HID: logitech: allow the DJ device to request the unifying name

The names of the DJ devices are stored in the receiver. These names
can be retrieved through a HID++ command. However, the protocol says
that you have to ask the receiver for that, not the device iteself.

Introduce a special case in the DJ handling where a device can request
its unifying name, and when such a name is given, forward it also to
the corresponding device.

On the HID++ side, the receiver talks only HID++ 1.0, so we need to
implement this part of the protocol in the module.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Tested-by: Andrew de los Reyes <adlr@chromium.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 21 insertions, 3 deletions

diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
index feddacd87b8b..9bc39421627f 100644
--- a/drivers/hid/hid-logitech-dj.c
+++ b/drivers/hid/hid-logitech-dj.c
@@ -667,6 +667,9 @@ static void logi_dj_ll_close(struct hid_device *hid)
         dbg_hid("%s:%s\n", __func__, hid->phys);
 }
 
+static u8 unifying_name_query[]  = {0x10, 0xff, 0x83, 0xb5, 0x40, 0x00, 0x00};
+static u8 unifying_name_answer[] = {0x11, 0xff, 0x83, 0xb5};
+
 static int logi_dj_ll_raw_request(struct hid_device *hid,
                                   unsigned char reportnum, __u8 *buf,
                                   size_t count, unsigned char report_type,
@@ -682,7 +685,13 @@ static int logi_dj_ll_raw_request(struct hid_device *hid,
                 if (count < 2)
                         return -EINVAL;
 
-                buf[1] = djdev->device_index;
+                /* special case where we should not overwrite
+                 * the device_index */
+                if (count == 7 && !memcmp(buf, unifying_name_query,
+                                          sizeof(unifying_name_query)))
+                        buf[4] |= djdev->device_index - 1;
+                else
+                        buf[1] = djdev->device_index;
                 return hid_hw_raw_request(djrcv_dev->hdev, reportnum, buf,
                                 count, report_type, reqtype);
         }
@@ -873,8 +882,17 @@ static int logi_dj_hidpp_event(struct hid_device *hdev,
         unsigned long flags;
         u8 device_index = dj_report->device_index;
 
-        if (device_index == HIDPP_RECEIVER_INDEX)
-                return false;
+        if (device_index == HIDPP_RECEIVER_INDEX) {
+                /* special case were the device wants to know its unifying
+                 * name */
+                if (size == HIDPP_REPORT_LONG_LENGTH &&
+                    !memcmp(data, unifying_name_answer,
+                            sizeof(unifying_name_answer)) &&
+                    ((data[4] & 0xF0) == 0x40))
+                        device_index = (data[4] & 0x0F) + 1;
+                else
+                        return false;
+        }
 
         /*
          * Data is from the HID++ collection, in this case, we forward the