Revert "xhci: replace xhci_write_64() with writeq()"

This reverts commit 7dd09a1af2c7150269350aaa567a11b06e831003.

Many xHCI host controllers can only handle 32-bit addresses, and writing
64-bits at a time causes them to fail.  Rafał reports that USB devices
simply do not enumerate, and reverting this patch helps.  Branimir
reports that his host controller doesn't respond to an Enable Slot
command and dies:

[   75.576160] xhci_hcd 0000:03:00.0: Timeout while waiting for a slot
[   88.991634] xhci_hcd 0000:03:00.0: Stopped the command ring failed, maybe the host is dead
[   88.991748] xhci_hcd 0000:03:00.0: Abort command ring failed
[   88.991845] xhci_hcd 0000:03:00.0: HC died; cleaning up
[   93.985489] xhci_hcd 0000:03:00.0: Timeout while waiting for a slot
[   93.985494] xhci_hcd 0000:03:00.0: Abort the command ring, but the xHCI is dead.
[   98.982586] xhci_hcd 0000:03:00.0: Timeout while waiting for a slot
[   98.982591] xhci_hcd 0000:03:00.0: Abort the command ring, but the xHCI is dead.
[  103.979696] xhci_hcd 0000:03:00.0: Timeout while waiting for a slot
[  103.979702] xhci_hcd 0000:03:00.0: Abort the command ring, but the xHCI is dead

Signed-off-by: Sarah Sharp <sarah.a.sharp@intel.com>
Reported-by: Rafał Miłecki <zajec5@gmail.com>
Reported-by: Branimir Maksimovic <branimir.maksimovic@gmail.com>
Cc: Xenia Ragiadakou <burzalodowa@gmail.com>

1 files changed, 20 insertions, 9 deletions

diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index f8416639bf3..60def15d129 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -28,15 +28,6 @@
 #include <linux/kernel.h>
 #include <linux/usb/hcd.h>
 
-/*
- * Registers should always be accessed with double word or quad word accesses.
- *
- * Some xHCI implementations may support 64-bit address pointers.  Registers
- * with 64-bit address pointers should be written to with dword accesses by
- * writing the low dword first (ptr[0]), then the high dword (ptr[1]) second.
- * xHCI implementations that do not support 64-bit address pointers will ignore
- * the high dword, and write order is irrelevant.
- */
 #include <asm-generic/io-64-nonatomic-lo-hi.h>
 
 /* Code sharing between pci-quirks and xhci hcd */
@@ -1614,6 +1605,26 @@ static inline struct usb_hcd *xhci_to_hcd(struct xhci_hcd *xhci)
 #define xhci_warn_ratelimited(xhci, fmt, args...) \
 	dev_warn_ratelimited(xhci_to_hcd(xhci)->self.controller , fmt , ## args)
 
+/*
+ * Registers should always be accessed with double word or quad word accesses.
+ *
+ * Some xHCI implementations may support 64-bit address pointers.  Registers
+ * with 64-bit address pointers should be written to with dword accesses by
+ * writing the low dword first (ptr[0]), then the high dword (ptr[1]) second.
+ * xHCI implementations that do not support 64-bit address pointers will ignore
+ * the high dword, and write order is irrelevant.
+ */
+static inline void xhci_write_64(struct xhci_hcd *xhci,
+				 const u64 val, __le64 __iomem *regs)
+{
+	__u32 __iomem *ptr = (__u32 __iomem *) regs;
+	u32 val_lo = lower_32_bits(val);
+	u32 val_hi = upper_32_bits(val);
+
+	writel(val_lo, ptr);
+	writel(val_hi, ptr + 1);
+}
+
 static inline int xhci_link_trb_quirk(struct xhci_hcd *xhci)
 {
 	return xhci->quirks & XHCI_LINK_TRB_QUIRK;