The ICACHE must be disabled on STM32H5 series due to documented
behaviour of the flash controller, not to an errata.
For a more technical explaination: (see RM0492 for references)
- on STM32H5, the ICACHE block is interposed on C-bus between
the Cortex-M33 and the FLASH (§2.1.1)
- the ICACHE determines if accesses are cacheable or non-cacheable
based on an AHB attribute; the Cortex-M33 sets this attribute or
not depending on the MPU configuration (§8.4.6)
- when a cacheable access is requested by the Cortex-M33, if the
requested data is not present in ICACHE (cache miss), a cache line
refill (128-bit burst read) is performed (§8.4.7)
- however, all accesses to OTP and Read-Only regions of the FLASH must
be done with caching disabled (§7.3.2); indeed, the accesses MUST be
16 or 32-bit sized - otherwise, the flash interface raises a bus
error (§7.5.9 / Table 38 "OTP/RO access constraints").
This is the behaviour that was observed and lead to the introduction
of ICACHE disable code in 065a8f25e1.
Signed-off-by: Mathieu Choplain <mathieu.choplain@st.com>
This commit modifies the STM32 internal voltage reference sensor
driver to handle erroneous usage more gracefully. More precisely:
- driver no longer builds if no ADC node is enabled
- fail builds with an explicit error message when the sensor
is enabled but the corresponding ADC is not. This can only
happen on STM32 series with more than one ADC (e.g., H7).
Signed-off-by: Mathieu Choplain <mathieu.choplain@st.com>
The STM32 temperature, battery and voltage reference sensors needs to
write the ADC common registers to enable the corresponding ADC features.
For that we need to ensure that the ADC is not suspended by using the
pm_device_runtime_get/put methods.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
When a sensor that depends on an ADC is enabled in devicetree, enable
the ADC subsystem. ADC is roughly equivalent to a bus for these sensors
(the mechanism through which data is transferred), which had the same
conversion applied in #48707.
The same benefits apply here, namely removing the need for the following
pattern in board `.kconfig` files:
```
configdefault ADC
default y if SENSOR
```
Signed-off-by: Jordan Yates <jordan@embeint.com>
Instead of using floating point operations to compute the vref voltage,
it is possible to use the sensor_value_from_milli() function.
On a STM32G0, this saves 130 bytes of flash, excluding the FP library
needed on a FPU less MCU.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
