Sometimes the gpio line can generates jitter while transitioning
from one state to another. Implement a way to filter such noise during
transitions.
Signed-off-by: Dmitry Baryshkov <dbaryshkov@xxxxxxxxx>
---
drivers/input/keyboard/Kconfig | 7 +++
drivers/input/keyboard/gpio_keys.c | 96 ++++++++++++++++++++++++++++++++++--
include/linux/gpio_keys.h | 6 ++
3 files changed, 104 insertions(+), 5 deletions(-)
diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index 8ea709b..0fb4592 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig
@@ -295,6 +295,13 @@ config KEYBOARD_GPIO
To compile this driver as a module, choose M here: the
module will be called gpio-keys.
+config KEYBOARD_GPIO_DEBOUNCE
+ bool "GPIO Buttons debouncer"
+ depends on KEYBOARD_GPIO
+ help
+ This driver will enable the debouncer in the gpio-keys
+ driver for pins that take some time to come to stable state.
+
config KEYBOARD_MAPLE
tristate "Maple bus keyboard"
depends on SH_DREAMCAST && MAPLE
diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
index 6a9ca4b..577dfea 100644
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/drivers/input/keyboard/gpio_keys.c
@@ -26,6 +26,39 @@
#include <asm/gpio.h>
+#ifdef CONFIG_KEYBOARD_GPIO_DEBOUNCE
+struct gpio_debounce_data {
+ struct platform_device *pdev;
+ struct gpio_keys_button *button;
+ int state;
+ int count;
+};
+
+static void gpio_debounce_timer(unsigned long _data)
+{
+ struct gpio_debounce_data *data = (struct gpio_debounce_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 input_dev *input = platform_get_drvdata(data->pdev);
+
+ if (state != data->state) {
+ data->count = 0;
+ data->state = state;
+ mod_timer(&button->timer, jiffies +
+ msecs_to_jiffies(button->interval));
+ } else if (data->count < button->count) {
+ data->count ++;
+ mod_timer(&button->timer, jiffies +
+ msecs_to_jiffies(button->interval));
+ } else {
+ input_event(input, type, button->code, !!state);
+ input_sync(input);
+ }
+}
+#endif
+
static irqreturn_t gpio_keys_isr(int irq, void *dev_id)
{
int i;
@@ -38,11 +71,21 @@ static irqreturn_t gpio_keys_isr(int irq, void *dev_id)
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;
+#ifdef CONFIG_KEYBOARD_GPIO_DEBOUNCE
+ if (button->count) {
+ if (!timer_pending(&button->timer))
+ mod_timer(&button->timer, jiffies +
+ msecs_to_jiffies(
+ button->interval));
+ } else
+#endif
+ {
+ 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);
+ input_event(input, type, button->code, !!state);
+ input_sync(input);
+ }
}
}
@@ -103,6 +146,31 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
gpio_free(button->gpio);
goto fail;
}
+#ifdef CONFIG_KEYBOARD_GPIO_DEBOUNCE
+ if (button->count && button->interval) {
+ struct gpio_debounce_data *data;
+ data = kzalloc(sizeof(struct gpio_debounce_data), GFP_KERNEL);
+ if (!data) {
+ error = -ENOMEM;
+ pr_err("gpio-keys: Unable to allocate debounce data"
+ " for GPIO %d, error %d\n",
+ button->gpio, error);
+ gpio_free(button->gpio);
+ goto fail;
+ }
+
+ data->pdev = pdev;
+ data->button = button;
+ data->state = -1;
+
+ init_timer(&button->timer);
+ button->timer.function = gpio_debounce_timer;
+ button->timer.data = (unsigned long)data;
+
+ mod_timer(&button->timer, jiffies +
+ msecs_to_jiffies(button->interval));
+ }
+#endif
error = request_irq(irq, gpio_keys_isr,
IRQF_SAMPLE_RANDOM | IRQF_TRIGGER_RISING |
@@ -112,6 +180,12 @@ 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);
+#ifdef CONFIG_KEYBOARD_GPIO_DEBOUNCE
+ if (button->count) {
+ del_timer_sync(&button->timer);
+ kfree((void*)button->timer.data);
+ }
+#endif
gpio_free(button->gpio);
goto fail;
}
@@ -136,6 +210,12 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
fail:
while (--i >= 0) {
free_irq(gpio_to_irq(pdata->buttons[i].gpio), pdev);
+#ifdef CONFIG_KEYBOARD_GPIO_DEBOUNCE
+ if (pdata->buttons[i].count) {
+ del_timer_sync(&pdata->buttons[i].timer);
+ kfree((void*)pdata->buttons[i].timer.data);
+ }
+#endif
gpio_free(pdata->buttons[i].gpio);
}
@@ -156,6 +236,12 @@ 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);
+#ifdef CONFIG_KEYBOARD_GPIO_DEBOUNCE
+ if (pdata->buttons[i].count) {
+ del_timer_sync(&pdata->buttons[i].timer);
+ kfree((void*)pdata->buttons[i].timer.data);
+ }
+#endif
gpio_free(pdata->buttons[i].gpio);
}
diff --git a/include/linux/gpio_keys.h b/include/linux/gpio_keys.h
index c6d3a9d..2432e62 100644
--- a/include/linux/gpio_keys.h
+++ b/include/linux/gpio_keys.h
@@ -9,6 +9,12 @@ 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 */
+#ifdef CONFIG_KEYBOARD_GPIO_DEBOUNCE
+ int count;
+ int interval; /* in msecs */
+ /* private: */
+ struct timer_list timer;
+#endif
};
struct gpio_keys_platform_data {
--
1.5.4.3
--
With best wishes
Dmitry
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