Hey guys,
I have few questions/comments on the GPIO APIs, maybe to André:
1.) Most of the APIs has a way to call the BSP specific functions: pin
input/output initialize, pin read/write, enable/disable interrupts etc,
but I couldn't find a way to call a BSP specific pin release (or
de-init). The rtems_gpio_release_pin() disables the interrupt for that
pin and updates the pin state global variable, but does not allows to do
a bsp specific pin de-initialize. While if I want to change the mode of
the pin (say from input to output), I can reinitialize the pin and it
works. But its important to bring back the state of the pin to its
default reset state, deactivating the pull resistors, if the pin is to
be released and not used.
Was wondering why this wasn't added. What are your comments on this? If
this is OK I have a patch for this.
2.) Second, the interrupts are registered based on ports (which it is in
most of the processors) and the pin that caused the interrupt is found
as a node in the chained list. But, unfortunately the processor that we
are using (STM32F4/F7) has pin based interrupts :(. The link below tells
in brief:
http://stm32f4-discovery.com/2014/08/stm32f4-external-interrupts-tutorial/
There are interrupt vectors defined for each pin in STM32F4/F7 but RTEMS
GPIO expects vector numbers for gpio banks using
rtems_gpio_bsp_get_vector(), which would not work for this processor.
I'm been trying to break my head to figure out a way to make the
interrupts work, without any modification to the GPIO APIs.
One way would be to send the enumerated pin_number as the argument to
rtems_gpio_bsp_get_vector(), decode pin number ( pin =
PIN_NUMBER(pin_number) ) and return the vector number for this pin and
install the interrupt handler. But based on the whole interrupt service
architecture in generic_bank_isr(), this would not work out. Everything
is based on bank interrupts.
Any possible solution for this?
Thanks and Regards,
Sudarshan Rajagopalan
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