V3U creates spurious interrupts which we need to handle. This costs time
until BUS_PHASE_DATA can be activated which is problematic for Gen2 SoCs
and earlier. Because of this we introduce two interrupt handlers here
which will call a generic main irq function once the timing critical
stuff is done.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Ensure this irq runs as fast as possible.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
'flags' and 'io' are needed first, so they should be at the beginning of
the private struct.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
To avoid the HW race condition on R-Car Gen2 and earlier, we need to
write to ICMCR as soon as possible in the interrupt handler. We can
improve this by writing a static value instead of masking out bits.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Pull i2c updates from Wolfram Sang:
- if a host can be a client, too, the I2C core can now use it to
emulate SMBus HostNotify support (STM32 and R-Car added this so far)
- also for client mode, a testunit has been added. It can create rare
situations on the bus, so host controllers can be tested
- a binding has been added to mark the bus as "single-master". This
allows for better timeout detections
- new driver for Mellanox Bluefield
- massive refactoring of the Tegra driver
- EEPROMs recognized by the at24 driver can now have custom names
- rest is driver updates
* 'i2c/for-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (80 commits)
Documentation: i2c: add testunit docs to index
i2c: tegra: Improve driver module description
i2c: tegra: Clean up whitespaces, newlines and indentation
i2c: tegra: Clean up and improve comments
i2c: tegra: Clean up printk messages
i2c: tegra: Clean up variable names
i2c: tegra: Improve formatting of variables
i2c: tegra: Check errors for both positive and negative values
i2c: tegra: Factor out hardware initialization into separate function
i2c: tegra: Factor out register polling into separate function
i2c: tegra: Factor out packet header setup from tegra_i2c_xfer_msg()
i2c: tegra: Factor out error recovery from tegra_i2c_xfer_msg()
i2c: tegra: Rename wait/poll functions
i2c: tegra: Remove "dma" variable from tegra_i2c_xfer_msg()
i2c: tegra: Remove redundant check in tegra_i2c_issue_bus_clear()
i2c: tegra: Remove likely/unlikely from the code
i2c: tegra: Remove outdated barrier()
i2c: tegra: Clean up variable types
i2c: tegra: Reorder location of functions in the code
i2c: tegra: Clean up probe function
...
The I2C core can now utilize a slave interface to handle SMBus
HostNotify events. Enable it in this driver.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
LOOP_TIMEOUT was only used back then because we didn't want to introduce
another constant. The timeout value can easily be a magnitude shorter
because the typical range is 3us - 8us. Refactor the code to use the
poll_timeout helper, use a specific timeout value and get rid of the
ugly LOOP_TIMEOUT constant.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
I2C doesn't define a timeout for bus busy, so an arbitrary value like
LOOP_TIMEOUT is not a good idea. Let's use the timeout value in struct
adapter which is meant for such cases and is user-configurable (via
IOCTL). To reduce the load, wait 10us instead of 1us which is good
enough for the slow frequencies used by I2C. Finally, use the
poll_timeout helper instead of open coding it.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Currently, a NACK in slave mode is set/cleared when SCL is held low by
the IP core right before the bit is about to be pushed out. This is too
late for clearing and then a NACK from the previous byte is still used
for the current one. Now, let's clear the NACK right after we detected
the STOP condition following the NACK.
Fixes: de20d1857d ("i2c: rcar: add slave support")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Due to the lockless design of the driver, it is theoretically possible
to access a NULL pointer, if a slave interrupt was running while we were
unregistering the slave. To make this rock solid, disable the interrupt
for a short time while we are clearing the interrupt_enable register.
This patch is purely based on code inspection. The OOPS is super-hard to
trigger because clearing SAR (the address) makes interrupts even more
unlikely to happen as well. While here, reinit SCR to SDBS because this
bit should always be set according to documentation. There is no effect,
though, because the interface is disabled.
Fixes: 7b814d852a ("i2c: rcar: avoid race when unregistering slave client")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
When the SSR interrupt is activated, it will detect every STOP condition
on the bus, not only the ones after we have been addressed. So, enable
this interrupt only after we have been addressed, and disable it
otherwise.
Fixes: de20d1857d ("i2c: rcar: add slave support")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
On R-Car Gen2, we get a timeout when reading from the address set in
ICSAR, even though the slave interface is disabled. Clearing it fixes
this situation. Note that Gen3 is not affected.
To reproduce: bind and undbind an I2C slave on some bus, run
'i2cdetect' on that bus.
Fixes: de20d1857d ("i2c: rcar: add slave support")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
use devm_platform_get_and_ioremap_resource() to simplify code, which
contains platform_get_resource() and devm_ioremap_resource(), it also
get the resource for use by the following code.
Signed-off-by: Dejin Zheng <zhengdejin5@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
The pointer is not really needed anymore since we have the timings
struct available in the function itself now. Remove the pointer and
access the struct directly.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Move i2c_parse_fw_timings() to rcar_i2c_clock_calculate() to consolidate
timings calls in one place.
