某主板按鍵dts配置如下
gpio_keys {
compatible = "gpio-keys";
input-name = "gpio-keys";
status = "okay";
key_power {
label = "Power Key";
linux,code = <116>;
gpios = <&pmic_eic 1 1>;
debounce-interval = <5>;
gpio-key,wakeup;
gpio-key,level-trigger;
};
key_0 {
label = "0 Key";
linux,code = <11>;
debounce-interval = <5>;
gpios = <&ap_gpio 145 1>;
};
};
使用的Kernel4.4下自帶的按鍵驅動drivers/input/keyboard/gpio_keys.c
/*
* Driver for keys on GPIO lines capable of generating interrupts.
*
* Copyright 2005 Phil Blundell
* Copyright 2010, 2011 David Jander <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/sched.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/gpio_keys.h>
#include <linux/workqueue.h>
#include <linux/gpio.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/spinlock.h>
struct gpio_button_data {
const struct gpio_keys_button *button;
struct input_dev *input;
struct timer_list release_timer;
unsigned int release_delay; /* in msecs, for IRQ-only buttons */
struct delayed_work work;
unsigned int software_debounce; /* in msecs, for GPIO-driven buttons */
unsigned int irq;
spinlock_t lock;
bool disabled;
bool key_pressed;
};
struct gpio_keys_drvdata {
const struct gpio_keys_platform_data *pdata;
struct input_dev *input;
struct mutex disable_lock;
struct gpio_button_data data[0];
};
/*
* SYSFS interface for enabling/disabling keys and switches:
*
* There are 4 attributes under /sys/devices/platform/gpio-keys/
* keys [ro] - bitmap of keys (EV_KEY) which can be
* disabled
* switches [ro] - bitmap of switches (EV_SW) which can be
* disabled
* disabled_keys [rw] - bitmap of keys currently disabled
* disabled_switches [rw] - bitmap of switches currently disabled
*
* Userland can change these values and hence disable event generation
* for each key (or switch). Disabling a key means its interrupt line
* is disabled.
*
* For example, if we have following switches set up as gpio-keys:
* SW_DOCK = 5
* SW_CAMERA_LENS_COVER = 9
* SW_KEYPAD_SLIDE = 10
* SW_FRONT_PROXIMITY = 11
* This is read from switches:
* 11-9,5
* Next we want to disable proximity (11) and dock (5), we write:
* 11,5
* to file disabled_switches. Now proximity and dock IRQs are disabled.
* This can be verified by reading the file disabled_switches:
* 11,5
* If we now want to enable proximity (11) switch we write:
* 5
* to disabled_switches.
*
* We can disable only those keys which don't allow sharing the irq.
*/
/**
* get_n_events_by_type() - returns maximum number of events per @type
* @type: type of button (%EV_KEY, %EV_SW)
*
* Return value of this function can be used to allocate bitmap
* large enough to hold all bits for given type.
*/
static inline int get_n_events_by_type(int type)
{
BUG_ON(type != EV_SW && type != EV_KEY);
return (type == EV_KEY) ? KEY_CNT : SW_CNT;
}
/**
* gpio_keys_disable_button() - disables given GPIO button
* @bdata: button data for button to be disabled
*
* Disables button pointed by @bdata. This is done by masking
* IRQ line. After this function is called, button won't generate
* input events anymore. Note that one can only disable buttons
* that don't share IRQs.
*
* Make sure that @bdata->disable_lock is locked when entering
* this function to avoid races when concurrent threads are
* disabling buttons at the same time.
*/
static void gpio_keys_disable_button(struct gpio_button_data *bdata)
{
if (!bdata->disabled) {
/*
* Disable IRQ and associated timer/work structure.
*/
disable_irq(bdata->irq);
if (gpio_is_valid(bdata->button->gpio))
cancel_delayed_work_sync(&bdata->work);
else
del_timer_sync(&bdata->release_timer);
bdata->disabled = true;
}
}
/**
* gpio_keys_enable_button() - enables given GPIO button
* @bdata: button data for button to be disabled
*
* Enables given button pointed by @bdata.
*
* Make sure that @bdata->disable_lock is locked when entering
* this function to avoid races with concurrent threads trying
* to enable the same button at the same time.
