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@@ -21,8 +21,8 @@ exact way to do it depends on the GPIO controller providing the GPIOs, see the
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device tree bindings for your controller.
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GPIOs mappings are defined in the consumer device's node, in a property named
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-<function>-gpios, where <function> is the function the driver will request
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-through gpiod_get(). For example:
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+either <function>-gpios or <function>-gpio, where <function> is the function
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+the driver will request through gpiod_get(). For example:
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foo_device {
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compatible = "acme,foo";
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@@ -31,7 +31,7 @@ through gpiod_get(). For example:
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<&gpio 16 GPIO_ACTIVE_HIGH>, /* green */
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<&gpio 17 GPIO_ACTIVE_HIGH>; /* blue */
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- power-gpios = <&gpio 1 GPIO_ACTIVE_LOW>;
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+ power-gpio = <&gpio 1 GPIO_ACTIVE_LOW>;
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};
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This property will make GPIOs 15, 16 and 17 available to the driver under the
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@@ -39,15 +39,24 @@ This property will make GPIOs 15, 16 and 17 available to the driver under the
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struct gpio_desc *red, *green, *blue, *power;
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- red = gpiod_get_index(dev, "led", 0);
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- green = gpiod_get_index(dev, "led", 1);
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- blue = gpiod_get_index(dev, "led", 2);
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+ red = gpiod_get_index(dev, "led", 0, GPIOD_OUT_HIGH);
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+ green = gpiod_get_index(dev, "led", 1, GPIOD_OUT_HIGH);
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+ blue = gpiod_get_index(dev, "led", 2, GPIOD_OUT_HIGH);
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- power = gpiod_get(dev, "power");
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+ power = gpiod_get(dev, "power", GPIOD_OUT_HIGH);
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The led GPIOs will be active-high, while the power GPIO will be active-low (i.e.
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gpiod_is_active_low(power) will be true).
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+The second parameter of the gpiod_get() functions, the con_id string, has to be
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+the <function>-prefix of the GPIO suffixes ("gpios" or "gpio", automatically
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+looked up by the gpiod functions internally) used in the device tree. With above
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+"led-gpios" example, use the prefix without the "-" as con_id parameter: "led".
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+
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+Internally, the GPIO subsystem prefixes the GPIO suffix ("gpios" or "gpio")
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+with the string passed in con_id to get the resulting string
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+(snprintf(... "%s-%s", con_id, gpio_suffixes[]).
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+
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ACPI
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----
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ACPI also supports function names for GPIOs in a similar fashion to DT.
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@@ -142,13 +151,14 @@ The driver controlling "foo.0" will then be able to obtain its GPIOs as follows:
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struct gpio_desc *red, *green, *blue, *power;
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- red = gpiod_get_index(dev, "led", 0);
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- green = gpiod_get_index(dev, "led", 1);
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- blue = gpiod_get_index(dev, "led", 2);
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+ red = gpiod_get_index(dev, "led", 0, GPIOD_OUT_HIGH);
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+ green = gpiod_get_index(dev, "led", 1, GPIOD_OUT_HIGH);
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+ blue = gpiod_get_index(dev, "led", 2, GPIOD_OUT_HIGH);
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- power = gpiod_get(dev, "power");
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- gpiod_direction_output(power, 1);
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+ power = gpiod_get(dev, "power", GPIOD_OUT_HIGH);
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-Since the "power" GPIO is mapped as active-low, its actual signal will be 0
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-after this code. Contrary to the legacy integer GPIO interface, the active-low
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-property is handled during mapping and is thus transparent to GPIO consumers.
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+Since the "led" GPIOs are mapped as active-high, this example will switch their
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+signals to 1, i.e. enabling the LEDs. And for the "power" GPIO, which is mapped
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+as active-low, its actual signal will be 0 after this code. Contrary to the legacy
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+integer GPIO interface, the active-low property is handled during mapping and is
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+thus transparent to GPIO consumers.
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