Input: silead - add support for capactive home button found on some x86 tablets

On some x86 tablets with a silead touchscreen the windows logo on the
front is a capacitive home button. Touching this button results in a touch
with bits 12-15 of the Y coordinates set, while normally only the lower 12
are used.

Detect this and report a KEY_LEFTMETA press when this happens. Note for
now we only respond to the Y coordinate bits 12-15 containing 0x01, on some
tablets *without* a capacative button I've noticed these bits containing
0x04 when crossing the edges of the screen.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/Documentation/devicetree/bindings/input/touchscreen/silead_gsl1680.txt b/Documentation/devicetree/bindings/input/touchscreen/silead_gsl1680.txt
index 6aa625e..84752de 100644 (file)
--- a/Documentation/devicetree/bindings/input/touchscreen/silead_gsl1680.txt
+++ b/Documentation/devicetree/bindings/input/touchscreen/silead_gsl1680.txt
@@ -23,6 +23,8 @@ Optional properties:
 - touchscreen-inverted-y  : See touchscreen.txt
 - touchscreen-swapped-x-y : See touchscreen.txt
 - silead,max-fingers     : maximum number of fingers the touchscreen can detect
+- silead,home-button     : Boolean, set to true on devices which have a
+                           capacitive home-button build into the touchscreen
 - vddio-supply           : regulator phandle for controller VDDIO
 - avdd-supply            : regulator phandle for controller AVDD
 

diff --git a/drivers/input/touchscreen/silead.c b/drivers/input/touchscreen/silead.c
index 0dbcf10..646b1e7 100644 (file)
--- a/drivers/input/touchscreen/silead.c
+++ b/drivers/input/touchscreen/silead.c
@@ -56,7 +56,7 @@
 #define SILEAD_POINT_Y_MSB_OFF 0x01
 #define SILEAD_POINT_X_OFF     0x02
 #define SILEAD_POINT_X_MSB_OFF 0x03
-#define SILEAD_TOUCH_ID_MASK   0xF0
+#define SILEAD_EXTRA_DATA_MASK 0xF0
 
 #define SILEAD_CMD_SLEEP_MIN   10000
 #define SILEAD_CMD_SLEEP_MAX   20000
@@ -109,6 +109,9 @@ static int silead_ts_request_input_dev(struct silead_ts_data *data)
                            INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED |
                            INPUT_MT_TRACK);
 
+       if (device_property_read_bool(dev, "silead,home-button"))
+               input_set_capability(data->input, EV_KEY, KEY_LEFTMETA);
+
        data->input->name = SILEAD_TS_NAME;
        data->input->phys = "input/ts";
        data->input->id.bustype = BUS_I2C;
@@ -139,7 +142,8 @@ static void silead_ts_read_data(struct i2c_client *client)
        struct input_dev *input = data->input;
        struct device *dev = &client->dev;
        u8 *bufp, buf[SILEAD_TS_DATA_LEN];
-       int touch_nr, error, i;
+       int touch_nr, softbutton, error, i;
+       bool softbutton_pressed = false;
 
        error = i2c_smbus_read_i2c_block_data(client, SILEAD_REG_DATA,
                                              SILEAD_TS_DATA_LEN, buf);
@@ -148,21 +152,40 @@ static void silead_ts_read_data(struct i2c_client *client)
                return;
        }
 
-       touch_nr = buf[0];
-       if (touch_nr > data->max_fingers) {
+       if (buf[0] > data->max_fingers) {
                dev_warn(dev, "More touches reported then supported %d > %d\n",
-                        touch_nr, data->max_fingers);
-               touch_nr = data->max_fingers;
+                        buf[0], data->max_fingers);
+               buf[0] = data->max_fingers;
        }
 
+       touch_nr = 0;
        bufp = buf + SILEAD_POINT_DATA_LEN;
-       for (i = 0; i < touch_nr; i++, bufp += SILEAD_POINT_DATA_LEN) {
-               /* Bits 4-7 are the touch id */
-               data->id[i] = (bufp[SILEAD_POINT_X_MSB_OFF] &
-                              SILEAD_TOUCH_ID_MASK) >> 4;
-               touchscreen_set_mt_pos(&data->pos[i], &data->prop,
+       for (i = 0; i < buf[0]; i++, bufp += SILEAD_POINT_DATA_LEN) {
+               softbutton = (bufp[SILEAD_POINT_Y_MSB_OFF] &
+                             SILEAD_EXTRA_DATA_MASK) >> 4;
+
+               if (softbutton) {
+                       /*
+                        * For now only respond to softbutton == 0x01, some
+                        * tablets *without* a capacative button send 0x04
+                        * when crossing the edges of the screen.
+                        */
+                       if (softbutton == 0x01)
+                               softbutton_pressed = true;
+
+                       continue;
+               }
+
+               /*
+                * Bits 4-7 are the touch id, note not all models have
+                * hardware touch ids so atm we don't use these.
+                */
+               data->id[touch_nr] = (bufp[SILEAD_POINT_X_MSB_OFF] &
+                                     SILEAD_EXTRA_DATA_MASK) >> 4;
+               touchscreen_set_mt_pos(&data->pos[touch_nr], &data->prop,
                        get_unaligned_le16(&bufp[SILEAD_POINT_X_OFF]) & 0xfff,
                        get_unaligned_le16(&bufp[SILEAD_POINT_Y_OFF]) & 0xfff);
+               touch_nr++;
        }
 
        input_mt_assign_slots(input, data->slots, data->pos, touch_nr, 0);
@@ -178,6 +201,7 @@ static void silead_ts_read_data(struct i2c_client *client)
        }
 
        input_mt_sync_frame(input);
+       input_report_key(input, KEY_LEFTMETA, softbutton_pressed);
        input_sync(input);
 }