I.MX6 gpio-keys driver hacking
2016-03-17 16:04
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/****************************************************************************
* I.MX6 gpio-keys driver hacking
* 说明：
* 1. 本文解读gpio-keys驱动是如何注册，最终处理函数在哪里。
* 2. 从最后生成的设备节点来看，我们直接可以通过操作该设备节点来来让系统
* 进行相关操作，譬如关机、挂起等操作。
*
* 2016-3-17 深圳 南山平山村 曾剑锋
***************************************************************************/
static struct platform_driver gpio_keys_device_driver = { <----+
.probe = gpio_keys_probe, ---------*-------+
.remove = __devexit_p(gpio_keys_remove), | |
.driver = { | |
.name = "gpio-keys", | |
.owner = THIS_MODULE, | |
#ifdef CONFIG_PM | |
.pm = &gpio_keys_pm_ops, | |
#endif | |
} | |
}; | |
| |
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); | |
} | |
| |
module_init(gpio_keys_init); -------------+ |
module_exit(gpio_keys_exit); |
|
MODULE_LICENSE("GPL"); |
MODULE_AUTHOR("Phil Blundell <pb@handhelds.org>"); |
MODULE_DESCRIPTION("Keyboard driver for CPU GPIOs"); |
MODULE_ALIAS("platform:gpio-keys"); |
|
static int __devinit gpio_keys_probe(struct platform_device *pdev) <-----+
{
struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
struct gpio_keys_drvdata *ddata;
struct device *dev = &pdev->dev;
struct input_dev *input;
int i, error;
int wakeup = 0;
ddata = kzalloc(sizeof(struct gpio_keys_drvdata) +
pdata->nbuttons * sizeof(struct gpio_button_data),
GFP_KERNEL);
input = input_allocate_device();
if (!ddata || !input) {
dev_err(dev, "failed to allocate state\n");
error = -ENOMEM;
goto fail1;
}
ddata->input = input;
ddata->n_buttons = pdata->nbuttons;
ddata->enable = pdata->enable;
ddata->disable = pdata->disable;
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++) {
struct gpio_keys_button *button = &pdata->buttons[i];
struct gpio_button_data *bdata = &ddata->data[i];
unsigned int type = button->type ?: EV_KEY;
bdata->input = input;
bdata->button = button;
error = gpio_keys_setup_key(pdev, bdata, button); -------+
if (error) |
goto fail2; |
|
if (button->wakeup) |
wakeup = 1; |
|
input_set_capability(input, type, button->code); |
} |
|
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); |
goto fail2; |
} |
|
error = input_register_device(input); |
if (error) { |
dev_err(dev, "Unable to register input device, error: %d\n", |
error); |
goto fail3; |
} |
|
/* get current state of buttons */ |
for (i = 0; i < pdata->nbuttons; i++) |
gpio_keys_report_event(&ddata->data[i]); |
input_sync(input); |
|
device_init_wakeup(&pdev->dev, wakeup); |
|
return 0; |
|
fail3: |
sysfs_remove_group(&pdev->dev.kobj, &gpio_keys_attr_group); |
fail2: |
while (--i >= 0) { |
free_irq(gpio_to_irq(pdata->buttons[i].gpio), &ddata->data[i]); |
if (ddata->data[i].timer_debounce) |
del_timer_sync(&ddata->data[i].timer); |
cancel_work_sync(&ddata->data[i].work); |
gpio_free(pdata->buttons[i].gpio); |
} |
|
platform_set_drvdata(pdev, NULL); |
fail1: |
input_free_device(input); |
kfree(ddata); |
+---------------------------------------+
return error; |
} |
V
static int __devinit gpio_keys_setup_key(struct platform_device *pdev,
struct gpio_button_data *bdata,
struct gpio_keys_button *button)
{
const char *desc = button->desc ? button->desc : "gpio_keys";
struct device *dev = &pdev->dev;
unsigned long irqflags;
int irq, error;
setup_timer(&bdata->timer, gpio_keys_timer, (unsigned long)bdata);
INIT_WORK(&bdata->work, gpio_keys_work_func); --------------------+
|
error = gpio_request(button->gpio, desc); |
if (error < 0) { |
dev_err(dev, "failed to request GPIO %d, error %d\n", |
button->gpio, error); |
goto fail2; |
} |
|
error = gpio_direction_input(button->gpio); |
if (error < 0) { |
dev_err(dev, "failed to configure" |
" direction for GPIO %d, error %d\n", |
button->gpio, error); |
goto fail3; |
} |
|
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->timer_debounce = button->debounce_interval; |
} |
|
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); |
goto fail3; |
} |
|
irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING; |
/* |
* 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; |
/* |
* Resume power key early during syscore instead of at device |
* resume time. |
* Some platform like Android need to konw the power key is pressed |
* then to reume the other devcies |
*/ |
if (button->wakeup) |
irqflags |= IRQF_NO_SUSPEND | IRQF_EARLY_RESUME; |
|
error = request_any_context_irq(irq, gpio_keys_isr, irqflags, desc, bdata); |
if (error < 0) { |
dev_err(dev, "Unable to claim irq %d; error %d\n", |
irq, error); |
goto fail3; |
} |
|
return 0; |
|
fail3: |
gpio_free(button->gpio); |
fail2: |
return error; |
} |
|
static void gpio_keys_work_func(struct work_struct *work) <-------------+
{
struct gpio_button_data *bdata =
container_of(work, struct gpio_button_data, work);
gpio_keys_report_event(bdata); -----------+
} |
|
static void gpio_keys_report_event(struct gpio_button_data *bdata) <---------+
{
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) ? 1 : 0) ^ button->active_low;
printk("zengjf check gpio-keys positon: %s in line %d.\n", __func__, _LINE__);
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);
}
/**
* root@android:/ # cat /proc/bus/input/devices
* I: Bus=0019 Vendor=0001 Product=0001 Version=0100
* N: Name="gpio-keys"
* P: Phys=gpio-keys/input0
* S: Sysfs=/devices/platform/gpio-keys/input/input0
* U: Uniq=
* H: Handlers=event0
* B: PROP=0
* B: EV=3
* B: KEY=100000 0 0 0
* ......
*/
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