HID: sony: Prevent duplicate controller connections.

If a Sixaxis or Dualshock 4 controller is connected via USB while already
connected via Bluetooth it will cause duplicate devices to be added to the
input device list.

To prevent this a global list of controllers and their MAC addresses is
maintained and new controllers are checked against this list.  If a duplicate
is found, the probe function will exit with -EEXIST.

On USB the MAC is retrieved via a feature report.  On Bluetooth neither
controller reports the MAC address in a feature report so the MAC is parsed from
the uniq string.  As uniq cannot be guaranteed to be a MAC address in every case
(uHID or the behavior of HIDP changing) a parsing failure will not prevent the
connection.

Signed-off-by: Frank Praznik <frank.praznik@oh.rr.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 140 insertions, 0 deletions

diff --git a/drivers/hid/hid-sony.c b/drivers/hid/hid-sony.c
index b39e3abd6cdd..b1aa6f00c827 100644
--- a/drivers/hid/hid-sony.c
+++ b/drivers/hid/hid-sony.c
@@ -33,6 +33,7 @@
 #include <linux/leds.h>
 #include <linux/power_supply.h>
 #include <linux/spinlock.h>
+#include <linux/list.h>
 #include <linux/input/mt.h>
 
 #include "hid-ids.h"
@@ -717,8 +718,12 @@ static enum power_supply_property sony_battery_props[] = {
         POWER_SUPPLY_PROP_STATUS,
 };
 
+static spinlock_t sony_dev_list_lock;
+static LIST_HEAD(sony_device_list);
+
 struct sony_sc {
         spinlock_t lock;
+        struct list_head list_node;
         struct hid_device *hdev;
         struct led_classdev *leds[MAX_LEDS];
         unsigned long quirks;
@@ -730,6 +735,7 @@ struct sony_sc {
         __u8 right;
 #endif
 
+        __u8 mac_address[6];
         __u8 worker_initialized;
         __u8 cable_state;
         __u8 battery_charging;
@@ -1489,6 +1495,133 @@ static int sony_register_touchpad(struct sony_sc *sc, int touch_count,
         return 0;
 }
 
+/*
+ * If a controller is plugged in via USB while already connected via Bluetooth
+ * it will show up as two devices. A global list of connected controllers and
+ * their MAC addresses is maintained to ensure that a device is only connected
+ * once.
+ */
+static int sony_check_add_dev_list(struct sony_sc *sc)
+{
+        struct sony_sc *entry;
+        unsigned long flags;
+        int ret;
+
+        spin_lock_irqsave(&sony_dev_list_lock, flags);
+
+        list_for_each_entry(entry, &sony_device_list, list_node) {
+                ret = memcmp(sc->mac_address, entry->mac_address,
+                                sizeof(sc->mac_address));
+                if (!ret) {
+                        ret = -EEXIST;
+                        hid_info(sc->hdev, "controller with MAC address %pMR already connected\n",
+                                sc->mac_address);
+                        goto unlock;
+                }
+        }
+
+        ret = 0;
+        list_add(&(sc->list_node), &sony_device_list);
+
+unlock:
+        spin_unlock_irqrestore(&sony_dev_list_lock, flags);
+        return ret;
+}
+
+static void sony_remove_dev_list(struct sony_sc *sc)
+{
+        unsigned long flags;
+
+        if (sc->list_node.next) {
+                spin_lock_irqsave(&sony_dev_list_lock, flags);
+                list_del(&(sc->list_node));
+                spin_unlock_irqrestore(&sony_dev_list_lock, flags);
+        }
+}
+
+static int sony_get_bt_devaddr(struct sony_sc *sc)
+{
+        int ret;
+
+        /* HIDP stores the device MAC address as a string in the uniq field. */
+        ret = strlen(sc->hdev->uniq);
+        if (ret != 17)
+                return -EINVAL;
+
+        ret = sscanf(sc->hdev->uniq,
+                "%02hhx:%02hhx:%02hhx:%02hhx:%02hhx:%02hhx",
+                &sc->mac_address[5], &sc->mac_address[4], &sc->mac_address[3],
+                &sc->mac_address[2], &sc->mac_address[1], &sc->mac_address[0]);
+
+        if (ret != 6)
+                return -EINVAL;
+
+        return 0;
+}
+
+static int sony_check_add(struct sony_sc *sc)
+{
+        int n, ret;
+
+        if ((sc->quirks & DUALSHOCK4_CONTROLLER_BT) ||
+            (sc->quirks & SIXAXIS_CONTROLLER_BT)) {
+                /*
+                 * sony_get_bt_devaddr() attempts to parse the Bluetooth MAC
+                 * address from the uniq string where HIDP stores it.
+                 * As uniq cannot be guaranteed to be a MAC address in all cases
+                 * a failure of this function should not prevent the connection.
+                 */
+                if (sony_get_bt_devaddr(sc) < 0) {
+                        hid_warn(sc->hdev, "UNIQ does not contain a MAC address; duplicate check skipped\n");
+                        return 0;
+                }
+        } else if (sc->quirks & DUALSHOCK4_CONTROLLER_USB) {
+                __u8 buf[7];
+
+                /*
+                 * The MAC address of a DS4 controller connected via USB can be
+                 * retrieved with feature report 0x81. The address begins at
+                 * offset 1.
+                 */
+                ret = hid_hw_raw_request(sc->hdev, 0x81, buf, sizeof(buf),
+                                HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
+
+                if (ret != 7) {
+                        hid_err(sc->hdev, "failed to retrieve feature report 0x81 with the DualShock 4 MAC address\n");
+                        return ret < 0 ? ret : -EINVAL;
+                }
+
+                memcpy(sc->mac_address, &buf[1], sizeof(sc->mac_address));
+        } else if (sc->quirks & SIXAXIS_CONTROLLER_USB) {
+                __u8 buf[18];
+
+                /*
+                 * The MAC address of a Sixaxis controller connected via USB can
+                 * be retrieved with feature report 0xf2. The address begins at
+                 * offset 4.
+                 */
+                ret = hid_hw_raw_request(sc->hdev, 0xf2, buf, sizeof(buf),
+                                HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
+
+                if (ret != 18) {
+                        hid_err(sc->hdev, "failed to retrieve feature report 0xf2 with the Sixaxis MAC address\n");
+                        return ret < 0 ? ret : -EINVAL;
+                }
+
+                /*
+                 * The Sixaxis device MAC in the report is big-endian and must
+                 * be byte-swapped.
+                 */
+                for (n = 0; n < 6; n++)
+                        sc->mac_address[5-n] = buf[4+n];
+        } else {
+                return 0;
+        }
+
+        return sony_check_add_dev_list(sc);
+}
+
+
 static int sony_probe(struct hid_device *hdev, const struct hid_device_id *id)
 {
         int ret;
@@ -1559,6 +1692,10 @@ static int sony_probe(struct hid_device *hdev, const struct hid_device_id *id)
         if (ret < 0)
                 goto err_stop;
 
+        ret = sony_check_add(sc);
+        if (ret < 0)
+                goto err_stop;
+
         if (sc->quirks & SONY_LED_SUPPORT) {
                 ret = sony_leds_init(hdev);
                 if (ret < 0)
@@ -1594,6 +1731,7 @@ err_stop:
                 sony_battery_remove(sc);
         if (sc->worker_initialized)
                 cancel_work_sync(&sc->state_worker);
+        sony_remove_dev_list(sc);
         hid_hw_stop(hdev);