[PATCH AUTOSEL 6.13 04/22] pinctrl: mcp23s08: Get rid of spurious level interrupts

[Sasha Levin <sashal@kernel.org>]

From: Dmitry Mastykin <mastichi@gmail.com>

[ Upstream commit 7b0671b97f0872d6950ccc925e210cb3f67721bf ]

irq_mask()/irq_unmask() are not called for nested interrupts. So level
interrupts are never masked, chip's interrupt output is not cleared on
INTCAP or GPIO read, the irq handler is uselessly called again. Nested
irq handler is not called again, because interrupt reason is cleared by
its first call.
/proc/interrupts shows that number of chip's irqs is greater than
number of nested irqs.

This patch adds masking and unmasking level interrupts inside irq handler.

Signed-off-by: Dmitry Mastykin <mastichi@gmail.com>
Link: https://lore.kernel.org/20250122120504.1279790-1-mastichi@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/pinctrl/pinctrl-mcp23s08.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/pinctrl/pinctrl-mcp23s08.c b/drivers/pinctrl/pinctrl-mcp23s08.c
index b96e6368a9568..4d1f41488017e 100644
--- a/drivers/pinctrl/pinctrl-mcp23s08.c
+++ b/drivers/pinctrl/pinctrl-mcp23s08.c
@@ -382,6 +382,7 @@ static irqreturn_t mcp23s08_irq(int irq, void *data)
 {
 	struct mcp23s08 *mcp = data;
 	int intcap, intcon, intf, i, gpio, gpio_orig, intcap_mask, defval, gpinten;
+	bool need_unmask = false;
 	unsigned long int enabled_interrupts;
 	unsigned int child_irq;
 	bool intf_set, intcap_changed, gpio_bit_changed,
@@ -396,9 +397,6 @@ static irqreturn_t mcp23s08_irq(int irq, void *data)
 		goto unlock;
 	}
 
-	if (mcp_read(mcp, MCP_INTCAP, &intcap))
-		goto unlock;
-
 	if (mcp_read(mcp, MCP_INTCON, &intcon))
 		goto unlock;
 
@@ -408,6 +406,16 @@ static irqreturn_t mcp23s08_irq(int irq, void *data)
 	if (mcp_read(mcp, MCP_DEFVAL, &defval))
 		goto unlock;
 
+	/* Mask level interrupts to avoid their immediate reactivation after clearing */
+	if (intcon) {
+		need_unmask = true;
+		if (mcp_write(mcp, MCP_GPINTEN, gpinten & ~intcon))
+			goto unlock;
+	}
+
+	if (mcp_read(mcp, MCP_INTCAP, &intcap))
+		goto unlock;
+
 	/* This clears the interrupt(configurable on S18) */
 	if (mcp_read(mcp, MCP_GPIO, &gpio))
 		goto unlock;
@@ -470,9 +478,18 @@ static irqreturn_t mcp23s08_irq(int irq, void *data)
 		}
 	}
 
+	if (need_unmask) {
+		mutex_lock(&mcp->lock);
+		goto unlock;
+	}
+
 	return IRQ_HANDLED;
 
 unlock:
+	if (need_unmask)
+		if (mcp_write(mcp, MCP_GPINTEN, gpinten))
+			dev_err(mcp->chip.parent, "can't unmask GPINTEN\n");
+
 	mutex_unlock(&mcp->lock);
 	return IRQ_HANDLED;
 }
-- 
2.39.5