[PATCH] gpio: pca953x: Add support for level-triggered interrupts

[Potin Lai]

Adds support for level-triggered interrupts in the PCA953x GPIO
expander driver. Previously, the driver only supported edge-triggered
interrupts, which could lead to missed events in scenarios where an
interrupt condition persists until it is explicitly cleared.

By enabling level-triggered interrupts, the driver can now detect and
respond to sustained interrupt conditions more reliably.

Signed-off-by: Potin Lai <potin.lai.pt@xxxxxxxxx>
---
Adds support for level-triggered interrupts in the PCA953x GPIO
expander driver.
---
 drivers/gpio/gpio-pca953x.c | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index be4c9981ebc4..2c4034b39aff 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -215,6 +215,8 @@ struct pca953x_chip {
 	DECLARE_BITMAP(irq_stat, MAX_LINE);
 	DECLARE_BITMAP(irq_trig_raise, MAX_LINE);
 	DECLARE_BITMAP(irq_trig_fall, MAX_LINE);
+	DECLARE_BITMAP(irq_trig_level_high, MAX_LINE);
+	DECLARE_BITMAP(irq_trig_level_low, MAX_LINE);
 #endif
 	atomic_t wakeup_path;
 
@@ -773,6 +775,8 @@ static void pca953x_irq_bus_sync_unlock(struct irq_data *d)
 	pca953x_read_regs(chip, chip->regs->direction, reg_direction);
 
 	bitmap_or(irq_mask, chip->irq_trig_fall, chip->irq_trig_raise, gc->ngpio);
+	bitmap_or(irq_mask, irq_mask, chip->irq_trig_level_high, gc->ngpio);
+	bitmap_or(irq_mask, irq_mask, chip->irq_trig_level_low, gc->ngpio);
 	bitmap_complement(reg_direction, reg_direction, gc->ngpio);
 	bitmap_and(irq_mask, irq_mask, reg_direction, gc->ngpio);
 
@@ -790,13 +794,15 @@ static int pca953x_irq_set_type(struct irq_data *d, unsigned int type)
 	struct device *dev = &chip->client->dev;
 	irq_hw_number_t hwirq = irqd_to_hwirq(d);
 
-	if (!(type & IRQ_TYPE_EDGE_BOTH)) {
+	if (!(type & IRQ_TYPE_SENSE_MASK)) {
 		dev_err(dev, "irq %d: unsupported type %d\n", d->irq, type);
 		return -EINVAL;
 	}
 
 	assign_bit(hwirq, chip->irq_trig_fall, type & IRQ_TYPE_EDGE_FALLING);
 	assign_bit(hwirq, chip->irq_trig_raise, type & IRQ_TYPE_EDGE_RISING);
+	assign_bit(hwirq, chip->irq_trig_level_low, type & IRQ_TYPE_LEVEL_LOW);
+	assign_bit(hwirq, chip->irq_trig_level_high, type & IRQ_TYPE_LEVEL_HIGH);
 
 	return 0;
 }
@@ -809,6 +815,8 @@ static void pca953x_irq_shutdown(struct irq_data *d)
 
 	clear_bit(hwirq, chip->irq_trig_raise);
 	clear_bit(hwirq, chip->irq_trig_fall);
+	clear_bit(hwirq, chip->irq_trig_level_low);
+	clear_bit(hwirq, chip->irq_trig_level_high);
 }
 
 static void pca953x_irq_print_chip(struct irq_data *data, struct seq_file *p)
@@ -839,6 +847,7 @@ static bool pca953x_irq_pending(struct pca953x_chip *chip, unsigned long *pendin
 	DECLARE_BITMAP(cur_stat, MAX_LINE);
 	DECLARE_BITMAP(new_stat, MAX_LINE);
 	DECLARE_BITMAP(trigger, MAX_LINE);
+	DECLARE_BITMAP(edges, MAX_LINE);
 	int ret;
 
 	if (chip->driver_data & PCA_PCAL) {
@@ -875,13 +884,25 @@ static bool pca953x_irq_pending(struct pca953x_chip *chip, unsigned long *pendin
 
 	bitmap_copy(chip->irq_stat, new_stat, gc->ngpio);
 
-	if (bitmap_empty(trigger, gc->ngpio))
-		return false;
+	if (!chip->irq_trig_level_high && !chip->irq_trig_level_low) {
+		if (bitmap_empty(trigger, gc->ngpio))
+			return false;
+	}
 
 	bitmap_and(cur_stat, chip->irq_trig_fall, old_stat, gc->ngpio);
 	bitmap_and(old_stat, chip->irq_trig_raise, new_stat, gc->ngpio);
-	bitmap_or(new_stat, old_stat, cur_stat, gc->ngpio);
-	bitmap_and(pending, new_stat, trigger, gc->ngpio);
+	bitmap_or(edges, old_stat, cur_stat, gc->ngpio);
+	bitmap_and(pending, edges, trigger, gc->ngpio);
+
+	bitmap_and(cur_stat, new_stat, chip->irq_trig_level_high, gc->ngpio);
+	bitmap_and(cur_stat, cur_stat, chip->irq_mask, gc->ngpio);
+	bitmap_or(pending, pending, cur_stat, gc->ngpio);
+
+	bitmap_complement(cur_stat, new_stat, gc->ngpio);
+	bitmap_and(cur_stat, cur_stat, reg_direction, gc->ngpio);
+	bitmap_and(old_stat, cur_stat, chip->irq_trig_level_low, gc->ngpio);
+	bitmap_and(old_stat, old_stat, chip->irq_mask, gc->ngpio);
+	bitmap_or(pending, pending, old_stat, gc->ngpio);
 
 	return !bitmap_empty(pending, gc->ngpio);
 }

---
base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b
change-id: 20250318-gpio-pca953x-level-triggered-irq-5cf7f1cab561

Best regards,
-- 
Potin Lai <potin.lai.pt@xxxxxxxxx>