SY24655: Support for current and voltage detection as well as
power calculation.
Signed-off-by: Wenliang Yan <wenliang202407@163.com>
Message-ID: <20241106150547.2538-1-wenliang202407@163.com>
[groeck: Changed order of compatible entries;
dropped spurious extra return statement in is_visible();
fixed code problems]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
INA260 is similar to other chips of the series, except it has an internal
shunt resistor. The calibration register is therefore not present. Also,
the current register address was changed, though that does not matter for
the driver since the shunt voltage register (which is now the current
register) value is already used to read the current.
Cc: Loic Guegan <loic.guegan@mailbox.org>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Add configuration flag indicating if the chip supports alerts and limits
to prepare for adding INA260 support.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Since the shunt voltage and the current register report the same values
when the chip is calibrated, we can calculate the current directly
from the shunt voltage without relying on chip calibration.
With this change, the current register is no longer accessed. Its
register address is only used to indicate if reading or writing
current or shunt voltage is desired when accessing registers.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
While the chips supported by this driver do not directly support current
limits, they do support setting shunt voltage limits. The shunt voltage
divided by the shunt resistor value is the current. On top of that,
calibration values are set such that in the shunt voltage register and
the current register report the same values. That means we can report and
configure current limits based on shunt voltage limits, and we can do so
with much better accuracy than by setting shunt voltage limits.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Pass the to-be-limited register to alert functions and use it to determine
conversion from limit to register value.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Convert driver to use the with_info hardware monitoring API
to reduce its dependency on sysfs attribute functions.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
ina2xx_get_value() will be needed earlier in the next patch, so move it.
No functional change.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Alerts should only be cleared after reported, not immediately after the
alert condition has been cleared. Set the latch enable bit to keep alerts
latched until the alert register has been read from the chip.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Move all chip initialization code into a single function.
No functional change.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Module tests show various overflow problems when writing limits
and other attributes.
in0_crit: Suspected overflow: [max=82, read 0, written 2147483648]
in0_lcrit: Suspected overflow: [max=82, read 0, written 2147483648]
in1_crit: Suspected overflow: [max=40959, read 0, written 2147483647]
in1_lcrit: Suspected overflow: [max=40959, read 0, written 2147483647]
power1_crit: Suspected overflow: [max=134218750, read 0, written 2147483648]
update_interval: Suspected overflow: [max=2253, read 2, written 2147483647]
Implement missing clamping on attribute write operations to avoid those
problems.
While at it, check in the probe function if the shunt resistor value
passed from devicetree is valid, and bail out if it isn't. Also limit
mutex use to the code calling ina2xx_set_shunt() since it isn't needed
when called from the probe function.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
If it is necessary to re-initialize the chip, for example because
it has been power cycled, use regmap functions to update register
contents. This ensures that all registers, including the configuration
register and alert registers, are updated to previously configured
values without having to locally cache everything.
For this to work, volatile registers have to be marked as volatile.
Also, the cache needs to be bypassed when reading the calibration
and mask_enable registers. While the calibration register is not
volatile, it will be reset to 0 if the chip has been power cycled.
Most of the bits in the mask_enable register are configuration bits,
except for bit 4 which reports if an alert has been observed.
Both registers need to be marked as non-volatile to be updated
after a power cycle, but it is necessary to bypass the cache when
reading them to detect if the chip has been power cycled and to
read the alert status.
The chip does not support register auto-increments. It is therefore
necessary to configure regmap to use single register read/write
operations. Otherwise regmap tries to write all registers in a single
operation when synchronizing register contents with the hardware,
and the synchronization fails.
Another necessary change is to declare ina226_alert_to_reg() as u16.
So far it returned an s16 which is sign extended to a large negative
value which is then sent to regmap as unsigned int, causing an -EINVAL
error return.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
If regmap is accessed more than once in a function, declare and used
local regmap variable.
While at it, drop low value debug messages.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Recent versions of checkpatch complain that struct regmap_config
should be declared as const.
WARNING: struct regmap_config should normally be const
Doing so reveals a potential problem in the driver: If both supported
chips are present in a single system, the maximum number of registers
may race when devices are instantiated since max_registers is updated
in the probe function. Solve the problem by setting .max_registers to the
maximum register address of all supported chips. This does not make a
practical difference while fixing the potential race condition and reducing
code complexity.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Use bit operations where possible to make the code more generic and to
align it with other drivers. Also use compile time conversion from bit
to mask to reduce runtime overhead.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
There are no in-tree users of ina2xx platform data. Drop it and support
device properties instead as alternative if it should ever be needed.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Simplify driver maintenance by reordering include files to alphabetic
order.
