Sometimes gpio line can generate jitter while transitioning from one state
to another one. Implement a way to filter such noise during transitions.
Signed-off-by: Dmitry Baryshkov <dbaryshkov@xxxxxxxxx>
---
drivers/input/keyboard/gpio_keys.c | 102 ++++++++++++++++++++++++++++++++---
include/linux/gpio_keys.h | 2 +
2 files changed, 95 insertions(+), 9 deletions(-)
diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
index bbd00c3..c5f7a3d 100644
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/drivers/input/keyboard/gpio_keys.c
@@ -26,23 +26,72 @@
#include <asm/gpio.h>
+struct gpio_button_data {
+ struct platform_device *pdev;
+ struct gpio_keys_button *button;
+
+ /* For debounce */
+ int state;
+ int count;
+ struct timer_list timer;
+};
+
+struct gpio_keys_drvdata {
+ struct input_dev *input;
+ struct gpio_button_data data[0];
+};
+
+static void gpio_debounce_timer(unsigned long _data)
+{
+ struct gpio_button_data *data = (struct gpio_button_data *)_data;
+ struct gpio_keys_button *button = data->button;
+ int gpio = button->gpio;
+ unsigned int type = button->type ?: EV_KEY;
+ int state = (gpio_get_value(gpio) ? 1 : 0) ^ button->active_low;
+ struct gpio_keys_drvdata *ddata = platform_get_drvdata(data->pdev);
+ struct input_dev *input = ddata->input;
+
+ if (state != data->state) {
+ data->count = 0;
+ data->state = state;
+ mod_timer(&data->timer, jiffies +
+ msecs_to_jiffies(button->interval));
+ } else if (data->count < button->count) {
+ data->count ++;
+ mod_timer(&data->timer, jiffies +
+ msecs_to_jiffies(button->interval));
+ } else {
+ input_event(input, type, button->code, !!state);
+ input_sync(input);
+ }
+}
+
static irqreturn_t gpio_keys_isr(int irq, void *dev_id)
{
int i;
struct platform_device *pdev = dev_id;
struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
- struct input_dev *input = platform_get_drvdata(pdev);
+ struct gpio_keys_drvdata *ddata = platform_get_drvdata(pdev);
+ struct input_dev *input = ddata->input;
for (i = 0; i < pdata->nbuttons; i++) {
struct gpio_keys_button *button = &pdata->buttons[i];
+ struct gpio_button_data *data = &ddata->data[i];
int gpio = button->gpio;
if (irq == gpio_to_irq(gpio)) {
- unsigned int type = button->type ?: EV_KEY;
- int state = (gpio_get_value(gpio) ? 1 : 0) ^ button->active_low;
-
- input_event(input, type, button->code, !!state);
- input_sync(input);
+ if (button->count) {
+ if (!timer_pending(&data->timer))
+ mod_timer(&data->timer, jiffies +
+ msecs_to_jiffies(
+ button->interval));
+ } else {
+ unsigned int type = button->type ?: EV_KEY;
+ int state = (gpio_get_value(gpio) ? 1 : 0) ^ button->active_low;
+
+ input_event(input, type, button->code, !!state);
+ input_sync(input);
+ }
return IRQ_HANDLED;
}
}
@@ -53,15 +102,26 @@ static irqreturn_t gpio_keys_isr(int irq, void *dev_id)
static int __devinit gpio_keys_probe(struct platform_device *pdev)
{
struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
+ struct gpio_keys_drvdata *ddata;
struct input_dev *input;
int i, error;
int wakeup = 0;
+ ddata = kzalloc(sizeof(struct gpio_keys_drvdata) +
+ sizeof(struct gpio_button_data) * pdata->nbuttons,
+ GFP_KERNEL);
+
+ if (!ddata)
+ return -ENOMEM;
+
input = input_allocate_device();
- if (!input)
+ if (!input) {
+ kfree(ddata);
return -ENOMEM;
+ }
+ ddata->input = input;
- platform_set_drvdata(pdev, input);
+ platform_set_drvdata(pdev, ddata);
input->evbit[0] = BIT_MASK(EV_KEY);
@@ -78,6 +138,10 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
struct gpio_keys_button *button = &pdata->buttons[i];
int irq;
unsigned int type = button->type ?: EV_KEY;
+ struct gpio_button_data *data = &ddata->data[i];
+
+ data->pdev = pdev;
+ data->button = button;
error = gpio_request(button->gpio, button->desc ?: "gpio_keys");
if (error < 0) {
@@ -104,6 +168,16 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
gpio_free(button->gpio);
goto fail;
}
+ if (button->count && button->interval) {
+ data->state = -1;
+
+ init_timer(&data->timer);
+ data->timer.function = gpio_debounce_timer;
+ data->timer.data = (unsigned long)data;
+
+ mod_timer(&data->timer, jiffies +
+ msecs_to_jiffies(button->interval));
+ }
error = request_irq(irq, gpio_keys_isr,
IRQF_SAMPLE_RANDOM | IRQF_TRIGGER_RISING |
@@ -113,7 +187,10 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
if (error) {
pr_err("gpio-keys: Unable to claim irq %d; error %d\n",
irq, error);
+ if (button->count)
+ del_timer_sync(&data->timer);
gpio_free(button->gpio);
+
goto fail;
}
@@ -137,11 +214,15 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
fail:
while (--i >= 0) {
free_irq(gpio_to_irq(pdata->buttons[i].gpio), pdev);
+ if (pdata->buttons[i].count) {
+ del_timer_sync(&ddata->data[i].timer);
+ }
gpio_free(pdata->buttons[i].gpio);
}
platform_set_drvdata(pdev, NULL);
input_free_device(input);
+ kfree(ddata);
return error;
}
@@ -149,7 +230,8 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
static int __devexit gpio_keys_remove(struct platform_device *pdev)
{
struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
- struct input_dev *input = platform_get_drvdata(pdev);
+ struct gpio_keys_drvdata *ddata = platform_get_drvdata(pdev);
+ struct input_dev *input = ddata->input;
int i;
device_init_wakeup(&pdev->dev, 0);
@@ -157,6 +239,8 @@ static int __devexit gpio_keys_remove(struct platform_device *pdev)
for (i = 0; i < pdata->nbuttons; i++) {
int irq = gpio_to_irq(pdata->buttons[i].gpio);
free_irq(irq, pdev);
+ if (pdata->buttons[i].count)
+ del_timer_sync(&ddata->data[i].timer);
gpio_free(pdata->buttons[i].gpio);
}
diff --git a/include/linux/gpio_keys.h b/include/linux/gpio_keys.h
index c6d3a9d..5d09862 100644
--- a/include/linux/gpio_keys.h
+++ b/include/linux/gpio_keys.h
@@ -9,6 +9,8 @@ struct gpio_keys_button {
char *desc;
int type; /* input event type (EV_KEY, EV_SW) */
int wakeup; /* configure the button as a wake-up source */
+ int count; /* debounce ticks count */
+ int interval; /* debounce ticks interval in msecs */
};
struct gpio_keys_platform_data {
--
1.5.5
--
With best wishes
Dmitry
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