#define DRV_AUTHOR
#define DRV_DESC "S3C24XX button driver"
/* Driver version*/
#define DRV_MAJOR_VER 1
#define DRV_MINOR_VER 0
#define DRV_REVER_VER 0
#define DEV_NAME DEV_BUTTON_NAME
//#define DEV_MAJOR DEV_BUTTON_MAJOR
#ifndef DEV_MAJOR
#define DEV_MAJOR 0 /* dynamic major by default */
#endif
#define BUTTON_UP 0 /* Button status is up */
#define BUTTON_DOWN 1 /* Button status is pushed down */
#define BUTTON_UNCERTAIN 2 /* Button status uncerntain */
#define TIMER_DELAY_DOWN (HZ/50) /*Remove button push down dithering timer delay 20ms */
#define TIMER_DELAY_UP (HZ/10) /*Remove button up dithering timer delay 100ms */
static int debug = DISABLE;
static int dev_major = DEV_MAJOR;
static int dev_minor = 0;
/*============================ Platform Device part ===============================*/
/* Button hardware informtation structure*/
struct s3c_button_info
{
unsigned char num; /*Button nubmer */
char * name; /*Button nubmer */
int nIRQ; /*Button IRQ number*/
unsigned int setting; /*Button IRQ Pin Setting*/
unsigned int gpio; /*Button GPIO port */
};
/* The button platform device private data structure */
struct s3c_button_platform_data
{
struct s3c_button_info *buttons;
int nbuttons;
};
/* Button hardware informtation data*/
static struct s3c_button_info s3c_buttons[] = {
[0] = {
.num = 1,
.name = "KEY1",
.nIRQ = IRQ_EINT0,
.gpio = S3C2410_GPF(0),
.setting = S3C2410_GPF0_EINT0,
},
[1] = {
.num = 2,
.name = "KEY2",
.nIRQ = IRQ_EINT2,
.gpio = S3C2410_GPF(2),
.setting = S3C2410_GPF2_EINT2,
},
[2] = {
.num = 3,
.name = "KEY3",
.nIRQ = IRQ_EINT3,
.gpio = S3C2410_GPF(3),
.setting = S3C2410_GPF3_EINT3,
},
[3] = {
.num = 4,
.name = "KEY4",
.nIRQ = IRQ_EINT4,
.gpio = S3C2410_GPF(4),
.setting = S3C2410_GPF4_EINT4,
},
};
/* The button platform device private data */
static struct s3c_button_platform_data s3c_button_data = {
.buttons = s3c_buttons,
.nbuttons = ARRAY_SIZE(s3c_buttons),
};
struct button_device
{
unsigned char *status; /* The buttons Push down or up status */
struct s3c_button_platform_data *data; /* The buttons hardware information data */
struct timer_list *timers; /* The buttons remove dithering timers */
//參考博客 http://blog.csdn.net/lanmanck/article/details/4528759
wait_queue_head_t waitq; /* Wait queue for poll() */
//參考博客http://blog.csdn.net/lanmanck/article/details/4770103
volatile int ev_press; /* Button pressed event */struct cdev cdev;
struct class *dev_class;
} button_device;
static void platform_button_release(struct device * dev)
{
return;
}
static struct platform_device s3c_button_device = {
.name = "s3c_button",
.id = 1,
.dev =
{
.platform_data = &s3c_button_data,
.release = platform_button_release,
},
};
static irqreturn_t s3c_button_intterupt(int irq,void *de_id)
{
關於中斷處理函數的返回值:中斷程序的返回值是一個特殊類型—irqreturn_t。但是中斷程序的返回值卻只有兩個—IRQ_NONE和IRQ_HANDLED。
#ifndef _LINUX_IRQRETURN_H
#define _LINUX_IRQRETURN_H
typedef int irqreturn_t;
