Date:	Sun, 18 Mar 2012 23:06:11 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Laxman Dewangan <ldewangan@...dia.com>
Cc:	grant.likely@...retlab.ca, linus.walleij@...ricsson.com,
	david@...tonic.nl, tklauser@...tanz.ch,
	alexander.stein@...ormatik.tu-chemnitz.de,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V1] input: keyboard: gpio: Support for interrupt only key

On Wed, Mar 14, 2012 at 09:00:11AM -0700, Dmitry Torokhov wrote:
> Hi Laxman,
> 
> On Wed, Mar 14, 2012 at 02:22:03PM +0530, Laxman Dewangan wrote:
> > Some of key in system generates interrupt only when it
> > pressed like power-on key or onkey. These keys do not
> > actually mapped as gpio in system.
> > Supporting the key pressed event on such keys which are
> > not actually gpio keys but generates interrupt only.
> > 
> > Signed-off-by: Laxman Dewangan <ldewangan@...dia.com>
> > ---
> > When I pushed the new driver for interrupt key, the suggestion came
> > to include this functionality in the gpio-key driver. I added require
> > changed in gpio-keys.c to support interrupt key only.
> > 
> 
> This looks much much better than a whole new driver. Let me look it over
> in more detail and get back to you.

OK, so I am generally happy with the patch; the only issue is that in
interrupt mode the only event type that makes sense is EV_KEY so we need
to make sure we do not accept anything else.

Also, I do not think that having button_irq() that is called all the
time is the best solution; I;d rather pulled RQ number up into button
data.

I tried doing the above in the patch below. Please let me know if it
still works for you. Note that it depends on some other patches for
gpio_keys that I have; I am attaching them for your reference.

Thanks.

-- 
Dmitry

Input: gpio_keys - add support for interrupt only keys

From: Laxman Dewangan <ldewangan@...dia.com>

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 <ldewangan@...dia.com>
Signed-off-by: Dmitry Torokhov <dtor@...l.ru>
---

 drivers/input/keyboard/gpio_keys.c |  196 +++++++++++++++++++++++++-----------
 include/linux/gpio_keys.h          |    3 -
 2 files changed, 139 insertions(+), 60 deletions(-)


diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
index 8f44f7b..5d369c2 100644
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/drivers/input/keyboard/gpio_keys.c
@@ -28,14 +28,18 @@
 #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 {
@@ -114,7 +118,7 @@ static void gpio_keys_disable_button(struct gpio_button_data *bdata)
 		/*
 		 * 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);
 
@@ -135,7 +139,7 @@ static void gpio_keys_disable_button(struct gpio_button_data *bdata)
 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;
 	}
 }
@@ -344,19 +348,18 @@ static void gpio_keys_work_func(struct work_struct *work)
 	gpio_keys_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,
@@ -367,6 +370,53 @@ static irqreturn_t gpio_keys_isr(int irq, void *dev_id)
 	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,
@@ -374,46 +424,79 @@ static int __devinit gpio_keys_setup_key(struct platform_device *pdev,
 {
 	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);
+	INIT_WORK(&bdata->work, gpio_keys_work_func);
 
-	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_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;
-	}
+		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;
+		}
 
-	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;
-	}
+		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;
+		}
 
-	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;
+		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;
+
+		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;
 	}
 
-	irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;
+	input_set_capability(input, button->type ?: EV_KEY, button->code);
+
 	/*
 	 * If platform has specified that the button can be disabled,
 	 * we don't want it to share the interrupt line.
@@ -421,19 +504,19 @@ static int __devinit gpio_keys_setup_key(struct platform_device *pdev,
 	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;
 }
 
@@ -553,11 +636,12 @@ static int gpio_keys_get_devtree_pdata(struct device *dev,
 
 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)
@@ -695,16 +779,13 @@ static int __devexit gpio_keys_remove(struct platform_device *pdev)
 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);
 		}
 	}
 
@@ -714,15 +795,12 @@ static int gpio_keys_suspend(struct device *dev)
 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]);
 	}
diff --git a/include/linux/gpio_keys.h b/include/linux/gpio_keys.h
index 004ff33..a7e977f 100644
--- a/include/linux/gpio_keys.h
+++ b/include/linux/gpio_keys.h
@@ -6,7 +6,7 @@ struct device;
 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) */
@@ -14,6 +14,7 @@ struct gpio_keys_button {
 	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 {

View attachment "gpio-keys-const.patch" of type "text/plain" (4675 bytes)

View attachment "gpio_keys-request-any-context-irq.patch" of type "text/plain" (1038 bytes)

View attachment "gpio_keys-rework-unwind.patch" of type "text/plain" (2496 bytes)

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