Re: [PATCH v4 2/4] gpiolib: add gpiod_get_array and gpiod_put_array functions

[Rojhalat Ibrahim <imr@xxxxxxxxxxx>]

On Wednesday 11 February 2015 22:31:12 Alexandre Courbot wrote:
> On Wed, Feb 11, 2015 at 9:14 PM, Rojhalat Ibrahim <imr@xxxxxxxxxxx> wrote:
> > On Wednesday 11 February 2015 12:30:01 Mika Westerberg wrote:
> >> On Tue, Feb 10, 2015 at 02:40:52PM +0100, Rojhalat Ibrahim wrote:
> >> > +#ifdef CONFIG_ACPI
> >> > +
> >> > +static unsigned int acpi_gpio_package_count(const union acpi_object *obj)
> >> > +{
> >> > +   const union acpi_object *element = obj->package.elements;
> >> > +   const union acpi_object *end = element + obj->package.count;
> >> > +   unsigned int count = 0;
> >> > +
> >> > +   while (element < end) {
> >> > +           if (element->type == ACPI_TYPE_LOCAL_REFERENCE)
> >> > +                   count++;
> >> > +
> >> > +           element++;
> >> > +   }
> >> > +   return count;
> >> > +}
> >> > +
> >> > +static int acpi_find_gpio_count(struct acpi_resource *ares, void *data)
> >> > +{
> >> > +   unsigned int *count = data;
> >> > +
> >> > +   if (ares->type == ACPI_RESOURCE_TYPE_GPIO)
> >> > +           *count += ares->data.gpio.pin_table_length;
> >> > +
> >> > +   return 1;
> >> > +}
> >> > +
> >> > +static int acpi_gpio_count(struct device *dev, const char *con_id)
> >> > +{
> >> > +   struct acpi_device *adev = ACPI_COMPANION(dev);
> >> > +   const union acpi_object *obj;
> >> > +   const struct acpi_gpio_mapping *gm;
> >> > +   int count = -ENOENT;
> >> > +   int ret;
> >> > +   char propname[32];
> >> > +   unsigned int i;
> >> > +
> >> > +   /* Try first from _DSD */
> >> > +   for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
> >> > +           if (con_id && strcmp(con_id, "gpios"))
> >> > +                   snprintf(propname, sizeof(propname), "%s-%s",
> >> > +                            con_id, gpio_suffixes[i]);
> >> > +           else
> >> > +                   snprintf(propname, sizeof(propname), "%s",
> >> > +                            gpio_suffixes[i]);
> >> > +
> >> > +           ret = acpi_dev_get_property(adev, propname, ACPI_TYPE_ANY,
> >> > +                                       &obj);
> >> > +           if (ret == 0) {
> >> > +                   if (obj->type == ACPI_TYPE_LOCAL_REFERENCE)
> >> > +                           count = 1;
> >> > +                   else if (obj->type == ACPI_TYPE_PACKAGE)
> >> > +                           count = acpi_gpio_package_count(obj);
> >> > +           } else if (adev->driver_gpios) {
> >> > +                   for (gm = adev->driver_gpios; gm->name; gm++)
> >> > +                           if (strcmp(propname, gm->name) == 0) {
> >> > +                                   count = gm->size;
> >> > +                                   break;
> >> > +                           }
> >> > +           }
> >> > +           if (count >= 0)
> >> > +                   break;
> >> > +   }
> >> > +
> >> > +   /* Then from plain _CRS GPIOs */
> >> > +   if (count < 0) {
> >> > +           struct list_head resource_list;
> >> > +           unsigned int crs_count = 0;
> >> > +
> >> > +           INIT_LIST_HEAD(&resource_list);
> >> > +           acpi_dev_get_resources(adev, &resource_list,
> >> > +                                  acpi_find_gpio_count, &crs_count);
> >> > +           acpi_dev_free_resource_list(&resource_list);
> >> > +           if (crs_count > 0)
> >> > +                   count = crs_count;
> >> > +   }
> >> > +   return count;
> >> > +}
> >> > +
> >> > +#else
> >> > +
> >> > +static int acpi_gpio_count(struct device *dev, const char *con_id)
> >> > +{
> >> > +   return -ENODEV;
> >> > +}
> >> > +
> >> > +#endif
> >>
> >> It just occured to me that it would be better to put this code to
> >> gpiolib-acpi.c and declare acpi_gpio_count() in drivers/gpio/gpiolib.h.
> >>
> >
> > Ok. I will also have to move the definition of gpio_suffixes[] (PATCH 1/4)
> > to drivers/gpio/gpiolib.h since it is needed by both the OF and the ACPI
> > portions of the code.
> 
> We will really need to factorize this lookup code. I will give it a
> look, but first I'd like to merge this good stuff.
> 
> I am mixed about moving these declarations into gpiolib.h - maybe have
> one static declaration per file instead, especially since lookup on
> ACPI is not necessarily the same as lookup on DT. It makes sense to
> have it that way.
> 

If we do one static declaration per file then acpi_find_gpio() in gpiolib.c
is going to use potentially different suffixes from acpi_gpio_count() in
gpiolib-acpi.c. That can't be good.

Furthermore it seems to me that while the suffixes do not necessarily have to
be the same for ACPI and DT, they are now, and it may even be desirable to
keep them consistent as long as there is no reason for not doing so.

> >
> >> That said, I tested this code on Lenovo Thinkpad10 by converting
> >> drivers/input/misc/soc_button_array.c to fetch its GPIOs using this new
> >> API -- it works just fine (and looks better).
> >>
> >> Once you have done the above change you can add for the ACPI parts,
> >>
> >> Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> >> Tested-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> >>
> >
> > Great. Thanks.
> 
> Hopefully the next revision will be the right one! :)
> 

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