w1: Add 1-Wire gpio driver

Add a bus driver for bitbanging a 1-Wire bus over a GPIO.

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
[eugen.hristev@microchip.com: fixed some issues]
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
diff --git a/drivers/w1/Kconfig b/drivers/w1/Kconfig
index 64b27c6..d6e0457 100644
--- a/drivers/w1/Kconfig
+++ b/drivers/w1/Kconfig
@@ -13,6 +13,13 @@
 
 if W1
 
+config W1_GPIO
+	bool "Enable 1-wire GPIO bitbanging"
+	default no
+	depends on DM_GPIO
+	help
+	  Emulate a 1-wire bus using a GPIO.
+
 endif
 
 endmenu