Input: tsc2007 - make get_pendown_state platform callback optional

In cases when get_pendown_state callback is not available have
the driver to fallback on pressure calculation to determine if
the pen is up.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 93 insertions, 79 deletions

diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscreen/tsc2007.c
index f710af4d0ff7..3714d19f1027 100644
--- a/drivers/input/touchscreen/tsc2007.c
+++ b/drivers/input/touchscreen/tsc2007.c
@@ -70,7 +70,6 @@ struct tsc2007 {
         struct input_dev        *input;
         char                    phys[32];
         struct delayed_work     work;
-        struct ts_event         tc;
 
         struct i2c_client       *client;
 
@@ -106,51 +105,96 @@ static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
         return val;
 }
 
-static void tsc2007_send_event(void *tsc)
+static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc)
 {
-        struct tsc2007  *ts = tsc;
-        u32             rt;
-        u16             x, y, z1, z2;
+        /* y- still on; turn on only y+ (and ADC) */
+        tc->y = tsc2007_xfer(tsc, READ_Y);
+
+        /* turn y- off, x+ on, then leave in lowpower */
+        tc->x = tsc2007_xfer(tsc, READ_X);
+
+        /* turn y+ off, x- on; we'll use formula #1 */
+        tc->z1 = tsc2007_xfer(tsc, READ_Z1);
+        tc->z2 = tsc2007_xfer(tsc, READ_Z2);
 
-        x = ts->tc.x;
-        y = ts->tc.y;
-        z1 = ts->tc.z1;
-        z2 = ts->tc.z2;
+        /* Prepare for next touch reading - power down ADC, enable PENIRQ */
+        tsc2007_xfer(tsc, PWRDOWN);
+}
+
+static u32 tsc2007_calculate_pressure(struct tsc2007 *tsc, struct ts_event *tc)
+{
+        u32 rt = 0;
 
         /* range filtering */
-        if (x == MAX_12BIT)
-                x = 0;
+        if (tc->x == MAX_12BIT)
+                tc->x = 0;
 
-        if (likely(x && z1)) {
+        if (likely(tc->x && tc->z1)) {
                 /* compute touch pressure resistance using equation #1 */
-                rt = z2;
-                rt -= z1;
-                rt *= x;
-                rt *= ts->x_plate_ohms;
-                rt /= z1;
+                rt = tc->z2 - tc->z1;
+                rt *= tc->x;
+                rt *= tsc->x_plate_ohms;
+                rt /= tc->z1;
                 rt = (rt + 2047) >> 12;
-        } else
-                rt = 0;
-
-        /*
-         * Sample found inconsistent by debouncing or pressure is beyond
-         * the maximum. Don't report it to user space, repeat at least
-         * once more the measurement
-         */
-        if (rt > MAX_12BIT) {
-                dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
-                return;
         }
 
+        return rt;
+}
+
+static void tsc2007_send_up_event(struct tsc2007 *tsc)
+{
+        struct input_dev *input = tsc->input;
+
+        dev_dbg(&tsc->client->dev, "UP\n");
+
+        input_report_key(input, BTN_TOUCH, 0);
+        input_report_abs(input, ABS_PRESSURE, 0);
+        input_sync(input);
+}
+
+static void tsc2007_work(struct work_struct *work)
+{
+        struct tsc2007 *ts =
+                container_of(to_delayed_work(work), struct tsc2007, work);
+        struct ts_event tc;
+        u32 rt;
+
         /*
          * NOTE: We can't rely on the pressure to determine the pen down
-         * state, even this controller has a pressure sensor.  The pressure
-         * value can fluctuate for quite a while after lifting the pen and
-         * in some cases may not even settle at the expected value.
+         * state, even though this controller has a pressure sensor.
+         * The pressure value can fluctuate for quite a while after
+         * lifting the pen and in some cases may not even settle at the
+         * expected value.
          *
          * The only safe way to check for the pen up condition is in the
-         * work function by reading the pen signal state (it's a GPIO and IRQ).
+         * work function by reading the pen signal state (it's a GPIO
+         * and IRQ). Unfortunately such callback is not always available,
+         * in that case we have rely on the pressure anyway.
          */
+        if (ts->get_pendown_state) {
+                if (unlikely(!ts->get_pendown_state())) {
+                        tsc2007_send_up_event(ts);
+                        ts->pendown = false;
+                        goto out;
+                }
+
+                dev_dbg(&ts->client->dev, "pen is still down\n");
+        }
+
+        tsc2007_read_values(ts, &tc);
+
+        rt = tsc2007_calculate_pressure(ts, &tc);
+        if (rt > MAX_12BIT) {
+                /*
+                 * Sample found inconsistent by debouncing or pressure is
+                 * beyond the maximum. Don't report it to user space,
+                 * repeat at least once more the measurement.
+                 */
+                dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
+                goto out;
+
+        }
+
         if (rt) {
                 struct input_dev *input = ts->input;
 
