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Subject[PATCH v6 2/5] Extcon: support generic GPIO extcon driver
Date
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>

--
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().
---
drivers/extcon/Kconfig | 7 ++
drivers/extcon/Makefile | 1 +
drivers/extcon/extcon_gpio.c | 175 ++++++++++++++++++++++++++++++++++++
include/linux/extcon/extcon_gpio.h | 52 +++++++++++
4 files changed, 235 insertions(+), 0 deletions(-)
create mode 100644 drivers/extcon/extcon_gpio.c
create mode 100644 include/linux/extcon/extcon_gpio.h

diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
index 11db865..cc3f5eb 100644
--- a/drivers/extcon/Kconfig
+++ b/drivers/extcon/Kconfig
@@ -25,4 +25,11 @@ config EXTCON_ANDROID_COMPATIBLE

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 6bc6921..2c46d41 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 0000000..f24ec67
--- /dev/null
+++ b/drivers/extcon/extcon_gpio.c
@@ -0,0 +1,175 @@
+/*
+ * 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 =
+ (struct gpio_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 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(extcon_data->gpio, pdev->name);
+ if (ret < 0)
+ goto err_request_gpio;
+
+ ret = gpio_direction_input(extcon_data->gpio);
+ if (ret < 0)
+ goto err_set_gpio_input;
+
+ 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:
+err_set_gpio_input:
+ 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 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 = 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");
diff --git a/include/linux/extcon/extcon_gpio.h b/include/linux/extcon/extcon_gpio.h
new file mode 100644
index 0000000..a2129b7
--- /dev/null
+++ b/include/linux/extcon/extcon_gpio.h
@@ -0,0 +1,52 @@
+/*
+ * External connector (extcon) class generic GPIO driver
+ *
+ * Copyright (C) 2012 Samsung Electronics
+ * Author: MyungJoo Ham <myungjoo.ham@samsung.com>
+ *
+ * based on switch class driver
+ * Copyright (C) 2008 Google, Inc.
+ * Author: Mike Lockwood <lockwood@android.com>
+ *
+ * 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.
+ *
+*/
+#ifndef __EXTCON_GPIO_H__
+#define __EXTCON_GPIO_H__ __FILE__
+
+#include <linux/extcon.h>
+
+/**
+ * struct gpio_extcon_platform_data - A simple GPIO-controlled extcon device.
+ * @name The name of this GPIO extcon device.
+ * @gpio Corresponding GPIO.
+ * @debounce Debounce time for GPIO IRQ in ms.
+ * @irq_flags IRQ Flags (e.g., IRQF_TRIGGER_LOW).
+ * @state_on print_state is overriden with state_on if attached. If Null,
+ * default method of extcon class is used.
+ * @state_off print_state is overriden with state_on if dettached. If Null,
+ * default method of extcon class is used.
+ *
+ * Note that in order for state_on or state_off to be valid, both state_on
+ * and state_off should be not NULL. If at least one of them is NULL,
+ * the print_state is not overriden.
+ */
+struct gpio_extcon_platform_data {
+ const char *name;
+ unsigned gpio;
+ unsigned long debounce;
+ unsigned long irq_flags;
+
+ /* if NULL, "0" or "1" will be printed */
+ const char *state_on;
+ const char *state_off;
+};
+
+#endif /* __EXTCON_GPIO_H__ */
--
1.7.4.1
--
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