Some rotary encoders have a stable state in all output state
combinations. Add support for this type of encoder.
Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Cc: Daniel Mack <daniel@xxxxxxxxxx>
Cc: linux-input@xxxxxxxxxxxxxxx
Cc: devicetree@xxxxxxxxxxxxxxx
---
.../devicetree/bindings/input/rotary-encoder.txt | 1 +
Documentation/input/rotary-encoder.txt | 9 +++++--
drivers/input/misc/rotary_encoder.c | 30 ++++++++++++++++++++--
include/linux/rotary_encoder.h | 1 +
4 files changed, 37 insertions(+), 4 deletions(-)
diff --git a/Documentation/devicetree/bindings/input/rotary-encoder.txt b/Documentation/devicetree/bindings/input/rotary-encoder.txt
index 3315495..cbdb29b 100644
--- a/Documentation/devicetree/bindings/input/rotary-encoder.txt
+++ b/Documentation/devicetree/bindings/input/rotary-encoder.txt
@@ -15,6 +15,7 @@ Optional properties:
- rotary-encoder,rollover: Automatic rollove when the rotary value becomes
greater than the specified steps or smaller than 0. For absolute axis only.
- rotary-encoder,half-period: Makes the driver work on half-period mode.
+- rotary-encoder,quarter-period: Makes the driver work on quarter-period mode.
See Documentation/input/rotary-encoder.txt for more information.
diff --git a/Documentation/input/rotary-encoder.txt b/Documentation/input/rotary-encoder.txt
index 92e68bc..0bbff7e 100644
--- a/Documentation/input/rotary-encoder.txt
+++ b/Documentation/input/rotary-encoder.txt
@@ -9,8 +9,10 @@ peripherals with two wires. The outputs are phase-shifted by 90 degrees
and by triggering on falling and rising edges, the turn direction can
be determined.
-Some encoders have both outputs low in stable states, whereas others also have
-a stable state with both outputs high (half-period mode).
+
+Some encoders have both outputs low in stable states, others also have
+a stable state with both outputs high (half-period mode) and some have
+a stable state in all steps (quarter-period mode).
The phase diagram of these two outputs look like this:
@@ -32,6 +34,9 @@ The phase diagram of these two outputs look like this:
|<-->|
one step (half-period mode)
+ |<>|
+ one step (quarter-period mode)
+
For more information, please see
http://en.wikipedia.org/wiki/Rotary_encoder
diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
index 5b1aff8..264501c 100644
--- a/drivers/input/misc/rotary_encoder.c
+++ b/drivers/input/misc/rotary_encoder.c
@@ -42,7 +42,7 @@ struct rotary_encoder {
bool armed;
unsigned char dir; /* 0 - clockwise, 1 - CCW */
- char last_stable;
+ int last_stable;
};
static int rotary_encoder_get_state(const struct rotary_encoder_platform_data *pdata)
@@ -117,6 +117,28 @@ static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
return IRQ_HANDLED;
}
+static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
+{
+ struct rotary_encoder *encoder = dev_id;
+ int state;
+ static const u8 states[4][4] = {
+ { -1, 1, 0, -1 },
+ { 0, -1, -1, 1 },
+ { 1, -1, -1, 0 },
+ { -1, 0, 1, -1 },
+ };
+
+ state = rotary_encoder_get_state(encoder->pdata);
+
+ encoder->dir = states[encoder->last_stable][state];
+ encoder->last_stable = state;
+
+ if (encoder->dir >= 0)
+ rotary_encoder_report_event(encoder);
+
+ return IRQ_HANDLED;
+}
+
static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
{
struct rotary_encoder *encoder = dev_id;
@@ -180,7 +202,8 @@ 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->quarter_period = !!of_get_property(np,
+ "rotary-encoder,quarter-period", NULL);
return pdata;
}
#else
@@ -254,6 +277,9 @@ 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->quarter_period) {
+ handler = &rotary_encoder_quarter_period_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..fd0a70f 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 quarter_period;
};
#endif /* __ROTARY_ENCODER_H__ */
--
1.8.5.1
--
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