Input: rotary_encoder - add support for REL_* axes
From: H Hartley Sweeten <hartleys@xxxxxxxxxxxxxxxxxxx>
The rotary encoder driver only supports returning input events
for ABS_* axes, this adds support for REL_* axes. The relative
axis input event is reported as -1 for each counter-clockwise
step and +1 for each clockwise step.
The ability to clamp the position of ABS_* axes between 0 and
a maximum of "steps" has also been added.
The rotary-encoder documentation has been updated to provide
additional information on the new available usage.
Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Mack <daniel@xxxxxxxx>
Signed-off-by: Dmitry Torokhov <dtor@xxxxxxx>
---
diff --git a/Documentation/input/rotary-encoder.txt
b/Documentation/input/rotary-encoder.txt
index 435102a..ae4f1a4 100644
--- a/Documentation/input/rotary-encoder.txt
+++ b/Documentation/input/rotary-encoder.txt
@@ -67,7 +67,17 @@ data with it.
struct rotary_encoder_platform_data is declared in
include/linux/rotary-encoder.h and needs to be filled with the number
of
steps the encoder has and can carry information about externally
inverted
-signals (because of used invertig buffer or other reasons).
+signals (because of an inverting buffer or other reasons). The encoder
+can be set up to deliver input information as either an absolute or
relative
+axis. For a relative axis the input event returns +/-1 for each step.
For an
+absolute axis the position of the encoder can either rollover between
zero
+and the number of steps or will clamp at the maximum and zero depending
on
+the configuration.
+
+Note that for an absolute axis that does not rollover, the steps value
does
+not have to match the actual encoder line count. A larger value will
make
+the encoder behave like a multi-turn potentiometer that returns input
+positions from 0 (full CCW) to "steps" (full CW).
Because GPIO to IRQ mapping is platform specific, this information must
be given in seperately to the driver. See the example below.
@@ -85,6 +95,8 @@ be given in seperately to the driver. See the example
below.
static struct rotary_encoder_platform_data my_rotary_encoder_info = {
.steps = 24,
.axis = ABS_X,
+ .relative_axis = false,
+ .rollover = false,
.gpio_a = GPIO_ROTARY_A,
.gpio_b = GPIO_ROTARY_B,
.inverted_a = 0,
diff --git a/drivers/input/misc/rotary_encoder.c
b/drivers/input/misc/rotary_encoder.c
index 5bb3ab5..c806fbf 100644
--- a/drivers/input/misc/rotary_encoder.c
+++ b/drivers/input/misc/rotary_encoder.c
@@ -26,13 +26,17 @@
#define DRV_NAME "rotary-encoder"
struct rotary_encoder {
- unsigned int irq_a;
- unsigned int irq_b;
- unsigned int pos;
- unsigned int armed;
- unsigned int dir;
struct input_dev *input;
struct rotary_encoder_platform_data *pdata;
+
+ unsigned int axis;
+ unsigned int pos;
+
+ unsigned int irq_a;
+ unsigned int irq_b;
+
+ bool armed;
+ unsigned char dir; /* 0 - clockwise, 1 - CCW */
};
static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
@@ -53,21 +57,32 @@ static irqreturn_t rotary_encoder_irq(int irq, void
*dev_id)
if (!encoder->armed)
break;
- if (encoder->dir) {
- /* turning counter-clockwise */
- encoder->pos += pdata->steps;
- encoder->pos--;
- encoder->pos %= pdata->steps;
+ if (pdata->relative_axis) {
+ input_report_rel(encoder->input, pdata->axis,
+ encoder->dir ? -1 : 1);
} else {
- /* turning clockwise */
- encoder->pos++;
- encoder->pos %= pdata->steps;
+ unsigned int pos = encoder->pos;
+
+ if (encoder->dir) {
+ /* turning counter-clockwise */
+ if (pdata->rollover)
+ pos += pdata->steps;
+ if (pos)
+ pos--;
+ } else {
+ /* turning clockwise */
+ if (pdata->rollover || pos <
pdata->steps)
+ pos++;
+ }
+ if (pdata->rollover)
+ pos %= pdata->steps;
+ encoder->pos = pos;
+ input_report_abs(encoder->input, pdata->axis,
+ encoder->pos);
}
-
- input_report_abs(encoder->input, pdata->axis,
encoder->pos);
input_sync(encoder->input);
- encoder->armed = 0;
+ encoder->armed = false;
break;
case 0x1:
@@ -77,7 +92,7 @@ static irqreturn_t rotary_encoder_irq(int irq, void
*dev_id)
break;
case 0x3:
- encoder->armed = 1;
+ encoder->armed = true;
break;
}
@@ -113,9 +128,15 @@ static int __devinit rotary_encoder_probe(struct
platform_device *pdev)
input->name = pdev->name;
input->id.bustype = BUS_HOST;
input->dev.parent = &pdev->dev;
- input->evbit[0] = BIT_MASK(EV_ABS);
- input_set_abs_params(encoder->input,
- pdata->axis, 0, pdata->steps, 0, 1);
+
+ if (pdata->relative_axis) {
+ input->evbit[0] = BIT_MASK(EV_REL);
+ input->relbit[0] = BIT_MASK(pdata->axis);
+ } else {
+ input->evbit[0] = BIT_MASK(EV_ABS);
+ input_set_abs_params(encoder->input,
+ pdata->axis, 0, pdata->steps, 0,
1);
+ }
err = input_register_device(input);
if (err) {
diff --git a/include/linux/rotary_encoder.h
b/include/linux/rotary_encoder.h
index 12d63a3..215278b 100644
--- a/include/linux/rotary_encoder.h
+++ b/include/linux/rotary_encoder.h
@@ -8,6 +8,8 @@ struct rotary_encoder_platform_data {
unsigned int gpio_b;
unsigned int inverted_a;
unsigned int inverted_b;
+ bool relative_axis;
+ bool rollover;
};
#endif /* __ROTARY_ENCODER_H__ */
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