device-tree-bindings/gpio/gpio.txt

4 1) gpios property
5 -----------------
7 Nodes that makes use of GPIOs should specify them using one or more
8 properties, each containing a 'gpio-list':
10 	gpio-list ::= <single-gpio> [gpio-list]
11 	single-gpio ::= <gpio-phandle> <gpio-specifier>
12 	gpio-phandle : phandle to gpio controller node
13 	gpio-specifier : Array of #gpio-cells specifying specific gpio
16 GPIO properties should be named "[<name>-]gpios", with <name> being the purpose
17 of this GPIO for the device. While a non-existent <name> is considered valid
18 for compatibility reasons (resolving to the "gpios" property), it is not allowed
21 GPIO properties can contain one or more GPIO phandles, but only in exceptional
22 cases should they contain more than one. If your device uses several GPIOs with
24 meaningful name. The only case where an array of GPIOs is accepted is when
25 several GPIOs serve the same function (e.g. a parallel data line).
27 The exact purpose of each gpios property must be documented in the device tree
31 and bit-banged data signals:
34 		gpio-controller
35 		 #gpio-cells = <2>;
38 		gpio-controller
39 		 #gpio-cells = <1>;
43 	enable-gpios = <&gpio2 2>;
44 	data-gpios = <&gpio1 12 0>,
49 Note that gpio-specifier length is controller dependent.  In the
53 gpio-specifier may encode: bank, pin position inside the bank,
54 whether pin is open-drain and whether pin is logically inverted.
56 be documented in the device tree binding for the device. Use the macros
57 defined in include/dt-bindings/gpio/gpio.h whenever possible:
59 Example of a node using GPIOs:
62 		enable-gpios = <&qe_pio_e 18 GPIO_ACTIVE_HIGH>;
65 GPIO_ACTIVE_HIGH is 0, so in this example gpio-specifier is "18 0" and encodes
66 GPIO pin number, and GPIO flags as accepted by the "qe_pio_e" gpio-controller.
69 ----------------------------------
71 A gpio-specifier should contain a flag indicating the GPIO polarity; active-
72 high or active-low. If it does, the following best practices should be
75 The gpio-specifier's polarity flag should represent the physical level at the
79 the GPIO controller and the device, then the gpio-specifier will represent the
91 a1) (Preferred) Dictated by a binding-specific DT property.
97 In particular, the polarity cannot be derived from the gpio-specifier, since
99 concepts of configurable signal polarity in the device, and possible board-
105 in the binding. The gpio-specifier should represent the polarity of the signal
112 2) gpio-controller nodes
113 ------------------------
115 Every GPIO controller node must contain both an empty "gpio-controller"
116 property, and a #gpio-cells integer property, which indicates the number of
117 cells in a gpio-specifier.
119 Example of two SOC GPIO banks defined as gpio-controller nodes:
121 	qe_pio_a: gpio-controller@1400 {
122 		compatible = "fsl,qe-pario-bank-a", "fsl,qe-pario-bank";
124 		gpio-controller;
125 		#gpio-cells = <2>;
128 	qe_pio_e: gpio-controller@1460 {
129 		compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank";
131 		gpio-controller;
132 		#gpio-cells = <2>;
135 2.1) gpio- and pin-controller interaction
136 -----------------------------------------
138 Some or all of the GPIOs provided by a GPIO controller may be routed to pins
142 It is useful to represent which GPIOs correspond to which pins on which pin
143 controllers. The gpio-ranges property described below represents this, and
146 	gpio-range-list ::= <single-gpio-range> [gpio-range-list]
147 	single-gpio-range ::= <numeric-gpio-range> | <named-gpio-range>
148 	numeric-gpio-range ::=
149 			<pinctrl-phandle> <gpio-base> <pinctrl-base> <count>
150 	named-gpio-range ::= <pinctrl-phandle> <gpio-base> '<0 0>'
151 	pinctrl-phandle : phandle to pin controller node
152 	gpio-base : Base GPIO ID in the GPIO controller
153 	pinctrl-base : Base pinctrl pin ID in the pin controller
154 	count : The number of GPIOs/pins in this range
157 described in ../pinctrl/pinctrl-bindings.txt.
159 In case named gpio ranges are used (ranges with both <pinctrl-base> and
160 <count> set to 0), the property gpio-ranges-group-names contains one string
161 for every single-gpio-range in gpio-ranges:
162 	gpiorange-names-list ::= <gpiorange-name> [gpiorange-names-list]
163 	gpiorange-name : Name of the pingroup associated to the GPIO range in
166 Elements of gpiorange-names-list corresponding to numeric ranges contain
167 the empty string. Elements of gpiorange-names-list corresponding to named
168 ranges contain the name of a pin group defined in the respective pin
169 controller. The number of pins/GPIOs in the range is the number of pins in
173 were referenced by any gpio-ranges property to contain a property named
174 #gpio-range-cells with value <3>. This requirement is now deprecated.
175 However, that property may still exist in older device trees for
176 compatibility reasons, and would still be required even in new device
181 	qe_pio_e: gpio-controller@1460 {
182 		#gpio-cells = <2>;
183 		compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank";
185 		gpio-controller;
186 		gpio-ranges = <&pinctrl1 0 20 10>, <&pinctrl2 10 50 20>;
189 Here, a single GPIO controller has GPIOs 0..9 routed to pin controller
190 pinctrl1's pins 20..29, and GPIOs 10..19 routed to pin controller pinctrl2's
195 	gpio_pio_i: gpio-controller@14B0 {
196 		#gpio-cells = <2>;
197 		compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank";
199 		gpio-controller;
200 		gpio-ranges =			<&pinctrl1 0 20 10>,
204 		gpio-ranges-group-names =	"",
215 -----------------------
219 gpio-controller's driver probe function.
223 - gpio-hog:   A property specifying that this child node represents a GPIO hog.
224 - gpios:      Store the GPIO information (id, flags) for the GPIO to
229 Only one of the following properties scanned in the order shown below.
230 - input:      A property specifying to set the GPIO direction as input.
231 - output-low  A property specifying to set the GPIO direction as output with
233 - output-high A property specifying to set the GPIO direction as output with
237 - line-name:  The GPIO label name. If not present the node name is used.
244                 #gpio-cells = <2>;
245                 gpio-controller;
248                         gpio-hog;
250                         gpios = <6 GPIO_ACTIVE_LOW>;
253                         gpio-hog;
255                         line-name = "foo-bar-gpio";
256                         gpios = <7 GPIO_ACTIVE_LOW>;
260 For the above Example you can than access the gpio in your boardcode