[PATCH] Input: introduce device information ioctl

[Henrik Rydberg]

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 handling 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.

Signed-off-by: Henrik Rydberg <rydberg@xxxxxxxxxxx>
---
 drivers/input/evdev.c       |    4 ++++
 drivers/input/input.c       |   15 +++++++++++++++
 drivers/input/misc/uinput.c |    4 ++++
 include/linux/input.h       |   16 ++++++++++++++++
 include/linux/uinput.h      |    1 +
 5 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index e3f7fc6..0cd97e8 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 37708d1..c3e5fc7 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -1318,11 +1318,26 @@ 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
 };
 
diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index bea8972..82542a1 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;
diff --git a/include/linux/input.h b/include/linux/input.h
index b3a1e02..8d9c76c 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -91,6 +91,7 @@ struct input_keymap_entry {
 #define EVIOCGNAME(len)		_IOC(_IOC_READ, 'E', 0x06, len)		/* get device name */
 #define EVIOCGPHYS(len)		_IOC(_IOC_READ, 'E', 0x07, len)		/* get physical location */
 #define EVIOCGUNIQ(len)		_IOC(_IOC_READ, 'E', 0x08, len)		/* get unique identifier */
+#define EVIOCGPROP(len)		_IOC(_IOC_READ, 'E', 0x09, len)		/* get device properties */
 
 #define EVIOCGKEY(len)		_IOC(_IOC_READ, 'E', 0x18, len)		/* get global key state */
 #define EVIOCGLED(len)		_IOC(_IOC_READ, 'E', 0x19, len)		/* get all LEDs */
@@ -108,6 +109,18 @@ struct input_keymap_entry {
 #define EVIOCGRAB		_IOW('E', 0x90, int)			/* Grab/Release device */
 
 /*
+ * Device properties and quirks
+ */
+
+#define INPUT_PROP_POINTER		0x00	/* needs a pointer */
+#define INPUT_PROP_DIRECT		0x01	/* direct input devices */
+#define INPUT_PROP_BUTTONPAD		0x02	/* has button(s) under pad */
+#define INPUT_PROP_SEMI_MT		0x03	/* touch rectangle only */
+
+#define INPUT_PROP_MAX			0x1f
+#define INPUT_PROP_CNT			(INPUT_PROP_MAX + 1)
+
+/*
  * Event types
  */
 
@@ -1090,6 +1103,7 @@ struct ff_effect {
  * @phys: physical path to the device in the system hierarchy
  * @uniq: unique identification code for the device (if device has it)
  * @id: id of the device (struct input_id)
+ * @propbit: bitmap of device properties and quirks
  * @evbit: bitmap of types of events supported by the device (EV_KEY,
  *	EV_REL, etc.)
  * @keybit: bitmap of keys/buttons this device has
@@ -1173,6 +1187,8 @@ struct input_dev {
 	const char *uniq;
 	struct input_id id;
 
+	unsigned long propbit[BITS_TO_LONGS(INPUT_PROP_CNT)];
+
 	unsigned long evbit[BITS_TO_LONGS(EV_CNT)];
 	unsigned long keybit[BITS_TO_LONGS(KEY_CNT)];
 	unsigned long relbit[BITS_TO_LONGS(REL_CNT)];
diff --git a/include/linux/uinput.h b/include/linux/uinput.h
index 05f7fed2..d28c726 100644
--- a/include/linux/uinput.h
+++ b/include/linux/uinput.h
@@ -104,6 +104,7 @@ struct uinput_ff_erase {
 #define UI_SET_FFBIT		_IOW(UINPUT_IOCTL_BASE, 107, int)
 #define UI_SET_PHYS		_IOW(UINPUT_IOCTL_BASE, 108, char*)
 #define UI_SET_SWBIT		_IOW(UINPUT_IOCTL_BASE, 109, int)
+#define UI_SET_PROPBIT		_IOW(UINPUT_IOCTL_BASE, 110, int)
 
 #define UI_BEGIN_FF_UPLOAD	_IOWR(UINPUT_IOCTL_BASE, 200, struct uinput_ff_upload)
 #define UI_END_FF_UPLOAD	_IOW(UINPUT_IOCTL_BASE, 201, struct uinput_ff_upload)
-- 
1.7.2.3

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