gpio: add API to be strict about GPIO IRQ usage

It is currently often possible in many GPIO drivers to request
a GPIO line to be used as IRQ after calling gpio_to_irq() and,
as the gpiolib is not aware of this, set the same line to
output and start driving it, with undesired side effects.

As it is a bogus usage scenario to request a line flagged as
output to used as IRQ, we introduce APIs to let gpiolib track
the use of a line as IRQ, and also set this flag from the
userspace ABI.

The API is symmetric so that lines can also be flagged from
.irq_enable() and unflagged from IRQ by .irq_disable().
The debugfs file is altered so that we see if a line is
reserved for IRQ.

Cc: Enric Balletbo i Serra <[email protected]>
Cc: Grant Likely <[email protected]>
Cc: Jean-Christophe PLAGNIOL-VILLARD <[email protected]>
Cc: Santosh Shilimkar <[email protected]>
Acked-by: Alexandre Courbot <[email protected]>
Reviewed-by: Stephen Warren <[email protected]>
Reviewed-by: Javier Martinez Canillas <[email protected]>
Signed-off-by: Linus Walleij <[email protected]>

0 files changed, 0 insertions, 0 deletions