Re: [Qemu-devel] [Qemu-arm] [PATCH v2] nrf51_gpio: reflect pull-up/pull-down to IRQs

[Peter Maydell]

On Sun, 17 Mar 2019 at 14:13, Paolo Bonzini <address@hidden> wrote:
>
> Some drivers do I2C bitbanging by keeping the output to 0 and flipping
> the GPIO direction between input and output (see for example in Linux
> gpio_set_open_drain_value_commit, in drivers/gpio/gpiolib.c).
> When the GPIO is set to input, the pull-up resistor brings the output
> to 1, while when the GPIO is set to output, the output driver brings
> the output to 0.
>
> Implement this for the nRF51 GPIO device model.  First, if both input and
> output are floating, and there is a pull-up or pull-down resistor
> configured, do not just set s->in, but also make any devices listening
> on the output qemu_irq receive that value.  Second, if the pin is
> driven both internally (output pin) and externally you don't get a
> short circuit if both sides drive the pin to the same value.
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>         v1->v2: fixed short circuit conditions, reordering the code according
>         to the schematic in the datasheet



Applied to target-arm.next, thanks.

-- PMM