[PATCH v2 2/2] iio: light: vcnl4000: add shared IRQ support

[Tsz Shan Chan]

The INT output of vcnl4010/4020 and vcnl4040/4200 is open drain active
low which can be shared with other devices.
Add IRQF_SHARED and switch the trigger type from IRQF_TRIGGER_FALLING to
IRQF_TRIGGER_LOW. Edge triggering can miss interrupts on a shared line.

Return IRQ_NONE from the irq handler when read fails or when none of the
interrupt source bits handled by the driver are set. This prevents
claiming interrupts from other devices on a shared line.

Signed-off-by: Tsz Shan Chan <tchan@xxxxxxxxxxxxxx>
---
 drivers/iio/light/vcnl4000.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/light/vcnl4000.c b/drivers/iio/light/vcnl4000.c
index 663e623da833..8a723eaadbb6 100644
--- a/drivers/iio/light/vcnl4000.c
+++ b/drivers/iio/light/vcnl4000.c
@@ -1470,7 +1470,11 @@ static irqreturn_t vcnl4040_irq_thread(int irq, void *p)
 
 	ret = i2c_smbus_read_word_data(data->client, data->chip_spec->int_reg);
 	if (ret < 0)
-		return IRQ_HANDLED;
+		return IRQ_NONE;
+
+	if (!(ret & (VCNL4040_PS_IF_CLOSE | VCNL4040_PS_IF_AWAY |
+		     VCNL4040_ALS_FALLING | VCNL4040_ALS_RISING)))
+		return IRQ_NONE;
 
 	if (ret & VCNL4040_PS_IF_CLOSE) {
 		iio_push_event(indio_dev,
@@ -1526,7 +1530,10 @@ static irqreturn_t vcnl4010_irq_thread(int irq, void *p)
 
 	ret = i2c_smbus_read_byte_data(data->client, VCNL4010_ISR);
 	if (ret < 0)
-		goto end;
+		return IRQ_NONE;
+
+	if (!(ret & (VCNL4010_INT_THR | VCNL4010_INT_DRDY)))
+		return IRQ_NONE;
 
 	isr = ret;
 
@@ -1558,7 +1565,6 @@ static irqreturn_t vcnl4010_irq_thread(int irq, void *p)
 	if (isr & VCNL4010_INT_DRDY && iio_buffer_enabled(indio_dev))
 		iio_trigger_poll_nested(indio_dev->trig);
 
-end:
 	return IRQ_HANDLED;
 }
 
@@ -1981,8 +1987,8 @@ static int vcnl4000_probe(struct i2c_client *client)
 	if (client->irq && data->chip_spec->irq_thread) {
 		ret = devm_request_threaded_irq(dev, client->irq, NULL,
 						data->chip_spec->irq_thread,
-						IRQF_TRIGGER_FALLING |
-						IRQF_ONESHOT,
+						IRQF_TRIGGER_LOW |
+						IRQF_ONESHOT | IRQF_SHARED,
 						"vcnl4000_irq",
 						indio_dev);
 		if (ret < 0)

-- 
2.55.0