drivers/extcon/extcon-gpio.c

   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
  34 struct 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
  46 static 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
  59 static 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
  68 static 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
  84 static 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
 108         extcon_data->gpio = pdata->gpio;
 109         extcon_data->gpio_active_low = pdata->gpio_active_low;
 110         extcon_data->state_on = pdata->state_on;
 111         extcon_data->state_off = pdata->state_off;
 112         extcon_data->check_on_resume = pdata->check_on_resume;
 113         if (pdata->state_on && pdata->state_off)
 114                 extcon_data->edev->print_state = extcon_gpio_print_state;
 115
 116         ret = devm_gpio_request_one(&pdev->dev, extcon_data->gpio, GPIOF_DIR_IN,
 117                                     pdev->name);
 118         if (ret < 0)
 119                 return ret;
 120
 121         if (pdata->debounce) {
 122                 ret = gpio_set_debounce(extcon_data->gpio,
 123                                         pdata->debounce * 1000);
 124                 if (ret < 0)
 125                         extcon_data->debounce_jiffies =
 126                                 msecs_to_jiffies(pdata->debounce);
 127         }
 128
 129         ret = devm_extcon_dev_register(&pdev->dev, extcon_data->edev);
 130         if (ret < 0)
 131                 return ret;
 132
 133         INIT_DELAYED_WORK(&extcon_data->work, gpio_extcon_work);
 134
 135         extcon_data->irq = gpio_to_irq(extcon_data->gpio);
 136         if (extcon_data->irq < 0)
 137                 return extcon_data->irq;
 138
 139         ret = request_any_context_irq(extcon_data->irq, gpio_irq_handler,
 140                                       pdata->irq_flags, pdev->name,
 141                                       extcon_data);
 142         if (ret < 0)
 143                 return ret;
 144
 145         platform_set_drvdata(pdev, extcon_data);
 146         /* Perform initial detection */
 147         gpio_extcon_work(&extcon_data->work.work);
 148
 149         return 0;
 150 }
 151
 152 static int gpio_extcon_remove(struct platform_device *pdev)
 153 {
 154         struct gpio_extcon_data *extcon_data = platform_get_drvdata(pdev);
 155
 156         cancel_delayed_work_sync(&extcon_data->work);
 157         free_irq(extcon_data->irq, extcon_data);
 158
 159         return 0;
 160 }
 161
 162 #ifdef CONFIG_PM_SLEEP
 163 static int gpio_extcon_resume(struct device *dev)
 164 {
 165         struct gpio_extcon_data *extcon_data;
 166
 167         extcon_data = dev_get_drvdata(dev);
 168         if (extcon_data->check_on_resume)
 169                 queue_delayed_work(system_power_efficient_wq,
 170                         &extcon_data->work, extcon_data->debounce_jiffies);
 171
 172         return 0;
 173 }
 174 #endif
 175
 176 static SIMPLE_DEV_PM_OPS(gpio_extcon_pm_ops, NULL, gpio_extcon_resume);
 177
 178 static struct platform_driver gpio_extcon_driver = {
 179         .probe          = gpio_extcon_probe,
 180         .remove         = gpio_extcon_remove,
 181         .driver         = {
 182                 .name   = "extcon-gpio",
 183                 .pm     = &gpio_extcon_pm_ops,
 184         },
 185 };
 186
 187 module_platform_driver(gpio_extcon_driver);
 188
 189 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 190 MODULE_DESCRIPTION("GPIO extcon driver");
 191 MODULE_LICENSE("GPL");