stm32: Support pins with multiple AFs for the same peripheral.
For example, on WB55, pin PD3 can be SPI2_SCK on AF3 and SPI2_MISO on AF5.
PortD,PD3,,,,SPI2_SCK,,SPI2_MISO,,,,,QUADSPI_BK1_NCS,,,,,EVENTOUT,
When we configure a default pin in mpconfigboard.h, it is unable (via pin_find_af and the generated code from make-pins.py) to resolve this because the AF_FN_SPI enum assumes that a given peripheral will always use the same AF number on all pins.
// This will fail, and make D3 be SPI2_SCK instead.
#define MICROPY_HW_SPI2_MISO (pin_D3)
Here are some other AF CSV files and peripherals where different AFs share the same peripheral. Other than the WB55 SPI2 example I didn't see any that are accessible from Python. (i.e. the I2C4 are conflicting with I2C_SMBA).
boards/stm32f091_af.csv
TIM15, USART7
boards/stm32f405_af.csv
OTG
boards/stm32f429_af.csv
LCD, OTG
boards/stm32f439_af.csv
LCD, OTG
boards/stm32f722_af.csv
OTG
boards/stm32f746_af.csv
LCD, OTG
boards/stm32f767_af.csv
OTG, DFSDM1, LCD, I2C4
boards/stm32h743_af.csv
DFSDM, TIM8, SDMMC1, LCD, SAI1, TIM1, I2C4, OTG, SAI4
boards/stm32h7b3_af.csv
OCTOSPIM, DFSDM1, PSSI, FMC, TIM8, LTDC, SDMMC1, SAI1, TIM1, I2C4
boards/stm32l072_af.csv
TIM2, LPUART1
boards/stm32l432_af.csv
TIM1, TIM2, COMP2, COMP1
boards/stm32l452_af.csv
TIM1, TIM2, COMP2, COMP1
boards/stm32l476_af.csv
TIM5, TIM2, TIM1, TIM8
boards/stm32l496_af.csv
TIM2, SPI2, TIM8, TIM5, TIM1, QUADSPI
boards/stm32wb55_af.csv
TIM2, TIM1, SAI1, SPI2
SPI2 on STM32WB55 pin error
Trying to use pin D3 as SPI2_MISO alternate function does not work, the pin D3 switches to the previous alternate funtion (SPI2_SCK).
This can be fixed by removing the AF3 declaration out of the stm32wb55_af.csv list:
PortD,PD3,,,,SPI2_SCK,,SPI2_MISO,,,,,QUADSPI_BK1_NCS,,,,,EVENTOUT, (Original)
PortD,PD3,,,,,,SPI2_MISO,,,,,QUADSPI_BK1_NCS,,,,,EVENTOUT, (fix)
But this causes the Pin D3 incapable of switching to SCK mode.
This is caused by the definition of a pin list in spi.c (line 294), not a function list. In the pin list, the actual output pin is defined, but the information what the pin should be doing is not remembered.
A sollution could be the sequnce of the list, it can be defined to hold the function. The function mp_hal_pin_config_alt then should be told what the pin function should be.