[PATCHv2 2/2] usb: pci-quirks: register USB mux found on Cherrytrail SOC

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

Intel Braswell/Cherrytrail has an internal mux that shares
one USB port between USB Device Controller and xHCI. The
same mux is found on several SOCs from Intel, but only on
a few Cherrytrail based platforms the OS is expected to
configure it. Normally BIOS takes care of it.

The driver for the mux is an "extcon" driver. With this we
only register the mux if it's detected.

Suggested-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
 drivers/usb/host/pci-quirks.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
index 26cb8c8..ee875e1 100644
--- a/drivers/usb/host/pci-quirks.c
+++ b/drivers/usb/host/pci-quirks.c
@@ -16,6 +16,7 @@
 #include <linux/export.h>
 #include <linux/acpi.h>
 #include <linux/dmi.h>
+#include <linux/extcon/intel_usb_mux.h>
 #include "pci-quirks.h"
 #include "xhci-ext-caps.h"
 
@@ -1022,9 +1023,32 @@ static void quirk_usb_handoff_xhci(struct pci_dev *pdev)
 	writel(val, base + ext_cap_offset + XHCI_LEGACY_CONTROL_OFFSET);
 
 hc_init:
-	if (pdev->vendor == PCI_VENDOR_ID_INTEL)
+	if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
 		usb_enable_intel_xhci_ports(pdev);
 
+		/*
+		 * Initialize the internal mux that shares a port between USB
+		 * Device Controller and xHCI on platforms that have it.
+		 */
+#define XHCI_INTEL_VENDOR_CAPS 192
+#define XHCI_INTEL_USB_MUX_OFFSET 0x80d8
+		if (xhci_find_next_ext_cap(base, 0, XHCI_INTEL_VENDOR_CAPS)) {
+			struct intel_usb_mux *mux;
+			struct resource r;
+
+			r.start = pci_resource_start(pdev, 0) +
+					XHCI_INTEL_USB_MUX_OFFSET;
+			r.end   = r.start + 8;
+			r.flags = IORESOURCE_MEM;
+
+			mux = intel_usb_mux_register(&pdev->dev, &r);
+			if (IS_ERR(mux) && PTR_ERR(mux) == -ENOTSUPP)
+				dev_dbg(&pdev->dev, "USB mux not supported\n");
+			else if (IS_ERR(mux))
+				dev_err(&pdev->dev, "failed to register mux\n");
+		}
+	}
+
 	op_reg_base = base + XHCI_HC_LENGTH(readl(base));
 
 	/* Wait for the host controller to be ready before writing any
-- 
2.6.2