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Date: Thu, 3 Nov 2016 17:41:33 +0800
From: "Ooi, Joyce" <joyce.ooi@...el.com>
To: Jonathan Cameron <jic23@...nel.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc: Hartmut Knaack <knaack.h@....de>,
Lars-Peter Clausen <lars@...afoo.de>,
Peter Meerwald-Stadler <pmeerw@...erw.net>,
linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
Ooi Joyce <joyce.ooi@...el.com>,
Kweh Hock Leong <hock.leong.kweh@...el.com>,
Ong Boon Leong <boon.leong.ong@...el.com>,
Lay Kuan Loon <kuan.loon.lay@...el.com>
Subject: [PATCH] iio: common: hid-sensors: change the precision of scale values
Extension of the scale precision is needed as there are some scale values
that exceed 6 decimal points precision. For example, the scale for
gyroscope from degrees/second to radians/second is 0.017453. If the unit
exponent for gyroscope is -5, it will be
0.017453 -> exp: -5 -> 0.00000017453
However, because the decimal precision is up to 6, the mentioned scale
value will be truncated to 0.000000. To avoid this, changes are made to
extend the precision to 9 decimal points precision.
Signed-off-by: Ooi, Joyce <joyce.ooi@...el.com>
---
.../iio/common/hid-sensors/hid-sensor-attributes.c | 65 +++++++++++-----------
1 file changed, 33 insertions(+), 32 deletions(-)
diff --git a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
index dc33c1d..c1f8c22 100644
--- a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
+++ b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
@@ -30,34 +30,34 @@
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 */
+ int scale_val1; /* scale, fraction in nanos */
} unit_conversion[] = {
- {HID_USAGE_SENSOR_ACCEL_3D, 0, 9, 806650},
+ {HID_USAGE_SENSOR_ACCEL_3D, 0, 9, 806650000},
{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_UNITS_G, 9, 806650000},
- {HID_USAGE_SENSOR_GYRO_3D, 0, 0, 17453},
+ {HID_USAGE_SENSOR_GYRO_3D, 0, 0, 17453293},
{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_UNITS_DEGREES_PER_SECOND, 0, 17453293},
- {HID_USAGE_SENSOR_COMPASS_3D, 0, 0, 1000},
+ {HID_USAGE_SENSOR_COMPASS_3D, 0, 0, 1000000},
{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, 0, 0, 17453293},
{HID_USAGE_SENSOR_INCLINOMETER_3D,
- HID_USAGE_SENSOR_UNITS_DEGREES, 0, 17453},
+ HID_USAGE_SENSOR_UNITS_DEGREES, 0, 17453293},
{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, 100, 0},
- {HID_USAGE_SENSOR_PRESSURE, HID_USAGE_SENSOR_UNITS_PASCAL, 0, 1000},
+ {HID_USAGE_SENSOR_PRESSURE, 0, 100000, 0},
+ {HID_USAGE_SENSOR_PRESSURE, HID_USAGE_SENSOR_UNITS_PASCAL, 0, 1000000},
};
static int pow_10(unsigned power)
@@ -266,16 +266,16 @@ int hid_sensor_write_raw_hyst_value(struct hid_sensor_common *st,
/*
* 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]
+ * 9.806650000 ->exp:2-> val0[980]val1[665000000]
+ * 9.000806000 ->exp:2-> val0[900]val1[80600000]
+ * 0.17453293 ->exp:2-> val0[17]val1[453293000]
+ * 1.00174532 ->exp:0-> val0[1]val1[1745320]
+ * 1.00174532 ->exp:2-> val0[100]val1[174532000]
+ * 1.00174532 ->exp:4-> val0[10017]val1[453200000]
+ * 9.80665000 ->exp:-2-> val0[0]val1[98066500]
*/
-static void adjust_exponent_micro(int *val0, int *val1, int scale0,
- int scale1, int exp)
+static void adjust_exponent_nano(int *val0, int *val1, int scale0,
+ int scale1, int exp)
{
int i;
int x;
@@ -285,32 +285,32 @@ static void adjust_exponent_micro(int *val0, int *val1, int scale0,
if (exp > 0) {
*val0 = scale0 * pow_10(exp);
res = 0;
- if (exp > 6) {
+ if (exp > 9) {
*val1 = 0;
return;
}
for (i = 0; i < exp; ++i) {
- x = scale1 / pow_10(5 - i);
+ x = scale1 / pow_10(8 - i);
res += (pow_10(exp - 1 - i) * x);
- scale1 = scale1 % pow_10(5 - i);
+ scale1 = scale1 % pow_10(8 - i);
}
*val0 += res;
*val1 = scale1 * pow_10(exp);
} else if (exp < 0) {
exp = abs(exp);
- if (exp > 6) {
+ if (exp > 9) {
*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);
+ for (i = 0; i < (9 - exp); ++i) {
+ x = scale1 / pow_10(8 - i);
+ res += (pow_10(8 - exp - i) * x);
+ scale1 = scale1 % pow_10(8 - i);
}
- *val1 = rem * pow_10(6 - exp) + res;
+ *val1 = rem * pow_10(9 - exp) + res;
} else {
*val0 = scale0;
*val1 = scale1;
@@ -332,14 +332,15 @@ int hid_sensor_format_scale(u32 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);
+ adjust_exponent_nano(val0, val1,
+ unit_conversion[i].scale_val0,
+ unit_conversion[i].scale_val1,
+ exp);
break;
}
}
- return IIO_VAL_INT_PLUS_MICRO;
+ return IIO_VAL_INT_PLUS_NANO;
}
EXPORT_SYMBOL(hid_sensor_format_scale);
--
1.9.1
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