Input: add input driver for polled GPIO buttons

The existing gpio-keys driver can be usable only for GPIO lines with
interrupt support. Several devices have buttons connected to a GPIO
line which is not capable to generate interrupts. This patch adds a
new input driver using the generic GPIO layer and the input-polldev
to support such buttons.

[Ben Gardiner <bengardiner@nanometrics.ca: fold code to use more
 of the original gpio_keys infrastructure; cleanups and other
 improvements.]

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
Tested-by: Ben Gardiner <bengardiner@nanometrics.ca>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

3 files changed, 278 insertions, 0 deletions

diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index b8c51b9781db..3a87f3ba5f75 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig
@@ -179,6 +179,22 @@ config KEYBOARD_GPIO
           To compile this driver as a module, choose M here: the
           module will be called gpio_keys.
 
+config KEYBOARD_GPIO_POLLED
+        tristate "Polled GPIO buttons"
+        depends on GENERIC_GPIO
+        select INPUT_POLLDEV
+        help
+          This driver implements support for buttons connected
+          to GPIO pins that are not capable of generating interrupts.
+
+          Say Y here if your device has buttons connected
+          directly to such GPIO pins.  Your board-specific
+          setup logic must also provide a platform device,
+          with configuration data saying which GPIOs are used.
+
+          To compile this driver as a module, choose M here: the
+          module will be called gpio_keys_polled.
+
 config KEYBOARD_TCA6416
         tristate "TCA6416 Keypad Support"
         depends on I2C
diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
index a34452e8ebe2..622de73a445d 100644
--- a/drivers/input/keyboard/Makefile
+++ b/drivers/input/keyboard/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_KEYBOARD_BFIN)		+= bf54x-keys.o
 obj-$(CONFIG_KEYBOARD_DAVINCI)          += davinci_keyscan.o
 obj-$(CONFIG_KEYBOARD_EP93XX)           += ep93xx_keypad.o
 obj-$(CONFIG_KEYBOARD_GPIO)             += gpio_keys.o
+obj-$(CONFIG_KEYBOARD_GPIO_POLLED)      += gpio_keys_polled.o
 obj-$(CONFIG_KEYBOARD_TCA6416)          += tca6416-keypad.o
 obj-$(CONFIG_KEYBOARD_HIL)              += hil_kbd.o
 obj-$(CONFIG_KEYBOARD_HIL_OLD)          += hilkbd.o
diff --git a/drivers/input/keyboard/gpio_keys_polled.c b/drivers/input/keyboard/gpio_keys_polled.c
new file mode 100644
index 000000000000..4c17aff20657
--- /dev/null
+++ b/drivers/input/keyboard/gpio_keys_polled.c
@@ -0,0 +1,261 @@
+/*
+ *  Driver for buttons on GPIO lines not capable of generating interrupts
+ *
+ *  Copyright (C) 2007-2010 Gabor Juhos <juhosg@openwrt.org>
+ *  Copyright (C) 2010 Nuno Goncalves <nunojpg@gmail.com>
+ *
+ *  This file was based on: /drivers/input/misc/cobalt_btns.c
+ *      Copyright (C) 2007 Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
+ *
+ *  also was based on: /drivers/input/keyboard/gpio_keys.c
+ *      Copyright 2005 Phil Blundell
+ *
+ *  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
+ *  published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/input-polldev.h>
+#include <linux/ioport.h>
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+#include <linux/gpio_keys.h>
+
+#define DRV_NAME        "gpio-keys-polled"
+
+struct gpio_keys_button_data {
+        int last_state;
+        int count;
+        int threshold;
+        int can_sleep;
+};
+
+struct gpio_keys_polled_dev {
+        struct input_polled_dev *poll_dev;
+        struct device *dev;
+        struct gpio_keys_platform_data *pdata;
+        struct gpio_keys_button_data data[0];
+};
+
+static void gpio_keys_polled_check_state(struct input_dev *input,
+                                         struct gpio_keys_button *button,
+                                         struct gpio_keys_button_data *bdata)
+{
+        int state;
+
+        if (bdata->can_sleep)
+                state = !!gpio_get_value_cansleep(button->gpio);
+        else
+                state = !!gpio_get_value(button->gpio);
+
+        if (state != bdata->last_state) {
+                unsigned int type = button->type ?: EV_KEY;
+
+                input_event(input, type, button->code,
+                            !!(state ^ button->active_low));
+                input_sync(input);
+                bdata->count = 0;
+                bdata->last_state = state;
+        }
+}
+
+static void gpio_keys_polled_poll(struct input_polled_dev *dev)
+{
+        struct gpio_keys_polled_dev *bdev = dev->private;
+        struct gpio_keys_platform_data *pdata = bdev->pdata;
+        struct input_dev *input = dev->input;
+        int i;
+
+        for (i = 0; i < bdev->pdata->nbuttons; i++) {
+                struct gpio_keys_button_data *bdata = &bdev->data[i];
+
+                if (bdata->count < bdata->threshold)
+                        bdata->count++;
+                else
+                        gpio_keys_polled_check_state(input, &pdata->buttons[i],
+                                                     bdata);
+        }
+}
+
+static void gpio_keys_polled_open(struct input_polled_dev *dev)
+{
+        struct gpio_keys_polled_dev *bdev = dev->private;
+        struct gpio_keys_platform_data *pdata = bdev->pdata;
+
+        if (pdata->enable)
+                pdata->enable(bdev->dev);
+}
+
