input: mt: Break out slots handling

In preparation for common code to handle a larger set of MT slots
devices, move the slots handling over to a separate file.

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

1 files changed, 58 insertions, 0 deletions

diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c
new file mode 100644
index 000000000000..463a4d7d54f2
--- /dev/null
+++ b/drivers/input/input-mt.c
@@ -0,0 +1,58 @@
+/*
+ * Input Multitouch Library
+ *
+ * Copyright (c) 2008-2010 Henrik Rydberg
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/input/mt.h>
+#include <linux/slab.h>
+
+/**
+ * input_mt_create_slots() - create 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.
+ */
+int input_mt_create_slots(struct input_dev *dev, unsigned int num_slots)
+{
+        int i;
+
+        if (!num_slots)
+                return 0;
+
+        dev->mt = kcalloc(num_slots, sizeof(struct input_mt_slot), GFP_KERNEL);
+        if (!dev->mt)
+                return -ENOMEM;
+
+        dev->mtsize = num_slots;
+        input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
+
+        /* Mark slots as 'unused' */
+        for (i = 0; i < num_slots; i++)
+                input_mt_set_value(&dev->mt[i], ABS_MT_TRACKING_ID, -1);
+
+        return 0;
+}
+EXPORT_SYMBOL(input_mt_create_slots);
+
+/**
+ * input_mt_destroy_slots() - frees the MT slots of the input device
+ * @dev: input device with allocated MT slots
+ *
+ * This function is only needed in error path as the input core will
+ * automatically free the MT slots when the device is destroyed.
+ */
+void input_mt_destroy_slots(struct input_dev *dev)
+{
+        kfree(dev->mt);
+        dev->mt = NULL;
+        dev->mtsize = 0;
+}
+EXPORT_SYMBOL(input_mt_destroy_slots);