lis3: remove automatic shutdown of the device

After measurement on my laptop, it seems that turning off the device does
not bring any energy saving (within 0.1W precision).  So let's keep the
device always on.  It simplifies the code, and it avoids the problem of
reading a wrong value sometimes just after turning the device on.

Moreover, since commit ef2cfc790bf5f0ff189b01eabc0f4feb5e8524df had been
too zealous, the device was actually never turned off anyway.  This patch
also restores the damages done by this commit concerning the
initialisation/poweroff.

Also do more clean up with the usage of the lis3_dev global variable.

Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: 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, 29 insertions, 59 deletions

diff --git a/drivers/hwmon/lis3lv02d.c b/drivers/hwmon/lis3lv02d.c
index 17f2003..df3f586 100644
--- a/drivers/hwmon/lis3lv02d.c
+++ b/drivers/hwmon/lis3lv02d.c
@@ -105,56 +105,39 @@ static void lis3lv02d_get_xyz(struct lis3lv02d *lis3, int *x, int *y, int *z)
 {
 	int position[3];
 
-	position[0] = lis3_dev.read_data(lis3, OUTX);
-	position[1] = lis3_dev.read_data(lis3, OUTY);
-	position[2] = lis3_dev.read_data(lis3, OUTZ);
+	position[0] = lis3->read_data(lis3, OUTX);
+	position[1] = lis3->read_data(lis3, OUTY);
+	position[2] = lis3->read_data(lis3, OUTZ);
 
-	*x = lis3lv02d_get_axis(lis3_dev.ac.x, position);
-	*y = lis3lv02d_get_axis(lis3_dev.ac.y, position);
-	*z = lis3lv02d_get_axis(lis3_dev.ac.z, position);
+	*x = lis3lv02d_get_axis(lis3->ac.x, position);
+	*y = lis3lv02d_get_axis(lis3->ac.y, position);
+	*z = lis3lv02d_get_axis(lis3->ac.z, position);
 }
 
 void lis3lv02d_poweroff(struct lis3lv02d *lis3)
 {
-	lis3_dev.is_on = 0;
+	/* disable X,Y,Z axis and power down */
+	lis3->write(lis3, CTRL_REG1, 0x00);
 }
 EXPORT_SYMBOL_GPL(lis3lv02d_poweroff);
 
 void lis3lv02d_poweron(struct lis3lv02d *lis3)
 {
-	lis3_dev.is_on = 1;
-	lis3_dev.init(lis3);
-}
-EXPORT_SYMBOL_GPL(lis3lv02d_poweron);
+	u8 reg;
 
-/*
- * To be called before starting to use the device. It makes sure that the
- * device will always be on until a call to lis3lv02d_decrease_use(). Not to be
- * used from interrupt context.
- */
-static void lis3lv02d_increase_use(struct lis3lv02d *dev)
-{
-	mutex_lock(&dev->lock);
-	dev->usage++;
-	if (dev->usage == 1) {
-		if (!dev->is_on)
-			lis3lv02d_poweron(dev);
-	}
-	mutex_unlock(&dev->lock);
-}
+	lis3->init(lis3);
 
-/*
- * To be called whenever a usage of the device is stopped.
- * It will make sure to turn off the device when there is not usage.
- */
-static void lis3lv02d_decrease_use(struct lis3lv02d *dev)
-{
-	mutex_lock(&dev->lock);
-	dev->usage--;
-	if (dev->usage == 0)
-		lis3lv02d_poweroff(dev);
-	mutex_unlock(&dev->lock);
+	/*
+	 * Common configuration
+	 * BDU: LSB and MSB values are not updated until both have been read.
+	 *      So the value read will always be correct.
+	 */
+	lis3->read(lis3, CTRL_REG2, &reg);
+	reg |= CTRL2_BDU;
+	lis3->write(lis3, CTRL_REG2, reg);
 }
+EXPORT_SYMBOL_GPL(lis3lv02d_poweron);
+
 
 static irqreturn_t lis302dl_interrupt(int irq, void *dummy)
 {
@@ -198,14 +181,12 @@ static int lis3lv02d_misc_open(struct inode *inode, struct file *file)
 		printk(KERN_ERR DRIVER_NAME ": IRQ%d allocation failed\n", lis3_dev.irq);
 		return -EBUSY;
 	}
-	lis3lv02d_increase_use(&lis3_dev);
 	return 0;
 }
 
 static int lis3lv02d_misc_release(struct inode *inode, struct file *file)
 {
 	fasync_helper(-1, file, 0, &lis3_dev.async_queue);
-	lis3lv02d_decrease_use(&lis3_dev);
 	free_irq(lis3_dev.irq, &lis3_dev);
 	clear_bit(0, &lis3_dev.misc_opened); /* release the device */
 	return 0;
@@ -314,10 +295,8 @@ static int lis3lv02d_joystick_kthread(void *data)
 
 static int lis3lv02d_joystick_open(struct input_dev *input)
 {
-	lis3lv02d_increase_use(&lis3_dev);
 	lis3_dev.kthread = kthread_run(lis3lv02d_joystick_kthread, NULL, "klis3lv02d");
 	if (IS_ERR(lis3_dev.kthread)) {
-		lis3lv02d_decrease_use(&lis3_dev);
 		return PTR_ERR(lis3_dev.kthread);
 	}
 
