HID: ntrig: identify firmware version

This adds firmware version polling to the end of probe and reports the
version both in the raw form and proccessed to match the formatting used
by N-Trig.
Signed-off-by: Rafi Rubin <rafi@seas.upenn.edu>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-ntrig.c

@@ -90,6 +90,55 @@ struct ntrig_data {
 };
 
 
+/*
+ * This function converts the 4 byte raw firmware code into
+ * a string containing 5 comma separated numbers.
+ */
+static int ntrig_version_string(unsigned char *raw, char *buf)
+{
+	__u8 a =  (raw[1] & 0x0e) >> 1;
+	__u8 b =  (raw[0] & 0x3c) >> 2;
+	__u8 c = ((raw[0] & 0x03) << 3) | ((raw[3] & 0xe0) >> 5);
+	__u8 d = ((raw[3] & 0x07) << 3) | ((raw[2] & 0xe0) >> 5);
+	__u8 e =   raw[2] & 0x07;
+
+	/*
+	 * As yet unmapped bits:
+	 * 0b11000000 0b11110001 0b00011000 0b00011000
+	 */
+
+	return sprintf(buf, "%u.%u.%u.%u.%u", a, b, c, d, e);
+}
+
+static void ntrig_report_version(struct hid_device *hdev)
+{
+	int ret;
+	char buf[20];
+	struct usb_device *usb_dev = hid_to_usb_dev(hdev);
+	unsigned char *data = kmalloc(8, GFP_KERNEL);
+
+	if (!data)
+		goto err_free;
+
+	ret = usb_control_msg(usb_dev, usb_rcvctrlpipe(usb_dev, 0),
+			      USB_REQ_CLEAR_FEATURE,
+			      USB_TYPE_CLASS | USB_RECIP_INTERFACE |
+			      USB_DIR_IN,
+			      0x30c, 1, data, 8,
+			      USB_CTRL_SET_TIMEOUT);
+
+	if (ret == 8) {
+		ret = ntrig_version_string(&data[2], buf);
+
+		dev_info(&hdev->dev,
+			 "Firmware version: %s (%02x%02x %02x%02x)\n",
+			 buf, data[2], data[3], data[4], data[5]);
+	}
+
+err_free:
+	kfree(data);
+}
+
 static ssize_t show_phys_width(struct device *dev,
 			       struct device_attribute *attr,
 			       char *buf)
@@ -848,6 +897,8 @@ static int ntrig_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	if (report)
 		usbhid_submit_report(hdev, report, USB_DIR_OUT);
 
+	ntrig_report_version(hdev);
+
 	ret = sysfs_create_group(&hdev->dev.kobj,
 			&ntrig_attribute_group);