Export a new sysfs attribute that describes the placement of the
sensor on the device in the form of a mounting matrix so that
userspace can do the required correction to get accurate data:
corrected X = MM[0] * X + MM[1] Y + MM[2] * Z
corrected Y = MM[3] * X + MM[4] Y + MM[5] * Z
corrected Z = MM[6] * X + MM[7] Y + MM[8] * Z
This information is read from the device properties of the parent of
the IIO device.
Signed-off-by: Octavian Purdila <octavian.purdila@xxxxxxxxx>
---
Documentation/ABI/testing/sysfs-bus-iio | 11 +++++++++
drivers/iio/industrialio-core.c | 42 +++++++++++++++++++++++++++++++++
include/linux/iio/iio.h | 9 +++++++
3 files changed, 62 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 866b4ec..d36476e 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -1375,3 +1375,14 @@ Description:
The emissivity ratio of the surface in the field of view of the
contactless temperature sensor. Emissivity varies from 0 to 1,
with 1 being the emissivity of a black body.
+
+What: /sys/bus/iio/devices/iio:deviceX/mounting_matrix
+KernelVersion: 4.2
+Contact: linux-iio@xxxxxxxxxxxxxxx
+Description:
+ A list of 9 floating point values that describes the
+ transformation needed to account for the way the sensor has been
+ placed on the PCB:
+ corrected X = MM[0] * X + MM[1] Y + MM[2] * Z
+ corrected Y = MM[3] * X + MM[4] Y + MM[5] * Z
+ corrected Z = MM[6] * X + MM[7] Y + MM[8] * Z
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 7c98bc1..9000c53 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -871,6 +871,45 @@ static ssize_t iio_show_dev_name(struct device *dev,
static DEVICE_ATTR(name, S_IRUGO, iio_show_dev_name, NULL);
+static bool iio_get_mounting_matrix(struct iio_dev *indio_dev)
+{
+ int i, err;
+
+ err = device_property_read_u32_array(&indio_dev->dev, "mounting-matrix",
+ indio_dev->mounting_matrix, 9);
+ if (!err) {
+ int *mm = indio_dev->mounting_matrix;
+
+ for (i = IIO_MM_SIZE - 2; i > 0; i -= 2) {
+ mm[i] = mm[i / 2];
+ mm[i + 1] = 0;
+ }
+
+ return true;
+ }
+
+ return false;
+}
+
+static ssize_t iio_show_mounting_matrix(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+ char *tmp = buf;
+ int i;
+
+ for (i = 0; i < IIO_MM_SIZE; i += 2) {
+ tmp += iio_format_value(tmp, IIO_VAL_INT_PLUS_MICRO, 2,
+ &indio_dev->mounting_matrix[i]);
+ if (((i + 2) / 2) % 3)
+ tmp[-1] = ' ';
+ }
+ return tmp - buf;
+}
+
+static DEVICE_ATTR(mounting_matrix, S_IRUGO, iio_show_mounting_matrix, NULL);
+
static int iio_device_register_sysfs(struct iio_dev *indio_dev)
{
int i, ret = 0, attrcount, attrn, attrcount_orig = 0;
@@ -920,6 +959,9 @@ static int iio_device_register_sysfs(struct iio_dev *indio_dev)
indio_dev->chan_attr_group.attrs[attrn++] = &p->dev_attr.attr;
if (indio_dev->name)
indio_dev->chan_attr_group.attrs[attrn++] = &dev_attr_name.attr;
+ if (iio_get_mounting_matrix(indio_dev))
+ indio_dev->chan_attr_group.attrs[attrn++] =
+ &dev_attr_mounting_matrix.attr;
indio_dev->groups[indio_dev->groupcounter++] =
&indio_dev->chan_attr_group;
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index b1e46ae..c1fa852 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -434,6 +434,8 @@ struct iio_buffer_setup_ops {
const unsigned long *scan_mask);
};
+#define IIO_MM_SIZE 18
+
/**
* struct iio_dev - industrial I/O device
* @id: [INTERN] used to identify device internally
@@ -469,6 +471,12 @@ struct iio_buffer_setup_ops {
* @groups: [INTERN] attribute groups
* @groupcounter: [INTERN] index of next attribute group
* @flags: [INTERN] file ops related flags including busy flag.
+ * @mounting_matrix: [INTERN] the mounting matrix is a series of 9
+ * IIO_VAL_INT_PLUS_MICRO pairs that describes the
+ * transformation needed to account for the way the sensor
+ * has been placed on the PCB. See the mounting_matrix
+ * entry in Documentation/ABI/testing/sysfs-bus-iio about
+ * details of the transformation operations.
* @debugfs_dentry: [INTERN] device specific debugfs dentry.
* @cached_reg_addr: [INTERN] cached register address for debugfs reads.
*/
@@ -509,6 +517,7 @@ struct iio_dev {
int groupcounter;
unsigned long flags;
+ int mounting_matrix[IIO_MM_SIZE];
#if defined(CONFIG_DEBUG_FS)
struct dentry *debugfs_dentry;
unsigned cached_reg_addr;
--
1.9.1
--
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