iio: st_sensors: support active-low interrupts

Most ST MEMS Sensors that support interrupts can also handle sending
an active low interrupt, i.e. going from high to low on data ready
(or other interrupt) and thus triggering on a falling edge to the
interrupt controller.

Set up logic to inspect the interrupt line we get for a sensor: if
it is triggering on rising edge, leave everything alone, but if it
triggers on falling edges, set up active low, and if unsupported
configurations appear: warn with errors and reconfigure the interrupt
to a rising edge, which all interrupt generating sensors support.

Create a local header for st_sensors_core.h to share functions
between the sensor core and the trigger setup code.

Cc: Giuseppe Barba <giuseppe.barba@st.com>
Cc: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/st_accel_core.c

@@ -67,6 +67,8 @@
 #define ST_ACCEL_1_DRDY_IRQ_ADDR		0x22
 #define ST_ACCEL_1_DRDY_IRQ_INT1_MASK		0x10
 #define ST_ACCEL_1_DRDY_IRQ_INT2_MASK		0x08
+#define ST_ACCEL_1_IHL_IRQ_ADDR			0x25
+#define ST_ACCEL_1_IHL_IRQ_MASK			0x02
 #define ST_ACCEL_1_MULTIREAD_BIT		true
 
 /* CUSTOM VALUES FOR SENSOR 2 */
@@ -92,6 +94,8 @@
 #define ST_ACCEL_2_DRDY_IRQ_ADDR		0x22
 #define ST_ACCEL_2_DRDY_IRQ_INT1_MASK		0x02
 #define ST_ACCEL_2_DRDY_IRQ_INT2_MASK		0x10
+#define ST_ACCEL_2_IHL_IRQ_ADDR			0x22
+#define ST_ACCEL_2_IHL_IRQ_MASK			0x80
 #define ST_ACCEL_2_MULTIREAD_BIT		true
 
 /* CUSTOM VALUES FOR SENSOR 3 */
@@ -125,6 +129,8 @@
 #define ST_ACCEL_3_DRDY_IRQ_ADDR		0x23
 #define ST_ACCEL_3_DRDY_IRQ_INT1_MASK		0x80
 #define ST_ACCEL_3_DRDY_IRQ_INT2_MASK		0x00
+#define ST_ACCEL_3_IHL_IRQ_ADDR			0x23
+#define ST_ACCEL_3_IHL_IRQ_MASK			0x40
 #define ST_ACCEL_3_IG1_EN_ADDR			0x23
 #define ST_ACCEL_3_IG1_EN_MASK			0x08
 #define ST_ACCEL_3_MULTIREAD_BIT		false
@@ -169,6 +175,8 @@
 #define ST_ACCEL_5_DRDY_IRQ_ADDR		0x22
 #define ST_ACCEL_5_DRDY_IRQ_INT1_MASK		0x04
 #define ST_ACCEL_5_DRDY_IRQ_INT2_MASK		0x20
+#define ST_ACCEL_5_IHL_IRQ_ADDR			0x22
+#define ST_ACCEL_5_IHL_IRQ_MASK			0x80
 #define ST_ACCEL_5_IG1_EN_ADDR			0x21
 #define ST_ACCEL_5_IG1_EN_MASK			0x08
 #define ST_ACCEL_5_MULTIREAD_BIT		false
@@ -292,6 +300,8 @@ static const struct st_sensor_settings st_accel_sensors_settings[] = {
 			.addr = ST_ACCEL_1_DRDY_IRQ_ADDR,
 			.mask_int1 = ST_ACCEL_1_DRDY_IRQ_INT1_MASK,
 			.mask_int2 = ST_ACCEL_1_DRDY_IRQ_INT2_MASK,
+			.addr_ihl = ST_ACCEL_1_IHL_IRQ_ADDR,
+			.mask_ihl = ST_ACCEL_1_IHL_IRQ_MASK,
 		},
 		.multi_read_bit = ST_ACCEL_1_MULTIREAD_BIT,
 		.bootime = 2,
@@ -355,6 +365,8 @@ static const struct st_sensor_settings st_accel_sensors_settings[] = {
 			.addr = ST_ACCEL_2_DRDY_IRQ_ADDR,
 			.mask_int1 = ST_ACCEL_2_DRDY_IRQ_INT1_MASK,
 			.mask_int2 = ST_ACCEL_2_DRDY_IRQ_INT2_MASK,
+			.addr_ihl = ST_ACCEL_2_IHL_IRQ_ADDR,
+			.mask_ihl = ST_ACCEL_2_IHL_IRQ_MASK,
 		},
 		.multi_read_bit = ST_ACCEL_2_MULTIREAD_BIT,
 		.bootime = 2,
@@ -430,6 +442,8 @@ static const struct st_sensor_settings st_accel_sensors_settings[] = {
 			.addr = ST_ACCEL_3_DRDY_IRQ_ADDR,
 			.mask_int1 = ST_ACCEL_3_DRDY_IRQ_INT1_MASK,
 			.mask_int2 = ST_ACCEL_3_DRDY_IRQ_INT2_MASK,
+			.addr_ihl = ST_ACCEL_3_IHL_IRQ_ADDR,
+			.mask_ihl = ST_ACCEL_3_IHL_IRQ_MASK,
 			.ig1 = {
 				.en_addr = ST_ACCEL_3_IG1_EN_ADDR,
 				.en_mask = ST_ACCEL_3_IG1_EN_MASK,
@@ -537,6 +551,8 @@ static const struct st_sensor_settings st_accel_sensors_settings[] = {
 			.addr = ST_ACCEL_5_DRDY_IRQ_ADDR,
 			.mask_int1 = ST_ACCEL_5_DRDY_IRQ_INT1_MASK,
 			.mask_int2 = ST_ACCEL_5_DRDY_IRQ_INT2_MASK,
+			.addr_ihl = ST_ACCEL_5_IHL_IRQ_ADDR,
+			.mask_ihl = ST_ACCEL_5_IHL_IRQ_MASK,
 		},
 		.multi_read_bit = ST_ACCEL_5_MULTIREAD_BIT,
 		.bootime = 2, /* guess */

