If the PVT sensor is suddenly powered down while a caller is waiting for
the conversion completion, the request won't be finished and the task will
hang up on this procedure until the power is back up again. Let's call the
wait_for_completion_timeout() method instead to prevent that. The cached
timeout is exactly what we need to predict for how long conversion could
normally last.
Fixes: 87976ce282 ("hwmon: Add Baikal-T1 PVT sensor driver")
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20200920110924.19741-4-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Instead of converting the update timeout data to the milliseconds each
time on the read procedure let's preserve the currently set timeout in the
dedicated driver private data cache. The cached value will be then used in
the timeout read method and in the alarm-less data conversion to prevent
the caller task hanging up in case if the PVT sensor is suddenly powered
down.
Fixes: 87976ce282 ("hwmon: Add Baikal-T1 PVT sensor driver")
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20200920110924.19741-3-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Baikal-T1 PVT sensor has got a dedicated power supply domain (feed up by
the external GPVT/VPVT_18 pins). In case if it isn't powered up, the
registers will be accessible, but the sensor conversion just won't happen.
Due to that an attempt to read data from any PVT sensor will cause the
task hanging up. For instance that will happen if XP11 jumper isn't
installed on the Baikal-T1-based BFK3.1 board. Let's at least test whether
the conversion work on the device probe procedure. By doing so will make
sure that the PVT sensor is powered up at least at boot time.
Fixes: 87976ce282 ("hwmon: Add Baikal-T1 PVT sensor driver")
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20200920110924.19741-2-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Clang-based kernel building with W=1 warns that some static const
variables are unused:
drivers/hwmon/bt1-pvt.c:67:30: warning: unused variable 'poly_temp_to_N' [-Wunused-const-variable]
static const struct pvt_poly poly_temp_to_N = {
^
drivers/hwmon/bt1-pvt.c:99:30: warning: unused variable 'poly_volt_to_N' [-Wunused-const-variable]
static const struct pvt_poly poly_volt_to_N = {
^
Indeed these polynomials are utilized only when the PVT sensor alarms are
enabled. In that case they are used to convert the temperature and
voltage alarm limits from normal quantities (Volts and degree Celsius) to
the sensor data representation N = [0, 1023]. Otherwise when alarms are
disabled the driver only does the detected data conversion to the human
readable form and doesn't need that polynomials defined. So let's mark the
Temp-to-N and Volt-to-N polynomials with __maybe_unused attribute.
Note gcc with W=1 doesn't notice the problem.
Fixes: 87976ce282 ("hwmon: Add Baikal-T1 PVT sensor driver")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Maxim Kaurkin <Maxim.Kaurkin@baikalelectronics.ru>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20200603000753.391-1-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Baikal-T1 SoC provides an embedded process, voltage and temperature
sensor to monitor an internal SoC environment (chip temperature, supply
voltage and process monitor) and on time detect critical situations,
which may cause the system instability and even damages. The IP-block
is based on the Analog Bits PVT sensor, but is equipped with a
dedicated control wrapper, which provides a MMIO registers-based access
to the sensor core functionality (APB3-bus based) and exposes an
additional functions like thresholds/data ready interrupts, its status
and masks, measurements timeout. All of these is used to create a hwmon
driver being added to the kernel by this commit.
The driver implements support for the hardware monitoring capabilities
of Baikal-T1 process, voltage and temperature sensors. PVT IP-core
consists of one temperature and four voltage sensors, each of which is
implemented as a dedicated hwmon channel config.
The driver can optionally provide the hwmon alarms for each sensor the
PVT controller supports. The alarms functionality is made compile-time
configurable due to the hardware interface implementation peculiarity,
which is connected with an ability to convert data from only one sensor
at a time. Additional limitation is that the controller performs the
thresholds checking synchronously with the data conversion procedure.
Due to these limitations in order to have the hwmon alarms
automatically detected the driver code must switch from one sensor to
another, read converted data and manually check the threshold status
bits. Depending on the measurements timeout settings this design may
cause additional burden on the system performance. By default if the
alarms kernel config is disabled the data conversion is performed by
the driver on demand when read operation is requested via corresponding
_input-file.
Co-developed-by: Maxim Kaurkin <maxim.kaurkin@baikalelectronics.ru>
Signed-off-by: Maxim Kaurkin <maxim.kaurkin@baikalelectronics.ru>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: devicetree@vger.kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Serge Semin