Re: [RFC PATCH 1/3] iio: export mounting matrix information
From: Jonathan Cameron <hidden>
Date: 2015-05-04 16:07:34
Also in:
linux-acpi, linux-iio, lkml
On 27/04/15 16:01, Octavian Purdila wrote:
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 <redacted>
Hmm. This could be done with existing code and a new info_mask element. The disadvantage is you'd have to change the read_raw to read_raw_multi callback, but that's hardly a big job. If I could be bothered, I'd move the whole subsystem over and drop read_raw entirely. It was introduced precisely for this sort of element. As I mentioned deeper in the thread. If we are going to introduce a mounting matrix, I'd prefer a version that includes translation. It might not matter to many devices but it has mattered a lot to me in the past and doesn't hurt others that much (I used to write papers on how to estimate this stuff from black box devices).
quoted hunk ↗ jump to hunk
--- 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-u79uwXL29TY76Z2rM5mHXA@public.gmane.org +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] * Zdiff --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)
Hmm. if (i != 8) should also do the job with slightly less feedling of magic..
quoted hunk ↗ jump to hunk
+ 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.
Hmm. No absolute need to have this new data in the iio_dev. I'd do it via the read_raw_multi callback, though this will require converting read_raw over to that more flexible version.
quoted hunk ↗ jump to hunk
+ * @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;