On Wed, May 27, 2015 at 5:26 AM, Gregory Fong [off-list ref] wrote:

I've now actually attempted to use the gpiolib irqchip code.  This
driver can't directly use gpiochip_irqchip_add() because of the
multiple gpiochip : one irqchip map.  At first, I thought it might be
possible to simply add a new argument (or break things into a helper
function) to allow setting the associated IRQ domain, but then I can't
use the generic map and unmap functions which expect the irq_domain
host_data member to be struct gpiochip *, which makes no sense in this
case.  That puts me right back to implementing a special version of
the map and unmap function.

I see.

I wonder if it is better to use one device per bank, and then set
IRQF_SHARED when you issue request_irq(), and have the
IRQ handler return IRQ_NONE if the IRQ comes from this
bank, or IRQ_HANDLED if it has handled an IRQ from its own
space.

This way multiple banks can share a single interrupt line.

Yours,
Linus Walleij