On 11/10/2015 05:36 PM, Dave Young wrote:
[snip]
diff --git a/drivers/usb/host/xhci-sysfs.c b/drivers/usb/host/xhci-sysfs.c
new file mode 100644
index 0000000..0192ac4
--- /dev/null
+++ b/drivers/usb/host/xhci-sysfs.c
@@ -0,0 +1,100 @@
+/*
+ * sysfs interface for xHCI host controller driver
+ *
+ * Copyright (C) 2015 Intel Corp.
+ *
+ * Author: Lu Baolu <baolu...@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/kernel.h>
+
+#include "xhci.h"
+
+/*
+ * Return the register offset of a extended capability specified
+ * by @cap_id. Return 0 if @cap_id capability is not supported or
+ * in error cases.
+ */
+static int get_extended_capability_offset(struct xhci_hcd *xhci,
+ int cap_id)
+{
+ u32 cap_reg;
+ unsigned long flags;
+ int offset;
+ void __iomem *base = (void __iomem *) xhci->cap_regs;
+ struct usb_hcd *hcd = xhci_to_hcd(xhci);
+ int time_to_leave = XHCI_EXT_MAX_CAPID;
+
+ spin_lock_irqsave(&xhci->lock, flags);
+
+ offset = xhci_find_next_cap_offset(base, XHCI_HCC_PARAMS_OFFSET);
+ if (!HCD_HW_ACCESSIBLE(hcd) || !offset) {
+ spin_unlock_irqrestore(&xhci->lock, flags);
+ return 0;
+ }
+
+ while (time_to_leave--) {
+ cap_reg = readl(base + offset);
+
+ if (XHCI_EXT_CAPS_ID(cap_reg) == cap_id)
+ break;
+
+ offset = xhci_find_next_cap_offset(base, offset);
+ if (!offset)
+ break;
+ }
+
+ spin_unlock_irqrestore(&xhci->lock, flags);
I'm not sure spin_lock is good and necessary here, also seems there's already
The lock is unnecessary here. I will remove it.
a function to find the cap offset:
xhci_find_ext_cap_by_id() in xhci-ext-caps.h
Yes, I will refactor the code.
Thanks,
Baolu
+
+ return offset;
+}
+
Thanks
Dave
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