[PATCH] input: gpio_keys: Polling mode support.

[Paul Mundt <lethal@linux-sh.org>]

This implements an optional polling mode for the gpio_keys driver,
necessary for GPIOs that are not able to generate IRQs.

Polling mode is done device granular, and can not be toggled for
individual GPIOs in order to maintain simplicity. Platforms with both
IRQ capable and incapable GPIOs are required to register multiple
times, once for each case.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

---

 drivers/input/keyboard/Kconfig     |    1 
 drivers/input/keyboard/gpio_keys.c |   91 ++++++++++++++++++++++++++++---------
 include/linux/gpio_keys.h          |    1 
 3 files changed, 72 insertions(+), 21 deletions(-)

diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index efd70a9..a8cefe9 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig
@@ -283,6 +283,7 @@ config KEYBOARD_AAED2000
 config KEYBOARD_GPIO
 	tristate "GPIO Buttons"
 	depends on GENERIC_GPIO
+	select INPUT_POLLDEV
 	help
 	  This driver implements support for buttons connected
 	  to GPIO pins of various CPUs (and some other chips).
diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
index 05f3f43..412a10d 100644
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/drivers/input/keyboard/gpio_keys.c
@@ -1,7 +1,8 @@
 /*
- * Driver for keys on GPIO lines capable of generating interrupts.
+ * Driver for keys on GPIO lines, either IRQ-driven or polled.
  *
  * Copyright 2005 Phil Blundell
+ * Copyright 2008 Paul Mundt
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -9,7 +10,6 @@
  */
 
 #include <linux/module.h>
-
 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/interrupt.h>
@@ -22,7 +22,7 @@
 #include <linux/platform_device.h>
 #include <linux/input.h>
 #include <linux/gpio_keys.h>
-
+#include <linux/input-polldev.h>
 #include <asm/gpio.h>
 
 struct gpio_button_data {
@@ -32,7 +32,8 @@ struct gpio_button_data {
 };
 
 struct gpio_keys_drvdata {
-	struct input_dev *input;
+	struct gpio_keys_platform_data *pdata;
+	struct input_polled_dev *poll_dev;
 	struct gpio_button_data data[0];
 };
 
@@ -54,6 +55,33 @@ static void gpio_check_button(unsigned long _data)
 	gpio_keys_report_event(data);
 }
 
+static void gpio_handle_button_event(struct gpio_keys_button *button,
+				     struct gpio_button_data *bdata)
+{
+	if (button->debounce_interval)
+		mod_timer(&bdata->timer,
+			jiffies + msecs_to_jiffies(button->debounce_interval));
+	else
+		gpio_keys_report_event(bdata);
+}
+
+static void gpio_keys_poll(struct input_polled_dev *dev)
+{
+	struct gpio_keys_drvdata *ddata = dev->private;
+	struct gpio_keys_platform_data *pdata = ddata->pdata;
+	int i;
+
+	for (i = 0; i < pdata->nbuttons; i++) {
+		struct gpio_keys_button *button = &pdata->buttons[i];
+		struct gpio_button_data *bdata = &ddata->data[i];
+
+		bdata->input = dev->input;
+		bdata->button = button;
+
+		gpio_handle_button_event(button, bdata);
+	}
+}
+
 static irqreturn_t gpio_keys_isr(int irq, void *dev_id)
 {
 	struct gpio_button_data *bdata = dev_id;
@@ -61,11 +89,7 @@ static irqreturn_t gpio_keys_isr(int irq, void *dev_id)
 
 	BUG_ON(irq != gpio_to_irq(button->gpio));
 
-	if (button->debounce_interval)
-		mod_timer(&bdata->timer,
-			jiffies + msecs_to_jiffies(button->debounce_interval));
-	else
-		gpio_keys_report_event(bdata);
+	gpio_handle_button_event(button, bdata);
 
 	return IRQ_HANDLED;
 }
@@ -74,6 +98,7 @@ 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_polled_dev *poll_dev;
 	struct input_dev *input;
 	int i, error;
 	int wakeup = 0;
@@ -81,14 +106,19 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
 	ddata = kzalloc(sizeof(struct gpio_keys_drvdata) +
 			pdata->nbuttons * sizeof(struct gpio_button_data),
 			GFP_KERNEL);
-	input = input_allocate_device();
-	if (!ddata || !input) {
+	poll_dev = input_allocate_polled_device();
+	if (!ddata || !poll_dev) {
 		error = -ENOMEM;
 		goto fail1;
 	}
 
 	platform_set_drvdata(pdev, ddata);
 