*/
static void gpio_keys_enable_button(struct gpio_button_data *bdata)
{
if (bdata->disabled) {
enable_irq(bdata->irq);
bdata->disabled = false;
}
}
/**
* gpio_keys_attr_show_helper() - fill in stringified bitmap of buttons
* @ddata: pointer to drvdata
* @buf: buffer where stringified bitmap is written
* @type: button type (%EV_KEY, %EV_SW)
* @only_disabled: does caller want only those buttons that are
* currently disabled or all buttons that can be
* disabled
*
* This function writes buttons that can be disabled to @buf. If
* @only_disabled is true, then @buf contains only those buttons
* that are currently disabled. Returns 0 on success or negative
* errno on failure.
*/
static ssize_t gpio_keys_attr_show_helper(struct gpio_keys_drvdata *ddata,
char *buf, unsigned int type,
bool only_disabled)
{
int n_events = get_n_events_by_type(type);
unsigned long *bits;
ssize_t ret;
int i;
bits = kcalloc(BITS_TO_LONGS(n_events), sizeof(*bits), GFP_KERNEL);
if (!bits)
return -ENOMEM;
for (i = 0; i < ddata->pdata->nbuttons; i++) {
struct gpio_button_data *bdata = &ddata->data[i];
if (bdata->button->type != type)
continue;
if (only_disabled && !bdata->disabled)
continue;
__set_bit(bdata->button->code, bits);
}
ret = scnprintf(buf, PAGE_SIZE - 1, "%*pbl", n_events, bits);
buf[ret++] = '\n';
buf[ret] = '\0';
kfree(bits);
return ret;
}
/**
* gpio_keys_attr_store_helper() - enable/disable buttons based on given bitmap
* @ddata: pointer to drvdata
* @buf: buffer from userspace that contains stringified bitmap
* @type: button type (%EV_KEY, %EV_SW)
*
* This function parses stringified bitmap from @buf and disables/enables
* GPIO buttons accordingly. Returns 0 on success and negative error
* on failure.
*/
static ssize_t gpio_keys_attr_store_helper(struct gpio_keys_drvdata *ddata,
const char *buf, unsigned int type)
{
int n_events = get_n_events_by_type(type);
unsigned long *bits;
ssize_t error;
int i;
bits = kcalloc(BITS_TO_LONGS(n_events), sizeof(*bits), GFP_KERNEL);
if (!bits)
return -ENOMEM;
error = bitmap_parselist(buf, bits, n_events);
if (error)
goto out;
/* First validate */
for (i = 0; i < ddata->pdata->nbuttons; i++) {
struct gpio_button_data *bdata = &ddata->data[i];
if (bdata->button->type != type)
continue;
if (test_bit(bdata->button->code, bits) &&
!bdata->button->can_disable) {
error = -EINVAL;
goto out;
}
}
if (i == ddata->pdata->nbuttons) {
error = -EINVAL;
goto out;
}
mutex_lock(&ddata->disable_lock);
for (i = 0; i < ddata->pdata->nbuttons; i++) {
struct gpio_button_data *bdata = &ddata->data[i];
if (bdata->button->type != type)
continue;
if (test_bit(bdata->button->code, bits))
gpio_keys_disable_button(bdata);
else
gpio_keys_enable_button(bdata);
}
mutex_unlock(&ddata->disable_lock);
out:
kfree(bits);
return error;
}
#define ATTR_SHOW_FN(name, type, only_disabled) \
static ssize_t gpio_keys_show_##name(struct device *dev, \
struct device_attribute *attr, \
char *buf) \
{ \
struct platform_device *pdev = to_platform_device(dev); \
struct gpio_keys_drvdata *ddata = platform_get_drvdata(pdev); \
\
return gpio_keys_attr_show_helper(ddata, buf, \
type, only_disabled); \
}
ATTR_SHOW_FN(keys, EV_KEY, false);
ATTR_SHOW_FN(switches, EV_SW, false);
ATTR_SHOW_FN(disabled_keys, EV_KEY, true);
ATTR_SHOW_FN(disabled_switches, EV_SW, true);
/*
* ATTRIBUTES:
*
* /sys/devices/platform/gpio-keys/keys [ro]
* /sys/devices/platform/gpio-keys/switches [ro]
