linux/drivers/extcon/extcon-gpio.c
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   1/*
   2 *  drivers/extcon/extcon_gpio.c
   3 *
   4 *  Single-state GPIO extcon driver based on extcon class
   5 *
   6 * Copyright (C) 2008 Google, Inc.
   7 * Author: Mike Lockwood <lockwood@android.com>
   8 *
   9 * Modified by MyungJoo Ham <myungjoo.ham@samsung.com> to support extcon
  10 * (originally switch class is supported)
  11 *
  12 * This software is licensed under the terms of the GNU General Public
  13 * License version 2, as published by the Free Software Foundation, and
  14 * may be copied, distributed, and modified under those terms.
  15 *
  16 * This program is distributed in the hope that it will be useful,
  17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 * GNU General Public License for more details.
  20 *
  21*/
  22
  23#include <linux/extcon.h>
  24#include <linux/extcon/extcon-gpio.h>
  25#include <linux/gpio.h>
  26#include <linux/init.h>
  27#include <linux/interrupt.h>
  28#include <linux/kernel.h>
  29#include <linux/module.h>
  30#include <linux/platform_device.h>
  31#include <linux/slab.h>
  32#include <linux/workqueue.h>
  33
  34struct gpio_extcon_data {
  35        struct extcon_dev *edev;
  36        unsigned gpio;
  37        bool gpio_active_low;
  38        const char *state_on;
  39        const char *state_off;
  40        int irq;
  41        struct delayed_work work;
  42        unsigned long debounce_jiffies;
  43        bool check_on_resume;
  44};
  45
  46static void gpio_extcon_work(struct work_struct *work)
  47{
  48        int state;
  49        struct gpio_extcon_data *data =
  50                container_of(to_delayed_work(work), struct gpio_extcon_data,
  51                             work);
  52
  53        state = gpio_get_value(data->gpio);
  54        if (data->gpio_active_low)
  55                state = !state;
  56        extcon_set_state(data->edev, state);
  57}
  58
  59static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
  60{
  61        struct gpio_extcon_data *extcon_data = dev_id;
  62
  63        queue_delayed_work(system_power_efficient_wq, &extcon_data->work,
  64                              extcon_data->debounce_jiffies);
  65        return IRQ_HANDLED;
  66}
  67
  68static ssize_t extcon_gpio_print_state(struct extcon_dev *edev, char *buf)
  69{
  70        struct device *dev = edev->dev.parent;
  71        struct gpio_extcon_data *extcon_data = dev_get_drvdata(dev);
  72        const char *state;
  73
  74        if (extcon_get_state(edev))
  75                state = extcon_data->state_on;
  76        else
  77                state = extcon_data->state_off;
  78
  79        if (state)
  80                return sprintf(buf, "%s\n", state);
  81        return -EINVAL;
  82}
  83
  84static int gpio_extcon_probe(struct platform_device *pdev)
  85{
  86        struct gpio_extcon_platform_data *pdata = dev_get_platdata(&pdev->dev);
  87        struct gpio_extcon_data *extcon_data;
  88        int ret;
  89
  90        if (!pdata)
  91                return -EBUSY;
  92        if (!pdata->irq_flags) {
  93                dev_err(&pdev->dev, "IRQ flag is not specified.\n");
  94                return -EINVAL;
  95        }
  96
  97        extcon_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_extcon_data),
  98                                   GFP_KERNEL);
  99        if (!extcon_data)
 100                return -ENOMEM;
 101
 102        extcon_data->edev = devm_extcon_dev_allocate(&pdev->dev, NULL);
 103        if (IS_ERR(extcon_data->edev)) {
 104                dev_err(&pdev->dev, "failed to allocate extcon device\n");
 105                return -ENOMEM;
 106        }
 107        extcon_data->edev->name = pdata->name;
 108
 109        extcon_data->gpio = pdata->gpio;
 110        extcon_data->gpio_active_low = pdata->gpio_active_low;
 111        extcon_data->state_on = pdata->state_on;
 112        extcon_data->state_off = pdata->state_off;
 113        extcon_data->check_on_resume = pdata->check_on_resume;
 114        if (pdata->state_on && pdata->state_off)
 115                extcon_data->edev->print_state = extcon_gpio_print_state;
 116
 117        ret = devm_gpio_request_one(&pdev->dev, extcon_data->gpio, GPIOF_DIR_IN,
 118                                    pdev->name);
 119        if (ret < 0)
 120                return ret;
 121
 122        if (pdata->debounce) {
 123                ret = gpio_set_debounce(extcon_data->gpio,
 124                                        pdata->debounce * 1000);
 125                if (ret < 0)
 126                        extcon_data->debounce_jiffies =
 127                                msecs_to_jiffies(pdata->debounce);
 128        }
 129
 130        ret = devm_extcon_dev_register(&pdev->dev, extcon_data->edev);
 131        if (ret < 0)
 132                return ret;
 133
 134        INIT_DELAYED_WORK(&extcon_data->work, gpio_extcon_work);
 135
 136        extcon_data->irq = gpio_to_irq(extcon_data->gpio);
 137        if (extcon_data->irq < 0)
 138                return extcon_data->irq;
 139
 140        ret = request_any_context_irq(extcon_data->irq, gpio_irq_handler,
 141                                      pdata->irq_flags, pdev->name,
 142                                      extcon_data);
 143        if (ret < 0)
 144                return ret;
 145
 146        platform_set_drvdata(pdev, extcon_data);
 147        /* Perform initial detection */
 148        gpio_extcon_work(&extcon_data->work.work);
 149
 150        return 0;
 151}
 152
 153static int gpio_extcon_remove(struct platform_device *pdev)
 154{
 155        struct gpio_extcon_data *extcon_data = platform_get_drvdata(pdev);
 156
 157        cancel_delayed_work_sync(&extcon_data->work);
 158        free_irq(extcon_data->irq, extcon_data);
 159
 160        return 0;
 161}
 162
 163#ifdef CONFIG_PM_SLEEP
 164static int gpio_extcon_resume(struct device *dev)
 165{
 166        struct gpio_extcon_data *extcon_data;
 167
 168        extcon_data = dev_get_drvdata(dev);
 169        if (extcon_data->check_on_resume)
 170                queue_delayed_work(system_power_efficient_wq,
 171                        &extcon_data->work, extcon_data->debounce_jiffies);
 172
 173        return 0;
 174}
 175#endif
 176
 177static SIMPLE_DEV_PM_OPS(gpio_extcon_pm_ops, NULL, gpio_extcon_resume);
 178
 179static struct platform_driver gpio_extcon_driver = {
 180        .probe          = gpio_extcon_probe,
 181        .remove         = gpio_extcon_remove,
 182        .driver         = {
 183                .name   = "extcon-gpio",
 184                .pm     = &gpio_extcon_pm_ops,
 185        },
 186};
 187
 188module_platform_driver(gpio_extcon_driver);
 189
 190MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 191MODULE_DESCRIPTION("GPIO extcon driver");
 192MODULE_LICENSE("GPL");
 193
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