iio: accel: bmc150: Get mount-matrix from ACPI

bmc150 accelerometers with an ACPI hardware-id of BOSC0200 have an ACPI
method providing their mount-matrix, add support for retrieving this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20201130141954.339805-3-hdegoede@redhat.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc150-accel-core.c
index 746555a..7e425eb 100644 (file)
--- a/drivers/iio/accel/bmc150-accel-core.c
+++ b/drivers/iio/accel/bmc150-accel-core.c
@@ -413,6 +413,103 @@ static int bmc150_accel_set_power_state(struct bmc150_accel_data *data, bool on)
 }
 #endif
 
+#ifdef CONFIG_ACPI
+/*
+ * Support for getting accelerometer information from BOSC0200 ACPI nodes.
+ *
+ * There are 2 variants of the BOSC0200 ACPI node. Some 2-in-1s with 360 degree
+ * hinges declare 2 I2C ACPI-resources for 2 accelerometers, 1 in the display
+ * and 1 in the base of the 2-in-1. On these 2-in-1s the ROMS ACPI object
+ * contains the mount-matrix for the sensor in the display and ROMK contains
+ * the mount-matrix for the sensor in the base. On devices using a single
+ * sensor there is a ROTM ACPI object which contains the mount-matrix.
+ *
+ * Here is an incomplete list of devices known to use 1 of these setups:
+ *
+ * Yoga devices with 2 accelerometers using ROMS + ROMK for the mount-matrices:
+ * Lenovo Thinkpad Yoga 11e 3th gen
+ * Lenovo Thinkpad Yoga 11e 4th gen
+ *
+ * Tablets using a single accelerometer using ROTM for the mount-matrix:
+ * Chuwi Hi8 Pro (CWI513)
+ * Chuwi Vi8 Plus (CWI519)
+ * Chuwi Hi13
+ * Irbis TW90
+ * Jumper EZpad mini 3
+ * Onda V80 plus
+ * Predia Basic Tablet
+ */
+static bool bmc150_apply_acpi_orientation(struct device *dev,
+                                         struct iio_mount_matrix *orientation)
+{
+       struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+       struct acpi_device *adev = ACPI_COMPANION(dev);
+       union acpi_object *obj, *elements;
+       char *name, *alt_name, *str;
+       acpi_status status;
+       int i, j, val[3];
+
+       if (!adev || !acpi_dev_hid_uid_match(adev, "BOSC0200", NULL))
+               return false;
+
+       if (strcmp(dev_name(dev), "i2c-BOSC0200:base") == 0)
+               alt_name = "ROMK";
+       else
+               alt_name = "ROMS";
+
+       if (acpi_has_method(adev->handle, "ROTM"))
+               name = "ROTM";
+       else if (acpi_has_method(adev->handle, alt_name))
+               name = alt_name;
+       else
+               return false;
+
+       status = acpi_evaluate_object(adev->handle, name, NULL, &buffer);
+       if (ACPI_FAILURE(status)) {
+               dev_warn(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)
+               goto unknown_format;
+
+       elements = obj->package.elements;
+       for (i = 0; i < 3; i++) {
+               if (elements[i].type != ACPI_TYPE_STRING)
+                       goto unknown_format;
+
+               str = elements[i].string.pointer;
+               if (sscanf(str, "%d %d %d", &val[0], &val[1], &val[2]) != 3)
+                       goto unknown_format;
+
+               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: goto unknown_format;
+                       }
+                       orientation->rotation[i * 3 + j] = str;
+               }
+       }
+
+       kfree(buffer.pointer);
+       return true;
+
+unknown_format:
+       dev_warn(dev, "Unknown ACPI mount matrix format, ignoring\n");
+       kfree(buffer.pointer);
+       return false;
+}
+#else
+static bool bmc150_apply_acpi_orientation(struct device *dev,
+                                         struct iio_mount_matrix *orientation)
+{
+       return false;
+}
+#endif
+
 static const struct bmc150_accel_interrupt_info {
        u8 map_reg;
        u8 map_bitmask;
@@ -1585,10 +1682,13 @@ int bmc150_accel_core_probe(struct device *dev, struct regmap *regmap, int irq,
 
        data->regmap = regmap;
 
-       ret = iio_read_mount_matrix(dev, "mount-matrix",
-                                    &data->orientation);
-       if (ret)
-               return ret;
+       if (!bmc150_apply_acpi_orientation(dev, &data->orientation)) {
+               ret = iio_read_mount_matrix(dev, "mount-matrix",
+                                            &data->orientation);
+               if (ret)
+                       return ret;
+       }
+
        /*
         * VDD   is the analog and digital domain voltage supply
         * VDDIO is the digital I/O voltage supply