Re: [PATCH 2/2] iio: st_accel: use ACPI orientation data

Jonathan Cameron
2018-12-22T18:09:23Z

On Thu, 20 Dec 2018 14:59:33 +0800
Daniel Drake <drake@endlessm.com> wrote:

> Platform-specific ST accelerometer mount matrix information can be
> provided by returning a package of 6 integers from the ACPI _ONT
> method. This has been seen on Acer products such as Veriton Z4860G,
> Z6860G and A890, which include a ST SMO8840 sensor. We have also
> confirmed experimentally that the Windows driver uses such information.
>
> The _ONT data format was explained by a ST vendor contact. However,
> strangely enough, the _ONT transformations must be applied after first
> applying another mount matrix which we determined experimentally. ST
> have not commented on why this is the case, but we imagine that perhaps
> earlier devices (before _ONT was introduced) required this translation
> and hence it became 'standard.'
>
> Interpret the _ONT data and export the equivalent mount matrix to
> userspace.
>
> If no _ONT data is present, no mount matrix is exported.
>
> Signed-off-by: Daniel Drake <drake@endlessm.com>
A trivial point. Please stick to the local (and most common in kernel)
multiline comment syntax of
/*
* asdfsdfs
* more...
*/

Otherwise looks sensible. However, I'd really like Dennis or someone
else at ST to take a look before I take this. We are early in the cycle
(well it hasn't quite started yet) so plenty of time. Give me a
bump in a few weeks if nothing is happening...

