Input: introduce device properties

Today, userspace sets up an input device based on the data it emits.
This is not always enough; a tablet and a touchscreen may emit exactly
the same data, for instance, but the former should be set up with a
pointer whereas the latter does not need to. Recently, a new type of
touchpad has emerged where the buttons are under the pad, which
changes logic without changing the emitted data. This patch introduces
a new ioctl, EVIOCGPROP, which enables user access to a set of device
properties useful during setup. The properties are given as a bitmap
in the same fashion as the event types, and are also made available
via sysfs, uevent and /proc/bus/input/devices.

Acked-by: Ping Cheng <pingc@wacom.com>
Acked-by: Chase Douglas <chase.douglas@canonical.com>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

3 files changed, 27 insertions, 0 deletions

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index e3f7fc6f9565..0cd97e8f0c9a 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -677,6 +677,10 @@ static long evdev_do_ioctl(struct file *file, unsigned int cmd,
 #define EVIOC_MASK_SIZE(nr)	((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
 	switch (EVIOC_MASK_SIZE(cmd)) {
 
+	case EVIOCGPROP(0):
+		return bits_to_user(dev->propbit, INPUT_PROP_MAX,
+				    size, p, compat_mode);
+
 	case EVIOCGKEY(0):
 		return bits_to_user(dev->key, KEY_MAX, size, p, compat_mode);
 
diff --git a/drivers/input/input.c b/drivers/input/input.c
index 37708d1d86ec..9ea713f4192b 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -1095,6 +1095,8 @@ static int input_devices_seq_show(struct seq_file *seq, void *v)
 		seq_printf(seq, "%s ", handle->name);
 	seq_putc(seq, '\n');
 
+	input_seq_print_bitmap(seq, "PROP", dev->propbit, INPUT_PROP_MAX);
+
 	input_seq_print_bitmap(seq, "EV", dev->evbit, EV_MAX);
 	if (test_bit(EV_KEY, dev->evbit))
 		input_seq_print_bitmap(seq, "KEY", dev->keybit, KEY_MAX);
@@ -1318,11 +1320,26 @@ static ssize_t input_dev_show_modalias(struct device *dev,
 }
 static DEVICE_ATTR(modalias, S_IRUGO, input_dev_show_modalias, NULL);
 
+static int input_print_bitmap(char *buf, int buf_size, unsigned long *bitmap,
+			      int max, int add_cr);
+
+static ssize_t input_dev_show_properties(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct input_dev *input_dev = to_input_dev(dev);
+	int len = input_print_bitmap(buf, PAGE_SIZE, input_dev->propbit,
+				     INPUT_PROP_MAX, true);
+	return min_t(int, len, PAGE_SIZE);
+}
+static DEVICE_ATTR(properties, S_IRUGO, input_dev_show_properties, NULL);
+
 static struct attribute *input_dev_attrs[] = {
 	&dev_attr_name.attr,
 	&dev_attr_phys.attr,
 	&dev_attr_uniq.attr,
 	&dev_attr_modalias.attr,
+	&dev_attr_properties.attr,
 	NULL
 };
 
@@ -1522,6 +1539,8 @@ static int input_dev_uevent(struct device *device, struct kobj_uevent_env *env)
 	if (dev->uniq)
 		INPUT_ADD_HOTPLUG_VAR("UNIQ=\"%s\"", dev->uniq);
 
+	INPUT_ADD_HOTPLUG_BM_VAR("PROP=", dev->propbit, INPUT_PROP_MAX);
+
 	INPUT_ADD_HOTPLUG_BM_VAR("EV=", dev->evbit, EV_MAX);
 	if (test_bit(EV_KEY, dev->evbit))
 		INPUT_ADD_HOTPLUG_BM_VAR("KEY=", dev->keybit, KEY_MAX);
diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index bea89722c4e9..82542a1c1098 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -680,6 +680,10 @@ static long uinput_ioctl_handler(struct file *file, unsigned int cmd,
 			retval = uinput_set_bit(arg, swbit, SW_MAX);
 			break;
 
+		case UI_SET_PROPBIT:
+			retval = uinput_set_bit(arg, propbit, INPUT_PROP_MAX);
+			break;
+
 		case UI_SET_PHYS:
 			if (udev->state == UIST_CREATED) {
 				retval = -EINVAL;