[PATCH v2 1/2] thunderbolt: Clear registers properly when auto clear isn't in use

[Mario Limonciello <mario.limonciello@xxxxxxx>]

When `QUIRK_AUTO_CLEAR_INT` isn't set, interrupt masking should be
cleared by writing to Interrupt Mask Clear (IMR) and interrupt
status should be cleared properly at shutdown/init.

This fixes an error where interrupts are left enabled during resume
from hibernation with `CONFIG_USB4=y`.

Fixes: 468c49f44759 ("thunderbolt: Disable interrupt auto clear for rings")
Reported-by: Takashi Iwai <tiwai@xxxxxxx>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217343
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
v1->v2:
 * Whitespace changes
 * Add new static functions for nhi_mask_interrupt() and
   nhi_clear_interrupt()

I tried to base this off thunderbolt.git/next (tag: thunderbolt-for-v6.4-rc1)
but the following 3 commits are missing from that branch but are in 6.3-rc7:

58cdfe6f58b3 thunderbolt: Rename shadowed variables bit to interrupt_bit and auto_clear_bit
468c49f44759 thunderbolt: Disable interrupt auto clear for rings
1716efdb0793 thunderbolt: Use const qualifier for `ring_interrupt_index`

I cherry picked them first as this patch builds on them. It's expected that
this patch should apply on top of 6.4-rc1 properly.
---
 drivers/thunderbolt/nhi.c      | 29 ++++++++++++++++++++++++-----
 drivers/thunderbolt/nhi_regs.h |  2 ++
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
index d76e923fbc6a..c0aee5dc5237 100644
--- a/drivers/thunderbolt/nhi.c
+++ b/drivers/thunderbolt/nhi.c
@@ -54,6 +54,21 @@ static int ring_interrupt_index(const struct tb_ring *ring)
 	return bit;
 }
 
+static void nhi_mask_interrupt(struct tb_nhi *nhi, int mask, int ring)
+{
+	if (nhi->quirks & QUIRK_AUTO_CLEAR_INT)
+		return;
+	iowrite32(mask, nhi->iobase + REG_RING_INTERRUPT_MASK_CLEAR_BASE + ring);
+}
+
+static void nhi_clear_interrupt(struct tb_nhi *nhi, int ring)
+{
+	if (nhi->quirks & QUIRK_AUTO_CLEAR_INT)
+		ioread32(nhi->iobase + REG_RING_NOTIFY_BASE + ring);
+	else
+		iowrite32(~0, nhi->iobase + REG_RING_INT_CLEAR + ring);
+}
+
 /*
  * ring_interrupt_active() - activate/deactivate interrupts for a single ring
  *
@@ -61,8 +76,8 @@ static int ring_interrupt_index(const struct tb_ring *ring)
  */
 static void ring_interrupt_active(struct tb_ring *ring, bool active)
 {
-	int reg = REG_RING_INTERRUPT_BASE +
-		  ring_interrupt_index(ring) / 32 * 4;
+	int index = ring_interrupt_index(ring) / 32 * 4;
+	int reg = REG_RING_INTERRUPT_BASE + index;
 	int interrupt_bit = ring_interrupt_index(ring) & 31;
 	int mask = 1 << interrupt_bit;
 	u32 old, new;
@@ -123,7 +138,11 @@ static void ring_interrupt_active(struct tb_ring *ring, bool active)
 					 "interrupt for %s %d is already %s\n",
 					 RING_TYPE(ring), ring->hop,
 					 active ? "enabled" : "disabled");
-	iowrite32(new, ring->nhi->iobase + reg);
+
+	if (active)
+		iowrite32(new, ring->nhi->iobase + reg);
+	else
+		nhi_mask_interrupt(ring->nhi, mask, index);
 }
 
 /*
@@ -136,11 +155,11 @@ static void nhi_disable_interrupts(struct tb_nhi *nhi)
 	int i = 0;
 	/* disable interrupts */
 	for (i = 0; i < RING_INTERRUPT_REG_COUNT(nhi); i++)
-		iowrite32(0, nhi->iobase + REG_RING_INTERRUPT_BASE + 4 * i);
+		nhi_mask_interrupt(nhi, ~0, 4 * i);
 
 	/* clear interrupt status bits */
 	for (i = 0; i < RING_NOTIFY_REG_COUNT(nhi); i++)
-		ioread32(nhi->iobase + REG_RING_NOTIFY_BASE + 4 * i);
+		nhi_clear_interrupt(nhi, 4 * i);
 }
 
 /* ring helper methods */
diff --git a/drivers/thunderbolt/nhi_regs.h b/drivers/thunderbolt/nhi_regs.h
index faef165a919c..6ba295815477 100644
--- a/drivers/thunderbolt/nhi_regs.h
+++ b/drivers/thunderbolt/nhi_regs.h
@@ -93,6 +93,8 @@ struct ring_desc {
 #define REG_RING_INTERRUPT_BASE	0x38200
 #define RING_INTERRUPT_REG_COUNT(nhi) ((31 + 2 * nhi->hop_count) / 32)
 
+#define REG_RING_INTERRUPT_MASK_CLEAR_BASE	0x38208
+
 #define REG_INT_THROTTLING_RATE	0x38c00
 
 /* Interrupt Vector Allocation */
-- 
2.34.1