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| author | Patrick Delaunay <patrick.delaunay@st.com> | 2020-01-13 11:34:58 +0100 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2020-04-16 23:06:54 -0400 |
| commit | 1bb257a9b33d499e1d9f6edad8d3396243741b81 (patch) | |
| tree | f4d2dd1b7e9af76707db4c6280621f19ff755c5e /doc | |
| parent | e93f39213a3d614a33989878d85724cba30a9deb (diff) | |
| download | u-boot-1bb257a9b33d499e1d9f6edad8d3396243741b81.zip u-boot-1bb257a9b33d499e1d9f6edad8d3396243741b81.tar.gz u-boot-1bb257a9b33d499e1d9f6edad8d3396243741b81.tar.bz2 | |
dt-bindings: gpio: document the new pull-up/pull-down flags
This commit extends the flags that can be used in GPIO specifiers to
indicate if a pull-up resistor or pull-down resistor should be
enabled.
It is the backport of linux commit ede033e1e863c ('dt-bindings:
gpio: document the new pull-up/pull-down flags')
from Thomas Petazzoni <thomas.petazzoni@bootlin.com>
and integrated in v5.1-rc1
https://github.com/torvalds/linux/commit/ede033e1e863c
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/device-tree-bindings/gpio/gpio.txt | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/doc/device-tree-bindings/gpio/gpio.txt b/doc/device-tree-bindings/gpio/gpio.txt index e146917..e9ef021 100644 --- a/doc/device-tree-bindings/gpio/gpio.txt +++ b/doc/device-tree-bindings/gpio/gpio.txt @@ -65,6 +65,30 @@ Example of a node using GPIOs: GPIO_ACTIVE_HIGH is 0, so in this example gpio-specifier is "18 0" and encodes GPIO pin number, and GPIO flags as accepted by the "qe_pio_e" gpio-controller. +Optional standard bitfield specifiers for the last cell: + +- Bit 0: 0 means active high, 1 means active low +- Bit 1: 0 mean push-pull wiring, see: + https://en.wikipedia.org/wiki/Push-pull_output + 1 means single-ended wiring, see: + https://en.wikipedia.org/wiki/Single-ended_triode +- Bit 2: 0 means open-source, 1 means open drain, see: + https://en.wikipedia.org/wiki/Open_collector +- Bit 3: 0 means the output should be maintained during sleep/low-power mode + 1 means the output state can be lost during sleep/low-power mode +- Bit 4: 0 means no pull-up resistor should be enabled + 1 means a pull-up resistor should be enabled + This setting only applies to hardware with a simple on/off + control for pull-up configuration. If the hardware has more + elaborate pull-up configuration, it should be represented + using a pin control binding. +- Bit 5: 0 means no pull-down resistor should be enabled + 1 means a pull-down resistor should be enabled + This setting only applies to hardware with a simple on/off + control for pull-down configuration. If the hardware has more + elaborate pull-down configuration, it should be represented + using a pin control binding. + 1.1) GPIO specifier best practices ---------------------------------- |