lis3: selftest support

Implement selftest feature as specified by chip manufacturer.  Control:
read selftest sysfs entry

Response: "OK x y z" or "FAIL x y z"

where x, y, and z are difference between selftest mode and normal mode.
Test is passed when values are within acceptance limit values.

Acceptance limits are provided via platform data.  See chip spesifications
for acceptance limits.  If limits are not properly set, OK / FAIL decision
is meaningless.  However, userspace application can still make decision
based on the numeric x, y, z values.

Selftest is meant for HW diagnostic purposes.  It is not meant to be
called during normal use of the chip.  It may cause false interrupt
events.  Selftest mode delays polling of the normal results but it doesn't
cause wrong values.  Chip must be in static state during selftest.  Any
acceration during the test causes most probably failure.

Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Acked-by: Éric Piel <Eric.Piel@tremplin-utc.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 66 insertions, 1 deletions

diff --git a/drivers/hwmon/lis3lv02d.c b/drivers/hwmon/lis3lv02d.c
index 39b9ac8e18e..55ec883e202 100644
--- a/drivers/hwmon/lis3lv02d.c
+++ b/drivers/hwmon/lis3lv02d.c
@@ -106,9 +106,11 @@ static void lis3lv02d_get_xyz(struct lis3lv02d *lis3, int *x, int *y, int *z)
 {
 	int position[3];
 
+	mutex_lock(&lis3->mutex);
 	position[0] = lis3->read_data(lis3, OUTX);
 	position[1] = lis3->read_data(lis3, OUTY);
 	position[2] = lis3->read_data(lis3, OUTZ);
+	mutex_unlock(&lis3->mutex);
 
 	*x = lis3lv02d_get_axis(lis3->ac.x, position);
 	*y = lis3lv02d_get_axis(lis3->ac.y, position);
@@ -133,6 +135,55 @@ static int lis3lv02d_get_odr(void)
 	return val;
 }
 
+static int lis3lv02d_selftest(struct lis3lv02d *lis3, s16 results[3])
+{
+	u8 reg;
+	s16 x, y, z;
+	u8 selftest;
+	int ret;
+
+	mutex_lock(&lis3->mutex);
+	if (lis3_dev.whoami == WAI_12B)
+		selftest = CTRL1_ST;
+	else
+		selftest = CTRL1_STP;
+
+	lis3->read(lis3, CTRL_REG1, &reg);
+	lis3->write(lis3, CTRL_REG1, (reg | selftest));
+	msleep(lis3->pwron_delay / lis3lv02d_get_odr());
+
+	/* Read directly to avoid axis remap */
+	x = lis3->read_data(lis3, OUTX);
+	y = lis3->read_data(lis3, OUTY);
+	z = lis3->read_data(lis3, OUTZ);
+
+	/* back to normal settings */
+	lis3->write(lis3, CTRL_REG1, reg);
+	msleep(lis3->pwron_delay / lis3lv02d_get_odr());
+
+	results[0] = x - lis3->read_data(lis3, OUTX);
+	results[1] = y - lis3->read_data(lis3, OUTY);
+	results[2] = z - lis3->read_data(lis3, OUTZ);
+
+	ret = 0;
+	if (lis3->pdata) {
+		int i;
+		for (i = 0; i < 3; i++) {
+			/* Check against selftest acceptance limits */
+			if ((results[i] < lis3->pdata->st_min_limits[i]) ||
+			    (results[i] > lis3->pdata->st_max_limits[i])) {
+				ret = -EIO;
+				goto fail;
+			}
+		}
+	}
+
+	/* test passed */
+fail:
+	mutex_unlock(&lis3->mutex);
+	return ret;
+}
+
 void lis3lv02d_poweroff(struct lis3lv02d *lis3)
 {
 	/* disable X,Y,Z axis and power down */
@@ -365,6 +416,17 @@ void lis3lv02d_joystick_disable(void)
 EXPORT_SYMBOL_GPL(lis3lv02d_joystick_disable);
 
 /* Sysfs stuff */
+static ssize_t lis3lv02d_selftest_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	int result;
+	s16 values[3];
+
+	result = lis3lv02d_selftest(&lis3_dev, values);
+	return sprintf(buf, "%s %d %d %d\n", result == 0 ? "OK" : "FAIL",
+		values[0], values[1], values[2]);
+}
+
 static ssize_t lis3lv02d_position_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
@@ -394,12 +456,14 @@ static ssize_t lis3lv02d_rate_show(struct device *dev,
 	return sprintf(buf, "%d\n", lis3lv02d_get_odr());
 }
 
+static DEVICE_ATTR(selftest, S_IRUSR, lis3lv02d_selftest_show, NULL);
 static DEVICE_ATTR(position, S_IRUGO, lis3lv02d_position_show, NULL);
 static DEVICE_ATTR(calibrate, S_IRUGO|S_IWUSR, lis3lv02d_calibrate_show,
 	lis3lv02d_calibrate_store);
 static DEVICE_ATTR(rate, S_IRUGO, lis3lv02d_rate_show, NULL);
 
 static struct attribute *lis3lv02d_attributes[] = {
+	&dev_attr_selftest.attr,
 	&dev_attr_position.attr,
 	&dev_attr_calibrate.attr,
 	&dev_attr_rate.attr,
@@ -455,6 +519,8 @@ int lis3lv02d_init_device(struct lis3lv02d *dev)
 		return -EINVAL;
 	}
 
+	mutex_init(&dev->mutex);
+
 	lis3lv02d_add_fs(dev);
 	lis3lv02d_poweron(dev);
 
@@ -507,4 +573,3 @@ EXPORT_SYMBOL_GPL(lis3lv02d_init_device);
 MODULE_DESCRIPTION("ST LIS3LV02Dx three-axis digital accelerometer driver");
 MODULE_AUTHOR("Yan Burman, Eric Piel, Pavel Machek");
 MODULE_LICENSE("GPL");
-