gpio键盘的原理1

#define GPIO_EVENT_DEV_NAME "gpio-event"

1，定义

static struct gpio_keys_button gpio_keys_buttons[] = {
 {
  .code           = SW_LID,
  .gpio           = LID_SENSOR_GPIO,
  .desc           = "Lid",
  .active_low     = 1,
  .type  = EV_SW,
  .wakeup  = 1
 },
};

static struct gpio_keys_platform_data gpio_keys_data = {
 .buttons        = gpio_keys_buttons,
 .nbuttons       = ARRAY_SIZE(gpio_keys_buttons),
 .rep  = 0,
};

static struct platform_device msm_gpio_keys = {
 .name           = "gpio-keys",
 .id             = -1,
 .dev            = {
  .platform_data  = &gpio_keys_data,
 },
};

2，

/* drivers/input/misc/gpio_event.c
 *
 * Copyright (C) 2007 Google, Inc.
 *
 * 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
#include
#include
#include
#include
#include

struct gpio_event {
 struct gpio_event_input_devs *input_devs;
 const struct gpio_event_platform_data *info;
 struct early_suspend early_suspend;
 void *state[0];
};

static int gpio_input_event(
 struct input_dev *dev, unsigned int type, unsigned int code, int value)
{
 int i;
 int devnr;
 int ret = 0;
 int tmp_ret;
 struct gpio_event_info **ii;
 struct gpio_event *ip = input_get_drvdata(dev);

 for (devnr = 0; devnr < ip->input_devs->count; devnr++)
  if (ip->input_devs->dev[devnr] == dev)
   break;
 if (devnr == ip->input_devs->count) {
  pr_err("gpio_input_event: unknown device %p/n", dev);
  return -EIO;
 }

 for (i = 0, ii = ip->info->info; i < ip->info->info_count; i++, ii++) {
  if ((*ii)->event) {
   tmp_ret = (*ii)->event(ip->input_devs, *ii,
      &ip->state[i],
      devnr, type, code, value);
   if (tmp_ret)
    ret = tmp_ret;
  }
 }
 return ret;
}

static int gpio_event_call_all_func(struct gpio_event *ip, int func)
{
 int i;
 int ret;
 struct gpio_event_info **ii;

 if (func == GPIO_EVENT_FUNC_INIT || func == GPIO_EVENT_FUNC_RESUME) {
  ii = ip->info->info;
  for (i = 0; i < ip->info->info_count; i++, ii++) {
   if ((*ii)->func == NULL) {
    ret = -ENODEV;
    pr_err("gpio_event_probe: Incomplete pdata, "
     "no function/n");
    goto err_no_func;
   }
   if (func == GPIO_EVENT_FUNC_RESUME && (*ii)->no_suspend)
    continue;
   ret = (*ii)->func(ip->input_devs, *ii, &ip->state[i],
       func);
   if (ret) {
    pr_err("gpio_event_probe: function failed/n");
    goto err_func_failed;
   }
  }
  return 0;
 }

 ret = 0;
 i = ip->info->info_count;
 ii = ip->info->info + i;
 while (i > 0) {
  i--;
  ii--;
  if ((func & ~1) == GPIO_EVENT_FUNC_SUSPEND && (*ii)->no_suspend)
   continue;
  (*ii)->func(ip->input_devs, *ii, &ip->state[i], func & ~1);
err_func_failed:
err_no_func:
  ;
 }
 return ret;
}

#ifdef CONFIG_HAS_EARLYSUSPEND
void gpio_event_suspend(struct early_suspend *h)
{
 struct gpio_event *ip;
 ip = container_of(h, struct gpio_event, early_suspend);
 gpio_event_call_all_func(ip, GPIO_EVENT_FUNC_SUSPEND);
 ip->info->power(ip->info, 0);
}

void gpio_event_resume(struct early_suspend *h)
{
 struct gpio_event *ip;
 ip = container_of(h, struct gpio_event, early_suspend);
 ip->info->power(ip->info, 1);
 gpio_event_call_all_func(ip, GPIO_EVENT_FUNC_RESUME);
}
#endif

static int __init gpio_event_probe(struct platform_device *pdev)
{
 int err;
 struct gpio_event *ip;
 struct gpio_event_platform_data *event_info;
 int dev_count = 1;
 int i;
 int registered = 0;

