Input: gpio_keys - add support for interrupt only keys

Some of buttons, like power-on key or onkey, may only generate interrupts
when pressed and not actually be mapped as gpio in the system. Allow
setting gpio to invalid value and specify IRQ instead to support such
keys. The debounce timer is used not to debounce but to ignore new IRQs
coming while button is kept pressed.

Signed-off-by: Laxman Dewangan <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/keyboard/gpio_keys.c

···
 #include <linux/gpio.h>
 #include <linux/of_platform.h>
 #include <linux/of_gpio.h>
+#include <linux/spinlock.h>
 
 struct gpio_button_data {
 	const struct gpio_keys_button *button;
 	struct input_dev *input;
 	struct timer_list timer;
 	struct work_struct work;
-	int timer_debounce;	/* in msecs */
+	unsigned int timer_debounce;	/* in msecs */
+	unsigned int irq;
+	spinlock_t lock;
 	bool disabled;
+	bool key_pressed;
 };
 
 struct gpio_keys_drvdata {
···
 		/*
 		 * Disable IRQ and possible debouncing timer.
 		 */
-		disable_irq(gpio_to_irq(bdata->button->gpio));
+		disable_irq(bdata->irq);
 		if (bdata->timer_debounce)
 			del_timer_sync(&bdata->timer);
 
···
 static void gpio_keys_enable_button(struct gpio_button_data *bdata)
 {
 	if (bdata->disabled) {
-		enable_irq(gpio_to_irq(bdata->button->gpio));
+		enable_irq(bdata->irq);
 		bdata->disabled = false;
 	}
 }
···
 	.attrs = gpio_keys_attrs,
 };
 
-static void gpio_keys_report_event(struct gpio_button_data *bdata)
+static void gpio_keys_gpio_report_event(struct gpio_button_data *bdata)
 {
 	const struct gpio_keys_button *button = bdata->button;
 	struct input_dev *input = bdata->input;
···
 	input_sync(input);
 }
 
-static void gpio_keys_work_func(struct work_struct *work)
+static void gpio_keys_gpio_work_func(struct work_struct *work)
 {
 	struct gpio_button_data *bdata =
 		container_of(work, struct gpio_button_data, work);
 
-	gpio_keys_report_event(bdata);
+	gpio_keys_gpio_report_event(bdata);
 }
 
-static void gpio_keys_timer(unsigned long _data)
+static void gpio_keys_gpio_timer(unsigned long _data)
 {
-	struct gpio_button_data *data = (struct gpio_button_data *)_data;
+	struct gpio_button_data *bdata = (struct gpio_button_data *)_data;
 
-	schedule_work(&data->work);
+	schedule_work(&bdata->work);
 }
 
-static irqreturn_t gpio_keys_isr(int irq, void *dev_id)
+static irqreturn_t gpio_keys_gpio_isr(int irq, void *dev_id)
 {
 	struct gpio_button_data *bdata = dev_id;
-	const struct gpio_keys_button *button = bdata->button;
 
-	BUG_ON(irq != gpio_to_irq(button->gpio));
+	BUG_ON(irq != bdata->irq);
 
 	if (bdata->timer_debounce)
 		mod_timer(&bdata->timer,
···
 	return IRQ_HANDLED;
 }
 
+static void gpio_keys_irq_timer(unsigned long _data)
+{
+	struct gpio_button_data *bdata = (struct gpio_button_data *)_data;
+	struct input_dev *input = bdata->input;
+	unsigned long flags;
+
+	spin_lock_irqsave(&bdata->lock, flags);
+	if (bdata->key_pressed) {
+		input_event(input, EV_KEY, bdata->button->code, 0);
+		input_sync(input);
+		bdata->key_pressed = false;
+	}
+	spin_unlock_irqrestore(&bdata->lock, flags);
+}
+
+static irqreturn_t gpio_keys_irq_isr(int irq, void *dev_id)
+{
+	struct gpio_button_data *bdata = dev_id;
+	const struct gpio_keys_button *button = bdata->button;
+	struct input_dev *input = bdata->input;
+	unsigned long flags;
+
+	BUG_ON(irq != bdata->irq);
+
+	spin_lock_irqsave(&bdata->lock, flags);
+
+	if (!bdata->key_pressed) {
+		input_event(input, EV_KEY, button->code, 1);
+		input_sync(input);
+
+		if (!bdata->timer_debounce) {
+			input_event(input, EV_KEY, button->code, 0);
+			input_sync(input);
+			goto out;
+		}
+
+		bdata->key_pressed = true;
+	}
+
+	if (bdata->timer_debounce)
+		mod_timer(&bdata->timer,
+			jiffies + msecs_to_jiffies(bdata->timer_debounce));
+out:
+	spin_unlock_irqrestore(&bdata->lock, flags);
+	return IRQ_HANDLED;
+}
+
 static int __devinit gpio_keys_setup_key(struct platform_device *pdev,
 					 struct input_dev *input,
 					 struct gpio_button_data *bdata,
···
 {
 	const char *desc = button->desc ? button->desc : "gpio_keys";
 	struct device *dev = &pdev->dev;
+	irq_handler_t isr;
 	unsigned long irqflags;
 	int irq, error;
 