#define IRQ_NONE (0)
#define IRQ_HANDLED (1)
#define IRQ_RETVAL(x) ((x) != 0) //這個宏只是返回0或非0
#endif
以上是在linux/irqreturn.h中的內容
int i;int found = 0;
struct s3c_button_platform_data *pdata = button_device.data;
for(i=0; i<pdata->nbuttons; i++)
{
if(irq == pdata->buttons[i].nIRQ)
{
found = 1;
break;
}
}
if(!found) /* An ERROR interrupt */
return IRQ_NONE;
/* Only when button is up then we will handle this event */
if(BUTTON_UP == button_device.status[i])
{
button_device.status[i] = BUTTON_UNCERTAIN;
mod_timer(&(button_device.timers[i]), jiffies+TIMER_DELAY_DOWN);
}
return IRQ_HANDLED;
}
static void button_timer_handler(unsigned long data)
{
struct s3c_button_platform_data *pdata = button_device.data;
int num =(int)data;
int status = s3c2410_gpio_getpin( pdata->buttons[num].gpio );
if(LOWLEVEL == status)
{
if(BUTTON_UNCERTAIN == button_device.status[num]) /* Come from interrupt */
{
//dbg_print("Key pressed!\n");
button_device.status[num] = BUTTON_DOWN;
printk("%s pressed.\n", pdata->buttons[num].name);
/* Wake up the wait queue for read()/poll() */
button_device.ev_press = 1;
wake_up_interruptible(&(button_device.waitq));//喚醒註冊到等待隊列上的進程
}
/* Cancel the dithering */
mod_timer(&(button_device.timers[num]), jiffies+TIMER_DELAY_UP);
}
else
{
//dbg_print("Key Released!\n");
button_device.status[num] = BUTTON_UP;
// enable_irq(pdata->buttons[num].nIRQ);
}
return ;
}
/*===================== Button device driver part ===========================*/
static int button_open(struct inode *inode, struct file *file)
{
struct button_device *pdev ;
struct s3c_button_platform_data *pdata;
int i, result;
pdev = container_of(inode->i_cdev,struct button_device, cdev);
//通過一個容器（結構體）中某個成員的指針得到指向這個容器（結構體）的指針，簡單的說就是通過成員找容器。
pdata = pdev->data;file->private_data = pdev;
/* Malloc for all the buttons remove dithering timer */
pdev->timers = (struct timer_list *) kmalloc(pdata->nbuttons*sizeof(struct timer_list), GFP_KERNEL);
/*
#define GFP_KERNEL (__GFP_WAIT | __GFP_IO | __GFP_FS) 在include/linux/gfp.h中定義的一個宏，是分配內核空間的一個標誌位。這個標誌位分配內存的一個選項，GFP_KERNEL是內核內存分配時最常
用的，無內存可用是則引起休眠。
*/
if(NULL == pdev->timers)
{
printk("Alloc %s driver for timers failure.\n", DEV_NAME);
return -ENOMEM;
}
memset(pdev->timers, 0, pdata->nbuttons*sizeof(struct timer_list));
/* Malloc for all the buttons status buffer */
pdev->status = (unsigned char *)kmalloc(pdata->nbuttons*sizeof(unsigned char), GFP_KERNEL);
if(NULL == pdev->status)
{
printk("Alloc %s driver for status failure.\n", DEV_NAME);
result = -ENOMEM;
goto ERROR;
}
memset(pdev->status, 0, pdata->nbuttons*sizeof(unsigned char));
init_waitqueue_head(&(pdev->waitq));
for(i=0; i<pdata->nbuttons; i++)
{
/* Initialize all the buttons status to UP */
pdev->status[i] = BUTTON_UP;
/* Initialize all the buttons' remove dithering timer */
setup_timer(&(pdev->timers[i]), button_timer_handler, i);
/* Set all the buttons GPIO to EDGE_FALLING interrupt mode */