Whule at it, drop unnecessary / unused jiffies.h.
No functional change.
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The INA230 has an Alert pin which is asserted when the alert
function selected in the Mask/Enable register exceeds the
value programmed into the Alert Limit register. Assertion is based
on the Alert Polarity Bit (APOL, bit 1 of the Mask/Enable register).
It is default set to value 0 i.e Normal (active-low open collector).
However, hardware can be designed in such a way that expects Alert pin
to become active high if a user-defined threshold in Alert limit
register has been exceeded. This patch adds a way to pass alert polarity
value to the driver via device tree.
Signed-off-by: Amna Waseem <Amna.Waseem@axis.com>
Link: https://lore.kernel.org/r/20240611-apol-ina2xx-fix-v4-2-8df1d2282fc5@axis.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The function i2c_match_id() is used to fetch the matching ID from
the i2c_device_id table. This is often used to then retrieve the
matching driver_data. This can be done in one step with the helper
i2c_get_match_data().
This helper has a couple other benefits:
* It doesn't need the i2c_device_id passed in so we do not need
to have that forward declared, allowing us to remove those or
move the i2c_device_id table down to its more natural spot
with the other module info.
* It also checks for device match data, which allows for OF and
ACPI based probing. That means we do not have to manually check
those first and can remove those checks.
Signed-off-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20240403203633.914389-12-afd@ti.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
'chip' is an enum, thus cast of pointer on 64-bit compile test with W=1
causes:
ina2xx.c:627:10: error: cast to smaller integer type 'enum ina2xx_ids' from 'const void *' [-Werror,-Wvoid-pointer-to-enum-cast]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230810093157.94244-4-krzysztof.kozlowski@linaro.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230714174607.4057185-1-robh@kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
After commit b8a1a4cd5a ("i2c: Provide a temporary .probe_new()
call-back type"), all drivers being converted to .probe_new() and then
03c835f498 ("i2c: Switch .probe() to not take an id parameter") convert
back to (the new) .probe() to be able to eventually drop .probe_new() from
struct i2c_driver.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230505131718.1210071-1-u.kleine-koenig@pengutronix.de
[groeck: Added missing change in pmbus/acbel-fsg032.c]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
TI ina2xx sensors according to datasheets have dedicated
vs supplies. Add it for proper work.
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Link: https://lore.kernel.org/r/20230407160508.20479-3-clamor95@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
coccicheck complains about the use of snprintf() in sysfs
show functions.
drivers/hwmon/ina3221.c:701:8-16: WARNING: use scnprintf or sprintf
This results in a large number of patch submissions. Fix it all in
one go using the following coccinelle rules. Use sysfs_emit instead
of scnprintf or sprintf since that makes more sense.
@depends on patch@
identifier show, dev, attr, buf;
@@
ssize_t show(struct device *dev, struct device_attribute *attr, char *buf)
{
<...
return
- snprintf(buf, \( PAGE_SIZE \| PAGE_SIZE - 1 \),
+ sysfs_emit(buf,
...);
...>
}
@depends on patch@
identifier show, dev, attr, buf, rc;
@@
ssize_t show(struct device *dev, struct device_attribute *attr, char *buf)
{
<...
rc =
- snprintf(buf, \( PAGE_SIZE \| PAGE_SIZE - 1 \),
+ sysfs_emit(buf,
...);
...>
}
While at it, remove unnecessary braces and as well as unnecessary
else after return statements to address checkpatch warnings in the
resulting patch.
Cc: Zihao Tang <tangzihao1@hisilicon.com>
Cc: Jay Fang <f.fangjian@huawei.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Fix the following coccicheck warning:
drivers/hwmon/ina2xx.c:313:8-16: WARNING: use scnprintf or sprintf
drivers/hwmon/ina2xx.c:453:8-16: WARNING: use scnprintf or sprintf
drivers/hwmon/ina2xx.c:484:8-16: WARNING: use scnprintf or sprintf
drivers/hwmon/ina2xx.c:540:8-16: WARNING: use scnprintf or sprintf
Signed-off-by: Zihao Tang <tangzihao1@hisilicon.com>
Signed-off-by: Jay Fang <f.fangjian@huawei.com>
Link: https://lore.kernel.org/r/1615892457-35501-1-git-send-email-f.fangjian@huawei.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Many hwmon drivers don't use the id information provided by the old
i2c probe function, and the remainder can easily be adapted to the new
form ("probe_new") by calling i2c_match_id explicitly.
