[PATCH v4 05/11] iio: accel: adxl313: prepare interrupt handling

[Lothar Rubusch <l.rubusch@gmail.com>]

Evaluate the devicetree property for an optional interrupt line, and
configure the interrupt mapping accordingly. When no interrupt line
is defined in the devicetree, keep the FIFO in bypass mode as before.

Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>
---
 drivers/iio/accel/adxl313.h      | 13 +++++++++
 drivers/iio/accel/adxl313_core.c | 49 +++++++++++++++++++++++++++++++-
 2 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/accel/adxl313.h b/drivers/iio/accel/adxl313.h
index 9bf2facdbf87..ab6b9e11fde4 100644
--- a/drivers/iio/accel/adxl313.h
+++ b/drivers/iio/accel/adxl313.h
@@ -21,7 +21,9 @@
 #define ADXL313_REG_ACT_INACT_CTL	0x27
 #define ADXL313_REG_BW_RATE		0x2C
 #define ADXL313_REG_POWER_CTL		0x2D
+#define ADXL313_REG_INT_ENABLE		0x2E
 #define ADXL313_REG_INT_MAP		0x2F
+#define ADXL313_REG_INT_SOURCE		0x30
 #define ADXL313_REG_DATA_FORMAT		0x31
 #define ADXL313_REG_DATA_AXIS(index)	(0x32 + ((index) * 2))
 #define ADXL313_REG_FIFO_CTL		0x38
@@ -45,6 +47,17 @@
 #define ADXL313_SPI_3WIRE		BIT(6)
 #define ADXL313_I2C_DISABLE		BIT(6)
 
+#define ADXL313_INT_OVERRUN		BIT(0)
+#define ADXL313_INT_WATERMARK		BIT(1)
+#define ADXL313_INT_INACTIVITY		BIT(3)
+#define ADXL313_INT_ACTIVITY		BIT(4)
+#define ADXL313_INT_DREADY		BIT(7)
+
+#define ADXL313_REG_FIFO_CTL_MODE_MSK		GENMASK(7, 6)
+
+#define ADXL313_FIFO_BYPASS			0
+#define ADXL313_FIFO_STREAM			2
+
 extern const struct regmap_access_table adxl312_readable_regs_table;
 extern const struct regmap_access_table adxl313_readable_regs_table;
 extern const struct regmap_access_table adxl314_readable_regs_table;
diff --git a/drivers/iio/accel/adxl313_core.c b/drivers/iio/accel/adxl313_core.c
index 6170c9daa30f..31ce1b218488 100644
--- a/drivers/iio/accel/adxl313_core.c
+++ b/drivers/iio/accel/adxl313_core.c
@@ -8,11 +8,17 @@
  */
 
 #include <linux/bitfield.h>
+#include <linux/interrupt.h>
 #include <linux/module.h>
+#include <linux/property.h>
 #include <linux/regmap.h>
 
 #include "adxl313.h"
 
+#define ADXL313_INT_NONE			U8_MAX
+#define ADXL313_INT1				1
+#define ADXL313_INT2				2
+
 static const struct regmap_range adxl312_readable_reg_range[] = {
 	regmap_reg_range(ADXL313_REG_DEVID0, ADXL313_REG_DEVID0),
 	regmap_reg_range(ADXL313_REG_OFS_AXIS(0), ADXL313_REG_OFS_AXIS(2)),
@@ -436,7 +442,9 @@ int adxl313_core_probe(struct device *dev,
 {
 	struct adxl313_data *data;
 	struct iio_dev *indio_dev;
-	int ret;
+	u8 int_line;
+	u8 int_map_msk;
+	int irq, ret;
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 	if (!indio_dev)
@@ -461,6 +469,45 @@ int adxl313_core_probe(struct device *dev,
 		return ret;
 	}
 
+	int_line = ADXL313_INT1;
+	irq = fwnode_irq_get_byname(dev_fwnode(dev), "INT1");
+	if (irq < 0) {
+		int_line = ADXL313_INT2;
+		irq = fwnode_irq_get_byname(dev_fwnode(dev), "INT2");
+		if (irq < 0)
+			int_line = ADXL313_INT_NONE;
+	}
+
+	if (int_line != ADXL313_INT_NONE) {
+		/* FIFO_STREAM mode */
+		int_map_msk = ADXL313_INT_DREADY | ADXL313_INT_ACTIVITY |
+			ADXL313_INT_INACTIVITY | ADXL313_INT_WATERMARK |
+			ADXL313_INT_OVERRUN;
+		ret = regmap_assign_bits(data->regmap, ADXL313_REG_INT_MAP,
+					 int_map_msk, int_line == ADXL313_INT2);
+		if (ret)
+			return ret;
+	} else {
+		/*
+		 * FIFO_BYPASSED mode
+		 *
+		 * When no interrupt lines are specified, the driver falls back
+		 * to use the sensor in FIFO_BYPASS mode. This means turning off
+		 * internal FIFO and interrupt generation (since there is no
+		 * line specified). Unmaskable interrupts such as overrun or
+		 * data ready won't interfere. Even that a FIFO_STREAM mode w/o
+		 * connected interrupt line might allow for obtaining raw
+		 * measurements, a fallback to disable interrupts when no
+		 * interrupt lines are connected seems to be the cleaner
+		 * solution.
+		 */
+		ret = regmap_write(data->regmap, ADXL313_REG_FIFO_CTL,
+				   FIELD_PREP(ADXL313_REG_FIFO_CTL_MODE_MSK,
+					      ADXL313_FIFO_BYPASS));
+		if (ret)
+			return ret;
+	}
+
 	return devm_iio_device_register(dev, indio_dev);
 }
 EXPORT_SYMBOL_NS_GPL(adxl313_core_probe, IIO_ADXL313);
-- 
2.39.5