iio:imu: inv_mpu6050: support more interrupt types

Currently, we support only rising edge interrupts, and in fact we assume
that the interrupt we're given is rising edge (and things won't work if
it's not). However, the device supports rising edge, falling edge, level
low, and level high interrupts.

Empirically, on my system, switching to level interrupts has fixed a
problem I had with significant (~40%) interrupt loss with edge
interrupts. This issue is likely related to the SoC I'm using (Allwinner
H3), but being able to switch the interrupt type is still a very useful
workaround.

I tested this with each interrupt type and verified correct behavior in
a logic analyzer.

Add support for these interrupt types while also eliminating the error
case of the device tree and driver using different interrupt types.

Signed-off-by: Martin Kelly <mkelly@xevo.com>
Acked-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/inv_mpu6050/inv_mpu_core.c

@@ -24,6 +24,7 @@
 #include <linux/spinlock.h>
 #include <linux/iio/iio.h>
 #include <linux/acpi.h>
+#include <linux/platform_device.h>
 #include "inv_mpu_iio.h"
 
 /*
@@ -52,6 +53,7 @@ static const struct inv_mpu6050_reg_map reg_set_6500 = {
 	.raw_accl               = INV_MPU6050_REG_RAW_ACCEL,
 	.temperature            = INV_MPU6050_REG_TEMPERATURE,
 	.int_enable             = INV_MPU6050_REG_INT_ENABLE,
+	.int_status             = INV_MPU6050_REG_INT_STATUS,
 	.pwr_mgmt_1             = INV_MPU6050_REG_PWR_MGMT_1,
 	.pwr_mgmt_2             = INV_MPU6050_REG_PWR_MGMT_2,
 	.int_pin_cfg		= INV_MPU6050_REG_INT_PIN_CFG,
@@ -287,6 +289,10 @@ static int inv_mpu6050_init_config(struct iio_dev *indio_dev)
 	if (result)
 		return result;
 
+	result = regmap_write(st->map, st->reg->int_pin_cfg, st->irq_mask);
+	if (result)
+		return result;
+
 	memcpy(&st->chip_config, hw_info[st->chip_type].config,
 	       sizeof(struct inv_mpu6050_chip_config));
 	result = inv_mpu6050_set_power_itg(st, false);
@@ -892,6 +898,8 @@ int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,
 	struct inv_mpu6050_platform_data *pdata;
 	struct device *dev = regmap_get_device(regmap);
 	int result;
+	struct irq_data *desc;
+	int irq_type;
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
 	if (!indio_dev)
@@ -923,6 +931,29 @@ int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,
 		st->plat_data = *pdata;
 	}
 
+	desc = irq_get_irq_data(irq);
+	if (!desc) {
+		dev_err(dev, "Could not find IRQ %d\n", irq);
+		return -EINVAL;
+	}
+
+	irq_type = irqd_get_trigger_type(desc);
+	if (irq_type == IRQF_TRIGGER_RISING)
+		st->irq_mask = INV_MPU6050_ACTIVE_HIGH;
+	else if (irq_type == IRQF_TRIGGER_FALLING)
+		st->irq_mask = INV_MPU6050_ACTIVE_LOW;
+	else if (irq_type == IRQF_TRIGGER_HIGH)
+		st->irq_mask = INV_MPU6050_ACTIVE_HIGH |
+			INV_MPU6050_LATCH_INT_EN;
+	else if (irq_type == IRQF_TRIGGER_LOW)
+		st->irq_mask = INV_MPU6050_ACTIVE_LOW |
+			INV_MPU6050_LATCH_INT_EN;
+	else {
+		dev_err(dev, "Invalid interrupt type 0x%x specified\n",
+			irq_type);
+		return -EINVAL;
+	}
+
 	/* power is turned on inside check chip type*/
 	result = inv_check_and_setup_chip(st);
 	if (result)
@@ -958,7 +989,7 @@ int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,
 		dev_err(dev, "configure buffer fail %d\n", result);
 		return result;
 	}
-	result = inv_mpu6050_probe_trigger(indio_dev);
+	result = inv_mpu6050_probe_trigger(indio_dev, irq_type);
 	if (result) {
 		dev_err(dev, "trigger probe fail %d\n", result);
 		goto out_unreg_ring;

drivers/iio/imu/inv_mpu6050/inv_mpu_i2c.c

@@ -38,8 +38,7 @@ static int inv_mpu6050_select_bypass(struct i2c_mux_core *muxc, u32 chan_id)
 		goto error_unlock;
 
 	ret = regmap_write(st->map, st->reg->int_pin_cfg,
-			   INV_MPU6050_INT_PIN_CFG |
-			   INV_MPU6050_BIT_BYPASS_EN);
+			   st->irq_mask | INV_MPU6050_BIT_BYPASS_EN);
 
 error_unlock:
 	mutex_unlock(&st->lock);
@@ -55,7 +54,7 @@ static int inv_mpu6050_deselect_bypass(struct i2c_mux_core *muxc, u32 chan_id)
 	mutex_lock(&st->lock);
 
