input: mt: Collect slots initialization code

The MT slots devices all follow the same initialization pattern
of creating slots and hinting about buffer size. Let drivers call
an initialization function instead, and make sure it can be called
repeatedly without side effects.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

4 files changed, 16 insertions, 10 deletions

diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c
index 463a4d7d54f..f400e47092c 100644
--- a/drivers/input/input-mt.c
+++ b/drivers/input/input-mt.c
@@ -12,20 +12,25 @@
 #include <linux/slab.h>
 
 /**
- * input_mt_create_slots() - create MT input slots
+ * input_mt_init_slots() - initialize MT input slots
  * @dev: input device supporting MT events and finger tracking
  * @num_slots: number of slots used by the device
  *
- * This function allocates all necessary memory for MT slot handling in the
- * input device, and adds ABS_MT_SLOT to the device capabilities. All slots
- * are initially marked as unused by setting ABS_MT_TRACKING_ID to -1.
+ * This function allocates all necessary memory for MT slot handling
+ * in the input device, adds ABS_MT_SLOT to the device capabilities
+ * and sets up appropriate event buffers. All slots are initially
+ * marked as unused by setting ABS_MT_TRACKING_ID to -1. May be called
+ * repeatedly. Returns -EINVAL if attempting to reinitialize with a
+ * different number of slots.
  */
-int input_mt_create_slots(struct input_dev *dev, unsigned int num_slots)
+int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots)
 {
 	int i;
 
 	if (!num_slots)
 		return 0;
+	if (dev->mt)
+		return dev->mtsize != num_slots ? -EINVAL : 0;
 
 	dev->mt = kcalloc(num_slots, sizeof(struct input_mt_slot), GFP_KERNEL);
 	if (!dev->mt)
@@ -33,6 +38,7 @@ int input_mt_create_slots(struct input_dev *dev, unsigned int num_slots)
 
 	dev->mtsize = num_slots;
 	input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
+	input_set_events_per_packet(dev, 6 * num_slots);
 
 	/* Mark slots as 'unused' */
 	for (i = 0; i < num_slots; i++)
@@ -40,7 +46,7 @@ int input_mt_create_slots(struct input_dev *dev, unsigned int num_slots)
 
 	return 0;
 }
-EXPORT_SYMBOL(input_mt_create_slots);
+EXPORT_SYMBOL(input_mt_init_slots);
 
 /**
  * input_mt_destroy_slots() - frees the MT slots of the input device
@@ -54,5 +60,6 @@ void input_mt_destroy_slots(struct input_dev *dev)
 	kfree(dev->mt);
 	dev->mt = NULL;
 	dev->mtsize = 0;
+	dev->slot = 0;
 }
 EXPORT_SYMBOL(input_mt_destroy_slots);
diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index 8f374143190..bea89722c4e 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -407,8 +407,7 @@ static int uinput_setup_device(struct uinput_device *udev, const char __user *bu
 			goto exit;
 		if (test_bit(ABS_MT_SLOT, dev->absbit)) {
 			int nslot = input_abs_get_max(dev, ABS_MT_SLOT) + 1;
-			input_mt_create_slots(dev, nslot);
-			input_set_events_per_packet(dev, 6 * nslot);
+			input_mt_init_slots(dev, nslot);
 		} else if (test_bit(ABS_MT_POSITION_X, dev->absbit)) {
 			input_set_events_per_packet(dev, 60);
 		}
diff --git a/drivers/input/tablet/wacom_wac.c b/drivers/input/tablet/wacom_wac.c
index bde612c6d36..f26e2238f6c 100644
--- a/drivers/input/tablet/wacom_wac.c
+++ b/drivers/input/tablet/wacom_wac.c
@@ -1273,7 +1273,7 @@ void wacom_setup_input_capabilities(struct input_dev *input_dev,
 			__set_bit(BTN_TOOL_FINGER, input_dev->keybit);
 			__set_bit(BTN_TOOL_DOUBLETAP, input_dev->keybit);
 
-			input_mt_create_slots(input_dev, 2);
+			input_mt_init_slots(input_dev, 2);
 			input_set_abs_params(input_dev, ABS_MT_POSITION_X,
 					     0, features->x_max,
 					     features->x_fuzz, 0);
diff --git a/drivers/input/touchscreen/wacom_w8001.c b/drivers/input/touchscreen/wacom_w8001.c
index 5d4f50e52a2..4a2e8cf4c8e 100644
--- a/drivers/input/touchscreen/wacom_w8001.c
+++ b/drivers/input/touchscreen/wacom_w8001.c
@@ -318,7 +318,7 @@ static int w8001_setup(struct w8001 *w8001)
 		case 5:
 			w8001->pktlen = W8001_PKTLEN_TOUCH2FG;
 
-			input_mt_create_slots(dev, 2);
+			input_mt_init_slots(dev, 2);
 			input_set_abs_params(dev, ABS_MT_TRACKING_ID,
 						0, MAX_TRACKING_ID, 0, 0);
 			input_set_abs_params(dev, ABS_MT_POSITION_X,