*/
static DEVICE_ATTR(keys, S_IRUGO, gpio_keys_show_keys, NULL);
static DEVICE_ATTR(switches, S_IRUGO, gpio_keys_show_switches, NULL);
#define ATTR_STORE_FN(name, type) \
static ssize_t gpio_keys_store_##name(struct device *dev, \
struct device_attribute *attr, \
const char *buf, \
size_t count) \
{ \
struct platform_device *pdev = to_platform_device(dev); \
struct gpio_keys_drvdata *ddata = platform_get_drvdata(pdev); \
ssize_t error; \
\
error = gpio_keys_attr_store_helper(ddata, buf, type); \
if (error) \
return error; \
\
return count; \
}
ATTR_STORE_FN(disabled_keys, EV_KEY);
ATTR_STORE_FN(disabled_switches, EV_SW);
/*
* ATTRIBUTES:
*
* /sys/devices/platform/gpio-keys/disabled_keys [rw]
* /sys/devices/platform/gpio-keys/disables_switches [rw]
*/
static DEVICE_ATTR(disabled_keys, S_IWUSR | S_IRUGO,
gpio_keys_show_disabled_keys,
gpio_keys_store_disabled_keys);
static DEVICE_ATTR(disabled_switches, S_IWUSR | S_IRUGO,
gpio_keys_show_disabled_switches,
gpio_keys_store_disabled_switches);
static struct attribute *gpio_keys_attrs[] = {
&dev_attr_keys.attr,
&dev_attr_switches.attr,
&dev_attr_disabled_keys.attr,
&dev_attr_disabled_switches.attr,
NULL,
};
static struct attribute_group gpio_keys_attr_group = {
.attrs = gpio_keys_attrs,
};
static void gpio_keys_gpio_report_event(struct gpio_button_data *bdata)
{
const struct gpio_keys_button *button = bdata->button;
struct input_dev *input = bdata->input;
unsigned int type = button->type ?: EV_KEY;
int state = gpio_get_value_cansleep(button->gpio);
if (state < 0) {
dev_err(input->dev.parent, "failed to get gpio state\n");
return;
}
state = (state ? 1 : 0) ^ button->active_low;
if (type == EV_ABS) {
if (state)
input_event(input, type, button->code, button->value);
} else {
input_event(input, type, button->code, !!state);
}
input_sync(input);
}
static void gpio_keys_gpio_work_func(struct work_struct *work)
{
struct gpio_button_data *bdata =
container_of(work, struct gpio_button_data, work.work);
gpio_keys_gpio_report_event(bdata);
if (bdata->button->wakeup)
pm_relax(bdata->input->dev.parent);
}
static irqreturn_t gpio_keys_gpio_isr(int irq, void *dev_id)
{
struct gpio_button_data *bdata = dev_id;
BUG_ON(irq != bdata->irq);
if (bdata->button->wakeup)
pm_stay_awake(bdata->input->dev.parent);
mod_delayed_work(system_wq,
&bdata->work,
msecs_to_jiffies(bdata->software_debounce));
return IRQ_HANDLED;
}
static void gpio_keys_irq_timer(unsigned long _data)
{
struct gpio_button_data *bdata = (struct gpio_button_data *)_data;
struct input_dev *input = bdata->input;
unsigned long flags;
spin_lock_irqsave(&bdata->lock, flags);
if (bdata->key_pressed) {
input_event(input, EV_KEY, bdata->button->code, 0);
input_sync(input);
bdata->key_pressed = false;
}
spin_unlock_irqrestore(&bdata->lock, flags);
}
static irqreturn_t gpio_keys_irq_isr(int irq, void *dev_id)
{
struct gpio_button_data *bdata = dev_id;
const struct gpio_keys_button *button = bdata->button;
struct input_dev *input = bdata->input;
unsigned long flags;
BUG_ON(irq != bdata->irq);
spin_lock_irqsave(&bdata->lock, flags);
if (!bdata->key_pressed) {
if (bdata->button->wakeup)
pm_wakeup_event(bdata->input->dev.parent, 0);
input_event(input, EV_KEY, button->code, 1);
input_sync(input);
if (!bdata->release_delay) {
input_event(input, EV_KEY, button->code, 0);
input_sync(input);
goto out;
}
bdata->key_pressed = true;
}
