[PATCH] extcon-usb-gpio: add enable pin support

Sergei Shtylyov
2015-12-10T23:07:24Z

Sometimes there's a real OTG chip behind the USB ID signal mapped to a GPIO
pin: in my case it's Maxim Integrated MAX3355E which integrates Vbus charge
pump and comparators and passes thru the ID signal from an OTG connector.
This chip also has the SHDN# pin which should be driven high for the normal
operation and low to save power; it is connected to a GPIO pin as well on,
hence we'll have to teach the driver to parse the new optional device tree
property, "enable-gpio"...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

---
The patch is against the 'extcon-next' branch of the 'extcon.git' repo.

Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt | 3 +++
drivers/extcon/extcon-usb-gpio.c | 5 +++++
2 files changed, 8 insertions(+)

Index: extcon/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
===================================================================
--- extcon.orig/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
+++ extcon/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
@@ -7,6 +7,9 @@ Required properties:
- compatible: Should be "linux,extcon-usb-gpio"
- id-gpio: gpio for USB ID pin. See gpio binding.

+Optional properties:
+- enable-gpio: gpio for the enable pin. See gpio binding.
+
Example: Examples of extcon-usb-gpio node in dra7-evm.dts as listed below:
extcon_usb1 {
compatible = "linux,extcon-usb-gpio";
Index: extcon/drivers/extcon/extcon-usb-gpio.c
===================================================================
--- extcon.orig/drivers/extcon/extcon-usb-gpio.c
+++ extcon/drivers/extcon/extcon-usb-gpio.c
@@ -33,6 +33,7 @@ struct usb_extcon_info {
struct device *dev;
struct extcon_dev *edev;

+ struct gpio_desc *enable_gpiod;
struct gpio_desc *id_gpiod;
int id_irq;

@@ -99,6 +100,8 @@ static int usb_extcon_probe(struct platf
return -ENOMEM;

info->dev = dev;
+ info->enable_gpiod = devm_gpiod_get_optional(&pdev->dev, "enable",
+ GPIOD_OUT_HIGH);
info->id_gpiod = devm_gpiod_get(&pdev->dev, "id", GPIOD_IN);
if (IS_ERR(info->id_gpiod)) {
dev_err(dev, "failed to get ID GPIO\n");
@@ -155,6 +158,8 @@ static int usb_extcon_remove(struct plat

cancel_delayed_work_sync(&info->wq_detcable);

+ gpiod_set_value_cansleep(info->enable_gpiod, 0);
+
return 0;
}