X-Git-Url: http://git.osdn.net/view?a=blobdiff_plain;f=description.c;h=302121fc05b4c4aed8a200ed1eb148484fafbf39;hb=378432a4f0cb62a7189340ee1424a529fcf2085a;hp=4d00d63af8cbcec720c244c62e22db7b5df98e0a;hpb=345931b294daa55f0ffdcd7332a69bdf9775a466;p=android-x86%2Fhardware-intel-libsensors.git

diff --git a/description.c b/description.c
index 4d00d63..302121f 100644
--- a/description.c
+++ b/description.c
@@ -1,24 +1,125 @@
 /*
- * Copyright (C) 2014 Intel Corporation.
+ * Copyright (C) 2014-2015 Intel Corporation.
  */
 
 #include <stdlib.h>
+#include <ctype.h>
 #include <utils/Log.h>
 #include <cutils/properties.h>
 #include <hardware/sensors.h>
+#include "common.h"
 #include "enumeration.h"
+#include "description.h"
+#include "utils.h"
 
 #define IIO_SENSOR_HAL_VERSION	1
 
+#define MIN_ON_CHANGE_SAMPLING_PERIOD_US   200000 /* For on change sensors (temperature, proximity, ALS, etc.) report we support 5 Hz max (0.2 s min period) */
+#define MAX_ON_CHANGE_SAMPLING_PERIOD_US 10000000 /* 0.1 Hz min (10 s max period)*/
+#define ANDROID_MAX_FREQ 1000 /* 1000 Hz - This is how much Android requests for the fastest frequency */
 
-static int sensor_get_st_prop (int s, const char* sel, char val[MAX_NAME_SIZE])
+/*
+ * About properties
+ *
+ * We acquire a number of parameters about sensors by reading properties.
+ * The idea here is that someone (either a script, or daemon, sets them
+ * depending on the set of sensors present on the machine.
+ *
+ * There are fallback paths in case the properties are not defined, but it is
+ * highly desirable to at least have the following for each sensor:
+ *
+ * ro.iio.anglvel.name = Gyroscope
+ * ro.iio.anglvel.vendor = Intel
+ * ro.iio.anglvel.max_range = 35
+ * ro.iio.anglvel.resolution = 0.002
+ * ro.iio.anglvel.power = 6.1
+ *
+ * Besides these, we have a couple of knobs initially used to cope with Intel
+ * Sensor Hub oddities, such as HID inspired units or firmware bugs:
+ *
+ * ro.iio.anglvel.transform = ISH
+ * ro.iio.anglvel.quirks = init-rate
+ *
+ * The "terse" quirk indicates that the underlying driver only sends events
+ * when the sensor reports a change. The HAL then periodically generates
+ * duplicate events so the sensor behaves as a continously firing one.
+ *
+ * The "noisy" quirk indicates that the underlying driver has a unusually high
+ * level of noise in its readings, and that the HAL has to accomodate it
+ * somehow, e.g. in the magnetometer calibration code path.
+ *
+ * This one is used specifically to pass a calibration scale to ALS drivers:
+ *
+ * ro.iio.illuminance.name = CPLM3218x Ambient Light Sensor
+ * ro.iio.illuminance.vendor = Capella Microsystems
+ * ro.iio.illuminance.max_range = 167000
+ * ro.iio.illuminance.resolution = 1
+ * ro.iio.illuminance.power = .001
+ * ro.iio.illuminance.illumincalib = 7400
+ *
+ * There's a 'opt_scale' specifier, documented as follows:
+ *
+ *  This adds support for a scaling factor that can be expressed
+ *  using properties, for all sensors, on a channel basis. That
+ *  scaling factor is applied after all other transforms have been
+ *  applied, and is intended as a way to compensate for problems
+ *  such as an incorrect axis polarity for a given sensor.
+ *
+ *  The syntax is <usual property prefix>.<channel>.opt_scale, e.g.
+ *  ro.iio.accel.y.opt_scale = -1 to negate the sign of the y readings
+ *  for the accelerometer.
+ *
+ *  For sensors using a single channel - and only those - the channel
+ *  name is implicitly void and a syntax such as ro.iio.illuminance.
+ *  opt_scale = 3 has to be used.
+ *
+ * 'panel' and 'rotation' specifiers can be used to express ACPI PLD placement
+ * information ; if found they will be used in priority over the actual ACPI
+ * data. That is intended as a way to verify values during development.
+ *
+ * It's possible to use the contents of the iio device name as a way to
+ * discriminate between sensors. Several sensors of the same type can coexist:
+ * e.g. ro.iio.temp.bmg160.name = BMG160 Thermometer will be used in priority
+ * over ro.iio.temp.name = BMC150 Thermometer if the sensor for which we query
+ * properties values happen to have its iio device name set to bmg160.
+ */
+
+int sensor_get_st_prop (int s, const char* sel, char val[MAX_NAME_SIZE])
 {
 	char prop_name[PROP_NAME_MAX];
 	char prop_val[PROP_VALUE_MAX];
-	int i			= sensor_info[s].catalog_index;
+	char extended_sel[PROP_VALUE_MAX];
+
+	int i			= sensor[s].catalog_index;
 	const char *prefix	= sensor_catalog[i].tag;
+	const char *shorthand = sensor_catalog[i].shorthand;
 
