On Thu, 10 Jan 2013 12:42:53 +0100, Linus Walleij <[email protected]> wrote: > On Tue, Jan 8, 2013 at 12:14 PM, Viresh Kumar <[email protected]> wrote: > > On 8 January 2013 16:41, Lee Jones <[email protected]> wrote: > >>> Hmm.. I tried a bit, but couldn't find any such call :( > >>> Probably an assumption is taken here. GPIO pins which are going to be > >>> used as > >>> interrupt lines, wouldn't be getting set in output mode at all. So, > >>> once they are put > >>> in input mode in beginning, nobody would change it ever. > >>> > >>> Much of gpio controllers configure gpio pins in input mode in their > >>> probe(). > >>> > >>> Maybe, there is something else :) > >> > >> Pinctrl? > > > > I don't think pinctrl is playing with it. I searched for > > "direction_input" string and > > pinctrl routine also had similar name. I couldn't fine use of > > direction_input anywhere > > in kernel, for setting them as irqs for OF cases. > > pinctrl has pinctrl_gpio_direction_input() and > pinctrl_gpio_direction_output() which are supposed to > be called *only* by GPIOlib frontends using pinctrl > as backend to control the pins. > > But if it's a pinctrl driver using standard pinconfig from > include/linux/pinctrl/pinconf-generic.h > I'm all for adding a PIN_CONFIG_INPUT_ENABLE > to these definintions so it can be set up as input > at boot from the device tree using hogs or something, > that make things easy when using GPIOs as IRQ > providers only. > > So the alternative is to just set up the IRQ using the > gpiolib functions for this: of_get_gpio() if you need the > number from DT, then gpio_request() and > gpio_direction_input() as on any GPIO. This can be > done in the device driver or board code depending > on use case. > > In the Nomadik I did this (maybe ugly) hack for a > similar case: > > +/* > + * The SMSC911x IRQ is connected to a GPIO pin, but the driver expects > + * to simply request an IRQ passed as a resource. So the GPIO pin needs > + * to be requested by this hog and set as input. > + */ > +static int __init cpu8815_eth_init(void) > +{ > + struct device_node *eth; > + int gpio, irq, err; > + > + eth = of_find_node_by_path("/external-bus@34000000/ethernet@300"); > + if (!eth) { > + pr_info("could not find any ethernet controller\n"); > + return 0; > + } > + gpio = of_get_gpio(eth, 0); > + err = gpio_request(gpio, "eth_irq"); > + if (err) { > + pr_info("failed to request ethernet GPIO\n"); > + return -ENODEV; > + } > + err = gpio_direction_input(gpio); > + if (err) { > + pr_info("failed to set ehernet GPIO as input\n"); > + return -ENODEV; > + } > + irq = gpio_to_irq(gpio); > + pr_info("enabled ethernet GPIO %d, IRQ %d\n", gpio, irq); > + return 0; > +} > +device_initcall(cpu8815_eth_init); > > I haven't read review comments on that patch. > > Maybe it's not such a good idea to add the GPIO to the device itself > when it's being hogged by board code like this. It's a bit of a grey area > so I'm a bit confused here. > > Maybe the GPIO lib actually needs a "hog" mechanism that can > request and set GPIO pins as input/output on boot and then > forget about them.
That would be reasonable. Probably as properties in the gpio controller node that specify how to set the inital state. g. _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
