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由 Simon Glass 提交于
At present U-Boot sort-of supports the standard way of reading GPIOs from device tree nodes, but the support is incomplete, a bit clunky and only works for GPIO bindings where #gpio-cells is 2. Add new functions to request GPIOs, taking full account of the device tree binding. These permit requesting a GPIO with a simple call like: gpio_request_by_name(dev, "cd-gpios", 0, &desc, GPIOD_IS_IN); This will request the GPIO, looking at the device's node which might be this, for example: cd-gpios = <&gpio TEGRA_GPIO(B, 3) GPIO_ACTIVE_LOW>; The GPIO will be set to input mode in this case and polarity will be honoured by the GPIO calls. It is also possible to request and free a list of GPIOs. Signed-off-by: NSimon Glass <sjg@chromium.org>
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