-	sprintf(prop_name, PROP_BASE, prefix, sel);
+	/* First try most specialized form, like ro.iio.anglvel.bmg160.name */
+
+	snprintf(extended_sel, PROP_NAME_MAX, "%s.%s",
+		 sensor[s].internal_name, sel);
+
+	snprintf(prop_name, PROP_NAME_MAX, PROP_BASE, prefix, extended_sel);
+
+	if (property_get(prop_name, prop_val, "")) {
+		strncpy(val, prop_val, MAX_NAME_SIZE-1);
+		val[MAX_NAME_SIZE-1] = '\0';
+		return 0;
+	}
+
+	if (shorthand[0] != '\0') {
+		/* Try with shorthand instead of prefix */
+		snprintf(prop_name, PROP_NAME_MAX, PROP_BASE, shorthand, extended_sel);
+
+		if (property_get(prop_name, prop_val, "")) {
+			strncpy(val, prop_val, MAX_NAME_SIZE-1);
+			val[MAX_NAME_SIZE-1] = '\0';
+			return 0;
+		}
+	}
+	/* Fall back to simple form, like ro.iio.anglvel.name */
+
+	snprintf(prop_name, PROP_NAME_MAX, PROP_BASE, prefix, sel);
 
 	if (property_get(prop_name, prop_val, "")) {
 		strncpy(val, prop_val, MAX_NAME_SIZE-1);
@@ -30,6 +131,18 @@ static int sensor_get_st_prop (int s, const char* sel, char val[MAX_NAME_SIZE])
 }
 
 
+int sensor_get_prop (int s, const char* sel, int* val)
+{
+	char buf[MAX_NAME_SIZE];
+
+	if (sensor_get_st_prop(s, sel, buf))
+		return -1;
+
+	*val = atoi(buf);
+	return 0;
+}
+
+
 int sensor_get_fl_prop (int s, const char* sel, float* val)
 {
 	char buf[MAX_NAME_SIZE];
@@ -44,33 +157,63 @@ int sensor_get_fl_prop (int s, const char* sel, float* val)
 
 char* sensor_get_name (int s)
 {
-	if (sensor_info[s].friendly_name[0] != '\0' ||
-		!sensor_get_st_prop(s, "name", sensor_info[s].friendly_name))
-			return sensor_info[s].friendly_name;
+	char buf[MAX_NAME_SIZE];
+
+	if (sensor[s].is_virtual) {
+		switch (sensor[s].type) {
+			case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
+			case SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED:
+				strcpy(buf, sensor[sensor[s].base[0]].friendly_name);
+				snprintf(sensor[s].friendly_name,
+					 MAX_NAME_SIZE,
+					 "%s %s", "Uncalibrated", buf);
+				return sensor[s].friendly_name;
+
+			default:
+				return "";
+		}
+	}
+
+	if (sensor[s].friendly_name[0] != '\0' ||
+		!sensor_get_st_prop(s, "name", sensor[s].friendly_name))
+			return sensor[s].friendly_name;
 
