[PATCH 1/2] xhci: add helper to check for pending interrupt

[Paul Menzel <pmenzel@molgen.mpg.de>]

From: Mathias Nyman <mathias.nyman@linux.intel.com>

xhci driver needs to manually check if xHC has raised an interrupt in
several places. Add a helper for it, use it in `xhci_pending_portevent()`.

Return 1 if there is a pending interrupt, -ENODEV on error (dead device),
0 otherwise.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
(cherry picked from commit 741aeecfd9a1b2437c5ee1d70745b1bfd90fb7d6
git://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git for-usb-next)

[pmenzel: As of 7.1-rc4, the commit is not Linus’ master branch, so port
  it from the ChromiumOS Linux kernel branch chromium/chromeos-6.12.]

BUG=b:192925463
TEST=Test S0ix for 500 cycles on brya.

Signed-off-by: George D Sworo <george.d.sworo@intel.com>
Change-Id: If7d584369e107a6497b10f3346c05e0c32920bcb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/3313527
Reviewed-by: Rajat Jain <rajatja@google.com>
Commit-Queue: Rajat Jain <rajatja@google.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/3399807
Tested-by: Rajat Jain <rajatja@google.com>

Origin-6-6: 8651d395a93eba47285700a373c12aa53be047ea
Signed-off-by: Tzung-Bi Shih <tzungbi@chromium.org>

Link: https://chromium.googlesource.com/chromiumos/third_party/kernel/+/9fc38e27c31ae70d7b7829ff61cfcd18c18d3514
Assisted-by: Claude Sonnet 4.6
Cc: Matt DeVillier <matt.devillier@gmail.com>
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
---
 drivers/usb/host/xhci.c | 17 ++++++++++++++---
 drivers/usb/host/xhci.h |  1 +
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index a54f5b57f205..8d4d6a524d05 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -97,6 +97,19 @@ int xhci_handshake(void __iomem *ptr, u32 mask, u32 done, u64 timeout_us)
 	return ret;
 }
 
+/* return 1 if there is a pending interrupt, -ENODEV on error, 0 otherwise */
+int xhci_pending_interrupt(struct xhci_hcd *xhci)
+{
+	u32 status;
+
+	status = readl(&xhci->op_regs->status);
+
+	if (status == ~(u32)0)
+		return -ENODEV;
+
+	return !!(status & STS_EINT);
+}
+
 /*
  * Disable interrupts and begin the xHCI halting process.
  */
@@ -918,11 +931,9 @@ static bool xhci_pending_portevent(struct xhci_hcd *xhci)
 {
 	struct xhci_port	**ports;
 	int			port_index;
-	u32			status;
 	u32			portsc;
 
-	status = readl(&xhci->op_regs->status);
-	if (status & STS_EINT)
+	if (xhci_pending_interrupt(xhci) > 0)
 		return true;
 	/*
 	 * Checking STS_EINT is not enough as there is a lag between a change
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index aeecd301f207..82a0596c0ae9 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1955,6 +1955,7 @@ void xhci_ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
 void xhci_cleanup_command_queue(struct xhci_hcd *xhci);
 void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring);
 unsigned int count_trbs(u64 addr, u64 len);
+int xhci_pending_interrupt(struct xhci_hcd *xhci);
 int xhci_stop_endpoint_sync(struct xhci_hcd *xhci, struct xhci_virt_ep *ep,
 			    int suspend, gfp_t gfp_flags);
 void xhci_process_cancelled_tds(struct xhci_virt_ep *ep);
-- 
2.53.0