if (bdata->release_delay)
mod_timer(&bdata->release_timer,
jiffies + msecs_to_jiffies(bdata->release_delay));
out:
spin_unlock_irqrestore(&bdata->lock, flags);
return IRQ_HANDLED;
}
static void gpio_keys_quiesce_key(void *data)
{
struct gpio_button_data *bdata = data;
if (gpio_is_valid(bdata->button->gpio))
cancel_delayed_work_sync(&bdata->work);
else
del_timer_sync(&bdata->release_timer);
}
static int gpio_keys_setup_key(struct platform_device *pdev,
struct input_dev *input,
struct gpio_button_data *bdata,
const struct gpio_keys_button *button)
{
const char *desc = button->desc ? button->desc : "gpio_keys";
struct device *dev = &pdev->dev;
irq_handler_t isr;
unsigned long irqflags;
int irq;
int error;
bdata->input = input;
bdata->button = button;
spin_lock_init(&bdata->lock);
if (gpio_is_valid(button->gpio)) {
error = devm_gpio_request_one(&pdev->dev, button->gpio,
GPIOF_IN, desc);
if (error < 0) {
dev_err(dev, "Failed to request GPIO %d, error %d\n",
button->gpio, error);
return error;
}
if (button->debounce_interval) {
error = gpio_set_debounce(button->gpio,
button->debounce_interval * 1000);
/* use timer if gpiolib doesn't provide debounce */
if (error < 0)
bdata->software_debounce =
button->debounce_interval;
}
if (button->irq) {
bdata->irq = button->irq;
} else {
irq = gpio_to_irq(button->gpio);
if (irq < 0) {
error = irq;
dev_err(dev,
"Unable to get irq number for GPIO %d, error %d\n",
button->gpio, error);
return error;
}
bdata->irq = irq;
}
INIT_DELAYED_WORK(&bdata->work, gpio_keys_gpio_work_func);
isr = gpio_keys_gpio_isr;
irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;
} else {
if (!button->irq) {
dev_err(dev, "No IRQ specified\n");
return -EINVAL;
}
bdata->irq = button->irq;
if (button->type && button->type != EV_KEY) {
dev_err(dev, "Only EV_KEY allowed for IRQ buttons.\n");
return -EINVAL;
}
bdata->release_delay = button->debounce_interval;
setup_timer(&bdata->release_timer,
gpio_keys_irq_timer, (unsigned long)bdata);
isr = gpio_keys_irq_isr;
irqflags = 0;
}
input_set_capability(input, button->type ?: EV_KEY, button->code);
/*
* Install custom action to cancel release timer and
* workqueue item.
*/
error = devm_add_action(&pdev->dev, gpio_keys_quiesce_key, bdata);
if (error) {
dev_err(&pdev->dev,
"failed to register quiesce action, error: %d\n",
error);
return error;
}
/*
* If platform has specified that the button can be disabled,
* we don't want it to share the interrupt line.
*/
if (!button->can_disable)
irqflags |= IRQF_SHARED;
error = devm_request_any_context_irq(&pdev->dev, bdata->irq,
isr, irqflags, desc, bdata);
if (error < 0) {
dev_err(dev, "Unable to claim irq %d; error %d\n",
bdata->irq, error);
return error;
}
return 0;
}
static void gpio_keys_report_state(struct gpio_keys_drvdata *ddata)
{
struct input_dev *input = ddata->input;
int i;
for (i = 0; i < ddata->pdata->nbuttons; i++) {
struct gpio_button_data *bdata = &ddata->data[i];
if (gpio_is_valid(bdata->button->gpio))
gpio_keys_gpio_report_event(bdata);
}
input_sync(input);
}
static int gpio_keys_open(struct input_dev *input)
{
struct gpio_keys_drvdata *ddata = input_get_drvdata(input);
const struct gpio_keys_platform_data *pdata = ddata->pdata;
int error;
if (pdata->enable) {
error = pdata->enable(input->dev.parent);
if (error)
return error;
}
/* Report current state of buttons that are connected to GPIOs */
gpio_keys_report_state(ddata);