 	/* If we got a iio device name from sysfs, use it */
-	if (sensor_info[s].internal_name[0]) {
-		snprintf(sensor_info[s].friendly_name, MAX_NAME_SIZE, "S%d-%s",
-			 s, sensor_info[s].internal_name);
+	if (sensor[s].internal_name[0]) {
+		snprintf(sensor[s].friendly_name, MAX_NAME_SIZE, "S%d-%s",
+			 s, sensor[s].internal_name);
 	} else {
-		sprintf(sensor_info[s].friendly_name, "S%d", s);
+		sprintf(sensor[s].friendly_name, "S%d", s);
 	}
 
-	return sensor_info[s].friendly_name;
+	return sensor[s].friendly_name;
 }
 
 
 char* sensor_get_vendor (int s)
 {
-	if (sensor_info[s].vendor_name[0] ||
-		!sensor_get_st_prop(s, "vendor", sensor_info[s].vendor_name))
-			return sensor_info[s].vendor_name;
+	if (sensor[s].is_virtual) {
+		switch (sensor[s].type) {
+			case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
+			case SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED:
+				return sensor[sensor[s].base[0]].vendor_name;
+			break;
+
+			default:
+				return "";
+
+		}
+	}
+
+	if (sensor[s].vendor_name[0] ||
+		!sensor_get_st_prop(s, "vendor", sensor[s].vendor_name))
+			return sensor[s].vendor_name;
 
 	return "";
 }
 
 
-int sensor_get_version (int s)
+int sensor_get_version (__attribute__((unused)) int s)
 {
 	return IIO_SENSOR_HAL_VERSION;
 }
@@ -78,21 +221,26 @@ int sensor_get_version (int s)
 
 float sensor_get_max_range (int s)
 {
-	int catalog_index;
-	int sensor_type;
+	if (sensor[s].is_virtual) {
+		switch (sensor[s].type) {
+			case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
+			case SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED:
+				return sensor[sensor[s].base[0]].max_range;
+
+			default:
+				return 0.0;
+		}
+	}
 
-	if (sensor_info[s].max_range != 0.0 ||
-		!sensor_get_fl_prop(s, "max_range", &sensor_info[s].max_range))
-			return sensor_info[s].max_range;
+	if (sensor[s].max_range != 0.0 ||
+		!sensor_get_fl_prop(s, "max_range", &sensor[s].max_range))
+			return sensor[s].max_range;
 
 	/* Try returning a sensible value given the sensor type */
 
 	/* We should cap returned samples accordingly... */
 
-	catalog_index = sensor_info[s].catalog_index;
-	sensor_type = sensor_catalog[catalog_index].type;
-
-	switch (sensor_type) {
+	switch (sensor_desc[s].type) {
 		case SENSOR_TYPE_ACCELEROMETER:		/* m/s^2	*/
 			return 50;
 
@@ -116,16 +264,63 @@ float sensor_get_max_range (int s)
 			return 100;
 
 		default:
-			return 0.0;
+			return 0;
 		}
 }
 
+static float sensor_get_min_freq (int s)
+{
+	/*
+	 * Check if a low cap has been specified for this sensor sampling rate.
+	 * In some case, even when the driver supports lower rate, we still
+	 * wish to receive a certain number of samples per seconds for various
+	 * reasons (calibration, filtering, no change in power consumption...).
+	 */
+
+	float min_freq;
+
+	if (!sensor_get_fl_prop(s, "min_freq", &min_freq))
+		return min_freq;
+
+	return 0;
+}
+
+
+static float sensor_get_max_freq (int s)
+{
+	float max_freq;
+
+	if (!sensor_get_fl_prop(s, "max_freq", &max_freq))
+		return max_freq;
+
+	return ANDROID_MAX_FREQ;
+}
+
+int sensor_get_cal_steps (int s)
+{
+	int cal_steps;
+	if (!sensor_get_prop(s, "cal_steps", &cal_steps))
+		return cal_steps;
+
+	return 0;
+}
 