 event_info = pdev->dev.platform_data;
 if (event_info == NULL) {
  pr_err("gpio_event_probe: No pdata/n");
  return -ENODEV;
 }
 if ((!event_info->name && !event_info->names[0]) ||
     !event_info->info || !event_info->info_count) {
  pr_err("gpio_event_probe: Incomplete pdata/n");
  return -ENODEV;
 }
 if (!event_info->name)
  while (event_info->names[dev_count])
   dev_count++;
 ip = kzalloc(sizeof(*ip) +
       sizeof(ip->state[0]) * event_info->info_count +
       sizeof(*ip->input_devs) +
       sizeof(ip->input_devs->dev[0]) * dev_count, GFP_KERNEL);
 if (ip == NULL) {
  err = -ENOMEM;
  pr_err("gpio_event_probe: Failed to allocate private data/n");
  goto err_kp_alloc_failed;
 }
 ip->input_devs = (void*)&ip->state[event_info->info_count];
 platform_set_drvdata(pdev, ip);

 for (i = 0; i < dev_count; i++) {
  struct input_dev *input_dev = input_allocate_device();
  if (input_dev == NULL) {
   err = -ENOMEM;
   pr_err("gpio_event_probe: "
    "Failed to allocate input device/n");
   goto err_input_dev_alloc_failed;
  }
  input_set_drvdata(input_dev, ip);
  input_dev->name = event_info->name ?
     event_info->name : event_info->names[i];
  input_dev->event = gpio_input_event;
  ip->input_devs->dev[i] = input_dev;
 }
 ip->input_devs->count = dev_count;
 ip->info = event_info;
 if (event_info->power) {
#ifdef CONFIG_HAS_EARLYSUSPEND
  ip->early_suspend.level = EARLY_SUSPEND_LEVEL_BLANK_SCREEN + 1;
  ip->early_suspend.suspend = gpio_event_suspend;
  ip->early_suspend.resume = gpio_event_resume;
  register_early_suspend(&ip->early_suspend);
#endif
  ip->info->power(ip->info, 1);
 }

 err = gpio_event_call_all_func(ip, GPIO_EVENT_FUNC_INIT);
 if (err)
  goto err_call_all_func_failed;

 for (i = 0; i < dev_count; i++) {
  err = input_register_device(ip->input_devs->dev[i]);
  if (err) {
   pr_err("gpio_event_probe: Unable to register %s "
    "input device/n", ip->input_devs->dev[i]->name);
   goto err_input_register_device_failed;
  }
  registered++;
 }

 return 0;

err_input_register_device_failed:
 gpio_event_call_all_func(ip, GPIO_EVENT_FUNC_UNINIT);
err_call_all_func_failed:
 if (event_info->power) {
#ifdef CONFIG_HAS_EARLYSUSPEND
  unregister_early_suspend(&ip->early_suspend);
#endif
  ip->info->power(ip->info, 0);
 }
 for (i = 0; i < registered; i++)
  input_unregister_device(ip->input_devs->dev[i]);
 for (i = dev_count - 1; i >= registered; i--) {
  input_free_device(ip->input_devs->dev[i]);
err_input_dev_alloc_failed:
  ;
 }
 kfree(ip);
err_kp_alloc_failed:
 return err;
}

static int gpio_event_remove(struct platform_device *pdev)
{
 struct gpio_event *ip = platform_get_drvdata(pdev);
 int i;

 gpio_event_call_all_func(ip, GPIO_EVENT_FUNC_UNINIT);
 if (ip->info->power) {
#ifdef CONFIG_HAS_EARLYSUSPEND
  unregister_early_suspend(&ip->early_suspend);
#endif
  ip->info->power(ip->info, 0);
 }
 for (i = 0; i < ip->input_devs->count; i++)
  input_unregister_device(ip->input_devs->dev[i]);
 kfree(ip);
 return 0;
}

static struct platform_driver gpio_event_driver = {
 .probe  = gpio_event_probe,
 .remove  = gpio_event_remove,
 .driver  = {
  .name = GPIO_EVENT_DEV_NAME,
 },
};

static int __devinit gpio_event_init(void)
{
 return platform_driver_register(&gpio_event_driver);
}

static void __exit gpio_event_exit(void)
{
 platform_driver_unregister(&gpio_event_driver);
}

module_init(gpio_event_init);
module_exit(gpio_event_exit);

MODULE_DESCRIPTION("GPIO Event Driver");
MODULE_LICENSE("GPL");

注册gpio键盘，设置gpio为输入状态，注册gpio的中断回调函数，设置gpio的唤醒功能