Re: GPIO driver for Intel Atom SoC

Hi Imre

This is great information. Thank you!

My device have an emmc chip on the pcb (non-removable).
Have you tested you code on that kind of system?

Current unmodified FreeBSD can detect the sdhci_pci controller and a mmc
card on slot0 but timeouts when trying to init the mmc. Not sure why it is
failing. I assumed it needed activating through some gpios but maybe it's
not that easy..


On Mon, Jun 13, 2016 at 2:38 AM, Imre Vadasz <imre_at_vdsz.com> wrote:

> Hi,
>
> Microsoft has some documentation on GPIO handling with SD card controllers,
> which should apply to most Cherryview devices:
>
> https://msdn.microsoft.com/windows/hardware/drivers/bringup/other-acpi-namespace-objects#sd
>
> I did some work on Cherryview SoC support in DragonFlyBSD.
> In DragonFly master, there is a simple GPIO driver for cherryview in
> /sys/bus/gpio/gpio_intel. In master, it's currently only used for
> handling the ACPI GeneralPurposeIo operation regions, and
> Acpi-Event-Interrupts (which replace GPE interrupts on reduced-hardware
> platforms).
>
> I have some further (more prototype level) code which also contains some
> code for Intel sdhci controller integration:
>
> https://gitweb.dragonflybsd.org/~ivadasz/dragonfly.git/shortlog/refs/heads/cherryview
>
> With this branch everything sdcard/eMMC related works quite nicely, e.g.
> it properly handles plugging in/out the sd-card on my HP X2 210 detachable
> on DragonFlyBSD.
>
> To handle everything properly this contains a bit of work on mostly ACPI
> related stuff:
>
> ACPI device initialization order needs to be according to the ACPI _DEP
> methods:
>
> https://gitweb.dragonflybsd.org/~ivadasz/dragonfly.git/commitdiff/25dec08cafa3ce9089eb5b216700f4e678b3356d
>
> We need to map ACPI nodes to the device objects (and at least track a
> reference count for debugging):
>
> https://gitweb.dragonflybsd.org/~ivadasz/dragonfly.git/commitdiff/23135590ffb33b40f170c786ea95fc133358ebdb
>
> Then some kind of API is needed for handling the GeneralPurposeIo resources
> declared for the device in the ACPI tables (e.g. the sdhci controller).
> (i.e. some way of attempting to "map" the resource from the device driver):
>
> https://gitweb.dragonflybsd.org/~ivadasz/dragonfly.git/commitdiff/d5b3d3447bbdd42a68359aebd61f271bfa830951
>
> And I have a prototype of adapting the sdhci driver to handle the GPIO
> ACPI resources, as described in "
> https://msdn.microsoft.com/windows/hardware/drivers/bringup/other-acpi-namespace-objects#sd
> ":
>
> https://gitweb.dragonflybsd.org/~ivadasz/dragonfly.git/commitdiff/5d2844c280211cbb256a5ecc3ea27f952149e452
>
> Regards,
> Imre Vadász
>

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