return 0;
}
static void gpio_keys_close(struct input_dev *input)
{
struct gpio_keys_drvdata *ddata = input_get_drvdata(input);
const struct gpio_keys_platform_data *pdata = ddata->pdata;
if (pdata->disable)
pdata->disable(input->dev.parent);
}
/*
* Handlers for alternative sources of platform_data
*/
#ifdef CONFIG_OF
/*
* Translate OpenFirmware node properties into platform_data
*/
static struct gpio_keys_platform_data *
gpio_keys_get_devtree_pdata(struct device *dev)
{
struct device_node *node, *pp;
struct gpio_keys_platform_data *pdata;
struct gpio_keys_button *button;
int error;
int nbuttons;
int i;
node = dev->of_node;
if (!node)
return ERR_PTR(-ENODEV);
nbuttons = of_get_child_count(node);
if (nbuttons == 0)
return ERR_PTR(-ENODEV);
pdata = devm_kzalloc(dev,
sizeof(*pdata) + nbuttons * sizeof(*button),
GFP_KERNEL);
if (!pdata)
return ERR_PTR(-ENOMEM);
pdata->buttons = (struct gpio_keys_button *)(pdata + 1);
pdata->nbuttons = nbuttons;
pdata->rep = !!of_get_property(node, "autorepeat", NULL);
i = 0;
for_each_child_of_node(node, pp) {
enum of_gpio_flags flags;
button = &pdata->buttons[i++];
button->gpio = of_get_gpio_flags(pp, 0, &flags);
if (button->gpio < 0) {
error = button->gpio;
if (error != -ENOENT) {
if (error != -EPROBE_DEFER)
dev_err(dev,
"Failed to get gpio flags, error: %d\n",
error);
return ERR_PTR(error);
}
} else {
button->active_low = flags & OF_GPIO_ACTIVE_LOW;
}
button->irq = irq_of_parse_and_map(pp, 0);
if (!gpio_is_valid(button->gpio) && !button->irq) {
dev_err(dev, "Found button without gpios or irqs\n");
return ERR_PTR(-EINVAL);
}
if (of_property_read_u32(pp, "linux,code", &button->code)) {
dev_err(dev, "Button without keycode: 0x%x\n",
button->gpio);
return ERR_PTR(-EINVAL);
}
button->desc = of_get_property(pp, "label", NULL);
if (of_property_read_u32(pp, "linux,input-type", &button->type))
button->type = EV_KEY;
button->wakeup = of_property_read_bool(pp, "wakeup-source") ||
/* legacy name */
of_property_read_bool(pp, "gpio-key,wakeup");
button->can_disable = !!of_get_property(pp, "linux,can-disable", NULL);
if (of_property_read_u32(pp, "debounce-interval",
&button->debounce_interval))
button->debounce_interval = 5;
}
if (pdata->nbuttons == 0)
return ERR_PTR(-EINVAL);
return pdata;
}
static const struct of_device_id gpio_keys_of_match[] = {
{ .compatible = "gpio-keys", },
{ },
};
MODULE_DEVICE_TABLE(of, gpio_keys_of_match);
#else
static inline struct gpio_keys_platform_data *
gpio_keys_get_devtree_pdata(struct device *dev)
{
return ERR_PTR(-ENODEV);
}
#endif
static int gpio_keys_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
const struct gpio_keys_platform_data *pdata = dev_get_platdata(dev);
struct gpio_keys_drvdata *ddata;
struct input_dev *input;
size_t size;
int i, error;
int wakeup = 0;
if (!pdata) {
pdata = gpio_keys_get_devtree_pdata(dev);
if (IS_ERR(pdata))
return PTR_ERR(pdata);
}
size = sizeof(struct gpio_keys_drvdata) +
pdata->nbuttons * sizeof(struct gpio_button_data);
ddata = devm_kzalloc(dev, size, GFP_KERNEL);
if (!ddata) {
dev_err(dev, "failed to allocate state\n");
return -ENOMEM;
}
input = devm_input_allocate_device(dev);
if (!input) {
dev_err(dev, "failed to allocate input device\n");
return -ENOMEM;
}
ddata->pdata = pdata;
ddata->input = input;
mutex_init(&ddata->disable_lock);
platform_set_drvdata(pdev, ddata);
input_set_drvdata(input, ddata);
