>From da44e961605d382829f90fdcfb90b61fa5ca9590 Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman@linux.intel.com>
Date: Tue, 19 Sep 2017 14:58:40 +0300
Subject: [PATCH 2/2] xhci: test xhci_find_next_ext_cap with 0 id

NOT for UPSTREAM, just testing/reference code

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci-ext-caps.h |  3 +++
 drivers/usb/host/xhci.c          | 30 ++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h
index c1b4042..7deb9e7 100644
--- a/drivers/usb/host/xhci-ext-caps.h
+++ b/drivers/usb/host/xhci-ext-caps.h
@@ -51,6 +51,9 @@
 #define XHCI_EXT_CAPS_ROUTE	5
 /* IDs 6-9 reserved */
 #define XHCI_EXT_CAPS_DEBUG	10
+/* IDs 192 - 255 vendor specific extensions */
+#define XHCI_EXT_CAPS_VENDOR_INTEL 192
+
 /* USB Legacy Support Capability - section 7.1.1 */
 #define XHCI_HC_BIOS_OWNED	(1 << 16)
 #define XHCI_HC_OS_OWNED	(1 << 24)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 870093a..99c804a 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4772,6 +4772,34 @@ static int xhci_get_frame(struct usb_hcd *hcd)
 	return readl(&xhci->run_regs->microframe_index) >> 3;
 }
 
+int xhci_ext_cap_init(struct xhci_hcd *xhci)
+{
+	void __iomem *base;
+	u32 cap_offset;
+	u32 val;
+
+	base = &xhci->cap_regs->hc_capbase;
+	cap_offset = xhci_find_next_ext_cap(base, 0, 0);
+
+	do {
+		val = readl(base + cap_offset);
+
+		switch (XHCI_EXT_CAPS_ID(val)) {
+		case XHCI_EXT_CAPS_VENDOR_INTEL:
+			printk(KERN_ERR "TEST EXT_CAPS_VENDOR_INTEL\n");
+			break;
+		default:
+			break;
+		}
+
+		printk(KERN_ERR "TEST EXT_CAP id %d\n", XHCI_EXT_CAPS_ID(val));
+
+		cap_offset = xhci_find_next_ext_cap(base, cap_offset, 0);
+	} while (cap_offset);
+
+	return 0;
+}
+
 int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
 {
 	struct xhci_hcd		*xhci;
@@ -4886,6 +4914,8 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
 		dma_set_coherent_mask(dev, DMA_BIT_MASK(32));
 	}
 
+	xhci_ext_cap_init(xhci);
+
 	xhci_dbg(xhci, "Calling HCD init\n");
 	/* Initialize HCD and host controller data structures. */
 	retval = xhci_init(hcd);
-- 
1.9.1