 float sensor_get_resolution (int s)
 {
-	if (sensor_info[s].resolution != 0.0 ||
-		!sensor_get_fl_prop(s, "resolution", &sensor_info[s].resolution))
-			return sensor_info[s].resolution;
+	if (sensor[s].is_virtual) {
+		switch (sensor[s].type) {
+			case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
+			case SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED:
+				return sensor[sensor[s].base[0]].resolution;
+
+			default:
+				return 0;
+		}
+	}
+
+	if (sensor[s].resolution != 0.0 ||
+		!sensor_get_fl_prop(s, "resolution", &sensor[s].resolution))
+			return sensor[s].resolution;
 
 	return 0;
 }
@@ -133,10 +328,22 @@ float sensor_get_resolution (int s)
 
 float sensor_get_power (int s)
 {
+
+	if (sensor[s].is_virtual) {
+		switch (sensor[s].type) {
+			case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
+			case SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED:
+				return sensor[sensor[s].base[0]].power;
+
+			default:
+				return 0;
+		}
+	}
+
 	/* mA used while sensor is in use ; not sure about volts :) */
-	if (sensor_info[s].power != 0.0 ||
-		!sensor_get_fl_prop(s, "power",	&sensor_info[s].power))
-			return sensor_info[s].power;
+	if (sensor[s].power != 0.0 ||
+		!sensor_get_fl_prop(s, "power",	&sensor[s].power))
+			return sensor[s].power;
 
 	return 0;
 }
@@ -145,37 +352,382 @@ float sensor_get_power (int s)
 float sensor_get_illumincalib (int s)
 {
 	/* calibrating the ALS Sensor*/
-	if (sensor_info[s].illumincalib != 0.0 ||
-		!sensor_get_fl_prop(s, "illumincalib", &sensor_info[s].illumincalib)) {
-			return sensor_info[s].illumincalib;
+	if (sensor[s].illumincalib != 0.0 ||
+		!sensor_get_fl_prop(s, "illumincalib", &sensor[s].illumincalib)) {
+			return sensor[s].illumincalib;
 	}
 
 	return 0;
 }
 
 
+uint32_t sensor_get_quirks (int s)
+{
+	char quirks_buf[MAX_NAME_SIZE];
+
+	/* Read and decode quirks property on first reference */
+	if (!(sensor[s].quirks & QUIRK_ALREADY_DECODED)) {
+		quirks_buf[0] = '\0';
+		sensor_get_st_prop(s, "quirks", quirks_buf);
+
+		if (strstr(quirks_buf, "init-rate"))
+			sensor[s].quirks |= QUIRK_INITIAL_RATE;
+
+		if (strstr(quirks_buf, "continuous"))
+			sensor[s].quirks |= QUIRK_FORCE_CONTINUOUS;
+
+		if (strstr(quirks_buf, "terse"))
+			sensor[s].quirks |= QUIRK_TERSE_DRIVER;
+
+		if (strstr(quirks_buf, "noisy"))
+			sensor[s].quirks |= QUIRK_NOISY;
+
+		if (strstr(quirks_buf, "biased"))
+			sensor[s].quirks |= QUIRK_BIASED;
+
+		if (strstr(quirks_buf, "spotty"))
+			sensor[s].quirks |= QUIRK_SPOTTY;
+
+		if (strstr(quirks_buf, "no-event"))
+			sensor[s].quirks |= QUIRK_NO_EVENT_MODE;
+
+		if (strstr(quirks_buf, "no-trig"))
+			sensor[s].quirks |= QUIRK_NO_TRIG_MODE;
+
+		if (strstr(quirks_buf, "no-poll"))
+			sensor[s].quirks |= QUIRK_NO_POLL_MODE;
+
+		if (strstr(quirks_buf, "hrtimer"))
+			sensor[s].quirks |= QUIRK_HRTIMER;
+
+		sensor[s].quirks |= QUIRK_ALREADY_DECODED;
+	}
+
+	return sensor[s].quirks;
+}
+
+
 int sensor_get_order (int s, unsigned char map[MAX_CHANNELS])
 {
 	char buf[MAX_NAME_SIZE];
 	int i;
-	int count = sensor_catalog[sensor_info[s].catalog_index].num_channels;
+	int count = sensor_catalog[sensor[s].catalog_index].num_channels;
 