drivers/iio/common/st_sensors/st_sensors_core.c

@@ -18,12 +18,14 @@
 #include <asm/unaligned.h>
 #include <linux/iio/common/st_sensors.h>
 
+#include "st_sensors_core.h"
+
 static inline u32 st_sensors_get_unaligned_le24(const u8 *p)
 {
 	return (s32)((p[0] | p[1] << 8 | p[2] << 16) << 8) >> 8;
 }
 
-static int st_sensors_write_data_with_mask(struct iio_dev *indio_dev,
+int st_sensors_write_data_with_mask(struct iio_dev *indio_dev,
 				    u8 reg_addr, u8 mask, u8 data)
 {
 	int err;

drivers/iio/common/st_sensors/st_sensors_core.h

+/*
+ * Local functions in the ST Sensors core
+ */
+#ifndef __ST_SENSORS_CORE_H
+#define __ST_SENSORS_CORE_H
+int st_sensors_write_data_with_mask(struct iio_dev *indio_dev,
+				    u8 reg_addr, u8 mask, u8 data);
+#endif

drivers/iio/common/st_sensors/st_sensors_trigger.c

@@ -14,32 +14,65 @@
 #include <linux/iio/iio.h>
 #include <linux/iio/trigger.h>
 #include <linux/interrupt.h>
-
 #include <linux/iio/common/st_sensors.h>
-
+#include "st_sensors_core.h"
 
 int st_sensors_allocate_trigger(struct iio_dev *indio_dev,
 				const struct iio_trigger_ops *trigger_ops)
 {
-	int err;
+	int err, irq;
 	struct st_sensor_data *sdata = iio_priv(indio_dev);
+	unsigned long irq_trig;
 
 	sdata->trig = iio_trigger_alloc("%s-trigger", indio_dev->name);
 	if (sdata->trig == NULL) {
-		err = -ENOMEM;
 		dev_err(&indio_dev->dev, "failed to allocate iio trigger.\n");
-		goto iio_trigger_alloc_error;
+		return -ENOMEM;
+	}
+
+	irq = sdata->get_irq_data_ready(indio_dev);
+	irq_trig = irqd_get_trigger_type(irq_get_irq_data(irq));
+	/*
+	 * If the IRQ is triggered on falling edge, we need to mark the
+	 * interrupt as active low, if the hardware supports this.
+	 */
+	if (irq_trig == IRQF_TRIGGER_FALLING) {
+		if (!sdata->sensor_settings->drdy_irq.addr_ihl) {
+			dev_err(&indio_dev->dev,
+				"falling edge specified for IRQ but hardware "
+				"only support rising edge, will request "
+				"rising edge\n");
+			irq_trig = IRQF_TRIGGER_RISING;
+		} else {
+			/* Set up INT active low i.e. falling edge */
+			err = st_sensors_write_data_with_mask(indio_dev,
+				sdata->sensor_settings->drdy_irq.addr_ihl,
+				sdata->sensor_settings->drdy_irq.mask_ihl, 1);
+			if (err < 0)
+				goto iio_trigger_free;
+			dev_info(&indio_dev->dev,
+				 "interrupts on the falling edge\n");
 		}
+	} else if (irq_trig == IRQF_TRIGGER_RISING) {
+		dev_info(&indio_dev->dev,
+			 "interrupts on the rising edge\n");
 