 	/* It doesn't really mattter, if any of the calls fails */
-	regmap_write(st->map, st->reg->int_pin_cfg, INV_MPU6050_INT_PIN_CFG);
+	regmap_write(st->map, st->reg->int_pin_cfg, st->irq_mask);
 	inv_mpu6050_set_power_itg(st, false);
 
 	mutex_unlock(&st->lock);

drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h

@@ -40,6 +40,7 @@
  *  @raw_accl:		Address of first accel register.
  *  @temperature:	temperature register
  *  @int_enable:	Interrupt enable register.
+ *  @int_status:	Interrupt status register.
  *  @pwr_mgmt_1:	Controls chip's power state and clock source.
  *  @pwr_mgmt_2:	Controls power state of individual sensors.
  *  @int_pin_cfg;	Controls interrupt pin configuration.
@@ -60,6 +61,7 @@ struct inv_mpu6050_reg_map {
 	u8 raw_accl;
 	u8 temperature;
 	u8 int_enable;
+	u8 int_status;
 	u8 pwr_mgmt_1;
 	u8 pwr_mgmt_2;
 	u8 int_pin_cfg;
@@ -126,6 +128,7 @@ struct inv_mpu6050_hw {
  *  @timestamps:        kfifo queue to store time stamp.
  *  @map		regmap pointer.
  *  @irq		interrupt number.
+ *  @irq_mask		the int_pin_cfg mask to configure interrupt type.
  */
 struct inv_mpu6050_state {
 #define TIMESTAMP_FIFO_SIZE 16
@@ -144,6 +147,7 @@ struct inv_mpu6050_state {
 	DECLARE_KFIFO(timestamps, long long, TIMESTAMP_FIFO_SIZE);
 	struct regmap *map;
 	int irq;
+	u8 irq_mask;
 };
 
 /*register and associated bit definition*/
@@ -167,6 +171,9 @@ struct inv_mpu6050_state {
 #define INV_MPU6050_REG_TEMPERATURE         0x41
 #define INV_MPU6050_REG_RAW_GYRO            0x43
 
+#define INV_MPU6050_REG_INT_STATUS          0x3A
+#define INV_MPU6050_BIT_RAW_DATA_RDY_INT    0x01
+
 #define INV_MPU6050_REG_USER_CTRL           0x6A
 #define INV_MPU6050_BIT_FIFO_RST            0x04
 #define INV_MPU6050_BIT_DMP_RST             0x08
@@ -216,8 +223,12 @@ struct inv_mpu6050_state {
 #define INV_MPU6050_OUTPUT_DATA_SIZE         24
 
 #define INV_MPU6050_REG_INT_PIN_CFG	0x37
+#define INV_MPU6050_ACTIVE_HIGH		0x00
+#define INV_MPU6050_ACTIVE_LOW		0x80
+/* enable level triggering */
+#define INV_MPU6050_LATCH_INT_EN	0x20
 #define INV_MPU6050_BIT_BYPASS_EN	0x2
-#define INV_MPU6050_INT_PIN_CFG		0
+
 
 /* init parameters */
 #define INV_MPU6050_INIT_FIFO_RATE           50
@@ -289,7 +300,7 @@ enum inv_mpu6050_clock_sel_e {
 
 irqreturn_t inv_mpu6050_irq_handler(int irq, void *p);
 irqreturn_t inv_mpu6050_read_fifo(int irq, void *p);
-int inv_mpu6050_probe_trigger(struct iio_dev *indio_dev);
+int inv_mpu6050_probe_trigger(struct iio_dev *indio_dev, int irq_type);
 void inv_mpu6050_remove_trigger(struct inv_mpu6050_state *st);
 int inv_reset_fifo(struct iio_dev *indio_dev);
 int inv_mpu6050_switch_engine(struct inv_mpu6050_state *st, bool en, u32 mask);

drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c

@@ -127,8 +127,23 @@ irqreturn_t inv_mpu6050_read_fifo(int irq, void *p)
 	u8 data[INV_MPU6050_OUTPUT_DATA_SIZE];
 	u16 fifo_count;
 	s64 timestamp;
+	int int_status;
 
 	mutex_lock(&st->lock);
+
+	/* ack interrupt and check status */
+	result = regmap_read(st->map, st->reg->int_status, &int_status);
+	if (result) {
+		dev_err(regmap_get_device(st->map),
+			"failed to ack interrupt\n");
+		goto flush_fifo;
+	}
+	if (!(int_status & INV_MPU6050_BIT_RAW_DATA_RDY_INT)) {
+		dev_warn(regmap_get_device(st->map),
+			"spurious interrupt with status 0x%x\n", int_status);
+		goto end_session;
+	}
+
 	if (!(st->chip_config.accl_fifo_enable |
 		st->chip_config.gyro_fifo_enable))
 		goto end_session;

drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c

@@ -117,7 +117,7 @@ static const struct iio_trigger_ops inv_mpu_trigger_ops = {
 	.set_trigger_state = &inv_mpu_data_rdy_trigger_set_state,
 };
 
-int inv_mpu6050_probe_trigger(struct iio_dev *indio_dev)
+int inv_mpu6050_probe_trigger(struct iio_dev *indio_dev, int irq_type)
 {
 	int ret;
 	struct inv_mpu6050_state *st = iio_priv(indio_dev);
@@ -131,7 +131,7 @@ int inv_mpu6050_probe_trigger(struct iio_dev *indio_dev)
 
 	ret = devm_request_irq(&indio_dev->dev, st->irq,
 			       &iio_trigger_generic_data_rdy_poll,
-			       IRQF_TRIGGER_RISING,
+			       irq_type,
 			       "inv_mpu",
 			       st->trig);
 	if (ret)