[PATCH v2] iio: proximity: vcnl3020: fix ISR bitmask check in IRQ handler

[Salah Triki <salah.triki@gmail.com>]

The threaded IRQ handler contained multiple issues in handling interrupt
events and clearing status flags:

1. ISR bit check: The handler incorrectly checked the Interrupt Status
   Register (VCNL_ISR) against VCNL_ICR_THRES_EN (BIT(1)), which is a
   bitmask meant for the Control Register (VCNL_PS_ICR). In VCNL_ISR,
   BIT(1) corresponds only to low-threshold interrupts. A high-threshold
   interrupt (VCNL_INT_TH_HI, BIT(0)) on its own was completely ignored and
   returned IRQ_NONE.

2. Event direction & channel index: The handler unconditionally pushed a
   RISING event code on channel index 1. The driver only registers a single
   proximity channel (index 0), and low-threshold interrupts should be
   reported with IIO_EV_DIR_FALLING.

3. ISR clearing: The write-back to acknowledge the interrupt only preserved
   BIT(1) instead of masking against both valid status bits.

Fix this by checking both VCNL_INT_TH_HI and VCNL_INT_TH_LOW bits in
VCNL_ISR, pushing separate IIO events with the correct direction and
channel index (0), and properly clearing handled status bits.

Fixes: 3363fbbe19e5 ("iio: proximity: vcnl3020: add periodic mode")
Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
Changes since v1:
  - Extended the patch to fix additional bugs found in vcnl3020_handle_irq_thread():
    - Corrected event directions (RISING for high threshold, FALLING for low threshold).
    - Fixed channel index from 1 to 0 (matching single proximity channel).
    - Corrected ISR W1C clear logic for both HI and LOW bits.
  - Updated commit message to detail all IRQ handler fixes.

 drivers/iio/proximity/vcnl3020.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/proximity/vcnl3020.c b/drivers/iio/proximity/vcnl3020.c
index 7f417372566a..d0b8f429999f 100644
--- a/drivers/iio/proximity/vcnl3020.c
+++ b/drivers/iio/proximity/vcnl3020.c
@@ -584,16 +584,26 @@ static irqreturn_t vcnl3020_handle_irq_thread(int irq, void *p)
 		return IRQ_HANDLED;
 	}
 
-	if (!(isr & VCNL_ICR_THRES_EN))
+	if (!(isr & (VCNL_INT_TH_HI | VCNL_INT_TH_LOW)))
 		return IRQ_NONE;
 
-	iio_push_event(indio_dev,
-		       IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, 1,
-				            IIO_EV_TYPE_THRESH,
-				            IIO_EV_DIR_RISING),
-		       iio_get_time_ns(indio_dev));
+	if (isr & VCNL_INT_TH_HI) {
+		iio_push_event(indio_dev,
+			       IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, 0,
+						    IIO_EV_TYPE_THRESH,
+						    IIO_EV_DIR_RISING),
+			       iio_get_time_ns(indio_dev));
+	}
+
+	if (isr & VCNL_INT_TH_LOW) {
+		iio_push_event(indio_dev,
+			       IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, 0,
+						    IIO_EV_TYPE_THRESH,
+						    IIO_EV_DIR_FALLING),
+			       iio_get_time_ns(indio_dev));
+	}
 
-	rc = regmap_write(data->regmap, VCNL_ISR, isr & VCNL_ICR_THRES_EN);
+	rc = regmap_write(data->regmap, VCNL_ISR, isr & (VCNL_INT_TH_HI | VCNL_INT_TH_LOW));
 	if (rc)
 		dev_err(data->dev, "Error (%d) writing in reg (0x%x)\n",
 			rc, VCNL_ISR);
-- 
2.43.0