Some rotary-encoder devices (such as those with detents) are capable
of producing a stable event on each step. This commit adds support
for this case, by implementing a new interruption handler.
The handler needs only detect the direction of the turn and generate
an event according to this detection.
Cc: Daniel Mack <zonque@xxxxxxxxx>
Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxxxxxxxxx>
---
v1->v2:
* Add DT property handling
* Replace binary representation by hexa-decimal in the sum encoding
drivers/input/misc/rotary_encoder.c | 41 +++++++++++++++++++++++++++++++++++++
include/linux/rotary_encoder.h | 1 +
2 files changed, 42 insertions(+)
diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
index 5b1aff8..6c7a554 100644
--- a/drivers/input/misc/rotary_encoder.c
+++ b/drivers/input/misc/rotary_encoder.c
@@ -117,6 +117,42 @@ static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
return IRQ_HANDLED;
}
+static irqreturn_t rotary_encoder_stepped_irq(int irq, void *dev_id)
+{
+ struct rotary_encoder *encoder = dev_id;
+ int state;
+ unsigned char sum;
+
+ state = rotary_encoder_get_state(encoder->pdata);
+
+ /*
+ * We encode the previous and the current state using a byte.
+ * The previous state in the MSB nibble, the current state in the LSB
+ * nibble. Then use a table to decide the direction of the turn.
+ */
+ sum = (encoder->last_stable << 4) + state;
+ switch (sum) {
+ case 0x31:
+ case 0x10:
+ case 0x02:
+ case 0x23:
+ encoder->dir = 0; /* clockwise */
+ break;
+ /*
+ * TODO: Add the other case, and the illegal values should
+ * say a WARN (it's a BUG, but we won't stop the kernel for it :)
+ */
+ default:
+ encoder->dir = 1;
+ }
+
+ rotary_encoder_report_event(encoder);
+
+ encoder->last_stable = state;
+
+ return IRQ_HANDLED;
+}
+
static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
{
struct rotary_encoder *encoder = dev_id;
@@ -180,6 +216,8 @@ static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct devic
"rotary-encoder,rollover", NULL);
pdata->half_period = !!of_get_property(np,
"rotary-encoder,half-period", NULL);
+ pdata->on_each_step = !!of_get_property(np,
+ "rotary-encoder,on-each-step", NULL);
return pdata;
}
@@ -254,6 +292,9 @@ static int rotary_encoder_probe(struct platform_device *pdev)
if (pdata->half_period) {
handler = &rotary_encoder_half_period_irq;
encoder->last_stable = rotary_encoder_get_state(pdata);
+ } else if (pdata->on_each_step) {
+ handler = &rotary_encoder_stepped_irq;
+ encoder->last_stable = rotary_encoder_get_state(pdata);
} else {
handler = &rotary_encoder_irq;
}
diff --git a/include/linux/rotary_encoder.h b/include/linux/rotary_encoder.h
index 3f594dc..499f6f7 100644
--- a/include/linux/rotary_encoder.h
+++ b/include/linux/rotary_encoder.h
@@ -11,6 +11,7 @@ struct rotary_encoder_platform_data {
bool relative_axis;
bool rollover;
bool half_period;
+ bool on_each_step;
};
#endif /* __ROTARY_ENCODER_H__ */
--
1.8.1.5
--
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