-	err = request_threaded_irq(sdata->get_irq_data_ready(indio_dev),
+	} else {
+		dev_err(&indio_dev->dev,
+		"unsupported IRQ trigger specified (%lx), only "
+			"rising and falling edges supported, enforce "
+			"rising edge\n", irq_trig);
+		irq_trig = IRQF_TRIGGER_RISING;
+	}
+	err = request_threaded_irq(irq,
 			iio_trigger_generic_data_rdy_poll,
 			NULL,
-			IRQF_TRIGGER_RISING,
+			irq_trig,
 			sdata->trig->name,
 			sdata->trig);
 	if (err) {
 		dev_err(&indio_dev->dev, "failed to request trigger IRQ.\n");
-		goto request_irq_error;
+		goto iio_trigger_free;
 	}
 
 	iio_trigger_set_drvdata(sdata->trig, indio_dev);
@@ -57,9 +90,8 @@ int st_sensors_allocate_trigger(struct iio_dev *indio_dev,
 
 iio_trigger_register_error:
 	free_irq(sdata->get_irq_data_ready(indio_dev), sdata->trig);
-request_irq_error:
+iio_trigger_free:
 	iio_trigger_free(sdata->trig);
-iio_trigger_alloc_error:
 	return err;
 }
 EXPORT_SYMBOL(st_sensors_allocate_trigger);

drivers/iio/gyro/st_gyro_core.c

@@ -185,6 +185,11 @@ static const struct st_sensor_settings st_gyro_sensors_settings[] = {
 		.drdy_irq = {
 			.addr = ST_GYRO_1_DRDY_IRQ_ADDR,
 			.mask_int2 = ST_GYRO_1_DRDY_IRQ_INT2_MASK,
+			/*
+			 * The sensor has IHL (active low) and open
+			 * drain settings, but only for INT1 and not
+			 * for the DRDY line on INT2.
+			 */
 		},
 		.multi_read_bit = ST_GYRO_1_MULTIREAD_BIT,
 		.bootime = 2,
@@ -248,6 +253,11 @@ static const struct st_sensor_settings st_gyro_sensors_settings[] = {
 		.drdy_irq = {
 			.addr = ST_GYRO_2_DRDY_IRQ_ADDR,
 			.mask_int2 = ST_GYRO_2_DRDY_IRQ_INT2_MASK,
+			/*
+			 * The sensor has IHL (active low) and open
+			 * drain settings, but only for INT1 and not
+			 * for the DRDY line on INT2.
+			 */
 		},
 		.multi_read_bit = ST_GYRO_2_MULTIREAD_BIT,
 		.bootime = 2,
@@ -307,6 +317,11 @@ static const struct st_sensor_settings st_gyro_sensors_settings[] = {
 		.drdy_irq = {
 			.addr = ST_GYRO_3_DRDY_IRQ_ADDR,
 			.mask_int2 = ST_GYRO_3_DRDY_IRQ_INT2_MASK,
+			/*
+			 * The sensor has IHL (active low) and open
+			 * drain settings, but only for INT1 and not
+			 * for the DRDY line on INT2.
+			 */
 		},
 		.multi_read_bit = ST_GYRO_3_MULTIREAD_BIT,
 		.bootime = 2,

drivers/iio/magnetometer/st_magn_core.c

@@ -175,6 +175,8 @@
 #define ST_MAGN_3_BDU_MASK			0x10
 #define ST_MAGN_3_DRDY_IRQ_ADDR			0x62
 #define ST_MAGN_3_DRDY_INT_MASK			0x01
+#define ST_MAGN_3_IHL_IRQ_ADDR			0x63
+#define ST_MAGN_3_IHL_IRQ_MASK			0x04
 #define ST_MAGN_3_FS_AVL_15000_GAIN		1500
 #define ST_MAGN_3_MULTIREAD_BIT			false
 #define ST_MAGN_3_OUT_X_L_ADDR			0x68
@@ -480,6 +482,8 @@ static const struct st_sensor_settings st_magn_sensors_settings[] = {
 		.drdy_irq = {
 			.addr = ST_MAGN_3_DRDY_IRQ_ADDR,
 			.mask_int1 = ST_MAGN_3_DRDY_INT_MASK,
+			.addr_ihl = ST_MAGN_3_IHL_IRQ_ADDR,
+			.mask_ihl = ST_MAGN_3_IHL_IRQ_MASK,
 		},
 		.multi_read_bit = ST_MAGN_3_MULTIREAD_BIT,
 		.bootime = 2,

