[RFC PATCH 3/3] iio: derive the mounting matrix from ACPI _PLD objects

[Octavian Purdila <octavian.purdila-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

This patch derives the mounting matrix for a particular IIO device
based ont the ACPI _PLD information. Note that if mounting matrix is
defined in the device properties it overrieds the _PLD information.

Signed-off-by: Octavian Purdila <octavian.purdila-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/iio/industrialio-core.c | 51 +++++++++++++++++++++++++++++++++++++++++
 include/linux/iio/iio.h         | 46 +++++++++++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 9000c53..90ee58a 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -31,6 +31,7 @@
 #include <linux/iio/sysfs.h>
 #include <linux/iio/events.h>
 #include <linux/iio/buffer.h>
+#include <linux/acpi.h>
 
 /* IDA to assign each registered device a unique id */
 static DEFINE_IDA(iio_ida);
@@ -871,6 +872,53 @@ static ssize_t iio_show_dev_name(struct device *dev,
 
 static DEVICE_ATTR(name, S_IRUGO, iio_show_dev_name, NULL);
 
+#if IS_ENABLED(CONFIG_ACPI)
+static bool iio_get_mounting_matrix_acpi(struct iio_dev *indio_dev)
+{
+	acpi_handle h = ACPI_HANDLE(indio_dev->dev.parent);
+	struct acpi_pld_info *info;
+
+	if (ACPI_SUCCESS(acpi_get_physical_device_location(h, &info))) {
+		IIO_MM_SET(indio_dev->mounting_matrix, X, X, 1, 0);
+		IIO_MM_SET(indio_dev->mounting_matrix, Y, Y, 1, 0);
+		IIO_MM_SET(indio_dev->mounting_matrix, Z, Z, 1, 0);
+
+		/* Chip placed on the back panel ; negate x and z */
+		if (info->panel == ACPI_PLD_PANEL_BACK) {
+			IIO_MM_MUL(indio_dev->mounting_matrix, X, X, -1, 0);
+			IIO_MM_MUL(indio_dev->mounting_matrix, Z, Z, -1, 0);
+		}
+
+		switch (info->rotation) {
+		case 2:
+			/* 90 deg clockwise: negate y then swap x,y */
+			IIO_MM_MUL(indio_dev->mounting_matrix, Y, Y, -1, 0);
+			IIO_MM_SWAP(indio_dev->mounting_matrix, X, Y);
+			break;
+		case 4:
+			/* Upside down: negate x and y */
+			IIO_MM_MUL(indio_dev->mounting_matrix, X, X, -1, 0);
+			IIO_MM_MUL(indio_dev->mounting_matrix, Y, Y, -1, 0);
+			break;
+		case 6:
+			/* 90 deg counter clockwise: negate x then swap x,y */
+			IIO_MM_MUL(indio_dev->mounting_matrix, X, X, -1, 0);
+			IIO_MM_SWAP(indio_dev->mounting_matrix, X, Y);
+			break;
+		}
+
+		return true;
+	}
+
+	return false;
+}
+#else
+static bool iio_get_mounting_matrix_acpi(struct iio_dev *indio_dev)
+{
+	return false;
+}
+#endif
+
 static bool iio_get_mounting_matrix(struct iio_dev *indio_dev)
 {
 	int i, err;
@@ -888,6 +936,9 @@ static bool iio_get_mounting_matrix(struct iio_dev *indio_dev)
 		return true;
 	}
 
+	if (ACPI_HANDLE(indio_dev->dev.parent))
+		return iio_get_mounting_matrix_acpi(indio_dev);
+
 	return false;
 }
 
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index c1fa852..feb7813 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -436,6 +436,52 @@ struct iio_buffer_setup_ops {
 
 #define IIO_MM_SIZE		18
 
+enum {
+	IIO_MM_XX0,
+	IIO_MM_XX1,
+	IIO_MM_XY0,
+	IIO_MM_XY1,
+	IIO_MM_XZ0,
+	IIO_MM_XZ1,
+	IIO_MM_YX0,
+	IIO_MM_YX1,
+	IIO_MM_YY0,
+	IIO_MM_YY1,
+	IIO_MM_YZ0,
+	IIO_MM_YZ1,
+	IIO_MM_ZX0,
+	IIO_MM_ZX1,
+	IIO_MM_ZY0,
+	IIO_MM_ZY1,
+	IIO_MM_ZZ0,
+	IIO_MM_ZZ1,
+};
+
+#define IIO_MM_SET(mm, a, b, val0, val1)	\
+	do {					\
+		mm[IIO_MM_##a##b##0] = val0;	\
+		mm[IIO_MM_##a##b##1] = val1;	\
+	} while (0)				\
+
+#define IIO_MM_MUL(mm, a, b, val0, val1)	\
+	do {					\
+		mm[IIO_MM_##a##b##0] *= val0;	\
+		mm[IIO_MM_##a##b##0] *= val1;	\
+	} while (0)				\
+
+#define IIO_MM_SWAP(mm, x, y)					\
+	do {							\
+		int tmp;					\
+								\
+		tmp = mm[IIO_MM_##x##x##0];			\
+		mm[IIO_MM_##x##x##0] = mm[IIO_MM_##y##y##0];	\
+		mm[IIO_MM_##y##y##0] = tmp;			\
+								\
+		tmp = mm[IIO_MM_##x##x##1];			\
+		mm[IIO_MM_##x##x##1] = mm[IIO_MM_##y##y##1];	\
+		mm[IIO_MM_##y##y##1] = tmp;			\
+	} while (0)						\
+
 /**
  * struct iio_dev - industrial I/O device
  * @id:			[INTERN] used to identify device internally
-- 
1.9.1