PowerPC: implement GPIO API

Hi all,

OF device tree GPIOs bindings are similar to IRQs:

pario0: gpio-controller@0 {
	#gpio-cells = <2>;
	num-ports = <7>;
};

device@0 {
	gpios = <bank pin bank pin bank pin>;
	gpio-parent = <&pario0>;
};

"bank pin" scheme is controller specific, so controllers that want to implement flat mappings or any other could do so.

So far I implemented GPIO API for QE and CPM2 chips. GPIO API for CPM1 implemented by Jochen Friedrich <[email protected]>, included in this patchset.

- QE GPIO API tested to work with FSL UPM NAND driver and MPC8360E-RDK (STMicro NAND512W3A2BN6E);
- CPM2 GPIO API tested to work with MPC8555E+Samsung HY27UF081G6 (LP);
- CPM1 GPIO API untested.

GPIO API is described in Documentation/gpio.txt, and these patches are tend to support most of it.

As an additional bonus, PowerPC now gets access to few pleasing drivers:

- drivers/leds/leds-gpio.c (we could use it to play with on-board LEDs);
- drivers/i2c/busses/i2c-gpio.c (generic I2C bit-banging driver);
- drivers/input/keyboard/gpio_keys.c - gpio keys (requires gpio_to_irq, so far not implemented);
- Could be more (I named the ones I knew about).

Also, in the upcoming kernels, there will be GPIOLIB[1] addition to the generic GPIO API, to support off-chip GPIO expanders (like MFDs on I2C/LBC). But so far we support on-chip GPIOs only, with single controller built-in.

Changes since RFC:
- Implemented #gpio-cells handling;
- Per-bank spinlocks removed;
- Added a patch which implements GPIO API for CPM1;
- Few minor fixes.

Thanks,

[1] http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.24-rc4/2.6.24-rc4-mm1/broken-out/generic-gpio-gpio_chip-support.patch

Anton Vorontsov
email: [email protected]
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