| Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 1 | Raspberry Pi GPIO expander |
| 2 | |
| 3 | The Raspberry Pi 3 GPIO expander is controlled by the VC4 firmware. The |
| 4 | firmware exposes a mailbox interface that allows the ARM core to control the |
| 5 | GPIO lines on the expander. |
| 6 | |
| 7 | The Raspberry Pi GPIO expander node must be a child node of the Raspberry Pi |
| 8 | firmware node. |
| 9 | |
| 10 | Required properties: |
| 11 | |
| 12 | - compatible : Should be "raspberrypi,firmware-gpio" |
| 13 | - gpio-controller : Marks the device node as a gpio controller |
| 14 | - #gpio-cells : Should be two. The first cell is the pin number, and |
| 15 | the second cell is used to specify the gpio polarity: |
| 16 | 0 = active high |
| 17 | 1 = active low |
| 18 | |
| 19 | Example: |
| 20 | |
| 21 | firmware: firmware-rpi { |
| 22 | compatible = "raspberrypi,bcm2835-firmware"; |
| 23 | mboxes = <&mailbox>; |
| 24 | |
| 25 | expgpio: gpio { |
| 26 | compatible = "raspberrypi,firmware-gpio"; |
| 27 | gpio-controller; |
| 28 | #gpio-cells = <2>; |
| 29 | }; |
| 30 | }; |