From e390909ac763589558ffb91856f121820f933e4b Mon Sep 17 00:00:00 2001
From: Sanjay R Mehta <sanju.mehta@amd.com>
Date: Fri, 6 Aug 2021 11:59:05 -0500
Subject: [PATCH] thunderbolt: Add vendor specific NHI quirk for auto-clearing
 interrupt status
Git-commit: e390909ac763589558ffb91856f121820f933e4b
References: jsc#SLE-19355 jsc#SLE-19359
Patch-mainline: v5.15-rc1

Introduce nhi_check_quirks() routine to handle any vendor specific quirks
to manage a hardware specific implementation.

On Intel hardware the USB4 controller supports clearing the interrupt
status register automatically right after it is being issued. For this
reason add a new quirk that does that on all Intel hardware.

Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Signed-off-by: Sanjay R Mehta <sanju.mehta@amd.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/thunderbolt/nhi.c   | 33 +++++++++++++++++++++++++--------
 include/linux/thunderbolt.h |  2 ++
 2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
index fa44332845a1..c7a2841ed3b7 100644
--- a/drivers/thunderbolt/nhi.c
+++ b/drivers/thunderbolt/nhi.c
@@ -35,6 +35,8 @@
 
 #define NHI_MAILBOX_TIMEOUT	500 /* ms */
 
+#define QUIRK_AUTO_CLEAR_INT	BIT(0)
+
 static int ring_interrupt_index(struct tb_ring *ring)
 {
 	int bit = ring->hop;
@@ -66,14 +68,17 @@ static void ring_interrupt_active(struct tb_ring *ring, bool active)
 		else
 			index = ring->hop + ring->nhi->hop_count;
 
-		/*
-		 * Ask the hardware to clear interrupt status bits automatically
-		 * since we already know which interrupt was triggered.
-		 */
-		misc = ioread32(ring->nhi->iobase + REG_DMA_MISC);
-		if (!(misc & REG_DMA_MISC_INT_AUTO_CLEAR)) {
-			misc |= REG_DMA_MISC_INT_AUTO_CLEAR;
-			iowrite32(misc, ring->nhi->iobase + REG_DMA_MISC);
+		if (ring->nhi->quirks & QUIRK_AUTO_CLEAR_INT) {
+			/*
+			 * Ask the hardware to clear interrupt status
+			 * bits automatically since we already know
+			 * which interrupt was triggered.
+			 */
+			misc = ioread32(ring->nhi->iobase + REG_DMA_MISC);
+			if (!(misc & REG_DMA_MISC_INT_AUTO_CLEAR)) {
+				misc |= REG_DMA_MISC_INT_AUTO_CLEAR;
+				iowrite32(misc, ring->nhi->iobase + REG_DMA_MISC);
+			}
 		}
 
 		ivr_base = ring->nhi->iobase + REG_INT_VEC_ALLOC_BASE;
@@ -1074,6 +1079,16 @@ static void nhi_shutdown(struct tb_nhi *nhi)
 		nhi->ops->shutdown(nhi);
 }
 
+static void nhi_check_quirks(struct tb_nhi *nhi)
+{
+	/*
+	 * Intel hardware supports auto clear of the interrupt status
+	 * reqister right after interrupt is being issued.
+	 */
+	if (nhi->pdev->vendor == PCI_VENDOR_ID_INTEL)
+		nhi->quirks |= QUIRK_AUTO_CLEAR_INT;
+}
+
 static int nhi_init_msi(struct tb_nhi *nhi)
 {
 	struct pci_dev *pdev = nhi->pdev;
@@ -1190,6 +1205,8 @@ static int nhi_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (!nhi->tx_rings || !nhi->rx_rings)
 		return -ENOMEM;
 
+	nhi_check_quirks(nhi);
+
 	res = nhi_init_msi(nhi);
 	if (res) {
 		dev_err(&pdev->dev, "cannot enable MSI, aborting\n");
diff --git a/include/linux/thunderbolt.h b/include/linux/thunderbolt.h
index e7c96c37174f..124e13cb1469 100644
--- a/include/linux/thunderbolt.h
+++ b/include/linux/thunderbolt.h
@@ -468,6 +468,7 @@ static inline struct tb_xdomain *tb_service_parent(struct tb_service *svc)
  * @interrupt_work: Work scheduled to handle ring interrupt when no
  *		    MSI-X is used.
  * @hop_count: Number of rings (end point hops) supported by NHI.
+ * @quirks: NHI specific quirks if any
  */
 struct tb_nhi {
 	spinlock_t lock;
@@ -480,6 +481,7 @@ struct tb_nhi {
 	bool going_away;
 	struct work_struct interrupt_work;
 	u32 hop_count;
+	unsigned long quirks;
 };
 
 /**
-- 
2.26.2