On Thursday 08 November 2012 05:24:19 Linus Walleij wrote:
> I would prefer to create, e.g. in <linux/gpio/consumer.h>
> something like:
>
> struct gpio;
>
> struct gpio *gpio_get(struct device *dev, const char *name);
>
> int gpio_get_value(struct gpio *g);
>
> Nothing more! I.e. struct gpio is an opaque cookie, nothing to be known
> about it.
>
> And then have the drivers using this *ONLY* include <linux/gpio/consumer.h>
> and not <linux/gpio.h>. So drivers have no clue what struct gpio is and
> will only operate on it using functions.
>
> This follows the pattern set by Thomas Gleixner for e.g. IRQ descriptors,
> and the style was also used in the redesign of the struct clk *.
Also pretty similar to the regulator framework, which might itself have been
inspired by IRQs and clocks.
> Of course the cross-referencing implementation can in e.g.
> drivers/gpio/gpiodev.c internally define that like this:
>
> #include <linux/gpio.h>
>
> /**
> * @gpio: pointer to global GPIO number
> */
> struct gpio {
> int gpio;
> };
>
> struct gpio *gpio_get(struct device *dev, const char *name)
> {
> /* Lookup in cross-ref table etc */
> }
>
> int gpioh_get_value(struct gpio *g)
> {
> return gpio_get_value(g->gpio);
> }
>
> (...)
>
> Then we can work from there. I think it adds the proper
> opaqueness factor.
Looks nice, simple and to the point! Let's see if I can find the time to cook
something based on this.
Thanks!
Alex.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