+static void gpio_keys_polled_close(struct input_polled_dev *dev)
+{
+        struct gpio_keys_polled_dev *bdev = dev->private;
+        struct gpio_keys_platform_data *pdata = bdev->pdata;
+
+        if (pdata->disable)
+                pdata->disable(bdev->dev);
+}
+
+static int __devinit gpio_keys_polled_probe(struct platform_device *pdev)
+{
+        struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
+        struct device *dev = &pdev->dev;
+        struct gpio_keys_polled_dev *bdev;
+        struct input_polled_dev *poll_dev;
+        struct input_dev *input;
+        int error;
+        int i;
+
+        if (!pdata || !pdata->poll_interval)
+                return -EINVAL;
+
+        bdev = kzalloc(sizeof(struct gpio_keys_polled_dev) +
+                       pdata->nbuttons * sizeof(struct gpio_keys_button_data),
+                       GFP_KERNEL);
+        if (!bdev) {
+                dev_err(dev, "no memory for private data\n");
+                return -ENOMEM;
+        }
+
+        poll_dev = input_allocate_polled_device();
+        if (!poll_dev) {
+                dev_err(dev, "no memory for polled device\n");
+                error = -ENOMEM;
+                goto err_free_bdev;
+        }
+
+        poll_dev->private = bdev;
+        poll_dev->poll = gpio_keys_polled_poll;
+        poll_dev->poll_interval = pdata->poll_interval;
+        poll_dev->open = gpio_keys_polled_open;
+        poll_dev->close = gpio_keys_polled_close;
+
+        input = poll_dev->input;
+
+        input->evbit[0] = BIT(EV_KEY);
+        input->name = pdev->name;
+        input->phys = DRV_NAME"/input0";
+        input->dev.parent = &pdev->dev;
+
+        input->id.bustype = BUS_HOST;
+        input->id.vendor = 0x0001;
+        input->id.product = 0x0001;
+        input->id.version = 0x0100;
+
+        for (i = 0; i < pdata->nbuttons; i++) {
+                struct gpio_keys_button *button = &pdata->buttons[i];
+                struct gpio_keys_button_data *bdata = &bdev->data[i];
+                unsigned int gpio = button->gpio;
+                unsigned int type = button->type ?: EV_KEY;
+
+                if (button->wakeup) {
+                        dev_err(dev, DRV_NAME " does not support wakeup\n");
+                        error = -EINVAL;
+                        goto err_free_gpio;
+                }
+
+                error = gpio_request(gpio,
+                                     button->desc ? button->desc : DRV_NAME);
+                if (error) {
+                        dev_err(dev, "unable to claim gpio %u, err=%d\n",
+                                gpio, error);
+                        goto err_free_gpio;
+                }
+
+                error = gpio_direction_input(gpio);
+                if (error) {
+                        dev_err(dev,
+                                "unable to set direction on gpio %u, err=%d\n",
+                                gpio, error);
+                        goto err_free_gpio;
+                }
+
+                bdata->can_sleep = gpio_cansleep(gpio);
+                bdata->last_state = -1;
+                bdata->threshold = DIV_ROUND_UP(button->debounce_interval,
+                                                pdata->poll_interval);
+
+                input_set_capability(input, type, button->code);
+        }
+
+        bdev->poll_dev = poll_dev;
+        bdev->dev = dev;
+        bdev->pdata = pdata;
+        platform_set_drvdata(pdev, bdev);
+
+        error = input_register_polled_device(poll_dev);
+        if (error) {
+                dev_err(dev, "unable to register polled device, err=%d\n",
+                        error);
+                goto err_free_gpio;
+        }
+
+        /* report initial state of the buttons */
+        for (i = 0; i < pdata->nbuttons; i++)
+                gpio_keys_polled_check_state(input, &pdata->buttons[i],
+                                         &bdev->data[i]);
+
+        return 0;
+
+err_free_gpio:
+        while (--i >= 0)
+                gpio_free(pdata->buttons[i].gpio);
+
+        input_free_polled_device(poll_dev);
+
+err_free_bdev:
+        kfree(bdev);
+
+        platform_set_drvdata(pdev, NULL);
+        return error;
+}
+
+static int __devexit gpio_keys_polled_remove(struct platform_device *pdev)
+{
+        struct gpio_keys_polled_dev *bdev = platform_get_drvdata(pdev);
+        struct gpio_keys_platform_data *pdata = bdev->pdata;
+        int i;
+
+        input_unregister_polled_device(bdev->poll_dev);
+
+        for (i = 0; i < pdata->nbuttons; i++)
+                gpio_free(pdata->buttons[i].gpio);
+
+        input_free_polled_device(bdev->poll_dev);
+
+        kfree(bdev);
+        platform_set_drvdata(pdev, NULL);
+
+        return 0;
+}
+
+static struct platform_driver gpio_keys_polled_driver = {
+        .probe  = gpio_keys_polled_probe,
+        .remove = __devexit_p(gpio_keys_polled_remove),
+        .driver = {
+                .name   = DRV_NAME,
+                .owner  = THIS_MODULE,
+        },
+};
+
+static int __init gpio_keys_polled_init(void)
+{
+        return platform_driver_register(&gpio_keys_polled_driver);
+}
+
+static void __exit gpio_keys_polled_exit(void)
+{
+        platform_driver_unregister(&gpio_keys_polled_driver);
+}
+
+module_init(gpio_keys_polled_init);
+module_exit(gpio_keys_polled_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
+MODULE_DESCRIPTION("Polled GPIO Buttons driver");
+MODULE_ALIAS("platform:" DRV_NAME);