1 files changed, 125 insertions, 0 deletions
diff --git a/drivers/iio/industrialio-acpi.c b/drivers/iio/industrialio-acpi.c
new file mode 100644
index 000000000000..d67a43843799
--- /dev/null
+++ b/drivers/iio/industrialio-acpi.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* IIO ACPI helper functions */
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/iio/iio.h>
+#include <linux/sprintf.h>
+
+/**
+ * iio_read_acpi_mount_matrix() - Read accelerometer mount matrix info from ACPI
+ * @dev:		Device structure
+ * @orientation:	iio_mount_matrix struct to fill
+ * @acpi_method:	ACPI method name to read the matrix from, usually "ROTM"
+ *
+ * Try to read the mount-matrix by calling the specified method on the device's
+ * ACPI firmware-node. If the device has no ACPI firmware-node; or the method
+ * does not exist then this will fail silently. This expects the method to
+ * return data in the ACPI "ROTM" format defined by Microsoft:
+ * https://learn.microsoft.com/en-us/windows-hardware/drivers/sensors/sensors-acpi-entries
+ * This is a Microsoft extension and not part of the official ACPI spec.
+ * The method name is configurable because some dual-accel setups define 2 mount
+ * matrices in a single ACPI device using separate "ROMK" and "ROMS" methods.
+ *
+ * Returns: true if the matrix was successfully, false otherwise.
+ */
+bool iio_read_acpi_mount_matrix(struct device *dev,
+				struct iio_mount_matrix *orientation,
+				char *acpi_method)
+{
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	char *str;
+	union acpi_object *obj, *elements;
+	acpi_handle handle;
+	acpi_status status;
+	int i, j, val[3];
+	bool ret = false;
+
+	handle = ACPI_HANDLE(dev);
+	if (!handle)
+		return false;
+
+	if (!acpi_has_method(handle, acpi_method))
+		return false;
+
+	status = acpi_evaluate_object(handle, acpi_method, NULL, &buffer);
+	if (ACPI_FAILURE(status)) {
+		dev_err(dev, "Failed to get ACPI mount matrix: %d\n", status);
+		return false;
+	}
+
+	obj = buffer.pointer;
+	if (obj->type != ACPI_TYPE_PACKAGE || obj->package.count != 3) {
+		dev_err(dev, "Unknown ACPI mount matrix package format\n");
+		goto out_free_buffer;
+	}
+
+	elements = obj->package.elements;
+	for (i = 0; i < 3; i++) {
+		if (elements[i].type != ACPI_TYPE_STRING) {
+			dev_err(dev, "Unknown ACPI mount matrix element format\n");
+			goto out_free_buffer;
+		}
+
+		str = elements[i].string.pointer;
+		if (sscanf(str, "%d %d %d", &val[0], &val[1], &val[2]) != 3) {
+			dev_err(dev, "Incorrect ACPI mount matrix string format\n");
+			goto out_free_buffer;
+		}
+
+		for (j = 0; j < 3; j++) {
+			switch (val[j]) {
+			case -1: str = "-1"; break;
+			case 0:  str = "0";  break;
+			case 1:  str = "1";  break;
+			default:
+				dev_err(dev, "Invalid value in ACPI mount matrix: %d\n", val[j]);
+				goto out_free_buffer;
+			}
+			orientation->rotation[i * 3 + j] = str;
+		}
+	}
+
+	ret = true;
+
+out_free_buffer:
+	kfree(buffer.pointer);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_acpi_mount_matrix);
+
+/**
+ * iio_get_acpi_device_name_and_data() - Return ACPI device instance name and driver data
+ * @dev:		Device structure
+ * @data:		Optional pointer to return driver data
+ *
+ * When device was enumerated by ACPI ID matching, the user might
+ * want to set description for the physical chip. In such cases
+ * the ACPI device instance name might be used. This call may be
+ * performed to retrieve this information.
+ *
+ * NOTE: This helper function exists only for backward compatibility,
+ * do not use in a new code!
+ *
+ * Returns: ACPI device instance name or %NULL.
+ */
+const char *iio_get_acpi_device_name_and_data(struct device *dev, const void **data)
+{
+	const struct acpi_device_id *id;
+	acpi_handle handle;
+
+	handle = ACPI_HANDLE(dev);
+	if (!handle)
+		return NULL;
+
+	id = acpi_match_device(dev->driver->acpi_match_table, dev);
+	if (!id)
+		return NULL;
+
+	if (data)
+		*data = (const void *)id->driver_data;
+
+	return dev_name(dev);
+}
+EXPORT_SYMBOL_GPL(iio_get_acpi_device_name_and_data);