Extcon: support generic GPIO extcon driver

The generic GPIO extcon driver (an external connector device based on
GPIO control) and imported from Android kernel.

switch: switch class and GPIO drivers. (splitted)
Author: Mike Lockwood <lockwood@android.com>

switch: gpio: Don't call request_irq with interrupts disabled
Author: Arve Hjønnevåg <arve@android.com>

switch_gpio: Add missing #include <linux/interrupt.h>
Author: Mike Lockwood <lockwood@android.com>

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

--
Changed from v7:
- Style updates mentioned by Stephen Boyd and Mark Brown
Changed from v5:
- Splitted at v5 from the main extcon patch.
- Added debounce time for irq handlers.
- Use request_any_context_irq instead of request_irq
- User needs to specify irq flags for GPIO interrupts (was fixed to
IRQF_TRIGGER_LOW before)
- Use module_platform_driver().
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 177 insertions, 0 deletions

diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
index 7932e1bd9b02..85cecff36db3 100644
--- a/drivers/extcon/Kconfig
+++ b/drivers/extcon/Kconfig
@@ -14,4 +14,11 @@ if EXTCON
 
 comment "Extcon Device Drivers"
 
+config EXTCON_GPIO
+        tristate "GPIO extcon support"
+        depends on GENERIC_GPIO
+        help
+          Say Y here to enable GPIO based extcon support. Note that GPIO
+          extcon supports single state per extcon instance.
+
 endif # MULTISTATE_SWITCH
diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
index 6bc69214fcd7..2c46d4176d18 100644
--- a/drivers/extcon/Makefile
+++ b/drivers/extcon/Makefile
@@ -3,3 +3,4 @@
 #
 
 obj-$(CONFIG_EXTCON)            += extcon_class.o
+obj-$(CONFIG_EXTCON_GPIO)       += extcon_gpio.o
diff --git a/drivers/extcon/extcon_gpio.c b/drivers/extcon/extcon_gpio.c
new file mode 100644
index 000000000000..5c0f08506f93
--- /dev/null
+++ b/drivers/extcon/extcon_gpio.c
@@ -0,0 +1,169 @@
+/*
+ *  drivers/extcon/extcon_gpio.c
+ *
+ *  Single-state GPIO extcon driver based on extcon class
+ *
+ * Copyright (C) 2008 Google, Inc.
+ * Author: Mike Lockwood <lockwood@android.com>
+ *
+ * Modified by MyungJoo Ham <myungjoo.ham@samsung.com> to support extcon
+ * (originally switch class is supported)
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+*/
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/extcon.h>
+#include <linux/workqueue.h>
+#include <linux/gpio.h>
+#include <linux/extcon.h>
+#include <linux/extcon/extcon_gpio.h>
+
+struct gpio_extcon_data {
+        struct extcon_dev edev;
+        unsigned gpio;
+        const char *state_on;
+        const char *state_off;
+        int irq;
+        struct delayed_work work;
+        unsigned long debounce_jiffies;
+};
+
+static void gpio_extcon_work(struct work_struct *work)
+{
+        int state;
+        struct gpio_extcon_data *data =
+                container_of(to_delayed_work(work), struct gpio_extcon_data,
+                             work);
+
+        state = gpio_get_value(data->gpio);
+        extcon_set_state(&data->edev, state);
+}
+
+static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
+{
+        struct gpio_extcon_data *extcon_data = dev_id;
+
+        schedule_delayed_work(&extcon_data->work,
+                              extcon_data->debounce_jiffies);
+        return IRQ_HANDLED;
+}
+
+static ssize_t extcon_gpio_print_state(struct extcon_dev *edev, char *buf)
+{
+        struct gpio_extcon_data *extcon_data =
+                container_of(edev, struct gpio_extcon_data, edev);
+        const char *state;
+        if (extcon_get_state(edev))
+                state = extcon_data->state_on;
+        else
+                state = extcon_data->state_off;
+
+        if (state)
+                return sprintf(buf, "%s\n", state);
+        return -EINVAL;
+}
+
+static int __devinit gpio_extcon_probe(struct platform_device *pdev)
+{
+        struct gpio_extcon_platform_data *pdata = pdev->dev.platform_data;
+        struct gpio_extcon_data *extcon_data;
+        int ret = 0;
+
+        if (!pdata)
+                return -EBUSY;
+        if (!pdata->irq_flags) {
+                dev_err(&pdev->dev, "IRQ flag is not specified.\n");
+                return -EINVAL;
+        }
+
+        extcon_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_extcon_data),
+                                   GFP_KERNEL);
+        if (!extcon_data)
+                return -ENOMEM;
+
+        extcon_data->edev.name = pdata->name;
+        extcon_data->gpio = pdata->gpio;
+        extcon_data->state_on = pdata->state_on;
+        extcon_data->state_off = pdata->state_off;
+        if (pdata->state_on && pdata->state_off)
+                extcon_data->edev.print_state = extcon_gpio_print_state;
+        extcon_data->debounce_jiffies = msecs_to_jiffies(pdata->debounce);
+
+        ret = extcon_dev_register(&extcon_data->edev, &pdev->dev);
+        if (ret < 0)
+                goto err_extcon_dev_register;
+
+        ret = gpio_request_one(extcon_data->gpio, GPIOF_DIR_IN, pdev->name);
+        if (ret < 0)
+                goto err_request_gpio;
+
+        INIT_DELAYED_WORK(&extcon_data->work, gpio_extcon_work);
+
+        extcon_data->irq = gpio_to_irq(extcon_data->gpio);
+        if (extcon_data->irq < 0) {
+                ret = extcon_data->irq;
+                goto err_detect_irq_num_failed;
+        }
+
+        ret = request_any_context_irq(extcon_data->irq, gpio_irq_handler,
+                                      pdata->irq_flags, pdev->name,
+                                      extcon_data);
+        if (ret < 0)
+                goto err_request_irq;
+
+        /* Perform initial detection */
+        gpio_extcon_work(&extcon_data->work.work);
+
+        return 0;
+
+err_request_irq:
+err_detect_irq_num_failed:
+        gpio_free(extcon_data->gpio);
+err_request_gpio:
+        extcon_dev_unregister(&extcon_data->edev);
+err_extcon_dev_register:
+        devm_kfree(&pdev->dev, extcon_data);
+
+        return ret;
+}
+
+static int __devexit gpio_extcon_remove(struct platform_device *pdev)
+{
+        struct gpio_extcon_data *extcon_data = platform_get_drvdata(pdev);
+
+        cancel_delayed_work_sync(&extcon_data->work);
+        gpio_free(extcon_data->gpio);
+        extcon_dev_unregister(&extcon_data->edev);
+        devm_kfree(&pdev->dev, extcon_data);
+
+        return 0;
+}
+
+static struct platform_driver gpio_extcon = {
+        .probe          = gpio_extcon_probe,
+        .remove         = __devexit_p(gpio_extcon_remove),
+        .driver         = {
+                .name   = "extcon-gpio",
+                .owner  = THIS_MODULE,
+        },
+};
+
+module_platform_driver(gpio_extcon);
+
+MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
+MODULE_DESCRIPTION("GPIO extcon driver");
+MODULE_LICENSE("GPL");