On Wed, Sep 4, 2013 at 9:56 PM, Stephen Warren [off-list ref] wrote:

On 09/04/2013 05:29 AM, Alexandre Courbot wrote:

quoted

Add gpiod_get() and gpiod_put() functions that provide safer handling of
GPIOs.

These functions put the GPIO framework in line with the conventions of
other frameworks in the kernel, and help ensure every GPIO is declared
properly and valid while it is used.

quoted

diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h

quoted

+struct gpio_desc *__must_check gpiod_get(struct device *dev,
+                                      const char *con_id);
+void gpiod_put(struct gpio_desc *desc);

It might be nice to add an "int index" parameter to this function. For
example, a bit-banged parallel bus protocol driver might have 1
chip-select GPIO, 1 clock GPIO, and 8 data GPIOs. gpiod_get(dev, "bus",
0)..gpiod_get(dev, "bus", 7) might be nicer than gpiod_get(dev,
"bus0")..gpiod_get(dev, "bus7")? Possibly for client-simplicity,
implement both gpiod_get(dev, con_id) (as an inline wrapper for ...) and
gpiod_get_index(dev, con_id, index)?

In DT terms, this would map to:

cs-gpios = <&gpio 3 0>;
clock-gpios = <&gpio 5 0>;
bus-gpios = <&gpio 10 0 ... &gpio 17 0>;

... and with the mapping table registration mechanism, we could
presumably add "int index" to struct gpiod_lookup.

This is an interesting usability aspect of the API, so I'd especially
like some input from the ACPI people on this as well.

Paging Mika, Rafael, Mathias.

Yours,
Linus Walleij
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