input->name = pdata->name ? : pdev->name;
input->phys = "gpio-keys/input0";
input->dev.parent = &pdev->dev;
input->open = gpio_keys_open;
input->close = gpio_keys_close;
input->id.bustype = BUS_HOST;
input->id.vendor = 0x0001;
input->id.product = 0x0001;
input->id.version = 0x0100;
/* Enable auto repeat feature of Linux input subsystem */
if (pdata->rep)
__set_bit(EV_REP, input->evbit);
for (i = 0; i < pdata->nbuttons; i++) {
const struct gpio_keys_button *button = &pdata->buttons[i];
struct gpio_button_data *bdata = &ddata->data[i];
error = gpio_keys_setup_key(pdev, input, bdata, button);
if (error)
return error;
if (button->wakeup)
wakeup = 1;
}
error = sysfs_create_group(&pdev->dev.kobj, &gpio_keys_attr_group);
if (error) {
dev_err(dev, "Unable to export keys/switches, error: %d\n",
error);
return error;
}
error = input_register_device(input);
if (error) {
dev_err(dev, "Unable to register input device, error: %d\n",
error);
goto err_remove_group;
}
device_init_wakeup(&pdev->dev, wakeup);
return 0;
err_remove_group:
sysfs_remove_group(&pdev->dev.kobj, &gpio_keys_attr_group);
return error;
}
static int gpio_keys_remove(struct platform_device *pdev)
{
sysfs_remove_group(&pdev->dev.kobj, &gpio_keys_attr_group);
device_init_wakeup(&pdev->dev, 0);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int gpio_keys_suspend(struct device *dev)
{
struct gpio_keys_drvdata *ddata = dev_get_drvdata(dev);
struct input_dev *input = ddata->input;
int i;
if (device_may_wakeup(dev)) {
for (i = 0; i < ddata->pdata->nbuttons; i++) {
struct gpio_button_data *bdata = &ddata->data[i];
if (bdata->button->wakeup)
enable_irq_wake(bdata->irq);
}
} else {
mutex_lock(&input->mutex);
if (input->users)
gpio_keys_close(input);
mutex_unlock(&input->mutex);
}
return 0;
}
static int gpio_keys_resume(struct device *dev)
{
struct gpio_keys_drvdata *ddata = dev_get_drvdata(dev);
struct input_dev *input = ddata->input;
int error = 0;
int i;
if (device_may_wakeup(dev)) {
for (i = 0; i < ddata->pdata->nbuttons; i++) {
struct gpio_button_data *bdata = &ddata->data[i];
if (bdata->button->wakeup)
disable_irq_wake(bdata->irq);
}
} else {
mutex_lock(&input->mutex);
if (input->users)
error = gpio_keys_open(input);
mutex_unlock(&input->mutex);
}
if (error)
return error;
gpio_keys_report_state(ddata);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(gpio_keys_pm_ops, gpio_keys_suspend, gpio_keys_resume);
static struct platform_driver gpio_keys_device_driver = {
.probe = gpio_keys_probe,
.remove = gpio_keys_remove,
.driver = {
.name = "gpio-keys",
.pm = &gpio_keys_pm_ops,
.of_match_table = of_match_ptr(gpio_keys_of_match),
}
};
static int __init gpio_keys_init(void)
{
return platform_driver_register(&gpio_keys_device_driver);
}
static void __exit gpio_keys_exit(void)
{
platform_driver_unregister(&gpio_keys_device_driver);
}
late_initcall(gpio_keys_init);
module_exit(gpio_keys_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Phil Blundell <[email protected]>");
MODULE_DESCRIPTION("Keyboard driver for GPIOs");
MODULE_ALIAS("platform:gpio-keys");
並非這個驅動有多複雜，但涉及的知識點較多，如
1.platform設備模型(設備和驅動匹配)
2.dts的使用(api的使用)
3.中斷的使用(申請中斷 休眠不關中斷enable_irq_wake 中斷處理流程)
4.低精度定時器(如何創建定時器 什麼時候執行定時器 高精度定時器 時間子系統)
5.工作隊列(如何創建 執行過程)
6.sys調試系統(如何使用sys來調試驅動 查看設備和驅動信息)
7.按鍵去抖原理(硬件/軟件去抖)
8.input子系統(input子系統的工作流程)
9.gpio子系統(平臺相應的gpio子系統)
10.kernel休眠和喚醒流程(休眠鎖 什麼時候休眠 什麼時候喚醒 喚醒的原因)
每一塊都有相應的知識構架，等待你深挖。