Input: psmouse - add support for Cortron PS/2 Trackballs

Cortron PS/2 Trackballs (700-0001A) report the 4th button using the 4th
bit of the first packet (yes, it breaks the standard PS/2 protocol).
This patch adds an extra protocol to generate BTN_SIDE based on the 4th
bit. There's no way to detect those trackballs using any kind of special
sequence, thus the protocol must be activated explicitely by writing
into 'protocol' sysfs attribute:

	echo -n "cortps" > /sys/devices/platform/i8042/serio1/protocol

Signed-off-by: Aristeu Rozanski <arozansk@redhat.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 29 insertions, 0 deletions

diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
index f15f695777f8..b9f0fb2530e2 100644
--- a/drivers/input/mouse/psmouse-base.c
+++ b/drivers/input/mouse/psmouse-base.c
@@ -178,6 +178,15 @@ static psmouse_ret_t psmouse_process_byte(struct psmouse *psmouse)
         }
 
 /*
+ * Cortron PS2 Trackball reports SIDE button on the 4th bit of the first
+ * byte.
+ */
+        if (psmouse->type == PSMOUSE_CORTRON) {
+                input_report_key(dev, BTN_SIDE, (packet[0] >> 3) & 1);
+                packet[0] |= 0x08;
+        }
+
+/*
  * Generic PS/2 Mouse
  */
 
@@ -539,6 +548,20 @@ static int ps2bare_detect(struct psmouse *psmouse, int set_properties)
         return 0;
 }
 
+/*
+ * Cortron PS/2 protocol detection. There's no special way to detect it, so it
+ * must be forced by sysfs protocol writing.
+ */
+static int cortron_detect(struct psmouse *psmouse, int set_properties)
+{
+        if (set_properties) {
+                psmouse->vendor = "Cortron";
+                psmouse->name = "PS/2 Trackball";
+                set_bit(BTN_SIDE, psmouse->dev->keybit);
+        }
+
+        return 0;
+}
 
 /*
  * psmouse_extensions() probes for any extensions to the basic PS/2 protocol
@@ -740,6 +763,12 @@ static const struct psmouse_protocol psmouse_protocols[] = {
         },
 #endif
         {
+                .type           = PSMOUSE_CORTRON,
+                .name           = "CortronPS/2",
+                .alias          = "cortps",
+                .detect         = cortron_detect,
+        },
+        {
                 .type           = PSMOUSE_AUTO,
                 .name           = "auto",
                 .alias          = "any",