i2c_dw_xfer_msg is only called internally so it can be static. It
original was, before the driver split. No idea why it was changed at
that time.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Acked-by: NDirk Brandewie <dirk.brandewie@gmail.com>

This patch adds config I2C_DESIGNWARE_CORE in Kconfig, and let
I2C_DESIGNWARE_PLATFORM and I2C_DESIGNWARE_PCI select I2C_DESIGNWARE_CORE.

Because both I2C_DESIGNWARE_PLATFORM and I2C_DESIGNWARE_PCI can be built as
built-in or module, we also need to export the functions in i2c-designware-core.

This fixes below build error when CONFIG_I2C_DESIGNWARE_PLATFORM=y &&
CONFIG_I2C_DESIGNWARE_PCI=y:

  LD      drivers/i2c/busses/built-in.o
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_clear_int':
i2c-designware-core.c:(.text+0xa10): multiple definition of `i2c_dw_clear_int'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x928): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_init':
i2c-designware-core.c:(.text+0x178): multiple definition of `i2c_dw_init'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x90): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `dw_readl':
i2c-designware-core.c:(.text+0xe8): multiple definition of `dw_readl'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x0): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_isr':
i2c-designware-core.c:(.text+0x724): multiple definition of `i2c_dw_isr'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x63c): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_xfer':
i2c-designware-core.c:(.text+0x4b0): multiple definition of `i2c_dw_xfer'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x3c8): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_is_enabled':
i2c-designware-core.c:(.text+0x9d4): multiple definition of `i2c_dw_is_enabled'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x8ec): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `dw_writel':
i2c-designware-core.c:(.text+0x124): multiple definition of `dw_writel'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x3c): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_xfer_msg':
i2c-designware-core.c:(.text+0x2e8): multiple definition of `i2c_dw_xfer_msg'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x200): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_enable':
i2c-designware-core.c:(.text+0x9c8): multiple definition of `i2c_dw_enable'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x8e0): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_read_comp_param':
i2c-designware-core.c:(.text+0xa24): multiple definition of `i2c_dw_read_comp_param'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x93c): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_disable':
i2c-designware-core.c:(.text+0x9dc): multiple definition of `i2c_dw_disable'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x8f4): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_func':
i2c-designware-core.c:(.text+0x710): multiple definition of `i2c_dw_func'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x628): first defined here
drivers/i2c/busses/i2c-designware-pci.o: In function `i2c_dw_disable_int':
i2c-designware-core.c:(.text+0xa18): multiple definition of `i2c_dw_disable_int'
drivers/i2c/busses/i2c-designware-platform.o:i2c-designware-platdrv.c:(.text+0x930): first defined here
make[3]: *** [drivers/i2c/busses/built-in.o] Error 1
make[2]: *** [drivers/i2c/busses] Error 2
make[1]: *** [drivers/i2c] Error 2
make: *** [drivers] Error 2
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Tested-by: NJiri Slaby <jslaby@suse.cz>
Cc: stable@vger.kernel.org [3.2+]

The STM SPEAr platform can only access the i2c controller register
via 16bit read/write functions. This patch adds support to
automatically detect this 16bit access mode.
Signed-off-by: NStefan Roese <sr@denx.de>
Signed-off-by: NWolfram Sang <w.sang@pengutronix.de>

Add runtime power management to the PCI driver.
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Move all register manipulation code into the core, also move register
offset definitions to i2c-designware-core.c since the bus specific
portions of the driver no longer need/use them.
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Add check to make sure that the core is enabled and has outstanding
interrupts. The activity bit is masked due to the fact that it will
stay active even after the controller has been disabled until the
contoller internal state machines have settled.
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

With multiple I2C adapters possible in the system each running at
(possibly) different speeds we need to move the controller
configuration bit field to the adapter.
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

The functionality of the adapter depends on the configuration of the
IP block at silicon compile time and is adapter specific.
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

The clock frequecy supplied to the IP core is specific to a single
instance of the driver.  This patch makes it possible to have multiple
Designware I2C cores in the system possibly running at different core
frequencies.
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

This patch splits i2c-designware.c into three pieces:
     i2c-designware-core.c, contains the code that interacts directly
     with the core.

     i2c-designware-platdrv.c, contains the code specific to the
     platform driver using the core.

     i2c-designware-core.h contains the definitions and declareations
     shared by i2c-designware-core.c and i2c-designware-platdrv.c.

This patch is the first in a set to allow multiple instances of the
designware I2C core in the system.
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Move checking IP core version to i2c_dw_init() in preparation for
splitting i2c-designware.c into core and bus specific portions.
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Allows CPUs of a given endianness to access a dw controller of a different
endianness. Endianncess difference is detected at run time through the dw
component type register.
Signed-off-by: NJean-Hugues Deschenes <jean-hugues.deschenes@octasic.com>
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Designware component type register is checked before attaching to the device.
Signed-off-by: NJean-Hugues Deschenes <jean-hugues.deschenes@octasic.com>
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Use local versions of readl & writel, so per-access manipulations may be performed
Signed-off-by: NJean-Hugues Deschenes <jean-hugues.deschenes@octasic.com>
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Since commit [c58543c8: genirq: Run irq handlers with interrupts disabled],
We run all interrupt handlers with interrupts disabled
and we even check and yell when an interrupt handler
returns with interrupts enabled (see commit [b738a50a:
genirq: Warn when handler enables interrupts]).

