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>

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");
-

drivers/hwmon/lis3lv02d.h

@@ -98,7 +98,7 @@ enum lis3_who_am_i {
 	WAI_6B		= 0x52, /* 6 bits: LIS331DLF - not supported */
 };
 
-enum lis3lv02d_ctrl1 {
+enum lis3lv02d_ctrl1_12b {
 	CTRL1_Xen	= 0x01,
 	CTRL1_Yen	= 0x02,
 	CTRL1_Zen	= 0x04,
@@ -107,8 +107,17 @@ enum lis3lv02d_ctrl1 {
 	CTRL1_DF1	= 0x20,
 	CTRL1_PD0	= 0x40,
 	CTRL1_PD1	= 0x80,
-	CTRL1_DR	= 0x80, /* Data rate on 8 bits */
 };
+
+/* Delta to ctrl1_12b version */
+enum lis3lv02d_ctrl1_8b {
+	CTRL1_STM	= 0x08,
+	CTRL1_STP	= 0x10,
+	CTRL1_FS	= 0x20,
+	CTRL1_PD	= 0x40,
+	CTRL1_DR	= 0x80,
+};
+
 enum lis3lv02d_ctrl2 {
 	CTRL2_DAS	= 0x01,
 	CTRL2_SIM	= 0x02,
@@ -218,6 +227,7 @@ struct lis3lv02d {
 	unsigned long		misc_opened; /* bit0: whether the device is open */
 
 	struct lis3lv02d_platform_data *pdata;	/* for passing board config */
+	struct mutex		mutex;     /* Serialize poll and selftest */
 };
 
 int lis3lv02d_init_device(struct lis3lv02d *lis3);

include/linux/lis3lv02d.h

@@ -55,6 +55,9 @@ struct lis3lv02d_platform_data {
 	s8 axis_z;
 	int (*setup_resources)(void);
 	int (*release_resources)(void);
+	/* Limits for selftest are specified in chip data sheet */
+	s16 st_min_limits[3]; /* min pass limit x, y, z */
+	s16 st_max_limits[3]; /* max pass limit x, y, z */
 };
 
 #endif /* __LIS3LV02D_H_ */