[PATCH v4 10/18] usb: dwc3: Add support for usb-conn-gpio connectors

[Bryan O'Donoghue <bryan.odonoghue@linaro.org>]

This patch adds the ability to probe and enumerate a connector based on
usb-conn-gpio. A device node label gpio_usb_connector is used to identify
a usb-conn-gpio as a child of the USB interface.

You would use usb-conn-gpio when a regulator in your system provides VBUS
directly to the connector instead of supplying via the USB PHY.

The parent device must have the "usb-role-switch" property, so that when
the usb-conn-gpio driver calls usb_role_switch_set_role() the notification
in dwc3 will run and the block registers will be updated to match the state
detected at the connector.

Cc: John Stultz <john.stultz@linaro.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
CC: ShuFan Lee <shufan_lee@richtek.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc: Yu Chen <chenyu56@huawei.com>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jun Li <lijun.kernel@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Jack Pham <jackp@codeaurora.org>
Cc: linux-usb@vger.kernel.org
Cc: devicetree@vger.kernel.org
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
---
 drivers/usb/dwc3/drd.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index c355166793d0..c1825fd655f6 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c
@@ -11,6 +11,7 @@
 #include <linux/of_graph.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
+#include <linux/of_platform.h>
 
 #include "debug.h"
 #include "core.h"
@@ -537,8 +538,29 @@ static int dwc3_setup_role_switch(struct dwc3 *dwc)
 	dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
 	return 0;
 }
+
+static int dwc3_register_gpio_usb_connector(struct dwc3 *dwc)
+{
+	struct device		*dev = dwc->dev;
+	struct device_node	*np = dev->of_node, *conn_np;
+	int			ret = 0;
+
+	conn_np = of_get_child_by_name(np, "connector");
+	if (!conn_np) {
+		dev_dbg(dev, "no connector child node specified\n");
+		goto done;
+	}
+
+	if (of_device_is_compatible(conn_np, "gpio-usb-b-connector"))
+		ret = of_platform_populate(np, NULL, NULL, dev);
+done:
+	of_node_put(conn_np);
+	return ret;
+}
+
 #else
 #define dwc3_setup_role_switch(x) 0
+#define dwc3_register_gpio_usb_connector(x) 0
 #endif
 
 int dwc3_drd_init(struct dwc3 *dwc)
@@ -554,6 +576,9 @@ int dwc3_drd_init(struct dwc3 *dwc)
 		ret = dwc3_setup_role_switch(dwc);
 		if (ret < 0)
 			return ret;
+		ret = dwc3_register_gpio_usb_connector(dwc);
+		if (ret < 0)
+			return ret;
 	} else if (dwc->edev) {
 		dwc->edev_nb.notifier_call = dwc3_drd_notifier;
 		ret = extcon_register_notifier(dwc->edev, EXTCON_USB_HOST,
-- 
2.25.0