-	memset(map, 0, MAX_CHANNELS);
-
-	if  (sensor_get_st_prop(s, "order", buf))
+	if (sensor_get_st_prop(s, "order", buf))
 		return 0; /* No order property */
 
 	/* Assume ASCII characters, in the '0'..'9' range */
 
 	for (i=0; i<count; i++)
-		map[i] = buf[i] - '0';
-
-	/* Check that our indices are in range */
-	for (i=0; i<count; i++)
-		if (map[i] >= count) {
+		if (buf[i] - '0' >= count) {
 			ALOGE("Order index out of range for sensor %d\n", s);
 			return 0;
 		}
 
+	for (i=0; i<count; i++)
+		map[i] = buf[i] - '0';
+
 	return 1;	/* OK to use modified ordering map */
 }
+
+int sensor_get_mounting_matrix (int s, float mm[9])
+{
+	int dev_num = sensor[s].dev_num, err, i;
+	char mm_path[PATH_MAX], mm_buf[100];
+	char *tmp1 = mm_buf, *tmp2;
+
+	switch (sensor[s].type) {
+	case SENSOR_TYPE_ACCELEROMETER:
+	case SENSOR_TYPE_MAGNETIC_FIELD:
+	case SENSOR_TYPE_GYROSCOPE:
+		break;
+	default:
+		return 0;
+	}
+
+	sprintf(mm_path, MOUNTING_MATRIX_PATH, dev_num);
+
+	err = sysfs_read_str(mm_path, mm_buf, sizeof(mm_buf));
+	if (err < 0)
+		return 0;
+
+	for(i = 0; i < 9; i++) {
+		float f;
+
+		f = strtof(tmp1, &tmp2);
+		if (!f && tmp1 == tmp2)
+			return 0;
+		mm[i] = f;
+		tmp1 = tmp2 + 1;
+	}
+
+	ALOGI("%s: %f %f %f %f %f %f %f %f %f\n", __func__, mm[0], mm[1], mm[2], mm[3], mm[4], mm[5], mm[6], mm[7], mm[8]);
+	return 1;
+}
+
+
+char* sensor_get_string_type (int s)
+{
+	switch (sensor_desc[s].type) {
+		case SENSOR_TYPE_ACCELEROMETER:
+			return SENSOR_STRING_TYPE_ACCELEROMETER;
+
+		case SENSOR_TYPE_MAGNETIC_FIELD:
+			return SENSOR_STRING_TYPE_MAGNETIC_FIELD;
+
+		case SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED:
+			return SENSOR_STRING_TYPE_MAGNETIC_FIELD_UNCALIBRATED;
+
+		case SENSOR_TYPE_ORIENTATION:
+			return SENSOR_STRING_TYPE_ORIENTATION;
+
+		case SENSOR_TYPE_GYROSCOPE:
+			return SENSOR_STRING_TYPE_GYROSCOPE;
+
+		case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
+			return SENSOR_STRING_TYPE_GYROSCOPE_UNCALIBRATED;
+
+		case SENSOR_TYPE_LIGHT:
+			return SENSOR_STRING_TYPE_LIGHT;
+
+		case SENSOR_TYPE_AMBIENT_TEMPERATURE:
+			return SENSOR_STRING_TYPE_AMBIENT_TEMPERATURE;
+
+		case SENSOR_TYPE_TEMPERATURE:
+			return SENSOR_STRING_TYPE_TEMPERATURE;
+
+		case SENSOR_TYPE_PROXIMITY:
+			return SENSOR_STRING_TYPE_PROXIMITY;
+
+		case SENSOR_TYPE_PRESSURE:
+			return SENSOR_STRING_TYPE_PRESSURE;
+
+		case SENSOR_TYPE_RELATIVE_HUMIDITY:
+			return SENSOR_STRING_TYPE_RELATIVE_HUMIDITY;
+
+		default:
+			return "";
+		}
+}
+
+
+flag_t sensor_get_flags (int s)
+{
+	flag_t flags = 0;
+
+	switch (sensor_desc[s].type) {
+		case SENSOR_TYPE_LIGHT:
+		case SENSOR_TYPE_AMBIENT_TEMPERATURE:
+		case SENSOR_TYPE_TEMPERATURE:
+		case SENSOR_TYPE_RELATIVE_HUMIDITY:
+		case SENSOR_TYPE_STEP_COUNTER:
