periph/gpio: add gpio_update_int() class of functions

[benpicco]

Contribution description

It can be desirable to change the function or behavior associated with a GPIO interrupt.
Currently this can only be achieved by calling gpio_init_int() again, which not only does lots of unnecessary and possibly time-consuming work, but also forces to expose the GPIO configuration to callers that only want to change the callback argument.

As proposed in #12082 (comment) this introduces three new functions:

void gpio_update_int(gpio_t pin, gpio_cb_t cb, void *arg);
void gpio_update_cb(gpio_t pin, gpio_cb_t cb);
void gpio_update_arg(gpio_t pin, void *arg);

gpio_init_int() must have been called successfully before on pin, so no error checking is needed which greatly simplifies the implementation.

If the API is acceptable, I will update the remaining GPIO drivers.

• stm32f1/periph/gpio.c
• mips_pic32_common/periph/gpio.c
• lpc1768/periph/gpio.c
• stm32_common/periph/gpio.c
• efm32/periph/gpio.c
• native/periph/gpio.c
• lm4f120/periph/gpio.c
• fe310/periph/gpio.c
• esp8266/periph/gpio.c
• msp430fxyz/periph/gpio.c
• cc26xx_cc13xx/periph/gpio.c
• cc2538/periph/gpio.c
• esp32/periph/gpio.c
• lpc2387/periph/gpio.c
• kinetis/periph/gpio.c
• atmega_common/periph/gpio.c
• sam0_common/periph/gpio.c
• nrf5x_common/periph/gpio.c
• sam3/periph/gpio.c
• ezr32wg/periph/gpio.c

Testing procedure

The following program should alternate between the two messages with each press of a button.

#include <stdio.h>
#include "periph/gpio.h"
#include "board.h"

static char* messages[] = {
    "Hello IRQ!",
    "Goodby IRQ!"
};

static void _irq_handler(void *arg)
{
    puts(arg);
    gpio_update_cb(BTN0_PIN, arg == messages[0] ? messages[1] : messages[0]);
}

int main(void)
{
    gpio_init_int(BTN0_PIN, GPIO_IN, GPIO_RISING, _irq_handler, messages[0]);
    return 0;
}

Issues/PRs references

alternative to #12082

[gschorcht]

@benpicco I would prefer to have only one function since each additional function will increase the RAM required for the driver interface gpio_driver_t in PR #14602.

[gschorcht]

What is the reason for having three different functions?

[benpicco]

Was suggested by @maribu to make the API easier to use / implement: #12082 (comment)

But at that point function pointers in RAM were not a concern yet, with the old API if a function was not used by the application the linker would just throw it out.