Messages in this thread | | | Date | Tue, 27 May 2008 15:02:36 +0200 | From | Uwe Kleine-König <> | Subject | configure gpio for interrupt function |
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Hello David,
I want to use a driver that in turn uses the gpio API (i.e. drivers/input/keyboard/gpio_keys.c). My problem with that is, that my machine[1]'s external irqs don't fit into the GPIO API model. The main problem is that gpio_direction_input isn't enough to get an irq. I need to explicitly set the gpio to an EXT_IRQ function. (I can workaround that because the EXT_IRQ function allows to read the state of the gpio. So I can use the EXT_IRQ function if input is requested.)
Another problem is that I cannot implement irq_to_gpio correctly, because several gpio's share the same irq. (Note this makes the workaround above less reliable. Consider two gpios sharing the same irq. I cannot assert that only one of them can trigger the interrupt.)
So I suggest to extend the gpio API with two functions like:
int gpio_direction_inputirq(unsigned gpio, unsigned flags); void gpio_ackirq(unsigned gpio);
with flags being similar to the IRQF_TRIGGER_* defines in include/linux/interrupt.h. I need gpio_ackirq because ns9xxx requires that an edge triggered irq is acknowledged separatly in the "External Interrupt X Control register"[2]. (If you have better names ...)
Moreover this makes the API more flexible because the irq type can be configured.
OTOH I'd like to deprecate irq_to_gpio. $(git grep -l irq_to_gpio drivers) suggests that this function is only used in two places. One of them[3] is AT91 specific, the other[4] seems specific for the RouterBoard 532. (There are some other users below arch/, but I expect no breakage here. I expect that every arch that uses the function have it implemented anyhow.)
What do you think?
Best regards Uwe
[1] http://www.digi.com/products/embeddedsolutions/ns9215.jsp Interesting sections are "Pinout -> General purpose I/O (GPIO)" and "I/O Control Module". E.g. GPIO4's func1 is "Ext Int Ch 2" [2] System Control Module -> External Interrupt 03 Control register [3] drivers/mmc/host/at91_mci.c [4] drivers/ata/pata_rb532_cf.c
-- Uwe Kleine-König, Software Engineer Digi International GmbH Branch Breisach, Küferstrasse 8, 79206 Breisach, Germany Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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