So now this flag is a NOOP and can be removed.
Signed-off-by: NYong Zhang <yong.zhang0@gmail.com>
Acked-by: NWolfram Sang <w.sang@pengutronix.de>
Acked-by: NLinus Walleij <linus.walleij@linaro.org>
Acked-by: NBarry Song <21cnbao@gmail.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

This is a resend from the original, changing the title from PATCH to
RFC(since this is a review for commit, and I should have put that the first go around).
and also removing some of the commit's with ia64 and bash since it is significant.
let me know if I might have missed anything etc..
Signed-off-by: NJustin P. Mattock <justinmattock@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

Rename for_each_bit to for_each_set_bit in the kernel source tree.  To
permit for_each_clear_bit(), should that ever be added.

The patch includes a macro to map the old for_each_bit() onto the new
for_each_set_bit().  This is a (very) temporary thing to ease the migration.

[akpm@linux-foundation.org: add temporary for_each_bit()]
Suggested-by: NAlexey Dobriyan <adobriyan@gmail.com>
Suggested-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Artem Bityutskiy <dedekind@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In the case of no-ACKs, we don't want to see dev_err() messages in the
console, because some utilities like i2c-tools are capable of printing
decorated console output.  This patch will ease such situations.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

* ABRT_MASTER_DIS: Fix a typo.

* i2c_dw_handle_tx_abort: Return an appropriate error number
  depending on abort_source.

* i2c_dw_xfer: Add a missing abort_source initialization.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Suppose TX_ABRT occurs in the middle of processing i2c_msg msgs[], and
a STOP condition has already been generated on the bus.  In this case,
subsequent i2c_dw_xfer_msg() might initiate a new and unnecessary I2C
transaction, which we'd have to avoid.

Furthermore, anytime TX_ABRT is set, the contents of tx/rx buffers are
flushed, so we don't have to process RX_FULL and TX_EMPTY.

Disable interrupts, and skip them.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Current error handling procedures are not good in two respects:

* Forgot to mark dev->cmd_complete as "completed" on errors

  Once an I2C transaction is initiated, wait_for_completion_
  interruptible_timeout() waits for dev->cmd_complete to be completed.
  We have to take care of it whenever an error is detected, otherwise
  we will have a needless HZ timeout.

* Forgot to disable interrupts

  In the previous patch, interrupt mask operations have been changed.
  We don't disable interrupts at the end of the interrupt handler any
  more, and try to keep RX_FULL (and TX_EMPTY if required) enabled
  during the transaction so that we can send longer data than the size
  of Tx/Rx FIFO.

  If an error is detected, we need to disable interrupts before
  quitting current transaction.

We can work around above points using dev->msg_err effectively.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Currently we disable TX_EMPTY interrupt when buf_len is zero, but this
is wrong.  (buf_len == 0) means that all transmit data in the current
i2c_msg message has been sent out, but that doesn't necessarily mean
all i2c_msg messages have been processed.

TX_EMPTY interrupt is used as the driving force of DW I2C transactions,
so we need to keep it enabled as long as i2c_msg messages are available.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Currently we process the first i2c_dw_xfer_msg() in i2c_dw_xfer(),
but in this case there is a possibility to be interrupted by certain
interrupts.  As described before in this patchset, we need to keep
providing new transmit data within a given time period, otherwise Tx
FIFO underrun takes place and STOP condition will be generated on the
bus, even if we have more bytes to be written.

In order to exclude all such possibilities, change TX_EMPTY interrupt
usage as below:

* DW_IC_INTR_DEFAULT_MASK: Define a default interrupt mask set, and
  put TX_EMPTY there.

* i2c_dw_xfer_init: Enable DW_IC_INTR_DEFAULT_MASK prior to initiating
  a new I2C transaction.  The first TX_EMPTY will be triggered shortly.
  With the help of it, we can make the first call to i2c_dw_xfer_msg()
  in the interrupt handler.

* i2c_dw_xfer_msg: Fixup intr_mask operation accordingly.  Make sure
  that TX_EMPTY operations need to be reversed.

* request_irq: Set IRQF_DISABLED so that we could load transmit data
  into Tx FIFO without being distracted by other interrupts.

* Remove i2c_dw_xfer_msg() in i2c_dw_xfer().
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

I2c_dw_xfer_msg() also has the same target address inconsistency check,
and furthermore it checks across all i2c_msg messages, while
i2c_dw_read() walks through i2c_msg messages only with_ I2C_M_RD flag.
That is, target address check in i2c_dw_read() is redundant and useless.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Set proper I2C_FUNC_SMBUS_* bits so that the driver could be used with
some utilities requiring SMBus functionalities, such as i2c-tools.

