[PATCH v3 1/4] iio: accel: adxl372: Add support for FIFO peak mode

[Alexandru Tachici]

From: Stefan Popa <stefan.popa@xxxxxxxxxx>

By default, if all three channels (x, y, z) are enabled, sample sets of
concurrent 3-axis data is stored in the FIFO. This patch adds the option
to configure the FIFO to store peak acceleration (x, y and z) of every
over-threshold event. When pushing to iio buffer we push only enabled
axis data.

Signed-off-by: Stefan Popa <stefan.popa@xxxxxxxxxx>
---
 drivers/iio/accel/adxl372.c | 74 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 73 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/accel/adxl372.c b/drivers/iio/accel/adxl372.c
index 67b8817995c0..90c37d6f10d3 100644
--- a/drivers/iio/accel/adxl372.c
+++ b/drivers/iio/accel/adxl372.c
@@ -133,6 +133,9 @@
 
 /* The ADXL372 includes a deep, 512 sample FIFO buffer */
 #define ADXL372_FIFO_SIZE			512
+#define ADXL372_X_AXIS_EN(x)			(((x) >> 0) & 0x1)
+#define ADXL372_Y_AXIS_EN(x)			(((x) >> 1) & 0x1)
+#define ADXL372_Z_AXIS_EN(x)			(((x) >> 2) & 0x1)
 
 /*
  * At +/- 200g with 12-bit resolution, scale is computed as:
@@ -253,6 +256,7 @@ struct adxl372_state {
 	struct iio_trigger		*dready_trig;
 	enum adxl372_fifo_mode		fifo_mode;
 	enum adxl372_fifo_format	fifo_format;
+	unsigned int			fifo_axis_mask;
 	enum adxl372_op_mode		op_mode;
 	enum adxl372_act_proc_mode	act_proc_mode;
 	enum adxl372_odr		odr;
@@ -264,6 +268,7 @@ struct adxl372_state {
 	u8				int2_bitmask;
 	u16				watermark;
 	__be16				fifo_buf[ADXL372_FIFO_SIZE];
+	bool				peak_fifo_mode_en;
 };
 
 static const unsigned long adxl372_channel_masks[] = {
@@ -522,6 +527,22 @@ static int adxl372_get_status(struct adxl372_state *st,
 	return ret;
 }
 
+static void adxl372_arrange_axis_data(struct adxl372_state *st, __be16 *sample)
+{
+	__be16	axis_sample[3];
+	int i = 0;
+
+	memset(axis_sample, 0, 3 * sizeof(__be16));
+	if (ADXL372_X_AXIS_EN(st->fifo_axis_mask))
+		axis_sample[i++] = sample[0];
+	if (ADXL372_Y_AXIS_EN(st->fifo_axis_mask))
+		axis_sample[i++] = sample[1];
+	if (ADXL372_Z_AXIS_EN(st->fifo_axis_mask))
+		axis_sample[i++] = sample[2];
+
+	memcpy(sample, axis_sample, 3 * sizeof(__be16));
+}
+
 static irqreturn_t adxl372_trigger_handler(int irq, void  *p)
 {
 	struct iio_poll_func *pf = p;
@@ -553,8 +574,12 @@ static irqreturn_t adxl372_trigger_handler(int irq, void  *p)
 			goto err;
 
 		/* Each sample is 2 bytes */
-		for (i = 0; i < fifo_entries; i += st->fifo_set_size)
+		for (i = 0; i < fifo_entries; i += st->fifo_set_size) {
+			/* filter peak detection data */
+			if (st->peak_fifo_mode_en)
+				adxl372_arrange_axis_data(st, &st->fifo_buf[i]);
 			iio_push_to_buffers(indio_dev, &st->fifo_buf[i]);
+		}
 	}
 err:
 	iio_trigger_notify_done(indio_dev->trig);
@@ -722,6 +747,43 @@ static int adxl372_write_raw(struct iio_dev *indio_dev,
 	}
 }
 
+static ssize_t adxl372_peak_fifo_en_get(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct adxl372_state *st = iio_priv(dev_to_iio_dev(dev));
+
+	return sprintf(buf, "%d\n", st->peak_fifo_mode_en);
+}
+
+static ssize_t adxl372_peak_fifo_en_set(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct adxl372_state *st = iio_priv(indio_dev);
+	bool val;
+	int ret;
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret < 0)
+		return ret;
+
+	ret = kstrtobool(buf, &val);
+	if (ret)
+		return ret;
+
+	st->peak_fifo_mode_en = val;
+
+	iio_device_release_direct_mode(indio_dev);
+
+	return len;
+}
+
+static IIO_DEVICE_ATTR(hwfifo_peak_mode_enable, 0644,
+		       adxl372_peak_fifo_en_get,
+		       adxl372_peak_fifo_en_set, 0);
+
 static ssize_t adxl372_show_filter_freq_avail(struct device *dev,
 					      struct device_attribute *attr,
 					      char *buf)
@@ -815,13 +877,22 @@ static int adxl372_buffer_postenable(struct iio_dev *indio_dev)
 	}
 
 	st->fifo_format = adxl372_axis_lookup_table[i].fifo_format;
+	st->fifo_axis_mask = adxl372_axis_lookup_table[i].bits;
 	st->fifo_set_size = bitmap_weight(indio_dev->active_scan_mask,
 					  indio_dev->masklength);
+
+	/* Configure the FIFO to store sets of impact event peak. */
+	if (st->peak_fifo_mode_en) {
+		st->fifo_set_size = 3;
+		st->fifo_format = ADXL372_XYZ_PEAK_FIFO;
+	}
+
 	/*
 	 * The 512 FIFO samples can be allotted in several ways, such as:
 	 * 170 sample sets of concurrent 3-axis data
 	 * 256 sample sets of concurrent 2-axis data (user selectable)
 	 * 512 sample sets of single-axis data
+	 * 170 sets of impact event peak (x, y, z)
 	 */
 	if ((st->watermark * st->fifo_set_size) > ADXL372_FIFO_SIZE)
 		st->watermark = (ADXL372_FIFO_SIZE  / st->fifo_set_size);
@@ -894,6 +965,7 @@ static IIO_DEVICE_ATTR(in_accel_filter_low_pass_3db_frequency_available,
 static struct attribute *adxl372_attributes[] = {
 	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
 	&iio_dev_attr_in_accel_filter_low_pass_3db_frequency_available.dev_attr.attr,
+	&iio_dev_attr_hwfifo_peak_mode_enable.dev_attr.attr,
 	NULL,
 };
 
-- 
2.20.1