Each GPIO should be mapped on the device tree as:
XX_YY_ZZ_LSIO_GPIO#_IO#
<details>
<summary>Click here</summary>
| Code Block | ||
|---|---|---|
| ||
imx8qxp-qx8x {
pinctrl_hog: hoggrp {
fsl,pins = <
SC_P_SPI2_SDO_LSIO_GPIO1_IO01 0x00000021 /* GPIO 0 (449) */
SC_P_SPI2_CS0_LSIO_GPIO1_IO00 0x00000021 /* GPIO 1 (448) */
SC_P_SPI2_SDI_LSIO_GPIO1_IO02 0x00000021 /* GPIO 2 (450) */
SC_P_SPI2_SCK_LSIO_GPIO1_IO03 0x00000021 /* GPIO 3 (451)*/
SC_P_SPI0_CS0_LSIO_GPIO1_IO08 0x00000021 /* GPIO 4 (456) */
SC_P_FLEXCAN2_RX_LSIO_GPIO1_IO19 0x00000021 /* GPIO 5 (467) */
SC_P_SPI0_SDI_LSIO_GPIO1_IO05 0x00000021 /* GPIO 6 (453) */
SC_P_FLEXCAN2_TX_LSIO_GPIO1_IO20 0x00000021 /* GPIO 7 (468) */
SC_P_MIPI_DSI0_GPIO0_01_LSIO_GPIO1_IO28 0x00000021 /* LVDS0_PPEN (476) */
SC_P_MIPI_DSI1_GPIO0_01_LSIO_GPIO2_IO00 0x00000021 /* LVDS0_BLEN (416) */
>;
}; |
</details>
the GPIO# matches the gpiochip
the IO# is the specific GPIO number into the chip
To calculate the number where the GPIO is mapped into the userspace this are the correspondence:
GPIO | #user space |
|---|---|
-- | -- |
0 | 480 |
1 | 448 |
2 | 416 |
3 | 384 |
4 | 352 |
5 | 320 |
6 | 288 |
7 | 256 |
Then add the specific number of the IO to the gpiochip and this will be the GPIO number into the userspace
e.g: SC_P_M40_GPIO0_01_LSIO_GPIO0_IO09
GPIO chip 0 → 480
IO number → 9
gpio number → 480+9 = 489
To have access to it do the following
| Code Block | ||
|---|---|---|
| ||
cd /sys/class/gpio
echo 489 > export
cd gpio489
echo out > direction
echo 1 > value
echo 0 > value
echo in > direction |