[PATCH v2 04/10] iio: adc: mcp3911: add support for interrupts

[Marcus Folkesson <marcus.folkesson@gmail.com>]

Make it possible to read values upon interrupts.
Configure Data Ready Signal Output Pin to either HiZ or push-pull and
use it as interrupt source.

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
---

Notes:
    v2:
        - Removed blank lines (Andy Shevchenko)
        - Removed dr_hiz variable (Andy Shevchenko)

 drivers/iio/adc/mcp3911.c | 65 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
index 2a4bf374f140..f4ee0c27c2ab 100644
--- a/drivers/iio/adc/mcp3911.c
+++ b/drivers/iio/adc/mcp3911.c
@@ -26,6 +26,7 @@
 #define MCP3911_REG_GAIN		0x09
 
 #define MCP3911_REG_STATUSCOM		0x0a
+#define MCP3911_STATUSCOM_DRHIZ         BIT(12)
 #define MCP3911_STATUSCOM_CH1_24WIDTH	BIT(4)
 #define MCP3911_STATUSCOM_CH0_24WIDTH	BIT(3)
 #define MCP3911_STATUSCOM_EN_OFFCAL	BIT(2)
@@ -58,6 +59,7 @@ struct mcp3911 {
 	struct regulator *vref;
 	struct clk *clki;
 	u32 dev_addr;
+	struct iio_trigger *trig;
 	struct {
 		u32 channels[2];
 		s64 ts __aligned(8);
@@ -252,6 +254,17 @@ static const struct iio_info mcp3911_info = {
 	.write_raw = mcp3911_write_raw,
 };
 
+static irqreturn_t mcp3911_interrupt(int irq, void *dev_id)
+{
+	struct iio_dev *indio_dev = dev_id;
+	struct mcp3911 *adc = iio_priv(indio_dev);
+
+	if (iio_buffer_enabled(indio_dev))
+		iio_trigger_poll(adc->trig);
+
+	return IRQ_HANDLED;
+};
+
 static int mcp3911_config(struct mcp3911 *adc)
 {
 	struct device *dev = &adc->spi->dev;
@@ -298,6 +311,23 @@ static int mcp3911_config(struct mcp3911 *adc)
 	return  mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
 }
 
+static int mcp3911_set_trigger_state(struct iio_trigger *trig, bool enable)
+{
+	struct mcp3911 *adc = iio_trigger_get_drvdata(trig);
+
+	if (enable)
+		enable_irq(adc->spi->irq);
+	else
+		disable_irq(adc->spi->irq);
+
+	return 0;
+}
+
+static const struct iio_trigger_ops mcp3911_trigger_ops = {
+	.validate_device = iio_trigger_validate_own_device,
+	.set_trigger_state = mcp3911_set_trigger_state,
+};
+
 static int mcp3911_probe(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev;
@@ -352,6 +382,15 @@ static int mcp3911_probe(struct spi_device *spi)
 	if (ret)
 		goto clk_disable;
 
+	if (device_property_read_bool(&adc->spi->dev, "microchip,data-ready-hiz"))
+		ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM, MCP3911_STATUSCOM_DRHIZ,
+				0, 2);
+	else
+		ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM, MCP3911_STATUSCOM_DRHIZ,
+				MCP3911_STATUSCOM_DRHIZ, 2);
+	if (ret < 0)
+		goto clk_disable;
+
 	indio_dev->name = spi_get_device_id(spi)->name;
 	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED;
 	indio_dev->info = &mcp3911_info;
@@ -362,6 +401,32 @@ static int mcp3911_probe(struct spi_device *spi)
 
 	mutex_init(&adc->lock);
 
+	if (spi->irq > 0) {
+		adc->trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
+				indio_dev->name,
+				iio_device_id(indio_dev));
+		if (!adc->trig)
+			goto clk_disable;
+
+		adc->trig->ops = &mcp3911_trigger_ops;
+		iio_trigger_set_drvdata(adc->trig, adc);
+		ret = devm_iio_trigger_register(&spi->dev, adc->trig);
+		if (ret)
+			goto clk_disable;
+
+		/*
+		 * The device generates interrupts as long as it is powered up.
+		 * Some platforms might not allow the option to power it down so
+		 * don't enable the interrupt to avoid extra load on the system
+		 */
+		ret = devm_request_irq(&spi->dev, spi->irq,
+				&mcp3911_interrupt,
+				IRQF_TRIGGER_FALLING | IRQF_NO_AUTOEN | IRQF_ONESHOT,
+				indio_dev->name, indio_dev);
+		if (ret)
+			goto clk_disable;
+	}
+
 	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
 			NULL,
 			mcp3911_trigger_handler, NULL);
-- 
2.36.1