Re: [PATCH] iio: proximity: as3935: noise detection + threshold changes

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On 08/05/17 02:50, Matt Ranostay wrote:
Most applications are too noisy to allow the default noise and
watchdog settings, and thus need to be configurable via DT
properties.

Also default settings to POR defaults on a reset, and register
distuber interrupts as noise since it prevents proper usage.

Cc: devicetree@xxxxxxxxxxxxxxx
Signed-off-by: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>
---
  .../devicetree/bindings/iio/proximity/as3935.txt   |  6 +++
  drivers/iio/proximity/as3935.c                     | 43 ++++++++++++++++++++--
  2 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/proximity/as3935.txt b/Documentation/devicetree/bindings/iio/proximity/as3935.txt
index ae23dd8da736..50d370fca533 100644
--- a/Documentation/devicetree/bindings/iio/proximity/as3935.txt
+++ b/Documentation/devicetree/bindings/iio/proximity/as3935.txt
@@ -15,14 +15,20 @@ Optional properties:
  	- ams,tuning-capacitor-pf: Calibration tuning capacitor stepping
  	  value 0 - 120pF. This will require using the calibration data from
  	  the manufacturer.
+	- ams,nflwdth: Set the noise and watchdog threshold register on
+	  startup. This will need to set according to the noise from the
+	  MCU board, and possibly the local environment. Refer to the
+	  datasheet for the threshold settings.
Example: as3935@0 {
  	compatible = "ams,as3935";
  	reg = <0>;
+	spi-max-frequency = <400000>;
Matt, this should be in a different patch.  Worthwhile addition
but not mentioned in the patch description or title at all...
  	spi-cpha;
  	interrupt-parent = <&gpio1>;
  	interrupts = <16 1>;
  	ams,tuning-capacitor-pf = <80>;
+	ams,nflwdth = <0x44>;
  };
diff --git a/drivers/iio/proximity/as3935.c b/drivers/iio/proximity/as3935.c
index aa4df0dcc8c9..ec2f40e0791c 100644
--- a/drivers/iio/proximity/as3935.c
+++ b/drivers/iio/proximity/as3935.c
@@ -39,8 +39,12 @@
  #define AS3935_AFE_GAIN_MAX	0x1F
  #define AS3935_AFE_PWR_BIT	BIT(0)
+#define AS3935_NFLWDTH 0x01
+#define AS3935_NFLWDTH_MASK	0x7f
+
  #define AS3935_INT		0x03
  #define AS3935_INT_MASK		0x0f
+#define AS3935_DISTURB_INT	BIT(2)
  #define AS3935_EVENT_INT	BIT(3)
  #define AS3935_NOISE_INT	BIT(0)
@@ -48,6 +52,7 @@
  #define AS3935_DATA_MASK	0x3F
#define AS3935_TUNE_CAP 0x08
+#define AS3935_DEFAULTS		0x3C
  #define AS3935_CALIBRATE	0x3D
#define AS3935_READ_DATA BIT(14)
@@ -62,7 +67,9 @@ struct as3935_state {
  	struct mutex lock;
  	struct delayed_work work;
+ unsigned long noise_tripped;
  	u32 tune_cap;
+	u32 nflwdth_reg;
  	u8 buffer[16]; /* 8-bit data + 56-bit padding + 64-bit timestamp */
  	u8 buf[2] ____cacheline_aligned;
  };
@@ -145,12 +152,29 @@ static ssize_t as3935_sensor_sensitivity_store(struct device *dev,
  	return len;
  }
+static ssize_t as3935_noise_level_tripped_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
+	int ret;
+
+	mutex_lock(&st->lock);
+	ret = sprintf(buf, "%d\n", !time_after(jiffies, st->noise_tripped + HZ));
Documentation of this attribute?
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
  static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
  	as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
+static IIO_DEVICE_ATTR(noise_level_tripped, S_IRUGO,
+	as3935_noise_level_tripped_show, NULL, 0);
static struct attribute *as3935_attributes[] = {
  	&iio_dev_attr_sensor_sensitivity.dev_attr.attr,
+	&iio_dev_attr_noise_level_tripped.dev_attr.attr,
  	NULL,
  };
@@ -246,7 +270,11 @@ static void as3935_event_work(struct work_struct *work)
  	case AS3935_EVENT_INT:
  		iio_trigger_poll_chained(st->trig);
  		break;
+	case AS3935_DISTURB_INT:
  	case AS3935_NOISE_INT:
+		mutex_lock(&st->lock);
+		st->noise_tripped = jiffies;
+		mutex_unlock(&st->lock);
  		dev_warn(&st->spi->dev, "noise level is too high\n");
  		break;
  	}
@@ -269,15 +297,14 @@ static irqreturn_t as3935_interrupt_handler(int irq, void *private)
static void calibrate_as3935(struct as3935_state *st)
  {
-	/* mask disturber interrupt bit */
-	as3935_write(st, AS3935_INT, BIT(5));
-
+	as3935_write(st, AS3935_DEFAULTS, 0x96);
  	as3935_write(st, AS3935_CALIBRATE, 0x96);
  	as3935_write(st, AS3935_TUNE_CAP,
  		BIT(5) | (st->tune_cap / TUNE_CAP_DIV));
mdelay(2);
  	as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
+	as3935_write(st, AS3935_NFLWDTH, st->nflwdth_reg);
  }
#ifdef CONFIG_PM_SLEEP
@@ -370,6 +397,15 @@ static int as3935_probe(struct spi_device *spi)
  		return -EINVAL;
  	}
+ ret = of_property_read_u32(np,
+			"ams,nflwdth", &st->nflwdth_reg);
+	if (!ret && st->nflwdth_reg > AS3935_NFLWDTH_MASK) {
+		dev_err(&spi->dev,
+			"invalid nflwdth setting of %d\n",
+			st->nflwdth_reg);
+		return -EINVAL;
+	}
+
  	indio_dev->dev.parent = &spi->dev;
  	indio_dev->name = spi_get_device_id(spi)->name;
  	indio_dev->channels = as3935_channels;
@@ -384,6 +420,7 @@ static int as3935_probe(struct spi_device *spi)
  		return -ENOMEM;
st->trig = trig;
+	st->noise_tripped = jiffies - HZ;
  	trig->dev.parent = indio_dev->dev.parent;
  	iio_trigger_set_drvdata(trig, indio_dev);
  	trig->ops = &iio_interrupt_trigger_ops;


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