usb: fotg210-udc: Implement VBUS session

Implement VBUS session handling for FOTG210. This is
mainly used by the UDC driver which needs to call down to
the FOTG210 core and enable/disable VBUS, as this needs to be
handled outside of the HCD and UDC drivers, by platform
specific glue code.

The Gemini has a special bit in a system register to turn
VBUS on and off so we implement this in the FOTG210 core.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230103-gemini-fotg210-usb-v2-7-100388af9810@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/fotg210/fotg210-core.c

@@ -95,6 +95,35 @@ static int fotg210_gemini_init(struct fotg210 *fotg, struct resource *res,
 	return 0;
 }
 
+/**
+ * fotg210_vbus() - Called by gadget driver to enable/disable VBUS
+ * @enable: true to enable VBUS, false to disable VBUS
+ */
+void fotg210_vbus(struct fotg210 *fotg, bool enable)
+{
+	u32 mask;
+	u32 val;
+	int ret;
+
+	switch (fotg->port) {
+	case GEMINI_PORT_0:
+		mask = GEMINI_MISC_USB0_VBUS_ON;
+		val = enable ? GEMINI_MISC_USB0_VBUS_ON : 0;
+		break;
+	case GEMINI_PORT_1:
+		mask = GEMINI_MISC_USB1_VBUS_ON;
+		val = enable ? GEMINI_MISC_USB1_VBUS_ON : 0;
+		break;
+	default:
+		return;
+	}
+	ret = regmap_update_bits(fotg->map, GEMINI_GLOBAL_MISC_CTRL, mask, val);
+	if (ret)
+		dev_err(fotg->dev, "failed to %s VBUS\n",
+			enable ? "enable" : "disable");
+	dev_info(fotg->dev, "%s: %s VBUS\n", __func__, enable ? "enable" : "disable");
+}
+
 static int fotg210_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;

drivers/usb/fotg210/fotg210-udc.c

@@ -1082,9 +1082,26 @@ static int fotg210_udc_stop(struct usb_gadget *g)
 	return 0;
 }
 
+/**
+ * fotg210_vbus_session - Called by external transceiver to enable/disable udc
+ * @_gadget: usb gadget
+ * @is_active: 0 if should disable UDC VBUS, 1 if should enable
+ *
+ * Returns 0
+ */
+static int fotg210_vbus_session(struct usb_gadget *g, int is_active)
+{
+	struct fotg210_udc *fotg210 = gadget_to_fotg210(g);
+
+	/* Call down to core integration layer to drive or disable VBUS */
+	fotg210_vbus(fotg210->fotg, is_active);
+	return 0;
+}
+
 static const struct usb_gadget_ops fotg210_gadget_ops = {
 	.udc_start		= fotg210_udc_start,
 	.udc_stop		= fotg210_udc_stop,
+	.vbus_session		= fotg210_vbus_session,
 };
 
 /**

drivers/usb/fotg210/fotg210.h

@@ -17,6 +17,8 @@ struct fotg210 {
 	enum gemini_port port;
 };
 
+void fotg210_vbus(struct fotg210 *fotg, bool enable);
+
 #ifdef CONFIG_USB_FOTG210_HCD
 int fotg210_hcd_probe(struct platform_device *pdev, struct fotg210 *fotg);
 int fotg210_hcd_remove(struct platform_device *pdev);