usb: chipidea: imx: implement workaround for ERR051725

ERR051725:
USB: With the USB controller configured as device mode, Clearing the RS
bit of USBCMD register fails to cause USB device to be detached

Description
1. USB controller working as high speed device mode with USB gadget
   function enabled
2. Cable plugged into USB host
3. Use case is software-controlled detach from USB device side

The expected result is device side terminations removed, increase in USB
signal amplitude, USB host detect device is detached. But the issue is
that the clear RS bit of USBCMD register cannot cause device detach event.

Workaround
- Use the below steps to detach from the host:
    write USBCMD.RS = 0b
    write CTRL2[7:6] = 01b
    write CTRL2[8] = 1b
- As CTRL2[8] is set at detach case, so attach the steps should add clear
  CTRL2[8]:
    write USBCMD.RS = 1b
    write CTRL2[8] = 0b

Signed-off-by: Xu Yang <[email protected]>
Acked-by: Peter Chen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Xu Yang

drivers/usb/chipidea/ci_hdrc_imx.c

@@ -331,6 +331,11 @@ static int ci_hdrc_imx_notify_event(struct ci_hdrc *ci, unsigned int event)
 		if (ci->usb_phy)
 			schedule_work(&ci->usb_phy->chg_work);
 		break;
+	case CI_HDRC_CONTROLLER_PULLUP_EVENT:
+		if (ci->role == CI_ROLE_GADGET)
+			imx_usbmisc_pullup(data->usbmisc_data,
+					   ci->gadget.connected);
+		break;
 	default:
 		break;
 	}

drivers/usb/chipidea/usbmisc_imx.c

@@ -998,6 +998,25 @@ static int usbmisc_imx7ulp_init(struct imx_usbmisc_data *data)
 	return 0;
 }
 
+static void usbmisc_imx7d_pullup(struct imx_usbmisc_data *data, bool on)
+{
+	struct imx_usbmisc *usbmisc = dev_get_drvdata(data->dev);
+	unsigned long flags;
+	u32 val;
+
+	spin_lock_irqsave(&usbmisc->lock, flags);
+	val = readl(usbmisc->base + MX7D_USBNC_USB_CTRL2);
+	if (!on) {
+		val &= ~MX7D_USBNC_USB_CTRL2_OPMODE_OVERRIDE_MASK;
+		val |= MX7D_USBNC_USB_CTRL2_OPMODE(1);
+		val |= MX7D_USBNC_USB_CTRL2_OPMODE_OVERRIDE_EN;
+	} else {
+		val &= ~MX7D_USBNC_USB_CTRL2_OPMODE_OVERRIDE_EN;
+	}
+	writel(val, usbmisc->base + MX7D_USBNC_USB_CTRL2);
+	spin_unlock_irqrestore(&usbmisc->lock, flags);
+}
+
 static int usbmisc_imx7d_power_lost_check(struct imx_usbmisc_data *data)
 {
 	struct imx_usbmisc *usbmisc = dev_get_drvdata(data->dev);
@@ -1115,6 +1134,7 @@ static const struct usbmisc_ops imx7d_usbmisc_ops = {
 	.set_wakeup = usbmisc_imx7d_set_wakeup,
 	.charger_detection = imx7d_charger_detection,
 	.power_lost_check = usbmisc_imx7d_power_lost_check,
+	.pullup = usbmisc_imx7d_pullup,
 	.vbus_comparator_on = usbmisc_imx7d_vbus_comparator_on,
 };
 
@@ -1131,6 +1151,7 @@ static const struct usbmisc_ops imx95_usbmisc_ops = {
 	.set_wakeup = usbmisc_imx95_set_wakeup,
 	.charger_detection = imx7d_charger_detection,
 	.power_lost_check = usbmisc_imx7d_power_lost_check,
+	.pullup = usbmisc_imx7d_pullup,
 	.vbus_comparator_on = usbmisc_imx7d_vbus_comparator_on,
 };