s3c2410_gpio_cfgpin(pdata->buttons[i].gpio, pdata->buttons[i].setting);
irq_set_irq_type(pdata->buttons[i].nIRQ, IRQ_TYPE_EDGE_FALLING);
//設置觸發類型的中斷的引腳
/* Request for button GPIO pin interrupt */
result = request_irq(pdata->buttons[i].nIRQ, s3c_button_intterupt, IRQF_DISABLED, DEV_NAME, (void *)i);
/*在linux內核中用於申請中斷的函數是request_irq（），函數原型在Kernel/irq/manage.c中定義：
int request_irq(unsigned int irq, irq_handler_t handler,
unsigned long irqflags, const char *devname, void *dev_id)
irq是要申請的硬件中斷號。
handler是向系統註冊的中斷處理函數，是一個回調函數，中斷髮生時，系統調用這個函數，dev_id參數將被傳遞給它。
irqflags是中斷處理的屬性，若設置了IRQF_DISABLED （老版本中的SA_INTERRUPT，本版zhon已經不支持了），則表示中斷處理程序是快速處理程序，快速處理程序被調用時屏蔽所有中斷，慢速處理程序不屏蔽；若設置了IRQF_SHARED （老版本中的SA_SHIRQ），則表示多個設備共享中斷，若設置了IRQF_SAMPLE_RANDOM（老版本中的SA_SAMPLE_RANDOM），表示對系統熵有貢獻，對系統獲取隨機數有好處。（這幾個flag是可以通過或的方式同時使用的）
devname設置中斷名稱，通常是設備驅動程序的名稱 在cat /proc/interrupts中可以看到此名稱。dev_id在中斷共享時會用到，一般設置爲這個設備的設備結構體或者NULL。
request_irq()返回0表示成功，返回-INVAL表示中斷號無效或處理函數指針爲NULL，返回-EBUSY表示中斷已經被佔用且不能共享。*/
if( result )
{
result = -EBUSY;
goto ERROR1;
}
}
return 0;
ERROR1:
kfree((unsigned char *)pdev->status);
while(--i)
{
disable_irq(pdata->buttons[i].nIRQ);
free_irq(pdata->buttons[i].nIRQ, (void *)i);
}
ERROR:
kfree(pdev->timers);
return result;
}
static int button_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
struct button_device *pdev = file->private_data;
struct s3c_button_platform_data *pdata;
int i, ret;
unsigned int status = 0;
pdata = pdev->data;
dbg_print("ev_press: %d\n", pdev->ev_press);
if(!pdev->ev_press)
{
if(file->f_flags & O_NONBLOCK)
//使I/O變成非擱置模式，在讀取不到數據或是寫入緩衝區已滿馬上return，而不會擱置程序動作，知道有數據或寫入完成。
{
dbg_print("read() without block mode.\n");
return -EAGAIN;
/* 從字面上看，是提示再試一次的意思。這個錯誤經常出現在當應用程序進行一些非阻塞(non-blocking)操作(對文件或socket）的時候。
*/
}
else
{
/* Read() will be blocked here */
dbg_print("read() blocked here now.\n");
wait_event_interruptible(pdev->waitq, pdev->ev_press);
/*
這個函數先將當前進程的狀態設置成TASK_INTERRUPTIBLE, 然後調用schedule(), 而schedule()會將位於TASK_INTERRUPTIBLE狀態的當前進程從runqueue隊列中刪除。從runqueue隊列中刪除的結果是，當前這個進程將不再參與調度，除非通過其他函數將這個進程重新放入到runqueue隊列中，這就是wake_up()的作用。
*/
}
}
pdev->ev_press = 0;
for(i=0; i<pdata->nbuttons; i++)
{
dbg_print("button[%d] status=%d\n", i, pdev->status[i]);
status |= (pdev->status[i]<<i);
}
ret = copy_to_user(buf, (void *)&status, min(sizeof(status), count));
return ret ? -EFAULT : min(sizeof(status), count);
}
static unsigned int button_poll(struct file *file, poll_table * wait)
{
struct button_device *pdev = file->private_data;
unsigned int mask = 0;
poll_wait(file, &(pdev->waitq), wait);
/* poll_wait()是用在select系統調用中的。一般你的代碼有一個struct
* file_operations結構，其中fop->poll函數指針指向一個你自己的函數，在這個函數裏應該調用poll_wait().當用戶調用select系統調用時，select系統調用會先調用poll_initwait(&table);然後調用你的fop->poll();從而將current加到某個等待隊列(這裏調用poll_wait());並檢查是否有效，如果無效就調用schedule_timeout()去睡眠。事件發生後，schedule_timeout()回來，調用fop->poll();檢查到可以運行，就調用poll_freewait(&table);從而完成select調用。重要的是fop->poll()裏面要檢查是否就緒。如果是，要返回相應標誌。
