[PATCH v4 02/10] gpio: mxc: fix wakeup_pads bit operations

[Peng Fan (OSS)]

From: Peng Fan <peng.fan@xxxxxxx>

gpio_set_wake_irq() can be called concurrently for different pins on
the same port, so we need to use atomic bitops when modifying
wakeup_pads.

wakeup_pads is a u32, while assign_bit() operates on unsigned long
pointers. On 64-bit platforms, this causes an 8-byte read-modify-write
on a 4-byte field, corrupting the adjacent is_pad_wakeup member.
Change wakeup_pads to unsigned long and reorder to avoid the overlap.

And the enable/disable path unconditionally sets/clears the wakeup_pads
bit even when enable_irq_wake()/disable_irq_wake() fails. Only update
the bit on success.

While at here, simplify the logic by consolidating into a single
irq_set_irq_wake() call based on the enable parameter.

Fixes: f60c9eac54af ("gpio: mxc: enable pad wakeup on i.MX8x platforms")
Assisted-by: LLM
Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
---
 drivers/gpio/gpio-mxc.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/gpio/gpio-mxc.c b/drivers/gpio/gpio-mxc.c
index e05f276a50e8..627fff6f1886 100644
--- a/drivers/gpio/gpio-mxc.c
+++ b/drivers/gpio/gpio-mxc.c
@@ -71,8 +71,8 @@ struct mxc_gpio_port {
 	u32 both_edges;
 	struct mxc_gpio_reg_saved gpio_saved_reg;
 	bool power_off;
-	u32 wakeup_pads;
 	bool is_pad_wakeup;
+	unsigned long wakeup_pads;
 	u32 pad_type[32];
 	const struct mxc_gpio_hwdata *hwdata;
 };
@@ -325,21 +325,16 @@ static int gpio_set_wake_irq(struct irq_data *d, u32 enable)
 	u32 gpio_idx = d->hwirq;
 	int ret;
 
-	if (enable) {
-		if (port->irq_high && (gpio_idx >= 16))
-			ret = enable_irq_wake(port->irq_high);
-		else
-			ret = enable_irq_wake(port->irq);
-		port->wakeup_pads |= BIT(gpio_idx);
-	} else {
-		if (port->irq_high && (gpio_idx >= 16))
-			ret = disable_irq_wake(port->irq_high);
-		else
-			ret = disable_irq_wake(port->irq);
-		port->wakeup_pads &= ~BIT(gpio_idx);
-	}
+	if (port->irq_high && (gpio_idx >= 16))
+		ret = irq_set_irq_wake(port->irq_high, enable);
+	else
+		ret = irq_set_irq_wake(port->irq, enable);
+	if (ret)
+		return ret;
 
-	return ret;
+	assign_bit(gpio_idx, &port->wakeup_pads, enable);
+
+	return 0;
 }
 
 static int mxc_gpio_init_gc(struct mxc_gpio_port *port, int irq_base)

-- 
2.51.0