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authorSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>2014-04-19 00:22:00 +0100
committerJonathan Cameron <jic23@kernel.org>2014-05-05 10:59:44 +0100
commit5d02edfc3957446fd625c0b018e14c6631a791f4 (patch)
tree3601d52baa45ff006e6bf7b2d13436c8046fa71e /drivers/iio
parentc7eeea93ac60aba3c037af8933a7ffc96ccd495c (diff)
iio: hid-sensors: Convert units and exponent
HID sensor hub specify a default unit and alternative units. This along with unit exponent can be used adjust scale. This change change HID sensor data units to IIO defined units for each sensor type. So in this way user space can use a simply use: "(data + offset) * scale" to get final result. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'drivers/iio')
-rw-r--r--drivers/iio/common/hid-sensors/hid-sensor-attributes.c114
1 files changed, 114 insertions, 0 deletions
diff --git a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
index 75b54730a96..e61b1faa1e0 100644
--- a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
+++ b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
@@ -26,6 +26,40 @@
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
+struct {
+ u32 usage_id;
+ int unit; /* 0 for default others from HID sensor spec */
+ int scale_val0; /* scale, whole number */
+ int scale_val1; /* scale, fraction in micros */
+} static unit_conversion[] = {
+ {HID_USAGE_SENSOR_ACCEL_3D, 0, 9, 806650},
+ {HID_USAGE_SENSOR_ACCEL_3D,
+ HID_USAGE_SENSOR_UNITS_METERS_PER_SEC_SQRD, 1, 0},
+ {HID_USAGE_SENSOR_ACCEL_3D,
+ HID_USAGE_SENSOR_UNITS_G, 9, 806650},
+
+ {HID_USAGE_SENSOR_GYRO_3D, 0, 0, 17453},
+ {HID_USAGE_SENSOR_GYRO_3D,
+ HID_USAGE_SENSOR_UNITS_RADIANS_PER_SECOND, 1, 0},
+ {HID_USAGE_SENSOR_GYRO_3D,
+ HID_USAGE_SENSOR_UNITS_DEGREES_PER_SECOND, 0, 17453},
+
+ {HID_USAGE_SENSOR_COMPASS_3D, 0, 0, 1000},
+ {HID_USAGE_SENSOR_COMPASS_3D, HID_USAGE_SENSOR_UNITS_GAUSS, 1, 0},
+
+ {HID_USAGE_SENSOR_INCLINOMETER_3D, 0, 0, 17453},
+ {HID_USAGE_SENSOR_INCLINOMETER_3D,
+ HID_USAGE_SENSOR_UNITS_DEGREES, 0, 17453},
+ {HID_USAGE_SENSOR_INCLINOMETER_3D,
+ HID_USAGE_SENSOR_UNITS_RADIANS, 1, 0},
+
+ {HID_USAGE_SENSOR_ALS, 0, 1, 0},
+ {HID_USAGE_SENSOR_ALS, HID_USAGE_SENSOR_UNITS_LUX, 1, 0},
+
+ {HID_USAGE_SENSOR_PRESSURE, 0, 100000, 0},
+ {HID_USAGE_SENSOR_PRESSURE, HID_USAGE_SENSOR_UNITS_PASCAL, 1, 0},
+};
+
static int pow_10(unsigned power)
{
int i;
@@ -209,6 +243,86 @@ int hid_sensor_write_raw_hyst_value(struct hid_sensor_common *st,
}
EXPORT_SYMBOL(hid_sensor_write_raw_hyst_value);
+/*
+ * This fuction applies the unit exponent to the scale.
+ * For example:
+ * 9.806650 ->exp:2-> val0[980]val1[665000]
+ * 9.000806 ->exp:2-> val0[900]val1[80600]
+ * 0.174535 ->exp:2-> val0[17]val1[453500]
+ * 1.001745 ->exp:0-> val0[1]val1[1745]
+ * 1.001745 ->exp:2-> val0[100]val1[174500]
+ * 1.001745 ->exp:4-> val0[10017]val1[450000]
+ * 9.806650 ->exp:-2-> val0[0]val1[98066]
+ */
+static void adjust_exponent_micro(int *val0, int *val1, int scale0,
+ int scale1, int exp)
+{
+ int i;
+ int x;
+ int res;
+ int rem;
+
+ if (exp > 0) {
+ *val0 = scale0 * pow_10(exp);
+ res = 0;
+ if (exp > 6) {
+ *val1 = 0;
+ return;
+ }
+ for (i = 0; i < exp; ++i) {
+ x = scale1 / pow_10(5 - i);
+ res += (pow_10(exp - 1 - i) * x);
+ scale1 = scale1 % pow_10(5 - i);
+ }
+ *val0 += res;
+ *val1 = scale1 * pow_10(exp);
+ } else if (exp < 0) {
+ exp = abs(exp);
+ if (exp > 6) {
+ *val0 = *val1 = 0;
+ return;
+ }
+ *val0 = scale0 / pow_10(exp);
+ rem = scale0 % pow_10(exp);
+ res = 0;
+ for (i = 0; i < (6 - exp); ++i) {
+ x = scale1 / pow_10(5 - i);
+ res += (pow_10(5 - exp - i) * x);
+ scale1 = scale1 % pow_10(5 - i);
+ }
+ *val1 = rem * pow_10(6 - exp) + res;
+ } else {
+ *val0 = scale0;
+ *val1 = scale1;
+ }
+}
+
+int hid_sensor_format_scale(u32 usage_id,
+ struct hid_sensor_hub_attribute_info *attr_info,
+ int *val0, int *val1)
+{
+ int i;
+ int exp;
+
+ *val0 = 1;
+ *val1 = 0;
+
+ for (i = 0; ARRAY_SIZE(unit_conversion); ++i) {
+ if (unit_conversion[i].usage_id == usage_id &&
+ unit_conversion[i].unit == attr_info->units) {
+ exp = hid_sensor_convert_exponent(
+ attr_info->unit_expo);
+ adjust_exponent_micro(val0, val1,
+ unit_conversion[i].scale_val0,
+ unit_conversion[i].scale_val1, exp);
+ break;
+ }
+ }
+
+ return IIO_VAL_INT_PLUS_MICRO;
+}
+EXPORT_SYMBOL(hid_sensor_format_scale);
+
int hid_sensor_parse_common_attributes(struct hid_sensor_hub_device *hsdev,
u32 usage_id,
struct hid_sensor_common *st)