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| -rw-r--r-- | Documentation/w1/masters/w1-gpio.rst | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/Documentation/w1/masters/w1-gpio.rst b/Documentation/w1/masters/w1-gpio.rst new file mode 100644 index 000000000..152366055 --- /dev/null +++ b/Documentation/w1/masters/w1-gpio.rst @@ -0,0 +1,47 @@ +===================== +Kernel driver w1-gpio +===================== + +Author: Ville Syrjala <syrjala@sci.fi> + + +Description +----------- + +GPIO 1-wire bus master driver. The driver uses the GPIO API to control the +wire and the GPIO pin can be specified using GPIO machine descriptor tables. +It is also possible to define the master using device tree, see +Documentation/devicetree/bindings/w1/w1-gpio.yaml + + +Example (mach-at91) +------------------- + +:: + + #include <linux/gpio/machine.h> + #include <linux/w1-gpio.h> + + static struct gpiod_lookup_table foo_w1_gpiod_table = { + .dev_id = "w1-gpio", + .table = { + GPIO_LOOKUP_IDX("at91-gpio", AT91_PIN_PB20, NULL, 0, + GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN), + }, + }; + + static struct w1_gpio_platform_data foo_w1_gpio_pdata = { + .ext_pullup_enable_pin = -EINVAL, + }; + + static struct platform_device foo_w1_device = { + .name = "w1-gpio", + .id = -1, + .dev.platform_data = &foo_w1_gpio_pdata, + }; + + ... + at91_set_GPIO_periph(foo_w1_gpio_pdata.pin, 1); + at91_set_multi_drive(foo_w1_gpio_pdata.pin, 1); + gpiod_add_lookup_table(&foo_w1_gpiod_table); + platform_device_register(&foo_w1_device); |