u-boot/doc/README.gpio
Patrick Delaunay 6a0388c5b1 dt-bindings: gpio: alignment with kernel v5.3
Update the binding file for gpio, it is just an alignment
with kernel v5.3.
The U-Boot code example for gpio-hog (not directly linked
to binding) is moved in a new file doc/README.gpio.
[commit 21676b706e99 ("gpio: fixes for gpio-hog support")
& 'commit 4762a9988ede ("gpio: add gpio-hog support")']

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2020-04-16 23:06:54 -04:00

43 lines
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GPIO hog (CONFIG_GPIO_HOG)
--------
All the GPIO hog are initialized in gpio_hog_probe_all() function called in
board_r.c just before board_late_init() but you can also acces directly to
the gpio with gpio_hog_lookup_name().
Example, for the device tree:
tca6416@20 {
compatible = "ti,tca6416";
reg = <0x20>;
#gpio-cells = <2>;
gpio-controller;
env_reset {
gpio-hog;
input;
gpios = <6 GPIO_ACTIVE_LOW>;
};
boot_rescue {
gpio-hog;
input;
line-name = "foo-bar-gpio";
gpios = <7 GPIO_ACTIVE_LOW>;
};
};
You can than access the gpio in your board code with:
struct gpio_desc *desc;
int ret;
ret = gpio_hog_lookup_name("boot_rescue", &desc);
if (ret)
return;
if (dm_gpio_get_value(desc) == 1)
printf("\nBooting into Rescue System\n");
else if (dm_gpio_get_value(desc) == 0)
printf("\nBoot normal\n");