While here, replace hard coded values with standard bus frequency definitions.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Some drivers may allow to override properties with 0 value when defaults
are not in use, thus, replace memset() with corresponding per property
update.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Variable "rate" already contains the current clock rate, so use that
rather than calling clk_get_rate() again.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Luca Ceresoli <luca@lucaceresoli.net>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
After we disabled interrupts, there might still be an active one
running. Sync before clearing the pointer to the slave device.
Fixes: de20d1857d ("i2c: rcar: add slave support")
Reported-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
When sending with DMA, the driver transfers the first byte with PIO (as
documented). However, it started DMA right after the first byte was
written. This worked, but was not according to the datasheet which
suggests to wait until data register was empty again. Implement this.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
We will need to know if enabling DMA was successful in a later patch.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Use a macro for the hardcoded value and apply a build check. If it is
not met, the driver logic will not work anymore.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
To make sure people can understand the lockless design of this driver
without the need to dive into git history, add a comment giving an
overview of the situation.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This patch fixes the problem that an interrupt may set up a new I2C
message and the DMA callback overwrites this setup.
By disabling the DMA Enable Register(ICDMAER), rcar_i2c_dma_unmap()
enables interrupts for register settings (such as Master Control
Register(ICMCR)) and advances the I2C transfer sequence.
If an interrupt occurs immediately after ICDMAER is disabled, the
callback handler later continues and overwrites the previous settings
from the interrupt. So, disable ICDMAER at the end of the callback to
ensure other interrupts are masked until then.
Note that this driver needs to work lock-free because there are IP cores
with a HW race condition which prevent us from using a spinlock in the
interrupt handler.
Reproduction test:
1. Add a delay after disabling ICDMAER. (It is expected to generate an
interrupt of rcar_i2c_irq())
void rcar_i2c_dma_unmap(struct rcar_i2c_priv *priv)
{
...
rcar_i2c_write(priv, ICDMAER, 0);
usleep_range(500, 800)
...
priv->dma_direction = DMA_NONE;
}
2. Execute DMA transfers
$ i2ctransfer -y 4 w9@0x6a 1 1+ r16
3. A log message of BUG_ON() will be displayed.
Fixes: 73e8b05283 ("i2c: rcar: add DMA support")
Signed-off-by: Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[wsa: updated test case to be more reliable, added note to comment]
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
The latest documentation made it clear that we need to initialize the
TCYC value independently of DMA. The old code used TCYC06 (wrongly) for
non-DMA transfers. The new code sets TCYC up independently from DMA.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Update copyright years and remove a comment which grew incorrect and
useless over time.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
When doing s2idle/s2ram on Salvator-X(S):
WARNING: CPU: 2 PID: 971 at drivers/i2c/i2c-core-base.c:1869 __i2c_transfer+0x608/0x910
[...]
Call trace:
__i2c_transfer+0x608/0x910
i2c_smbus_xfer_emulated+0x158/0x5b0
__i2c_smbus_xfer+0x17c/0x818
i2c_smbus_xfer+0x64/0x98
i2c_smbus_read_byte_data+0x40/0x70
cs2000_bset.isra.1+0x2c/0x68
__cs2000_set_rate.constprop.7+0x80/0x148
cs2000_resume+0x18/0x20
dpm_run_callback+0x74/0x330
device_resume_early+0xd4/0x120
dpm_resume_early+0x158/0x4f8
suspend_devices_and_enter+0x36c/0xd98
[...]
On second resume, the sound driver fails with:
cs2000-cp 2-004f: pll lock failed
rcar_sound ec500000.sound: can't use clk 1
As the CS2000 clock driver needs to send I2C messages during suspend,
the I2C controller driver should be suspended later, and resumed
earlier. Fix this by using the noirq sleep ops instead of the normal
sleep ops, which are called after the late sleep ops, as used by the
CS2000 clock driver.
Fixes: 18569fa89a ("i2c: rcar: add suspend/resume support")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Because the adapter will be set up before every transaction anyhow, we
just need to mark it as suspended to the I2C core.
Signed-off-by: Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
We should check the bus state before reinitializing the IP core.
Otherwise, the internal bus busy state which also tracks multi-master
activity is lost.
Credits go to the Renesas BSP team for suggesting this change.
Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Fixes: ae481cc139 ("i2c: rcar: fix resume by always initializing registers before transfer")
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
DMA needs to be cleaned up not only on timeout, but on all errors where
it has been setup before.
Fixes: 73e8b05283 ("i2c: rcar: add DMA support")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
When doing a REP_START after a read message, the driver used to trigger
a STOP first which would then be overwritten by REP_START. This was the
only stable method found when doing the last refactoring. However, this
was not in accordance with the documentation.
After research from our BSP team and myself, we now can implement a
version which works and is according to the documentation. The new
approach ensures the ICMCR register is only changed when really needed.
Tested on a R-Car Gen2 (H2) and Gen3 with DMA (M3N).
