input: add debouncing for generic gpio input device gpio_key.c

This patch add debouncing support for the generic gpio input device, since debouncing is most likely to happen.

Comments welcome.

---
Keith Mok

index 6a9ca4b..79b460e 100644
@@ -26,26 +26,36 @@
 

#include <asm/gpio.h>

+static void do_gpio_keys_tasklet(unsigned long);
+static void do_gpio_keys_timer(unsigned long);
+
+static struct timer_list gpio_keys_timer; +DECLARE_TASKLET_DISABLED(gpio_keys_tasklet, do_gpio_keys_tasklet, 0); +static spinlock_t suspend_lock;
+static int suspended;
+
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);
-
- for (i = 0; i < pdata->nbuttons; i++) {
- struct gpio_keys_button *button = &pdata->buttons[i];
- int gpio = button->gpio;
+ int i;
+ unsigned long flags;

- if (irq == gpio_to_irq(gpio)) {
- unsigned int type = button->type ?: EV_KEY;
- int state = (gpio_get_value(gpio) ? 1 : 0) ^ button->active_low;
+ spin_lock_irqsave(&suspend_lock, flags);
+ if (suspended) {
+ spin_unlock_irqrestore(&suspend_lock, flags);
+ return IRQ_HANDLED;
+ }
+ spin_unlock_irqrestore(&suspend_lock, flags);

- input_event(input, type, button->code, !!state);
- input_sync(input);
- }
+ /* disable keyboard interrupt and schedule for handling */
+ for (i = 0; i < pdata->nbuttons; i++) {
+ int irq = gpio_to_irq(pdata->buttons[i].gpio);

+		disable_irq(irq);
	}

+ tasklet_schedule(&gpio_keys_tasklet);
+

	return IRQ_HANDLED;
}

@@ -63,6 +73,11 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)

	platform_set_drvdata(pdev, input);

	input->evbit[0] = BIT_MASK(EV_KEY);

+ setup_timer(&gpio_keys_timer, do_gpio_keys_timer, (unsigned long) pdev);
+ tasklet_enable(&gpio_keys_tasklet);
+ gpio_keys_tasklet.data = (unsigned long) pdev;
+ spin_lock_init(&suspend_lock);
+ suspended = 0;

	input->name = pdev->name;
	input->phys = "gpio-keys/input0";
@@ -156,9 +171,14 @@ 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);
-		gpio_free(pdata->buttons[i].gpio);
	}

+ del_timer_sync(&gpio_keys_timer);
+ tasklet_kill(&gpio_keys_tasklet);
+
+ for (i = 0; i < pdata->nbuttons; i++)
+ gpio_free(pdata->buttons[i].gpio);
+

	input_unregister_device(input);

	return 0;

@@ -168,9 +188,29 @@ static int __devexit gpio_keys_remove(struct platform_device *pdev) #ifdef CONFIG_PM
static int gpio_keys_suspend(struct platform_device *pdev, pm_message_t state) {

+	unsigned long flags;
	struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
	int i;

+ spin_lock_irqsave(&suspend_lock, flags);
+
+ /*
+ * Re-enable the interrupt in case it has been masked by the
+ * handler and a key is still pressed. We need the interrupt
+ * to wake us up from suspended.
+ */
+
+ suspended = 1;
+
+ spin_unlock_irqrestore(&suspend_lock, flags);
+ del_timer_sync(&gpio_keys_timer);
+ tasklet_kill(&gpio_keys_tasklet);
+
+ for (i = 0; i < pdata->nbuttons; i++) {
+ int irq = gpio_to_irq(pdata->buttons[i].gpio);
+ enable_irq(irq);
+ }
+

	if (device_may_wakeup(&pdev->dev)) {
		for (i = 0; i < pdata->nbuttons; i++) {
			struct gpio_keys_button *button = &pdata->buttons[i];
@@ -189,6 +229,7 @@ static int gpio_keys_resume(struct platform_device *pdev)
	struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
	int i;

+	suspended = 0;
	if (device_may_wakeup(&pdev->dev)) {
		for (i = 0; i < pdata->nbuttons; i++) {
			struct gpio_keys_button *button = &pdata->buttons[i];

@@ -206,6 +247,45 @@ static int gpio_keys_resume(struct platform_device *pdev)
#define gpio_keys_resume NULL
#endif

+static void do_gpio_keys_tasklet(unsigned long data) +{
+ int pressed;
+ int i;
+ struct platform_device *pdev = (struct platform_device*)data;
+ struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
+ struct input_dev *input = platform_get_drvdata(pdev);
+
+ /* check for any changes */
+ pressed = 0;
+ for (i = 0; i < pdata->nbuttons; i++) {
+ struct gpio_keys_button *button = &pdata->buttons[i];
+ int gpio = button->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);
+ pressed |= !!state;
+ input_sync(input);
+ }
+ if(pressed) {
+ int delay = HZ / 20;
+ /* some key is pressed - keep irq disabled and use timer
+ * to poll */
+ mod_timer(&gpio_keys_timer, jiffies + delay);
+ } else {
+ for (i = 0; i < pdata->nbuttons; i++) {
+ int irq = gpio_to_irq(pdata->buttons[i].gpio);
+ enable_irq(irq);
+ }
+ }
+}
+
+static void do_gpio_keys_timer(unsigned long data) +{
+ tasklet_schedule(&gpio_keys_tasklet);
+}
+

struct platform_driver gpio_keys_device_driver = {
	.probe		= gpio_keys_probe,
	.remove		= __devexit_p(gpio_keys_remove),