Thanks,

Jonathan

> ---
> drivers/iio/accel/st_accel_core.c | 171 +++++++++++++++++++++++++-
> include/linux/iio/common/st_sensors.h | 1 +
> 2 files changed, 171 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/accel/st_accel_core.c b/drivers/iio/accel/st_accel_core.c
> index 3e6fd5a8ac5b..54cc1a0c6a1d 100644
> --- a/drivers/iio/accel/st_accel_core.c
> +++ b/drivers/iio/accel/st_accel_core.c
> @@ -11,6 +11,7 @@
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/slab.h>
> +#include <linux/acpi.h>
> #include <linux/errno.h>
> #include <linux/types.h>
> #include <linux/mutex.h>
> @@ -917,12 +918,167 @@ static const struct iio_trigger_ops st_accel_trigger_ops = {
> #define ST_ACCEL_TRIGGER_OPS NULL
> #endif
>
> +static const struct iio_mount_matrix *
> +get_mount_matrix(const struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan)
> +{
> + struct st_sensor_data *adata = iio_priv(indio_dev);
> +
> + return adata->mount_matrix;
> +}
> +
> +static const struct iio_chan_spec_ext_info mount_matrix_ext_info[] = {
> + IIO_MOUNT_MATRIX(IIO_SHARED_BY_ALL, get_mount_matrix),
> + { },
> +};
> +
> +/* Read ST-specific _ONT orientation data from ACPI and generate an
> + * appropriate mount matrix.
> + */
> +static int apply_acpi_orientation(struct iio_dev *indio_dev,
> + struct iio_chan_spec *channels)
> +{
> +#ifdef CONFIG_ACPI
> + struct st_sensor_data *adata = iio_priv(indio_dev);
> + struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
> + struct acpi_device *adev;
> + union acpi_object *ont;
> + union acpi_object *elements;
> + acpi_status status;
> + int ret = -EINVAL;
> + unsigned int val;
> + int i, j;
> + int final_ont[3][3] = { 0 };
> +
> + /* For some reason, ST's _ONT translation does not apply directly
> + * to the data read from the sensor. Another translation must be
> + * performed first, as described by the matrix below. Perhaps
> + * ST required this specific translation for the first product
> + * where the device was mounted?
> + */
> + const int default_ont[3][3] = {
> + { 0, 1, 0 },
> + { -1, 0, 0 },
> + { 0, 0, -1 },
> + };
> +
> +
> + adev = ACPI_COMPANION(adata->dev);
> + if (!adev)
> + return 0;
> +
> + /* Read _ONT data, which should be a package of 6 integers. */
> + status = acpi_evaluate_object(adev->handle, "_ONT", NULL, &buffer);
> + if (status == AE_NOT_FOUND) {
> + return 0;
> + } else if (ACPI_FAILURE(status)) {
> + dev_warn(&indio_dev->dev, "failed to execute _ONT: %d\n",
> + status);
> + return status;
> + }
> +
> + ont = buffer.pointer;
> + if (ont->type != ACPI_TYPE_PACKAGE || ont->package.count != 6)
> + goto out;
> +
> + /* The first 3 integers provide axis order information.
> + * e.g. 0 1 2 would indicate normal X,Y,Z ordering.
> + * e.g. 1 0 2 indicates that data arrives in order Y,X,Z.
> + */
> + elements = ont->package.elements;
> + for (i = 0; i < 3; i++) {
> + if (elements[i].type != ACPI_TYPE_INTEGER)
> + goto out;
> +
> + val = elements[i].integer.value;
> + if (val < 0 || val > 2)
> + goto out;
> +
> + /* Avoiding full matrix multiplication, we simply reorder the
> + * columns in the default_ont matrix according to the
> + * ordering provided by _ONT.
> + */
> + final_ont[0][i] = default_ont[0][val];
> + final_ont[1][i] = default_ont[1][val];
> + final_ont[2][i] = default_ont[2][val];
> + }
> +
> + /* The final 3 integers provide sign flip information.
> + * 0 means no change, 1 means flip.
> + * e.g. 0 0 1 means that Z data should be sign-flipped.
> + * This is applied after the axis reordering from above.
> + */
> + elements += 3;
> + for (i = 0; i < 3; i++) {
> + if (elements[i].type != ACPI_TYPE_INTEGER)
> + goto out;
> +
> + val = elements[i].integer.value;
> + if (val != 0 && val != 1)
> + goto out;
> + if (!val)
> + continue;
> +
> + /* Flip the values in the indicated column */
> + final_ont[0][i] *= -1;
> + final_ont[1][i] *= -1;
> + final_ont[2][i] *= -1;
> + }
> +
> + /* Convert our integer matrix to a string-based iio_mount_matrix */
> + adata->mount_matrix = devm_kmalloc(&indio_dev->dev,
> + sizeof(*adata->mount_matrix),
> + GFP_KERNEL);
> + if (!adata->mount_matrix) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + for (i = 0; i < 3; i++) {
> + for (j = 0; j < 3; j++) {
> + int matrix_val = final_ont[i][j];
> + char *str_value;
> +
> + switch (matrix_val) {
> + case -1:
> + str_value = "-1";
> + break;
> + case 0:
> + str_value = "0";
> + break;
> + case 1:
> + str_value = "1";
> + break;
> + default:
> + goto out;
> + }
> + adata->mount_matrix->rotation[i * 3 + j] = str_value;
> + }
> + }
> +
> + /* Expose the mount matrix via ext_info */
> + for (i = 0; i < indio_dev->num_channels; i++)
> + channels[i].ext_info = mount_matrix_ext_info;
> +
> + ret = 0;
> + dev_info(&indio_dev->dev, "computed mount matrix from ACPI\n");
> +
> +out:
> + kfree(buffer.pointer);
> + return ret;
> +#else /* !CONFIG_ACPI */
> + return 0;
> +#endif
> +}
> +
> int st_accel_common_probe(struct iio_dev *indio_dev)
> {
> struct st_sensor_data *adata = iio_priv(indio_dev);
> struct st_sensors_platform_data *pdata =
> (struct st_sensors_platform_data *)adata->dev->platform_data;
> int irq = adata->get_irq_data_ready(indio_dev);
> + struct iio_chan_spec *channels;
> + size_t channels_size;
> int err;
>
> indio_dev->modes = INDIO_DIRECT_MODE;
> @@ -941,9 +1097,22 @@ int st_accel_common_probe(struct iio_dev *indio_dev)
>
> adata->num_data_channels = ST_ACCEL_NUMBER_DATA_CHANNELS;
> adata->multiread_bit = adata->sensor_settings->multi_read_bit;
> - indio_dev->channels = adata->sensor_settings->ch;
> indio_dev->num_channels = ST_SENSORS_NUMBER_ALL_CHANNELS;
>
> + channels_size = indio_dev->num_channels * sizeof(struct iio_chan_spec);
> + channels = devm_kmemdup(&indio_dev->dev,
> + adata->sensor_settings->ch,
> + channels_size, GFP_KERNEL);
> + if (!channels) {
> + err = -ENOMEM;
> + goto st_accel_power_off;
> + }
> +
> + if (apply_acpi_orientation(indio_dev, channels))
> + dev_warn(&indio_dev->dev,
> + "failed to apply ACPI orientation data: %d\n", err);
> +
> + indio_dev->channels = channels;
> adata->current_fullscale = (struct st_sensor_fullscale_avl *)
> &adata->sensor_settings->fs.fs_avl[0];
> adata->odr = adata->sensor_settings->odr.odr_avl[0].hz;
> diff --git a/include/linux/iio/common/st_sensors.h b/include/linux/iio/common/st_sensors.h
> index f9bd6e8ab138..fe15694128ac 100644
> --- a/include/linux/iio/common/st_sensors.h
> +++ b/include/linux/iio/common/st_sensors.h
> @@ -260,6 +260,7 @@ struct st_sensor_settings {
> struct st_sensor_data {
> struct device *dev;
> struct iio_trigger *trig;
> + struct iio_mount_matrix *mount_matrix;
> struct st_sensor_settings *sensor_settings;
> struct st_sensor_fullscale_avl *current_fullscale;
> struct regulator *vdd;