Messages in this thread | | | From | Alex Courbot <> | Subject | Re: How about a gpio_get(device *, char *) function? | Date | Thu, 8 Nov 2012 15:14:34 +0900 |
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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.
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