+			flags |= SENSOR_FLAG_ON_CHANGE_MODE;
+			break;
+
+
+		case SENSOR_TYPE_PROXIMITY:
+			flags |= SENSOR_FLAG_WAKE_UP;
+			flags |= SENSOR_FLAG_ON_CHANGE_MODE;
+			break;
+		case SENSOR_TYPE_STEP_DETECTOR:
+			flags |= SENSOR_FLAG_SPECIAL_REPORTING_MODE;
+			break;
+		default:
+			break;
+		}
+	return flags;
+}
+
+
+static int get_cdd_freq (int s, int must)
+{
+	switch (sensor_desc[s].type) {
+		case SENSOR_TYPE_ACCELEROMETER:
+			return (must ? 100 : 200); /* must 100 Hz, should 200 Hz, CDD compliant */
+
+		case SENSOR_TYPE_GYROSCOPE:
+			return (must ? 200 : 200); /* must 200 Hz, should 200 Hz, CDD compliant */
+
+		case SENSOR_TYPE_MAGNETIC_FIELD:
+			return (must ? 10 : 50);   /* must 10 Hz, should 50 Hz, CDD compliant */
+
+		case SENSOR_TYPE_LIGHT:
+		case SENSOR_TYPE_AMBIENT_TEMPERATURE:
+		case SENSOR_TYPE_TEMPERATURE:
+			return (must ? 1 : 2);     /* must 1 Hz, should 2Hz, not mentioned in CDD */
+
+		default:
+			return 1; /* Use 1 Hz by default, e.g. for proximity */
+	}
+}
+
+/* 
+ * This value is defined only for continuous mode and on-change sensors. It is the delay between two sensor events corresponding to the lowest frequency that
+ * this sensor supports. When lower frequencies are requested through batch()/setDelay() the events will be generated at this frequency instead. It can be used
+ * by the framework or applications to estimate when the batch FIFO may be full. maxDelay should always fit within a 32 bit signed integer. It is declared as
+ * 64 bit on 64 bit architectures only for binary compatibility reasons. Availability: SENSORS_DEVICE_API_VERSION_1_3
+ */
+max_delay_t sensor_get_max_delay (int s)
+{
+	char avail_sysfs_path[PATH_MAX];
+	int dev_num	= sensor[s].dev_num;
+	char freqs_buf[100];
+	char* cursor;
+	float min_supported_rate;
+	float rate_cap;
+	float sr;
+
+	/*
+	 * continuous, on-change: maximum sampling period allowed in microseconds.
+	 * one-shot, special : 0
+	 */
+	switch (REPORTING_MODE(sensor_desc[s].flags)) {
+		case SENSOR_FLAG_ONE_SHOT_MODE:
+		case SENSOR_FLAG_SPECIAL_REPORTING_MODE:
+			return 0;
+
+		case SENSOR_FLAG_ON_CHANGE_MODE:
+			return MAX_ON_CHANGE_SAMPLING_PERIOD_US;
+
+		default:
+			break;
+	}
+
+	if (sensor[s].is_virtual) {
+		switch (sensor[s].type) {
+			case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
+			case SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED:
+				return sensor_desc[sensor[s].base[0]].maxDelay;
+			default:
+				return 0;
+		}
+	}
+
+	switch (sensor[s].mode) {
+		case MODE_TRIGGER:
+			/* For interrupt-based devices, obey the list of supported sampling rates */
+			sprintf(avail_sysfs_path, DEVICE_AVAIL_FREQ_PATH, dev_num);
+			if (sysfs_read_str(avail_sysfs_path, freqs_buf, sizeof(freqs_buf)) > 0) {
+
+				min_supported_rate = 1000;
