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authorEzequiel Garcia <ezequiel@vanguardiasur.com.ar>2015-10-14 09:39:50 +0300
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2015-10-17 01:32:18 +0300
commit3a341a4c30d427fd05617087db1564a595f65093 (patch)
tree84898e187b5128e1e51e9f5ed41114176181b71e /drivers/input
parent648b15cb79e90d80f7b53d0184bdb14132a03754 (diff)
downloadlinux-3a341a4c30d427fd05617087db1564a595f65093.tar.xz
Input: rotary-encoder - add support for quarter-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 driver used to support the former states and with this change it can also support the later. This commit also deprecates the 'half-period' property and introduces a new property 'steps-per-period'. This property specifies the number of steps (stable states) produced by the rotary encoder for each GPIO period. Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar> Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'drivers/input')
-rw-r--r--drivers/input/misc/rotary_encoder.c86
1 files changed, 81 insertions, 5 deletions
diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
index 962f9e86310b..8aee71986430 100644
--- a/drivers/input/misc/rotary_encoder.c
+++ b/drivers/input/misc/rotary_encoder.c
@@ -143,6 +143,55 @@ static irqreturn_t rotary_encoder_half_period_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;
+ unsigned char sum;
+ int state;
+
+ 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;
+
+ case 0x13:
+ case 0x01:
+ case 0x20:
+ case 0x32:
+ encoder->dir = 1; /* counter-clockwise */
+ break;
+
+ default:
+ /*
+ * Ignore all other values. This covers the case when the
+ * state didn't change (a spurious interrupt) and the
+ * cases where the state changed by two steps, making it
+ * impossible to tell the direction.
+ *
+ * In either case, don't report any event and save the
+ * state for later.
+ */
+ goto out;
+ }
+
+ rotary_encoder_report_event(encoder);
+
+out:
+ encoder->last_stable = state;
+ return IRQ_HANDLED;
+}
+
#ifdef CONFIG_OF
static const struct of_device_id rotary_encoder_of_match[] = {
{ .compatible = "rotary-encoder", },
@@ -157,6 +206,7 @@ static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct devic
struct device_node *np = dev->of_node;
struct rotary_encoder_platform_data *pdata;
enum of_gpio_flags flags;
+ int error;
if (!of_id || !np)
return NULL;
@@ -178,8 +228,23 @@ static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct devic
pdata->relative_axis =
of_property_read_bool(np, "rotary-encoder,relative-axis");
pdata->rollover = of_property_read_bool(np, "rotary-encoder,rollover");
- pdata->half_period =
- of_property_read_bool(np, "rotary-encoder,half-period");
+
+ error = of_property_read_u32(np, "rotary-encoder,steps-per-period",
+ &pdata->steps_per_period);
+ if (error) {
+ /*
+ * The 'half-period' property has been deprecated, you must use
+ * 'steps-per-period' and set an appropriate value, but we still
+ * need to parse it to maintain compatibility.
+ */
+ if (of_property_read_bool(np, "rotary-encoder,half-period")) {
+ pdata->steps_per_period = 2;
+ } else {
+ /* Fallback to one step per period behavior */
+ pdata->steps_per_period = 1;
+ }
+ }
+
pdata->wakeup_source = of_property_read_bool(np, "wakeup-source");
return pdata;
@@ -251,12 +316,23 @@ static int rotary_encoder_probe(struct platform_device *pdev)
encoder->irq_a = gpio_to_irq(pdata->gpio_a);
encoder->irq_b = gpio_to_irq(pdata->gpio_b);
- /* request the IRQs */
- if (pdata->half_period) {
+ switch (pdata->steps_per_period) {
+ case 4:
+ handler = &rotary_encoder_quarter_period_irq;
+ encoder->last_stable = rotary_encoder_get_state(pdata);
+ break;
+ case 2:
handler = &rotary_encoder_half_period_irq;
encoder->last_stable = rotary_encoder_get_state(pdata);
- } else {
+ break;
+ case 1:
handler = &rotary_encoder_irq;
+ break;
+ default:
+ dev_err(dev, "'%d' is not a valid steps-per-period value\n",
+ pdata->steps_per_period);
+ err = -EINVAL;
+ goto exit_free_gpio_b;
}
err = request_irq(encoder->irq_a, handler,