This avoids scanning the identifier tables during probes.
Drivers which didn't use the id are converted as-is; drivers which did
are modified as follows:
* if the information in i2c_client is sufficient, that's used instead
(client->name);
* anything else is handled by calling i2c_match_id() with the same
level of error-handling (if any) as before.
A few drivers aren't included in this patch because they have a
different set of maintainers. They will be covered by other patches.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200813160222.1503401-1-steve@sk2.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.
Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `\bxmlns\b`:
For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`:
If both the HTTP and HTTPS versions
return 200 OK and serve the same content:
Replace HTTP with HTTPS.
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Link: https://lore.kernel.org/r/20200719181530.60878-1-grandmaster@al2klimov.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Implement alert functions for INA226, INA230 and INA231. Expose 06h
Mask/Enable and 07h Alert Limit registers via alert setting and alarm
files.
Signed-off-by: Alex Qiu <xqiu@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation version 2 of the license
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 315 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The following build warning is seen if CONFIG_OF is disabled.
drivers/hwmon/ina2xx.c:510:34: warning:
‘ina2xx_of_match’ defined but not used
Mark ina2xx_of_match as __maybe_unused to fix the problem.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The current register (04h) has a sign bit at MSB. The comments
for this calculation also mention that it's a signed register.
However, the regval is unsigned type so result of calculation
turns out to be an incorrect value when current is negative.
This patch simply fixes this by adding a casting to s16.
Fixes: 5d389b1251 ("hwmon: (ina2xx) Make calibration register value fixed")
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
When using DT configurations, the id pointer might turn out to
be NULL. Then the driver encounters NULL pointer access:
Unable to handle kernel read from unreadable memory at vaddr 00000018
[...]
PC is at ina2xx_probe+0x114/0x200
LR is at ina2xx_probe+0x10c/0x200
[...]
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
The reason is that i2c core returns the id pointer by matching
id_table with client->name, while the client->name is actually
using the name from the first string in the DT compatible list,
not the best one. So i2c core would fail to match the id_table
if the best matched compatible string isn't the first one, and
then would return a NULL id pointer.
This probably should be fixed in i2c core. But it doesn't hurt
to make the driver robust. So this patch fixes it by using the
"chip" that's added to unify both DT and non-DT configurations.
Additionally, since id pointer could be null, so as id->name:
ina2xx 10-0047: power monitor (null) (Rshunt = 1000 uOhm)
ina2xx 10-0048: power monitor (null) (Rshunt = 10000 uOhm)
So this patch also fixes NULL name pointer, using client->name
to play safe and to align with hwmon->name.
Fixes: bd0ddd4d08 ("hwmon: (ina2xx) Add OF device ID table")
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Initialize data->config_lock mutex before it is used by the driver code.
This fixes following warning on Odroid XU3 boards:
INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 5 PID: 1 Comm: swapper/0 Not tainted 4.15.0-rc7-next-20180115-00001-gb75575dee3f2 #107
Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[<c0111504>] (unwind_backtrace) from [<c010dbec>] (show_stack+0x10/0x14)
[<c010dbec>] (show_stack) from [<c09b3f74>] (dump_stack+0x90/0xc8)
[<c09b3f74>] (dump_stack) from [<c0179528>] (register_lock_class+0x1c0/0x59c)
[<c0179528>] (register_lock_class) from [<c017bd1c>] (__lock_acquire+0x78/0x1850)
[<c017bd1c>] (__lock_acquire) from [<c017de30>] (lock_acquire+0xc8/0x2b8)
[<c017de30>] (lock_acquire) from [<c09ca59c>] (__mutex_lock+0x60/0xa0c)
[<c09ca59c>] (__mutex_lock) from [<c09cafd0>] (mutex_lock_nested+0x1c/0x24)
[<c09cafd0>] (mutex_lock_nested) from [<c068b0d0>] (ina2xx_set_shunt+0x70/0xb0)
[<c068b0d0>] (ina2xx_set_shunt) from [<c068b218>] (ina2xx_probe+0x88/0x1b0)
[<c068b218>] (ina2xx_probe) from [<c0673d90>] (i2c_device_probe+0x1e0/0x2d0)
[<c0673d90>] (i2c_device_probe) from [<c053a268>] (driver_probe_device+0x2b8/0x4a0)
[<c053a268>] (driver_probe_device) from [<c053a54c>] (__driver_attach+0xfc/0x120)
[<c053a54c>] (__driver_attach) from [<c05384cc>] (bus_for_each_dev+0x58/0x7c)
[<c05384cc>] (bus_for_each_dev) from [<c0539590>] (bus_add_driver+0x174/0x250)
[<c0539590>] (bus_add_driver) from [<c053b5e0>] (driver_register+0x78/0xf4)
