gpiopps support patch

[yamori813_yahoo.co.jp]

Summary

This is dev/gpio/gpiopps.c support patch. I added code base on
arm/freescale/imx/imx_gpio.c. I add this to my dts.

pps {
        compatible = "pps-gpio";
        gpios = <&gpio0 10 GPIO_ACTIVE_LOW>;
        status = "okay";
        assert-falling-edge;
};

Also add gpiopps device to kernel configuration.

I check use this module. Sorry only Japanes page.

http://akizukidenshi.com/catalog/g/gK-09991/

Test Plan

FON2405(RT3050) with 8M SPI Flash

[mizhka]

@sgalabov , could you please have a look? Thanks!

sys/mips/mediatek/mtk_gpio_v1.c

294–297 ↗

(On Diff #25648)

sc->pins[i].pin_caps |= GPIO_PIN_INPUT | GPIO_PIN_OUTPUT |

GPIO_PIN_INVIN | GPIO_PIN_INVOUT | 
GPIO_INTR_EDGE_RISING | GPIO_INTR_EDGE_FALLING;

508 ↗

(On Diff #25648)

uint32_t?

571–573 ↗

(On Diff #25648)

error may be EINVAL. It's better to printf error before lost of context.

[yamori813_yahoo.co.jp]

• review refict

[yamori813_yahoo.co.jp]

I seem irq is u_int from other code.