Re: [PATCH 07/11] x86, olpc-xo1-sci: Add GPE handler and ebook switchfunctionality
From: Sebastian Andrzej Siewior
Date: Tue May 31 2011 - 07:28:55 EST
Daniel Drake wrote:
I looked into irq_chip alongside the CS5535 docs. Initially this
looked like a good suggestion - any CS5535 GPIO can be mapped to one
of 8 PIC-level interrupts, which seems like a good match for irq_chip.
However, this isn't what we're doing here.
CS5535 GPIOs can either be mapped to interrupts, *or* to a Power
Management Event (PME). A PME is a CS5535-specific concept; its an
event that will bring the system out of suspend if it is sleeping. In
this case, we are mapping a GPIO to a PME. I'm not aware of any
appropriate Linux abstraction for this. Thats all done in
cs5535_gpio_setup_event().
Is this something like pin multiplexing? So it is either a GPIO pin with
interrupt ability _or_ that PME thingy.
If so, would it make sense to hide it behind enable_irq_wake()? That call
could fail if you have already gpio_request() users for instance.
The CS5535 also has a highly programmable PIC, with loads of possible
input and mapping options. The call to cs5535_gpio_set_irq() then
programs the PIC to map PME input to an IRQ line. This function is
both misnamed and misplaced; it is unrelated to GPIOs and is simply
one of the many generic knobs on the PIC. If there was one, this
function should belong in a cs5535-pic driver, named something
according to "IRQ Mapper Unrestricted Z Select High".
And once that is done, you can not use as a GPIO anymore, right?
Thanks,
Daniel
Sebastian
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/