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>

2 files changed, 97 insertions, 7 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
diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 48dec394dd38..e748e45b5b2f 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -205,6 +205,31 @@ static int hidpp_send_fap_command_sync(struct hidpp_device *hidpp,
         return ret;
 }
 
+static int hidpp_send_rap_command_sync(struct hidpp_device *hidpp_dev,
+        u8 report_id, u8 sub_id, u8 reg_address, u8 *params, int param_count,
+        struct hidpp_report *response)
+{
+        struct hidpp_report *message = kzalloc(sizeof(struct hidpp_report),
+                        GFP_KERNEL);
+        int ret;
+
+        if ((report_id != REPORT_ID_HIDPP_SHORT) &&
+            (report_id != REPORT_ID_HIDPP_LONG))
+                return -EINVAL;
+
+        if (param_count > sizeof(message->rap.params))
+                return -EINVAL;
+
+        message->report_id = report_id;
+        message->rap.sub_id = sub_id;
+        message->rap.reg_address = reg_address;
+        memcpy(&message->rap.params, params, param_count);
+
+        ret = hidpp_send_message_sync(hidpp_dev, message, response);
+        kfree(message);
+        return ret;
+}
+
 static inline bool hidpp_match_answer(struct hidpp_report *question,
                 struct hidpp_report *answer)
 {
@@ -221,6 +246,45 @@ static inline bool hidpp_match_error(struct hidpp_report *question,
 }
 
 /* -------------------------------------------------------------------------- */
+/* HIDP++ 1.0 commands                                                        */
+/* -------------------------------------------------------------------------- */
+
+#define HIDPP_SET_REGISTER                              0x80
+#define HIDPP_GET_REGISTER                              0x81
+#define HIDPP_SET_LONG_REGISTER                         0x82
+#define HIDPP_GET_LONG_REGISTER                         0x83
+
+#define HIDPP_REG_PAIRING_INFORMATION                   0xB5
+#define DEVICE_NAME                                     0x40
+
+static char *hidpp_get_unifying_name(struct hidpp_device *hidpp_dev)
+{
+        struct hidpp_report response;
+        int ret;
+        /* hid-logitech-dj is in charge of setting the right device index */
+        u8 params[1] = { DEVICE_NAME };
+        char *name;
+        int len;
+
+        ret = hidpp_send_rap_command_sync(hidpp_dev,
+                                        REPORT_ID_HIDPP_SHORT,
+                                        HIDPP_GET_LONG_REGISTER,
+                                        HIDPP_REG_PAIRING_INFORMATION,
+                                        params, 1, &response);
+        if (ret)
+                return NULL;
+
+        len = response.rap.params[1];
+
+        name = kzalloc(len + 1, GFP_KERNEL);
+        if (!name)
+                return NULL;
+
+        memcpy(name, &response.rap.params[2], len);
+        return name;
+}
+
+/* -------------------------------------------------------------------------- */
 /* 0x0000: Root                                                               */
 /* -------------------------------------------------------------------------- */
 
@@ -726,13 +790,21 @@ static int hidpp_raw_event(struct hid_device *hdev, struct hid_report *report,
         return 0;
 }
 
-static void hidpp_overwrite_name(struct hid_device *hdev)
+static void hidpp_overwrite_name(struct hid_device *hdev, bool use_unifying)
 {
         struct hidpp_device *hidpp = hid_get_drvdata(hdev);
         char *name;
         u8 name_length;
 
-        name = hidpp_get_device_name(hidpp, &name_length);
+        if (use_unifying)
+                /*
+                 * the device is connected through an Unifying receiver, and
+                 * might not be already connected.
+                 * Ask the receiver for its name.
+                 */
+                name = hidpp_get_unifying_name(hidpp);
+        else
+                name = hidpp_get_device_name(hidpp, &name_length);
 
         if (!name)
                 hid_err(hdev, "unable to retrieve the name of the device");
@@ -783,12 +855,12 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
                         goto hid_parse_fail;
                 }
 
-                /* the device is connected, we can ask for its name */
                 hid_info(hdev, "HID++ %u.%u device connected.\n",
                          hidpp->protocol_major, hidpp->protocol_minor);
-                hidpp_overwrite_name(hdev);
         }
 
+        hidpp_overwrite_name(hdev, id->group == HID_GROUP_LOGITECH_DJ_DEVICE);
+
         if (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP) {
                 ret = wtp_get_config(hidpp);
                 if (ret)