-	setup_timer(&bdata->timer, gpio_keys_timer, (unsigned long)bdata);
-	INIT_WORK(&bdata->work, gpio_keys_work_func);
 	bdata->input = input;
 	bdata->button = button;
+	spin_lock_init(&bdata->lock);
 
-	error = gpio_request(button->gpio, desc);
-	if (error < 0) {
-		dev_err(dev, "failed to request GPIO %d, error %d\n",
-			button->gpio, error);
-		goto fail2;
+	if (gpio_is_valid(button->gpio)) {
+
+		error = gpio_request(button->gpio, desc);
+		if (error < 0) {
+			dev_err(dev, "Failed to request GPIO %d, error %d\n",
+				button->gpio, error);
+			return error;
+		}
+
+		error = gpio_direction_input(button->gpio);
+		if (error < 0) {
+			dev_err(dev,
+				"Failed to configure direction for GPIO %d, error %d\n",
+				button->gpio, error);
+			goto fail;
+		}
+
+		if (button->debounce_interval) {
+			error = gpio_set_debounce(button->gpio,
+					button->debounce_interval * 1000);
+			/* use timer if gpiolib doesn't provide debounce */
+			if (error < 0)
+				bdata->timer_debounce =
+						button->debounce_interval;
+		}
+
+		irq = gpio_to_irq(button->gpio);
+		if (irq < 0) {
+			error = irq;
+			dev_err(dev,
+				"Unable to get irq number for GPIO %d, error %d\n",
+				button->gpio, error);
+			goto fail;
+		}
+		bdata->irq = irq;
+
+		INIT_WORK(&bdata->work, gpio_keys_gpio_work_func);
+		setup_timer(&bdata->timer,
+			    gpio_keys_gpio_timer, (unsigned long)bdata);
+
+		isr = gpio_keys_gpio_isr;
+		irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;
+
+	} else {
+		if (!button->irq) {
+			dev_err(dev, "No IRQ specified\n");
+			return -EINVAL;
+		}
+		bdata->irq = button->irq;
+
+		if (button->type && button->type != EV_KEY) {
+			dev_err(dev, "Only EV_KEY allowed for IRQ buttons.\n");
+			return -EINVAL;
+		}
+
+		bdata->timer_debounce = button->debounce_interval;
+		setup_timer(&bdata->timer,
+			    gpio_keys_irq_timer, (unsigned long)bdata);
+
+		isr = gpio_keys_irq_isr;
+		irqflags = 0;
 	}
 
-	error = gpio_direction_input(button->gpio);
-	if (error < 0) {
-		dev_err(dev, "failed to configure"
-			" direction for GPIO %d, error %d\n",
-			button->gpio, error);
-		goto fail3;
-	}
+	input_set_capability(input, button->type ?: EV_KEY, button->code);
 
-	if (button->debounce_interval) {
-		error = gpio_set_debounce(button->gpio,
-					  button->debounce_interval * 1000);
-		/* use timer if gpiolib doesn't provide debounce */
-		if (error < 0)
-			bdata->timer_debounce = button->debounce_interval;
-	}
-
-	irq = gpio_to_irq(button->gpio);
-	if (irq < 0) {
-		error = irq;
-		dev_err(dev, "Unable to get irq number for GPIO %d, error %d\n",
-			button->gpio, error);
-		goto fail3;
-	}
-
-	irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;
 	/*
 	 * If platform has specified that the button can be disabled,
 	 * we don't want it to share the interrupt line.
···
 	if (!button->can_disable)
 		irqflags |= IRQF_SHARED;
 