[<c053b5e0>] (driver_register) from [<c0675ef0>] (i2c_register_driver+0x38/0xa8)
[<c0675ef0>] (i2c_register_driver) from [<c0102b40>] (do_one_initcall+0x48/0x18c)
[<c0102b40>] (do_one_initcall) from [<c0e00df0>] (kernel_init_freeable+0x110/0x1d4)
[<c0e00df0>] (kernel_init_freeable) from [<c09c8120>] (kernel_init+0x8/0x114)
[<c09c8120>] (kernel_init) from [<c01010b4>] (ret_from_fork+0x14/0x20)
Fixes: 5d389b1251 ("hwmon: (ina2xx) Make calibration register value fixed")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Calibration register is used for calculating current register in
hardware according to datasheet:
current = shunt_volt * calib_register / 2048 (ina 226)
current = shunt_volt * calib_register / 4096 (ina 219)
Fix calib_register value to 2048 for ina226 and 4096 for ina 219 in
order to avoid truncation error and provide best precision allowed
by shunt_voltage measurement. Make current scale value follow changes
of shunt_resistor from sysfs as calib_register value is now fixed.
Power_lsb value should also follow shunt_resistor changes as stated in
datasheet:
power_lsb = 25 * current_lsb (ina 226)
power_lsb = 20 * current_lsb (ina 219)
Signed-off-by: Maciej Purski <m.purski@samsung.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The driver doesn't have a struct of_device_id table but supported devices
are registered via Device Trees. This is working on the assumption that a
I2C device registered via OF will always match a legacy I2C device ID and
that the MODALIAS reported will always be of the form i2c:<device>.
But this could change in the future so the correct approach is to have an
OF device ID table if the devices are registered via OF.
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
when checking for the value of the shunt resistor.
Signed-off-by: Marc Titinger <mtitinger@baylibre.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Any sysfs "show" read access from the client app will result in reading
all registers (8 with ina226). Depending on the host this can limit the
best achievable read rate.
This changeset allows for individual register accesses through regmap.
Tested with BeagleBone Black (Baylibre-ACME) and ina226.
Signed-off-by: Marc Titinger <mtitinger@baylibre.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Use find_closest() to locate the closest average in ina226_avg_tab.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add support for "ina231" as compatible string, and update
Documentation and Kconfig accordingly.
Tested with the Exynos5422-based odroid-xu3 board which has on-board
INA231 sensors.
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Use DIV_ROUND_CLOSEST() when dealing with the calibration values to make the
calculations less error prone.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This attribute allows to configure the update interval of ina226. Although
the bus and shunt voltage conversion times remain hardcoded to 1.1 ms, we can
now modify said interval by changing the averaging rate.
While we're at it - add an additional variable to ina2xx_data, which holds
the current configuration settings - this way we'll be able to restore the
configuration in case of an unexpected chip reset.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The shunt resistance can only be set via platform_data or device tree. This
isn't suitable for devices in which the shunt resistance can change/isn't
known at boot-time.
Add a sysfs attribute that allows to read and set the shunt resistance.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Shunt resistance values greater than the chip's calibration factor make no
sense since the actual value written to the register equals:
<calibration factor> / <shunt>
Bail-out from ina2xx_probe() if the configured value is greater than the
calibration factor.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Chips from the ina family don't like to be uninitialized. In case the power
is cut-off and restored again the calibration register will be reset
to 0 and both the power and current registers will remain at 0.
Check the calibration register in ina2xx_update_device() and reinitialize
the chip if needed.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
The return value of i2c_smbus_write_word_swapped() isn't checked in
ina2xx_probe(). This leads to devices being registered even if they cannot
be physically detected (e.g. device is not powered-up at boot-time).
Even after restoring power to such device, it is left unconfigured as the
configuration has never been actually written to the register.
Error out in case of write errors in probe and notify the user.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
[Guenter Roeck: Fixed multi-line comment style]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