@@ -327,7 +306,6 @@ static int lis3lv02d_joystick_open(struct input_dev *input)
 static void lis3lv02d_joystick_close(struct input_dev *input)
 {
 	kthread_stop(lis3_dev.kthread);
-	lis3lv02d_decrease_use(&lis3_dev);
 }
 
 static inline void lis3lv02d_calibrate_joystick(void)
@@ -390,9 +368,7 @@ static ssize_t lis3lv02d_position_show(struct device *dev,
 {
 	int x, y, z;
 
-	lis3lv02d_increase_use(&lis3_dev);
 	lis3lv02d_get_xyz(&lis3_dev, &x, &y, &z);
-	lis3lv02d_decrease_use(&lis3_dev);
 	return sprintf(buf, "(%d,%d,%d)\n", x, y, z);
 }
 
@@ -406,9 +382,7 @@ static ssize_t lis3lv02d_calibrate_store(struct device *dev,
 				struct device_attribute *attr,
 				const char *buf, size_t count)
 {
-	lis3lv02d_increase_use(&lis3_dev);
 	lis3lv02d_calibrate_joystick();
-	lis3lv02d_decrease_use(&lis3_dev);
 	return count;
 }
 
@@ -420,9 +394,7 @@ static ssize_t lis3lv02d_rate_show(struct device *dev,
 	u8 ctrl;
 	int val;
 
-	lis3lv02d_increase_use(&lis3_dev);
 	lis3_dev.read(&lis3_dev, CTRL_REG1, &ctrl);
-	lis3lv02d_decrease_use(&lis3_dev);
 	val = (ctrl & (CTRL1_DF0 | CTRL1_DF1)) >> 4;
 	return sprintf(buf, "%d\n", lis3lv02dl_df_val[val]);
 }
@@ -446,17 +418,17 @@ static struct attribute_group lis3lv02d_attribute_group = {
 
 static int lis3lv02d_add_fs(struct lis3lv02d *lis3)
 {
-	lis3_dev.pdev = platform_device_register_simple(DRIVER_NAME, -1, NULL, 0);
-	if (IS_ERR(lis3_dev.pdev))
-		return PTR_ERR(lis3_dev.pdev);
+	lis3->pdev = platform_device_register_simple(DRIVER_NAME, -1, NULL, 0);
+	if (IS_ERR(lis3->pdev))
+		return PTR_ERR(lis3->pdev);
 
-	return sysfs_create_group(&lis3_dev.pdev->dev.kobj, &lis3lv02d_attribute_group);
+	return sysfs_create_group(&lis3->pdev->dev.kobj, &lis3lv02d_attribute_group);
 }
 
-int lis3lv02d_remove_fs(void)
+int lis3lv02d_remove_fs(struct lis3lv02d *lis3)
 {
-	sysfs_remove_group(&lis3_dev.pdev->dev.kobj, &lis3lv02d_attribute_group);
-	platform_device_unregister(lis3_dev.pdev);
+	sysfs_remove_group(&lis3->pdev->dev.kobj, &lis3lv02d_attribute_group);
+	platform_device_unregister(lis3->pdev);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(lis3lv02d_remove_fs);
@@ -482,13 +454,12 @@ int lis3lv02d_init_device(struct lis3lv02d *dev)
 		break;
 	default:
 		printk(KERN_ERR DRIVER_NAME
-			": unknown sensor type 0x%X\n", lis3_dev.whoami);
+			": unknown sensor type 0x%X\n", dev->whoami);
 		return -EINVAL;
 	}
 
-	mutex_init(&dev->lock);
 	lis3lv02d_add_fs(dev);
-	lis3lv02d_increase_use(dev);
+	lis3lv02d_poweron(dev);
 
 	if (lis3lv02d_joystick_enable())
 		printk(KERN_ERR DRIVER_NAME ": joystick initialization failed\n");
@@ -503,7 +474,6 @@ int lis3lv02d_init_device(struct lis3lv02d *dev)
 	if (misc_register(&lis3lv02d_misc_device))
 		printk(KERN_ERR DRIVER_NAME ": misc_register failed\n");
 out:
-	lis3lv02d_decrease_use(dev);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(lis3lv02d_init_device);