-	error = request_any_context_irq(irq, gpio_keys_isr, irqflags, desc, bdata);
+	error = request_any_context_irq(bdata->irq, isr, irqflags, desc, bdata);
 	if (error < 0) {
 		dev_err(dev, "Unable to claim irq %d; error %d\n",
-			irq, error);
-		goto fail3;
+			bdata->irq, error);
+		goto fail;
 	}
 
-	input_set_capability(input, button->type ?: EV_KEY, button->code);
 	return 0;
 
-fail3:
-	gpio_free(button->gpio);
-fail2:
+fail:
+	if (gpio_is_valid(button->gpio))
+		gpio_free(button->gpio);
+
 	return error;
 }
 
···
 
 static void gpio_remove_key(struct gpio_button_data *bdata)
 {
-	free_irq(gpio_to_irq(bdata->button->gpio), bdata);
+	free_irq(bdata->irq, bdata);
 	if (bdata->timer_debounce)
 		del_timer_sync(&bdata->timer);
 	cancel_work_sync(&bdata->work);
-	gpio_free(bdata->button->gpio);
+	if (gpio_is_valid(bdata->button->gpio))
+		gpio_free(bdata->button->gpio);
 }
 
 static int __devinit gpio_keys_probe(struct platform_device *pdev)
···
 		goto fail3;
 	}
 
-	/* get current state of buttons */
-	for (i = 0; i < pdata->nbuttons; i++)
-		gpio_keys_report_event(&ddata->data[i]);
+	/* get current state of buttons that are connected to GPIOs */
+	for (i = 0; i < pdata->nbuttons; i++) {
+		struct gpio_button_data *bdata = &ddata->data[i];
+		if (gpio_is_valid(bdata->button->gpio))
+			gpio_keys_gpio_report_event(bdata);
+	}
 	input_sync(input);
 
 	device_init_wakeup(&pdev->dev, wakeup);
···
 static int gpio_keys_suspend(struct device *dev)
 {
 	struct gpio_keys_drvdata *ddata = dev_get_drvdata(dev);
-	const struct gpio_keys_button *button;
 	int i;
 
 	if (device_may_wakeup(dev)) {
 		for (i = 0; i < ddata->n_buttons; i++) {
-			button = ddata->data[i].button;
-			if (button->wakeup) {
-				int irq = gpio_to_irq(button->gpio);
-				enable_irq_wake(irq);
-			}
+			struct gpio_button_data *bdata = &ddata->data[i];
+			if (bdata->button->wakeup)
+				enable_irq_wake(bdata->irq);
 		}
 	}
 
···
 static int gpio_keys_resume(struct device *dev)
 {
 	struct gpio_keys_drvdata *ddata = dev_get_drvdata(dev);
-	const struct gpio_keys_button *button;
 	int i;
 
 	for (i = 0; i < ddata->n_buttons; i++) {
-		button = ddata->data[i].button;
-		if (button->wakeup && device_may_wakeup(dev)) {
-			int irq = gpio_to_irq(button->gpio);
-			disable_irq_wake(irq);
-		}
+		struct gpio_button_data *bdata = &ddata->data[i];
+		if (bdata->button->wakeup && device_may_wakeup(dev))
+			disable_irq_wake(bdata->irq);
 
-		gpio_keys_report_event(&ddata->data[i]);
+		if (gpio_is_valid(bdata->button->gpio))
+			gpio_keys_gpio_report_event(bdata);
 	}
 	input_sync(ddata->input);
 

include/linux/gpio_keys.h

···
 struct gpio_keys_button {
 	/* Configuration parameters */
 	unsigned int code;	/* input event code (KEY_*, SW_*) */
-	int gpio;
+	int gpio;		/* -1 if this key does not support gpio */
 	int active_low;
 	const char *desc;
 	unsigned int type;	/* input event type (EV_KEY, EV_SW, EV_ABS) */
···
 	int debounce_interval;	/* debounce ticks interval in msecs */
 	bool can_disable;
 	int value;		/* axis value for EV_ABS */
+	unsigned int irq;	/* Irq number in case of interrupt keys */
 };
 
 struct gpio_keys_platform_data {