Note that DW I2C core doesn't support I2C_FUNC_SMBUS_QUICK, as it's not
capable of zero-length data transactions.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

As the driver and hardware always process the given data in parallel,
then it would be better to initialize tx_limit, rx_limit and rx_valid
variables just prior to being used.

This will help us to send / receive as much data as possible.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

While we have a local variable "buf_len" for dev->tx_buf_len, we don't
have such local variable for dev->tx_buf pointer.  While "buf_len" is
restored at first then updated when we start processing a new i2c_msg
(determined by STATUS_WRITE_IN_PROGRESS flag), ->tx_buf is different.

Such inconsistency makes the code slightly hard to follow.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

We have some steps at the top of i2c_dw_xfer_msg() to set up a slave
address and enable DW I2C core.  And it's executed only when we don't
have STATUS_WRITE_IN_PROGRESS.

But we need to make sure that STATUS_WRITE_IN_PROGRESS only indicates
that we have a pending i2c_msg to process.  In other words, even if
STATUS_WRITE_IN_PROGRESS is not set, that doesn't mean we're at initial
state in the I2C transaction.

Since i2c_dw_xfer_msg() will be invoked again and again during a
transaction, those init steps have a possibility to be re-processed
needlessly.  For example, this issue easily takes place when processing
a combined transaction with a certain condition (the number of tx bytes
in the first i2c_msg, equals to the Tx FIFO depth).

Consequently we should not use STATUS_WRITE_IN_PROGRESS to determine
where we're at in an I2C transaction.  It would be better to separate
those initialization steps from i2c_dw_xfer_msg().
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Enable RX_FULL interrupt mask by default, and hook it in the interrupt
handler.  If requested amount of rx data (defined by IC_RX_TL) is not
available, we don't have to process i2c_dw_read().
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

As a hardware feature, DW I2C core generates a STOP condition whenever
the Tx FIFO becomes empty (strictly speaking, whenever the last byte in
the Tx FIFO is sent out), even if we have more bytes to be written.

In other words, we must never make "Tx FIFO underrun" happen during
a transaction, except for the last byte.  For the safety's sake, we'd
make TX_EMPTY interrupt get triggered every time one byte is processed.

The Rx FIFO threshold needs to be set as well.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Symptom:
--------
When we're going to send/receive the longer size of data than the Tx
FIFO length, the I2C transaction will be divided into several separated
transactions, limited by the Tx FIFO length.

Details:
--------
As a hardware feature, DW I2C core generates a STOP condition whenever
the Tx FIFO becomes empty (strictly speaking, whenever the last byte in
the Tx FIFO is sent out), even if we have more bytes to be written.
Then, once a new transmit data is written to the Tx FIFO, DW I2C core
will initiate a new transaction, which leads to another START condition.

This explains how the transaction in question goes, and implies that
current tasklet-based dw_i2c_pump_msg() strategy couldn't meet the
timing constraint required for avoiding Tx FIFO underrun.

To avoid this scenario, we must keep providing new transmit data within
a given time period.  In case of Fast-mode + 32-byte Tx FIFO, for
instance, it takes about 22.5[us] to process single byte, and 720[us] in
total.

This patch removes the existing tasklet-based "pump" system, and move
its jobs into the interrupt handler.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

In case a work-in-progress i2c_msg has more bytes to be written, we
need to set STATUS_WRITE_IN_PROGRESS and exit from the msg_write_idx-
searching loop.  Otherwise, we will overtake the current msg_write_idx
without waiting for its transmission to be processed.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

* Calculate with accurate conditional expressions from DW manuals.
* Round ic_clk by adding 0.5 as it's important at high ic_clk rate.
* Take into account "tHD;STA" issue for _HCNT calculation.
* Take into account "tf" for _LCNT calculation.
* Add "cond" and "offset" fot further correction requirements.

For _HCNT calculation, there's one issue needs to be carefully
considered; DesignWare I2C core doesn't seem to have solid strategy
to meet the tHD;STA timing spec.  If you configure _HCNT based on the
tHIGH timing spec, it easily results in violation of the tHD;STA spec.

After many trials, we came to the conclusion that the tHD;STA period
is proportional to (_HCNT + 3).  For the safety's sake, this should be
selected by default.

As for _LCNT calculation, DW I2C core has one characteristic behavior;
he starts counting the SCL CNTs for the LOW period of the SCL clock
(tLOW) as soon as it pulls the SCL line.  At that time, he doesn't take
into account the fall time of SCL signal (tf), IOW, he starts counting
CNTs without confirming the SCL input voltage has dropped to below VIL.

This characteristics becomes a problem on some platforms where tf is
considerably long, and results in violation of the tLOW timing spec.

To make the driver configurable as much as possible for various cases,
we'd have separated arguments "tf" and "offset", and for safety default
values should be 0.3 us and 0, respectively.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

We couldn't know the original intent for this variable, but at this
point it's useless.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

We don't have to use "struct i2c_adapter" pointer here.
Let's use a local "struct dw_i2c_dev" pointer, instead.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

We don't have to use "struct i2c_adapter" pointer here.
Let's use a local "struct dw_i2c_dev" pointer, instead.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>

Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NBen Dooks <ben-linux@fluff.org>