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author | Gregor Boirie <gregor.boirie@parrot.com> | 2016-04-20 19:23:43 +0200 |
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committer | Jonathan Cameron <jic23@kernel.org> | 2016-04-23 22:13:05 +0100 |
commit | dfc57732ad38f93ae6232a3b4e64fd077383a0f1 (patch) | |
tree | 180c004346687cc3d6204239a25bc630c30ea569 /drivers/iio | |
parent | dc2c57153ec5119eae7770042197eff627184d74 (diff) | |
download | op-kernel-dev-dfc57732ad38f93ae6232a3b4e64fd077383a0f1.zip op-kernel-dev-dfc57732ad38f93ae6232a3b4e64fd077383a0f1.tar.gz |
iio:core: mounting matrix support
Expose a rotation matrix to indicate userspace the chip placement with
respect to the overall hardware system. This is needed to adjust
coordinates sampled from a sensor chip when its position deviates from the
main hardware system.
Final coordinates computation is delegated to userspace since:
* computation may involve floating point arithmetics ;
* it allows an application to combine adjustments with arbitrary
transformations.
This 3 dimentional space rotation matrix is expressed as 3x3 array of
strings to support floating point numbers. It may be retrieved from a
"[<dir>_][<type>_]mount_matrix" sysfs attribute file. It is declared into a
device / driver specific DTS property or platform data.
Signed-off-by: Gregor Boirie <gregor.boirie@parrot.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'drivers/iio')
-rw-r--r-- | drivers/iio/industrialio-core.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index 190a593..e6319a9 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -412,6 +412,88 @@ ssize_t iio_enum_write(struct iio_dev *indio_dev, } EXPORT_SYMBOL_GPL(iio_enum_write); +static const struct iio_mount_matrix iio_mount_idmatrix = { + .rotation = { + "1", "0", "0", + "0", "1", "0", + "0", "0", "1" + } +}; + +static int iio_setup_mount_idmatrix(const struct device *dev, + struct iio_mount_matrix *matrix) +{ + *matrix = iio_mount_idmatrix; + dev_info(dev, "mounting matrix not found: using identity...\n"); + return 0; +} + +ssize_t iio_show_mount_matrix(struct iio_dev *indio_dev, uintptr_t priv, + const struct iio_chan_spec *chan, char *buf) +{ + const struct iio_mount_matrix *mtx = ((iio_get_mount_matrix_t *) + priv)(indio_dev, chan); + + if (IS_ERR(mtx)) + return PTR_ERR(mtx); + + if (!mtx) + mtx = &iio_mount_idmatrix; + + return snprintf(buf, PAGE_SIZE, "%s, %s, %s; %s, %s, %s; %s, %s, %s\n", + mtx->rotation[0], mtx->rotation[1], mtx->rotation[2], + mtx->rotation[3], mtx->rotation[4], mtx->rotation[5], + mtx->rotation[6], mtx->rotation[7], mtx->rotation[8]); +} +EXPORT_SYMBOL_GPL(iio_show_mount_matrix); + +/** + * of_iio_read_mount_matrix() - retrieve iio device mounting matrix from + * device-tree "mount-matrix" property + * @dev: device the mounting matrix property is assigned to + * @propname: device specific mounting matrix property name + * @matrix: where to store retrieved matrix + * + * If device is assigned no mounting matrix property, a default 3x3 identity + * matrix will be filled in. + * + * Return: 0 if success, or a negative error code on failure. + */ +#ifdef CONFIG_OF +int of_iio_read_mount_matrix(const struct device *dev, + const char *propname, + struct iio_mount_matrix *matrix) +{ + if (dev->of_node) { + int err = of_property_read_string_array(dev->of_node, + propname, matrix->rotation, + ARRAY_SIZE(iio_mount_idmatrix.rotation)); + + if (err == ARRAY_SIZE(iio_mount_idmatrix.rotation)) + return 0; + + if (err >= 0) + /* Invalid number of matrix entries. */ + return -EINVAL; + + if (err != -EINVAL) + /* Invalid matrix declaration format. */ + return err; + } + + /* Matrix was not declared at all: fallback to identity. */ + return iio_setup_mount_idmatrix(dev, matrix); +} +#else +int of_iio_read_mount_matrix(const struct device *dev, + const char *propname, + struct iio_mount_matrix *matrix) +{ + return iio_setup_mount_idmatrix(dev, matrix); +} +#endif +EXPORT_SYMBOL(of_iio_read_mount_matrix); + /** * iio_format_value() - Formats a IIO value into its string representation * @buf: The buffer to which the formatted value gets written |