Input: allow certain EV_ABS events to bypass all filtering

With the upcoming multi-touch interface as an example, there is
a need to make certain that all reported events actually get passed
to the event handler. This patch equips the input core with the
ability to bypass all filtering for certain EV_ABS events.
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/input.c

@@ -29,6 +29,14 @@ MODULE_LICENSE("GPL");
 
 #define INPUT_DEVICES	256
 
+/*
+ * EV_ABS events which should not be cached are listed here.
+ */
+static unsigned int input_abs_bypass_init_data[] __initdata = {
+	0
+};
+static unsigned long input_abs_bypass[BITS_TO_LONGS(ABS_CNT)];
+
 static LIST_HEAD(input_dev_list);
 static LIST_HEAD(input_handler_list);
 
@@ -192,6 +200,11 @@ static void input_handle_event(struct input_dev *dev,
 	case EV_ABS:
 		if (is_event_supported(code, dev->absbit, ABS_MAX)) {
 
+			if (test_bit(code, input_abs_bypass)) {
+				disposition = INPUT_PASS_TO_HANDLERS;
+				break;
+			}
+
 			value = input_defuzz_abs_event(value,
 					dev->abs[code], dev->absfuzz[code]);
 
@@ -1634,10 +1647,20 @@ static const struct file_operations input_fops = {
 	.open = input_open_file,
 };
 
+static void __init input_init_abs_bypass(void)
+{
+	const unsigned int *p;
+
+	for (p = input_abs_bypass_init_data; *p; p++)
+		input_abs_bypass[BIT_WORD(*p)] |= BIT_MASK(*p);
+}
+
 static int __init input_init(void)
 {
 	int err;
 
+	input_init_abs_bypass();
+
 	err = class_register(&input_class);
 	if (err) {
 		printk(KERN_ERR "input: unable to register input_dev class\n");