+	poll_dev->private = ddata;
+	poll_dev->poll = gpio_keys_poll;
+	poll_dev->poll_interval = 50; /* msec */
+
+	input = poll_dev->input;
 	input->name = pdev->name;
 	input->phys = "gpio-keys/input0";
 	input->dev.parent = &pdev->dev;
@@ -98,7 +128,8 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
 	input->id.product = 0x0001;
 	input->id.version = 0x0100;
 
-	ddata->input = input;
+	ddata->poll_dev = poll_dev;
+	ddata->pdata = pdata;
 
 	for (i = 0; i < pdata->nbuttons; i++) {
 		struct gpio_keys_button *button = &pdata->buttons[i];
@@ -127,6 +158,15 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
 			goto fail2;
 		}
 
+		input_set_capability(input, type, button->code);
+
+		/*
+		 * Skip the IRQ setup and wakeup source initialization if
+		 * we are going to be polled.
+		 */
+		if (pdata->polling)
+			continue;
+
 		irq = gpio_to_irq(button->gpio);
 		if (irq < 0) {
 			error = irq;
@@ -151,11 +191,12 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
 
 		if (button->wakeup)
 			wakeup = 1;
-
-		input_set_capability(input, type, button->code);
 	}
 
-	error = input_register_device(input);
+	if (pdata->polling)
+		error = input_register_polled_device(poll_dev);
+	else
+		error = input_register_device(input);
 	if (error) {
 		pr_err("gpio-keys: Unable to register input device, "
 			"error: %d\n", error);
@@ -168,7 +209,9 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
 
  fail2:
 	while (--i >= 0) {
-		free_irq(gpio_to_irq(pdata->buttons[i].gpio), &ddata->data[i]);
+		if (!pdata->polling)
+			free_irq(gpio_to_irq(pdata->buttons[i].gpio),
+				 &ddata->data[i]);
 		if (pdata->buttons[i].debounce_interval)
 			del_timer_sync(&ddata->data[i].timer);
 		gpio_free(pdata->buttons[i].gpio);
@@ -176,7 +219,7 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, NULL);
  fail1:
-	input_free_device(input);
+	input_free_polled_device(poll_dev);
 	kfree(ddata);
 
 	return error;
@@ -186,20 +229,26 @@ static int __devexit gpio_keys_remove(struct platform_device *pdev)
 {
 	struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
 	struct gpio_keys_drvdata *ddata = platform_get_drvdata(pdev);
-	struct input_dev *input = ddata->input;
+	struct input_polled_dev *poll_dev = ddata->poll_dev;
 	int i;
 
 	device_init_wakeup(&pdev->dev, 0);
 
 	for (i = 0; i < pdata->nbuttons; i++) {
-		int irq = gpio_to_irq(pdata->buttons[i].gpio);
-		free_irq(irq, &ddata->data[i]);
+		if (!pdata->polling) {
+			int irq = gpio_to_irq(pdata->buttons[i].gpio);
+			free_irq(irq, &ddata->data[i]);
+		}
+
 		if (pdata->buttons[i].debounce_interval)
 			del_timer_sync(&ddata->data[i].timer);
 		gpio_free(pdata->buttons[i].gpio);
 	}
 
-	input_unregister_device(input);
+	if (pdata->polling)
+		input_unregister_polled_device(poll_dev);
+	else
+		input_unregister_device(poll_dev->input);
 
 	return 0;
 }
diff --git a/include/linux/gpio_keys.h b/include/linux/gpio_keys.h
index ec6ecd7..e869752 100644
--- a/include/linux/gpio_keys.h
+++ b/include/linux/gpio_keys.h
@@ -15,6 +15,7 @@ struct gpio_keys_button {
 struct gpio_keys_platform_data {
 	struct gpio_keys_button *buttons;
 	int nbuttons;
+	int polling;		/* force polling mode */
 };
 
 #endif