@@ -161,68 +205,38 @@ static void tsc2007_send_event(void *tsc)
                         ts->pendown = true;
                 }
 
-                input_report_abs(input, ABS_X, x);
-                input_report_abs(input, ABS_Y, y);
+                input_report_abs(input, ABS_X, tc.x);
+                input_report_abs(input, ABS_Y, tc.y);
                 input_report_abs(input, ABS_PRESSURE, rt);
 
                 input_sync(input);
 
                 dev_dbg(&ts->client->dev, "point(%4d,%4d), pressure (%4u)\n",
-                        x, y, rt);
-        }
-}
-
-static int tsc2007_read_values(struct tsc2007 *tsc)
-{
-        /* y- still on; turn on only y+ (and ADC) */
-        tsc->tc.y = tsc2007_xfer(tsc, READ_Y);
-
-        /* turn y- off, x+ on, then leave in lowpower */
-        tsc->tc.x = tsc2007_xfer(tsc, READ_X);
-
-        /* turn y+ off, x- on; we'll use formula #1 */
-        tsc->tc.z1 = tsc2007_xfer(tsc, READ_Z1);
-        tsc->tc.z2 = tsc2007_xfer(tsc, READ_Z2);
-
-        /* Prepare for next touch reading - power down ADC, enable PENIRQ */
-        tsc2007_xfer(tsc, PWRDOWN);
-
-        return 0;
-}
-
-static void tsc2007_work(struct work_struct *work)
-{
-        struct tsc2007 *ts =
-                container_of(to_delayed_work(work), struct tsc2007, work);
-
-        if (unlikely(!ts->get_pendown_state() && ts->pendown)) {
-                struct input_dev *input = ts->input;
-
-                dev_dbg(&ts->client->dev, "UP\n");
-
-                input_report_key(input, BTN_TOUCH, 0);
-                input_report_abs(input, ABS_PRESSURE, 0);
-                input_sync(input);
+                        tc.x, tc.y, rt);
 
+        } else if (!ts->get_pendown_state && ts->pendown) {
+                /*
+                 * We don't have callback to check pendown state, so we
+                 * have to assume that since pressure reported is 0 the
+                 * pen was lifted up.
+                 */
+                tsc2007_send_up_event(ts);
                 ts->pendown = false;
-                enable_irq(ts->irq);
-        } else {
-                /* pen is still down, continue with the measurement */
-                dev_dbg(&ts->client->dev, "pen is still down\n");
-
-                tsc2007_read_values(ts);
-                tsc2007_send_event(ts);
+        }
 
+ out:
+        if (ts->pendown)
                 schedule_delayed_work(&ts->work,
                                       msecs_to_jiffies(TS_POLL_PERIOD));
-        }
+        else
+                enable_irq(ts->irq);
 }
 
 static irqreturn_t tsc2007_irq(int irq, void *handle)
 {
         struct tsc2007 *ts = handle;
 
-        if (likely(ts->get_pendown_state())) {
+        if (!ts->get_pendown_state || likely(ts->get_pendown_state())) {
                 disable_irq_nosync(ts->irq);
                 schedule_delayed_work(&ts->work,
                                       msecs_to_jiffies(TS_POLL_DELAY));
@@ -255,7 +269,7 @@ static int __devinit tsc2007_probe(struct i2c_client *client,
         struct input_dev *input_dev;
         int err;
 
-        if (!pdata || !pdata->get_pendown_state) {
+        if (!pdata) {
                 dev_err(&client->dev, "platform data is required!\n");
                 return -EINVAL;
         }