Only perform IMU self test when sysfs file is written to.

Change-Id: I2d07b2e8c3783ee9551b35dec542208f42007d4b

3 files changed, 16 insertions, 11 deletions

diff --git a/drivers/staging/iio/imu/mpu/README b/drivers/staging/iio/imu/mpu/README
index e7dcc7a6dc33..d8f7a187d0a4 100644
--- a/drivers/staging/iio/imu/mpu/README
+++ b/drivers/staging/iio/imu/mpu/README
@@ -161,9 +161,9 @@ Check which clock-source is used by the chip.
 power_state (Read/write)
 turn on/off the power supply
 
-self_test (read-only)
-read this entry trigger self test. The return value is D.
-D is the success/fail.
+self_test (Read/write)
+Write to this entry to trigger self test. Read to get result of self test.
+The return value is D. D is the success/fail.
 For different chip, the result is different for success/fail.
 1 means success 0 means fail. The LSB of D is for gyro; the bit
 next to LSB of D is for accel. The bit 2 of D is for compass result.
diff --git a/drivers/staging/iio/imu/mpu/inv_mpu_core.c b/drivers/staging/iio/imu/mpu/inv_mpu_core.c
index c9dd7ab60efa..11f22107d3a8 100644
--- a/drivers/staging/iio/imu/mpu/inv_mpu_core.c
+++ b/drivers/staging/iio/imu/mpu/inv_mpu_core.c
@@ -1122,11 +1122,7 @@ static ssize_t inv_attr_show(struct device *dev,
 				       f[st->chip_config.lpa_freq]);
 	}
 	case ATTR_SELF_TEST:
-		if (INV_MPU3050 == st->chip_type)
-			result = 0;
-		else
-			result = inv_hw_self_test(st);
-		return sprintf(buf, "%d\n", result);
+		return sprintf(buf, "%d\n", st->chip_config.self_test_result);
 	case ATTR_KEY:
 		key = st->plat_data.key;
 		result = 0;
@@ -1395,13 +1391,20 @@ static ssize_t inv_attr_store(struct device *dev,
 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 	int data;
 	int result;
-	if (check_enable(st))
+	// Self-test doesn't require enable bit to already be set.
+	if (check_enable(st) && this_attr->address != ATTR_SELF_TEST)
 		return -EPERM;
 	result = kstrtoint(buf, 10, &data);
 	if (result)
 		return -EINVAL;
 
 	switch (this_attr->address) {
+	case ATTR_SELF_TEST:
+		if (INV_MPU3050 != st->chip_type)
+			st->chip_config.self_test_result = inv_hw_self_test(st);
+		// Allow the next calibration-read to redo inv_do_test.
+		st->chip_config.self_test_run_once = 0;
+		break;
 	case ATTR_GYRO_ENABLE:
 		result = inv_gyro_enable(st, ring, !!data);
 		break;
@@ -1552,8 +1555,8 @@ static IIO_DEVICE_ATTR(lpa_mode, S_IRUGO | S_IWUGO, inv_attr_show,
 static IIO_DEVICE_ATTR(lpa_freq, S_IRUGO | S_IWUGO, inv_attr_show,
 	inv_attr_store, ATTR_LPA_FREQ);
 static DEVICE_ATTR(reg_dump, S_IRUGO, inv_reg_dump_show, NULL);
-static IIO_DEVICE_ATTR(self_test, S_IRUGO, inv_attr_show, NULL,
-	ATTR_SELF_TEST);
+static IIO_DEVICE_ATTR(self_test, S_IRUGO | S_IWUGO, inv_attr_show,
+	inv_attr_store, ATTR_SELF_TEST);
 static IIO_DEVICE_ATTR(key, S_IRUGO, inv_attr_show, NULL, ATTR_KEY);
 static IIO_DEVICE_ATTR(gyro_matrix, S_IRUGO, inv_attr_show, NULL,
 	ATTR_GYRO_MATRIX);
diff --git a/drivers/staging/iio/imu/mpu/inv_mpu_iio.h b/drivers/staging/iio/imu/mpu/inv_mpu_iio.h
index 655830438b9a..bc5e37e8f07b 100644
--- a/drivers/staging/iio/imu/mpu/inv_mpu_iio.h
+++ b/drivers/staging/iio/imu/mpu/inv_mpu_iio.h
@@ -120,6 +120,7 @@ struct inv_hw_s {
  *  @lpf:		Digital low pass filter frequency.
  *  @accl_fs:		accel full scale range.
  *  @self_test_run_once flag for self test run ever.
+ *  @self_test_result:	result of last self_test
  *  @has_footer:	MPU3050 specific work around.
  *  @has_compass:	has compass or not.
  *  @enable:		master enable to enable output
@@ -150,6 +151,7 @@ struct inv_chip_config_s {
 	u32 lpf:3;
 	u32 accl_fs:2;
 	u32 self_test_run_once:1;
+	u32 self_test_result:3;
 	u32 has_footer:1;
 	u32 has_compass:1;
 	u32 enable:1;