drivers/iio/pressure/st_pressure_core.c

@@ -62,6 +62,8 @@
 #define ST_PRESS_LPS331AP_DRDY_IRQ_ADDR		0x22
 #define ST_PRESS_LPS331AP_DRDY_IRQ_INT1_MASK	0x04
 #define ST_PRESS_LPS331AP_DRDY_IRQ_INT2_MASK	0x20
+#define ST_PRESS_LPS331AP_IHL_IRQ_ADDR		0x22
+#define ST_PRESS_LPS331AP_IHL_IRQ_MASK		0x80
 #define ST_PRESS_LPS331AP_MULTIREAD_BIT		true
 #define ST_PRESS_LPS331AP_TEMP_OFFSET		42500
 
@@ -100,6 +102,8 @@
 #define ST_PRESS_LPS25H_DRDY_IRQ_ADDR		0x23
 #define ST_PRESS_LPS25H_DRDY_IRQ_INT1_MASK	0x01
 #define ST_PRESS_LPS25H_DRDY_IRQ_INT2_MASK	0x10
+#define ST_PRESS_LPS25H_IHL_IRQ_ADDR		0x22
+#define ST_PRESS_LPS25H_IHL_IRQ_MASK		0x80
 #define ST_PRESS_LPS25H_MULTIREAD_BIT		true
 #define ST_PRESS_LPS25H_TEMP_OFFSET		42500
 #define ST_PRESS_LPS25H_OUT_XL_ADDR		0x28
@@ -220,6 +224,8 @@ static const struct st_sensor_settings st_press_sensors_settings[] = {
 			.addr = ST_PRESS_LPS331AP_DRDY_IRQ_ADDR,
 			.mask_int1 = ST_PRESS_LPS331AP_DRDY_IRQ_INT1_MASK,
 			.mask_int2 = ST_PRESS_LPS331AP_DRDY_IRQ_INT2_MASK,
+			.addr_ihl = ST_PRESS_LPS331AP_IHL_IRQ_ADDR,
+			.mask_ihl = ST_PRESS_LPS331AP_IHL_IRQ_MASK,
 		},
 		.multi_read_bit = ST_PRESS_LPS331AP_MULTIREAD_BIT,
 		.bootime = 2,
@@ -304,6 +310,8 @@ static const struct st_sensor_settings st_press_sensors_settings[] = {
 			.addr = ST_PRESS_LPS25H_DRDY_IRQ_ADDR,
 			.mask_int1 = ST_PRESS_LPS25H_DRDY_IRQ_INT1_MASK,
 			.mask_int2 = ST_PRESS_LPS25H_DRDY_IRQ_INT2_MASK,
+			.addr_ihl = ST_PRESS_LPS25H_IHL_IRQ_ADDR,
+			.mask_ihl = ST_PRESS_LPS25H_IHL_IRQ_MASK,
 		},
 		.multi_read_bit = ST_PRESS_LPS25H_MULTIREAD_BIT,
 		.bootime = 2,

include/linux/iio/common/st_sensors.h

@@ -119,6 +119,8 @@ struct st_sensor_bdu {
  * @addr: address of the register.
  * @mask_int1: mask to enable/disable IRQ on INT1 pin.
  * @mask_int2: mask to enable/disable IRQ on INT2 pin.
+ * @addr_ihl: address to enable/disable active low on the INT lines.
+ * @mask_ihl: mask to enable/disable active low on the INT lines.
  * struct ig1 - represents the Interrupt Generator 1 of sensors.
  * @en_addr: address of the enable ig1 register.
  * @en_mask: mask to write the on/off value for enable.
@@ -127,6 +129,8 @@ struct st_sensor_data_ready_irq {
 	u8 addr;
 	u8 mask_int1;
 	u8 mask_int2;
+	u8 addr_ihl;
+	u8 mask_ihl;
 	struct {
 		u8 en_addr;
 		u8 en_mask;