLK_STRETCH to drivers/i2c/algos/i2c-algo-bit.c when getscl
is not available.
Signed-off-by: NNicola Corna <nicola@corna.info>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Add I2C_AQ_NO_CLK_STRETCH quirk flag, to be used when clock stretching is
not supported.
Signed-off-by: NNicola Corna <nicola@corna.info>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

All protected sections are only called from sleep-able context, so there is
no need to use a spinlock.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Reviewed-by: NShubhrajyoti Datta <shubhraj@xilinx.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

The simple_strtoul function is marked as obsolete.
This patch replace it by kstrtou8.
Reviewed-by: NJean Delvare <jdelvare@suse.de>
Tested-by: NJean Delvare <jdelvare@suse.de>
Signed-off-by: NLABBE Corentin <clabbe.montjoie@gmail.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

This patch adds support for port names for the SB800 chipset.
Since the chipset supports a multiplexed main SMBus controller, adding
the channel name to the adapter name is necessary to differentiate the
ports better (for example in sensors output).
Signed-off-by: NChristian Fetzer <fetzer.ch@gmail.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

The SB800 chipset supports a multiplexed main SMBus controller with
four ports. The multiplexed ports share the same SMBus address and
register set. The port is selected by bits 2:1 of the smb_en register
(0x2C).

Only one port can be active at any point in time therefore a mutex is
needed in order to synchronize access.

Additionally, the commit avoids requesting and releasing the SMBus base
address index region on every multiplexed transfer by moving the
request_region call into piix4_probe.

Tested on HP ProLiant MicroServer G7 N54L (where this patch adds
support to access sensor data from the w83795adg).

Cc: Thomas Brandon <tbrandonau@gmail.com>
Cc: Eddi De Pieri <eddi@depieri.net>
Signed-off-by: NChristian Fetzer <fetzer.ch@gmail.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

The SB800 chipset supports a multiplexed main SMBus controller with
four ports. Therefore the static variable piix4_main_adapter is
converted into a piix4_main_adapters array that can hold one
i2c_adapter for each multiplexed port.

The auxiliary adapter remains unchanged since it represents the second
(not multiplexed) SMBus controller on the SB800 chipset.
Signed-off-by: NChristian Fetzer <fetzer.ch@gmail.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Signed-off-by: NRyo Kataoka <ryo.kataoka.wt@renesas.com>
Signed-off-by: NHiromitsu Yamasaki <hiromitsu.yamasaki.ym@renesas.com>
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Update the comments to match current behaviour. Shorten some comments.
Update copyrights.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

If we don't clear START generation as soon as possible, it may cause
another message to be generated, e.g. when receiving NACK in address
phase. To keep the race window as small as possible, we clear it right
at the beginning of the interrupt. We don't need any checks since we
always want to stop START and STOP generation on the next occasion after
we started it.

This patch improves the situation but sadly does not completely fix it.
It is still to be researched if we can do better given this HW design.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Due to the HW design, master IRQs are timing critical, so give them
precedence over slave IRQ.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

The manual says (55.4.8.6) that HW does automatically send STOP after
NACK was received. My measuerments confirm that.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Setting up new messages was done in process context while handling a
message was in interrupt context. Because of the HW design, this IP core
is sensitive to timing, so the context switches were too expensive. Move
this setup to interrupt context as well.

In my test setup, this fixed the occasional 'data byte sent twice' issue
which a number of people have seen. It also fixes to send REP_START
after a read message which was wrongly send as a STOP + START sequence
before.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

We want to reuse this function later.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

After making sure to reinit the HW and clear interrupts in the timeout
case, we know that interrupts are always disabled in the sections
protected by the spinlock. Thus, we can simply remove it which is a
preparation for further refactoring. While here, rename the timeout
variable to time_left which is way more readable.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

We don't need to init HW before every transfer since we know the HW
state then. HW init at probe time is enough. While here, add setting the
clock register which belongs to init HW. Also, set MDBS bit since not
setting it is prohibited according to the manual.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

When calculating the bus speed, the clock should be on, of course. Most
bootloaders left them on, so this went unnoticed so far.

Move the ioremapping out of this clock-enabled-block and prepare for
adding hw initialization there, too.
Reported-by: NKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>