drivers/extcon/extcon-gpio.c

   1 /*
   2  * extcon_gpio.c - Single-state GPIO extcon driver based on extcon class
   3  *
   4  * Copyright (C) 2008 Google, Inc.
   5  * Author: Mike Lockwood <lockwood@android.com>
   6  *
   7  * Modified by MyungJoo Ham <myungjoo.ham@samsung.com> to support extcon
   8  * (originally switch class is supported)
   9  *
  10  * This software is licensed under the terms of the GNU General Public
  11  * License version 2, as published by the Free Software Foundation, and
  12  * may be copied, distributed, and modified under those terms.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  */
  19
  20 #include <linux/extcon-provider.h>
  21 #include <linux/gpio/consumer.h>
  22 #include <linux/init.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/slab.h>
  28 #include <linux/workqueue.h>
  29
  30 /**
  31  * struct gpio_extcon_data - A simple GPIO-controlled extcon device state container.
  32  * @edev:               Extcon device.
  33  * @irq:                Interrupt line for the external connector.
  34  * @work:               Work fired by the interrupt.
  35  * @debounce_jiffies:   Number of jiffies to wait for the GPIO to stabilize, from the debounce
  36  *                      value.
  37  * @gpiod:              GPIO descriptor for this external connector.
  38  * @extcon_id:          The unique id of specific external connector.
  39  * @debounce:           Debounce time for GPIO IRQ in ms.
  40  * @irq_flags:          IRQ Flags (e.g., IRQF_TRIGGER_LOW).
  41  * @check_on_resume:    Boolean describing whether to check the state of gpio
  42  *                      while resuming from sleep.
  43  */
  44 struct gpio_extcon_data {
  45         struct extcon_dev *edev;
  46         int irq;
  47         struct delayed_work work;
  48         unsigned long debounce_jiffies;
  49         struct gpio_desc *gpiod;
  50         unsigned int extcon_id;
  51         unsigned long debounce;
  52         unsigned long irq_flags;
  53         bool check_on_resume;
  54 };
  55
  56 static void gpio_extcon_work(struct work_struct *work)
  57 {
  58         int state;
  59         struct gpio_extcon_data *data =
  60                 container_of(to_delayed_work(work), struct gpio_extcon_data,
  61                              work);
  62
  63         state = gpiod_get_value_cansleep(data->gpiod);
  64         extcon_set_state_sync(data->edev, data->extcon_id, state);
  65 }
  66
  67 static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
  68 {
  69         struct gpio_extcon_data *data = dev_id;
  70
  71         queue_delayed_work(system_power_efficient_wq, &data->work,
  72                               data->debounce_jiffies);
  73         return IRQ_HANDLED;
  74 }
  75
  76 static int gpio_extcon_probe(struct platform_device *pdev)
  77 {
  78         struct gpio_extcon_data *data;
  79         struct device *dev = &pdev->dev;
  80         int ret;
  81
  82         data = devm_kzalloc(dev, sizeof(struct gpio_extcon_data), GFP_KERNEL);
  83         if (!data)
  84                 return -ENOMEM;
  85
  86         /*
  87          * FIXME: extcon_id represents the unique identifier of external
  88          * connectors such as EXTCON_USB, EXTCON_DISP_HDMI and so on. extcon_id
  89          * is necessary to register the extcon device. But, it's not yet
  90          * developed to get the extcon id from device-tree or others.
  91          * On later, it have to be solved.
  92          */
  93         if (!data->irq_flags || data->extcon_id > EXTCON_NONE)
  94                 return -EINVAL;
  95
  96         data->gpiod = devm_gpiod_get(dev, "extcon", GPIOD_IN);
  97         if (IS_ERR(data->gpiod))
  98                 return PTR_ERR(data->gpiod);
  99         data->irq = gpiod_to_irq(data->gpiod);
 100         if (data->irq <= 0)
 101                 return data->irq;
 102
 103         /* Allocate the memory of extcon devie and register extcon device */
 104         data->edev = devm_extcon_dev_allocate(dev, &data->extcon_id);
 105         if (IS_ERR(data->edev)) {
 106                 dev_err(dev, "failed to allocate extcon device\n");
 107                 return -ENOMEM;
 108         }
 109
 110         ret = devm_extcon_dev_register(dev, data->edev);
 111         if (ret < 0)
 112                 return ret;
 113
 114         INIT_DELAYED_WORK(&data->work, gpio_extcon_work);
 115
 116         /*
 117          * Request the interrupt of gpio to detect whether external connector
 118          * is attached or detached.
 119          */
 120         ret = devm_request_any_context_irq(dev, data->irq,
 121                                         gpio_irq_handler, data->irq_flags,
 122                                         pdev->name, data);
 123         if (ret < 0)
 124                 return ret;
 125
 126         platform_set_drvdata(pdev, data);
 127         /* Perform initial detection */
 128         gpio_extcon_work(&data->work.work);
 129
 130         return 0;
 131 }
 132
 133 static int gpio_extcon_remove(struct platform_device *pdev)
 134 {
 135         struct gpio_extcon_data *data = platform_get_drvdata(pdev);
 136
 137         cancel_delayed_work_sync(&data->work);
 138
 139         return 0;
 140 }
 141
 142 #ifdef CONFIG_PM_SLEEP
 143 static int gpio_extcon_resume(struct device *dev)
 144 {
 145         struct gpio_extcon_data *data;
 146
 147         data = dev_get_drvdata(dev);
 148         if (data->check_on_resume)
 149                 queue_delayed_work(system_power_efficient_wq,
 150                         &data->work, data->debounce_jiffies);
 151
 152         return 0;
 153 }
 154 #endif
 155
 156 static SIMPLE_DEV_PM_OPS(gpio_extcon_pm_ops, NULL, gpio_extcon_resume);
 157
 158 static struct platform_driver gpio_extcon_driver = {
 159         .probe          = gpio_extcon_probe,
 160         .remove         = gpio_extcon_remove,
 161         .driver         = {
 162                 .name   = "extcon-gpio",
 163                 .pm     = &gpio_extcon_pm_ops,
 164         },
 165 };
 166
 167 module_platform_driver(gpio_extcon_driver);
 168
 169 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 170 MODULE_DESCRIPTION("GPIO extcon driver");
 171 MODULE_LICENSE("GPL");