iio:ak8975: add mounting matrix support

Expose a rotation matrix to indicate userspace the chip orientation with
respect to the overall hardware system.
Matrix is retrieved from "in_mount_matrix". It is declared into ak8975 DTS
entry as a "mount-matrix" property.

Signed-off-by: Gregor Boirie <gregor.boirie@parrot.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
index 34a3206..e1e7dd3 100644 (file)
--- a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
+++ b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
@@ -9,6 +9,7 @@ Optional properties:
 
   - gpios : should be device tree identifier of the magnetometer DRDY pin
   - vdd-supply: an optional regulator that needs to be on to provide VDD
+  - mount-matrix: an optional 3x3 mounting rotation matrix
 
 Example:
 
@@ -17,4 +18,13 @@ ak8975@0c {
         reg = <0x0c>;
         gpios = <&gpj0 7 0>;
         vdd-supply = <&ldo_3v3_gnss>;
+        mount-matrix = "-0.984807753012208",  /* x0 */
+                       "0",                   /* y0 */
+                       "-0.173648177666930",  /* z0 */
+                       "0",                   /* x1 */
+                       "-1",                  /* y1 */
+                       "0",                   /* z1 */
+                       "-0.173648177666930",  /* x2 */
+                       "0",                   /* y2 */
+                       "0.984807753012208";   /* z2 */
 };

diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
index a2aac50..dbf0661 100644 (file)
--- a/drivers/iio/magnetometer/ak8975.c
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -40,7 +40,8 @@
 #include <linux/iio/trigger.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
-#include <linux/regulator/consumer.h>
+
+#include <linux/iio/magnetometer/ak8975.h>
 
 /*
  * Register definitions, as well as various shifts and masks to get at the
@@ -376,6 +377,7 @@ struct ak8975_data {
        wait_queue_head_t       data_ready_queue;
        unsigned long           flags;
        u8                      cntl_cache;
+       struct iio_mount_matrix orientation;
        struct regulator        *vdd;
 };
 
@@ -726,6 +728,18 @@ static int ak8975_read_raw(struct iio_dev *indio_dev,
        return -EINVAL;
 }
 
+static const struct iio_mount_matrix *
+ak8975_get_mount_matrix(const struct iio_dev *indio_dev,
+                       const struct iio_chan_spec *chan)
+{
+       return &((struct ak8975_data *)iio_priv(indio_dev))->orientation;
+}
+
+static const struct iio_chan_spec_ext_info ak8975_ext_info[] = {
+       IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, ak8975_get_mount_matrix),
+       { },
+};
+
 #define AK8975_CHANNEL(axis, index)                                    \
        {                                                               \
                .type = IIO_MAGN,                                       \
@@ -740,7 +754,8 @@ static int ak8975_read_raw(struct iio_dev *indio_dev,
                        .realbits = 16,                                 \
                        .storagebits = 16,                              \
                        .endianness = IIO_CPU                           \
-               }                                                       \
+               },                                                      \
+               .ext_info = ak8975_ext_info,                            \
        }
 
 static const struct iio_chan_spec ak8975_channels[] = {
@@ -837,10 +852,12 @@ static int ak8975_probe(struct i2c_client *client,
        int err;
        const char *name = NULL;
        enum asahi_compass_chipset chipset;
+       const struct ak8975_platform_data *pdata =
+               dev_get_platdata(&client->dev);
 
        /* Grab and set up the supplied GPIO. */
-       if (client->dev.platform_data)
-               eoc_gpio = *(int *)(client->dev.platform_data);
+       if (pdata)
+               eoc_gpio = pdata->eoc_gpio;
        else if (client->dev.of_node)
                eoc_gpio = of_get_gpio(client->dev.of_node, 0);
        else
@@ -874,6 +891,15 @@ static int ak8975_probe(struct i2c_client *client,
        data->eoc_gpio = eoc_gpio;
        data->eoc_irq = 0;
 
+       if (!pdata) {
+               err = of_iio_read_mount_matrix(&client->dev,
+                                              "mount-matrix",
+                                              &data->orientation);
+               if (err)
+                       return err;
+       } else
+               data->orientation = pdata->orientation;
+
        /* id will be NULL when enumerated via ACPI */
        if (id) {
                chipset = (enum asahi_compass_chipset)(id->driver_data);

diff --git a/include/linux/iio/magnetometer/ak8975.h b/include/linux/iio/magnetometer/ak8975.h
new file mode 100644 (file)
index 0000000..c840095
--- /dev/null
+++ b/include/linux/iio/magnetometer/ak8975.h
@@ -0,0 +1,16 @@
+#ifndef __IIO_MAGNETOMETER_AK8975_H__
+#define __IIO_MAGNETOMETER_AK8975_H__
+
+#include <linux/iio/iio.h>
+
+/**
+ * struct ak8975_platform_data - AK8975 magnetometer driver platform data
+ * @eoc_gpio:    data ready event gpio
+ * @orientation: mounting matrix relative to main hardware
+ */
+struct ak8975_platform_data {
+       int                     eoc_gpio;
+       struct iio_mount_matrix orientation;
+};
+
+#endif