HID: roccat: allow readout of koneplus sensor register data

tcu sysfs attr was used to only control calibration process so far. Direct
sensor register access possibility has been revealed. Allowing readout of tcu
permits usage of this feature.

Signed-off-by: Stefan Achatz <erazor_de@users.sourceforge.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Documentation/ABI/testing/sysfs-driver-hid-roccat-koneplus

@@ -104,9 +104,9 @@ What:		/sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/<hid-
 Date:		October 2010
 Contact:	Stefan Achatz <erazor_de@users.sourceforge.net>
 Description:	When written a calibration process for the tracking control unit
-		can be initiated/cancelled.
+		can be initiated/cancelled. Also lets one read/write sensor
-		The data has to be 3 bytes long.
+		registers.
-		This file is writeonly.
+		The data has to be 4 bytes long.
 Users:		http://roccat.sourceforge.net
 
 What:		/sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/<hid-bus>:<vendor-id>:<product-id>.<num>/koneplus/roccatkoneplus<minor>/tcu_image

drivers/hid/hid-roccat-koneplus.c

@@ -222,6 +222,14 @@ static ssize_t koneplus_sysfs_write_tcu(struct file *fp,
 			sizeof(struct koneplus_tcu), KONEPLUS_COMMAND_TCU);
 }
 
+static ssize_t koneplus_sysfs_read_tcu(struct file *fp,
+		struct kobject *kobj, struct bin_attribute *attr, char *buf,
+		loff_t off, size_t count)
+{
+	return koneplus_sysfs_read(fp, kobj, buf, off, count,
+			sizeof(struct koneplus_tcu), KONEPLUS_COMMAND_TCU);
+}
+
 static ssize_t koneplus_sysfs_read_tcu_image(struct file *fp,
 		struct kobject *kobj, struct bin_attribute *attr, char *buf,
 		loff_t off, size_t count)
@@ -426,8 +434,9 @@ static struct bin_attribute koneplus_bin_attributes[] = {
 		.write = koneplus_sysfs_write_sensor
 	},
 	{
-		.attr = { .name = "tcu", .mode = 0220 },
+		.attr = { .name = "tcu", .mode = 0660 },
 		.size = sizeof(struct koneplus_tcu),
+		.read = koneplus_sysfs_read_tcu,
 		.write = koneplus_sysfs_write_tcu
 	},
 	{