+				cursor = freqs_buf;
+
+				while (*cursor && cursor[0]) {
+
+					/* Decode a single value */
+					sr = strtod(cursor, NULL);
+
+					if (sr < min_supported_rate)
+						min_supported_rate = sr;
+
+					/* Skip digits */
+					while (cursor[0] && !isspace(cursor[0]))
+						cursor++;
+
+					/* Skip spaces */
+					while (cursor[0] && isspace(cursor[0]))
+						cursor++;
+				}
+
+				break;
+			}
+
+			/* Fall through ... */
+
+		default:
+			/* Report 1 Hz */
+			min_supported_rate = 1;
+			break;
+	}
+
+	/* Check if a minimum rate was specified for this sensor */
+	rate_cap = sensor_get_min_freq(s);
+
+	if (min_supported_rate < rate_cap)
+		min_supported_rate = rate_cap;
+
+	/* return 0 for wrong values */
+	if (min_supported_rate < 0.1)
+		return 0;
+
+	/* Return microseconds */
+	return (max_delay_t) (1000000.0 / min_supported_rate);
+}
+
+
+int32_t sensor_get_min_delay (int s)
+{
+	char avail_sysfs_path[PATH_MAX];
+	int dev_num	= sensor[s].dev_num;
+	char freqs_buf[100];
+	char* cursor;
+	float max_supported_rate = 0;
+	float max_from_prop = sensor_get_max_freq(s);
+	float sr;
+
+	/* continuous, on change: minimum sampling period allowed in microseconds.
+	 * special : 0, unless otherwise noted
+	 * one-shot:-1
+	 */
+	switch (REPORTING_MODE(sensor_desc[s].flags)) {
+		case SENSOR_FLAG_ON_CHANGE_MODE:
+			return MIN_ON_CHANGE_SAMPLING_PERIOD_US;
+
+		case SENSOR_FLAG_SPECIAL_REPORTING_MODE:
+			return 0;
+
+		case SENSOR_FLAG_ONE_SHOT_MODE:
+			return -1;
+
+		default:
+			break;
+	}
+
+	if (sensor[s].is_virtual) {
+		switch (sensor[s].type) {
+			case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
+			case SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED:
+				return sensor_desc[sensor[s].base[0]].minDelay;
+			default:
+				return 0;
+		}
+	}
+
+	sprintf(avail_sysfs_path, DEVICE_AVAIL_FREQ_PATH, dev_num);
+
+	if (sysfs_read_str(avail_sysfs_path, freqs_buf, sizeof(freqs_buf)) < 0) {
+		if (sensor[s].mode == MODE_POLL) {
+			/* If we have max specified via a property use it */
+			if (max_from_prop != ANDROID_MAX_FREQ)
+				max_supported_rate = max_from_prop;
+			else
+				/* The should rate */
+				max_supported_rate = get_cdd_freq(s, 0);
+		}
+	} else {
+		cursor = freqs_buf;
+		while (*cursor && cursor[0]) {
+
+			/* Decode a single value */
+			sr = strtod(cursor, NULL);
+
+			if (sr > max_supported_rate && sr <= max_from_prop)
+				max_supported_rate = sr;
+
+			/* Skip digits */
+			while (cursor[0] && !isspace(cursor[0]))
+				cursor++;
+
+			/* Skip spaces */
+			while (cursor[0] && isspace(cursor[0]))
+				cursor++;
+		}
+	}
+
+	/* return 0 for wrong values */
+	if (max_supported_rate < 0.1)
+		return 0;
+
+	/* Return microseconds */
+	return (int32_t) (1000000.0 / max_supported_rate);
+}