Signed-off-by: Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Use BIT macro to avoid shift-31-problem, indent a little more and use
GENMASK to make it easier to add new flags.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
And don't reimplement in the driver.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
On Gen3, we can only do RXDMA once per transfer reliably. For that, we
must reset the device, then we can have RXDMA once. This patch
implements this. When there is no reset controller or the reset fails,
RXDMA will be blocked completely. Otherwise, it will be disabled after
the first RXDMA transfer. Based on a commit from the BSP by Hiromitsu
Yamasaki, yet completely refactored to handle multiple read messages
within one transfer.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
To break out of recovery as early as possible, feed back the bus_free
logic state.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Because it looks neater.
For diolan, this allows factoring out some code that is now common
between if and else.
For eg20t, pch_i2c_writebytes is always called with a write in
msgs->flags, and pch_i2c_readbytes with a read.
For imx, i2c_imx_dma_write and i2c_imx_write are always called with a
write in msgs->flags, and i2c_imx_read with a read.
For qup, qup_i2c_write_tx_fifo_v1 is always called with a write in
qup->msg->flags.
For stu300, also restructure debug output for resends, since that
code as a result is only handling debug output.
Reviewed-by: Guenter Roeck <linux@roeck-us.net> [diolan]
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> [efm32 and imx]
Acked-by: Linus Walleij <linus.walleij@linaro.org> [stu300]
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Give a clear testcase for people wishing to change this code. It is also
a reminder for me if people ask about it.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
According to documentation, Bit 7 of ICMSR is unused and 0 should be
written to it. Fix the mask accordingly.
Signed-off-by: Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@renesas.com>
[wsa: edited commit message]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Nothing big, but they get annoying after a while ;)
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
We can force levels of SCL and SDA, so we can use that for bus recovery.
Note that we cannot read SDA back, because we will only get the internal
state of the bus free detection.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This HW is prone to races, so it needs to setup new messages in irq
context. That means we can't alloc bounce buffers if a message buffer is
not DMA safe. So, in that case, simply fall back to PIO.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Pull i2c updates from Wolfram Sang:
"This pull request contains:
- i2c core reorganization. One source file became too monolithic. It
is now split up, yet we still have the same named object as the
final output. This should ease maintenance.
- new drivers: ZTE ZX2967 family, ASPEED 24XX/25XX
- designware driver gained slave mode support
- xgene-slimpro driver gained ACPI support
- bigger overhaul for pca-platform driver
- the algo-bit module now supports messages with enforced STOP
- slightly bigger than usual set of driver updates and improvements
and with much appreciated quality assurance from Andy Shevchenko"
* 'i2c/for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (51 commits)
i2c: Provide a stub for i2c_detect_slave_mode()
i2c: designware: Let slave adapter support be optional
i2c: designware: Make HW init functions static
i2c: designware: fix spelling mistakes
i2c: pca-platform: propagate error from i2c_pca_add_numbered_bus
i2c: pca-platform: correctly set algo_data.reset_chip
i2c: acpi: Do not create i2c-clients for LNXVIDEO ACPI devices
i2c: designware: enable SLAVE in platform module
i2c: designware: add SLAVE mode functions
i2c: zx2967: drop COMPILE_TEST dependency
i2c: zx2967: always use the same device when printing errors
i2c: pca-platform: use dev_warn/dev_info instead of printk
i2c: pca-platform: use device managed allocations
i2c: pca-platform: add devicetree awareness
i2c: pca-platform: switch to struct gpio_desc
dt-bindings: add bindings for i2c-pca-platform
i2c: cadance: fix ctrl/addr reg write order
i2c: zx2967: add i2c controller driver for ZTE's zx2967 family
dt: bindings: add documentation for zx2967 family i2c controller
i2c: algo-bit: add support for I2C_M_STOP
...
Add recent findings (IGNORE_NAK) and document in a bit more detail why
the feature is not possible.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
It is 'R-Car', not 'RCar'. No code or binding changes, only descriptive text.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Because we need to transfer some bytes with PIO, the msg length is not
the length of the DMA buffer. Use the correct value which we used when
doing the mapping.
Fixes: 73e8b05283 ("i2c: rcar: add DMA support")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
PM handling is correct but might be a bit subtle. Add some comments for
clarification.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Resume failed because of uninitialized registers. Instead of adding a
resume callback, we simply initialize registers before every transfer.
This lightweight change is more robust and will keep us safe if we ever
need support for power domains or dynamic frequency changes.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
In the case of Renesas R-Car hardware we know that there are generations of
SoCs, e.g. Gen 2 and Gen 3. But beyond that it's not clear what the
relationship between IP blocks might be. For example, I believe that
r8a7790 is older than r8a7791 but that doesn't imply that the latter is a
descendant of the former or vice versa.
We can, however, by examining the documentation and behaviour of the
hardware at run-time observe that the current driver implementation appears
to be compatible with the IP blocks on SoCs within a given generation.
For the above reasons and convenience when enabling new SoCs a
per-generation fallback compatibility string scheme is being adopted for
drivers for Renesas SoCs.
Also:
* Deprecate renesas,i2c-rcar. It seems poorly named as it is only
compatible with R-Car Gen 1. It also appears unused in mainline.
* Add some text to describe per-SoC bindings
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
