lsm6ds0: Cache ODR and range on EC.

For the driver functions get_range and get_data_rate, each call would
end up executing an i2c transaction even if the value had not
changed. Therefore, I modified the lsm6ds0 driver to cache the output
data rate as well as the range. This prevents unecessary i2c
transactions from occuring.

BUG=chromium:476226
TEST=Flashed EC on samus and verified that the accelrange and accelrate
commands still worked and that the sensors were functional.
TEST=Verified Double Tap still worked.
TEST=make -j buildall tests
BRANCH=none

Change-Id: Ie432979266dc4e4892978005de5d1df62cc0654f
Signed-off-by: Aseda Aboagye <aaboagye@google.com>
Reviewed-on: https://chromium-review.googlesource.com/265933
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Commit-Queue: Aseda Aboagye <aaboagye@chromium.org>
Tested-by: Aseda Aboagye <aaboagye@chromium.org>

1 files changed, 18 insertions, 20 deletions

diff --git a/driver/accelgyro_lsm6ds0.c b/driver/accelgyro_lsm6ds0.c
index bb8f6d8fc9..a93166c1de 100644
--- a/driver/accelgyro_lsm6ds0.c
+++ b/driver/accelgyro_lsm6ds0.c
@@ -169,6 +169,7 @@ static int set_range(const struct motion_sensor_t *s,
 	int ret, ctrl_val, range_tbl_size;
 	uint8_t ctrl_reg, reg_val;
 	const struct accel_param_pair *ranges;
+	struct lsm6ds0_data *data = (struct lsm6ds0_data *)s->drv_data;
 
 	ctrl_reg = get_ctrl_reg(s->type);
 	ranges = get_range_table(s->type, &range_tbl_size);
@@ -188,6 +189,11 @@ static int set_range(const struct motion_sensor_t *s,
 	ctrl_val = (ctrl_val & ~LSM6DS0_RANGE_MASK) | reg_val;
 	ret = raw_write8(s->i2c_addr, ctrl_reg, ctrl_val);
 
+	/* Now that we have set the range, update the driver's value. */
+	if (ret == EC_SUCCESS)
+		data->sensor_range = get_engineering_val(reg_val, ranges,
+							 range_tbl_size);
+
 accel_cleanup:
 	mutex_unlock(s->mutex);
 	return EC_SUCCESS;
@@ -196,15 +202,10 @@ accel_cleanup:
 static int get_range(const struct motion_sensor_t *s,
 				int *range)
 {
-	int ret, ctrl_val, range_tbl_size;
-	uint8_t ctrl_reg;
-	const struct accel_param_pair *ranges;
-	ranges = get_range_table(s->type, &range_tbl_size);
-	ctrl_reg = get_ctrl_reg(s->type);
-	ret = raw_read8(s->i2c_addr, ctrl_reg, &ctrl_val);
-	*range = get_engineering_val(ctrl_val & LSM6DS0_RANGE_MASK,
-		ranges, range_tbl_size);
-	return ret;
+	struct lsm6ds0_data *data = (struct lsm6ds0_data *)s->drv_data;
+
+	*range = data->sensor_range;
+	return EC_SUCCESS;
 }
 
 static int set_resolution(const struct motion_sensor_t *s,
@@ -229,6 +230,7 @@ static int set_data_rate(const struct motion_sensor_t *s,
 	int ret, val, odr_tbl_size;
 	uint8_t ctrl_reg, reg_val;
 	const struct accel_param_pair *data_rates;
+	struct lsm6ds0_data *data = s->drv_data;
 
 	ctrl_reg = get_ctrl_reg(s->type);
 	data_rates = get_odr_table(s->type, &odr_tbl_size);
@@ -247,6 +249,11 @@ static int set_data_rate(const struct motion_sensor_t *s,
 	val = (val & ~LSM6DS0_ODR_MASK) | reg_val;
 	ret = raw_write8(s->i2c_addr, ctrl_reg, val);
 
+	/* Now that we have set the odr, update the driver's value. */
+	if (ret == EC_SUCCESS)
+		data->sensor_odr = get_engineering_val(reg_val, data_rates,
+						       odr_tbl_size);
+
 	/* CTRL_REG3_G 12h
 	 * [7] low-power mode = 0;
 	 * [6] high pass filter disabled;
@@ -273,18 +280,9 @@ accel_cleanup:
 static int get_data_rate(const struct motion_sensor_t *s,
 				int *rate)
 {
-	int ret, ctrl_val, odr_tbl_size;
-	uint8_t ctrl_reg;
-	const struct accel_param_pair *data_rates;
-	ctrl_reg = get_ctrl_reg(s->type);
-
-	ret = raw_read8(s->i2c_addr, ctrl_reg, &ctrl_val);
-	if (ret != EC_SUCCESS)
-		return EC_ERROR_UNKNOWN;
+	struct lsm6ds0_data *data = s->drv_data;
 
-	data_rates = get_odr_table(s->type, &odr_tbl_size);
-	*rate = get_engineering_val(ctrl_val & LSM6DS0_ODR_MASK,
-			data_rates, odr_tbl_size);
+	*rate = data->sensor_odr;
 	return EC_SUCCESS;
 }