*/
if(pdev->ev_press)
{
mask |= POLLIN | POLLRDNORM; /* The data aviable */
//POLLIN普通或優先級帶數據可讀；POLLRDNORM普通數據可讀
}
return mask;
}
static int button_release(struct inode *inode, struct file *file)
{
int i;
struct button_device *pdev = file->private_data;
struct s3c_button_platform_data *pdata;
pdata = pdev->data;
for(i=0; i<pdata->nbuttons; i++)
{
disable_irq(pdata->buttons[i].nIRQ);
free_irq(pdata->buttons[i].nIRQ, (void *)i);
del_timer(&(pdev->timers[i]));
}
kfree(pdev->timers);
kfree((unsigned char *)pdev->status);
return 0;
}
static struct file_operations button_fops = {
.owner = THIS_MODULE,
.open = button_open,
.read = button_read,
.poll = button_poll,
.release = button_release,
};
static int s3c_button_probe(struct platform_device *dev)
{
int result = 0;
dev_t devno;
/* Alloc the device for driver */
if (0 != dev_major)
{
devno = MKDEV(dev_major, dev_minor);
result = register_chrdev_region(devno, 1, DEV_NAME);
}
else
{
result = alloc_chrdev_region(&devno, dev_minor, 1, DEV_NAME);
dev_major = MAJOR(devno);
}
/* Alloc for device major failure */
if (result < 0)
{
printk("%s driver can't get major %d\n", DEV_NAME, dev_major);
return result;
}
/* Initialize button_device structure and register cdev*/
memset(&button_device, 0, sizeof(button_device));
button_device.data = dev->dev.platform_data;
cdev_init (&(button_device.cdev), &button_fops);
button_device.cdev.owner = THIS_MODULE;
result = cdev_add (&(button_device.cdev), devno , 1);
if (result)
{
printk (KERN_NOTICE "error %d add %s device", result, DEV_NAME);
goto ERROR;
}
button_device.dev_class = class_create(THIS_MODULE, DEV_NAME);
if(IS_ERR(button_device.dev_class))
{
printk("%s driver create class failture\n",DEV_NAME);
result = -ENOMEM;
goto ERROR;
}
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)
device_create(button_device.dev_class, NULL, devno, NULL, DEV_NAME);
#else
device_create (button_device.dev_class, NULL, devno, DEV_NAME);
#endif
printk("S3C %s driver version %d.%d.%d initiliazed.\n", DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);
return 0;
ERROR:
printk("S3C %s driver version %d.%d.%d install failure.\n", DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);
cdev_del(&(button_device.cdev));
unregister_chrdev_region(devno, 1);
return result;
}
static int s3c_button_remove(struct platform_device *dev)
{
dev_t devno = MKDEV(dev_major, dev_minor);
cdev_del(&(button_device.cdev));
device_destroy(button_device.dev_class, devno);
class_destroy(button_device.dev_class);
unregister_chrdev_region(devno, 1);
printk("S3C %s driver removed\n", DEV_NAME);
return 0;
}
/*===================== Platform Device and driver regist part ===========================*/
static struct platform_driver s3c_button_driver = {
.probe = s3c_button_probe,
.remove = s3c_button_remove,
.driver = {
.name = "s3c_button",
.owner = THIS_MODULE,
},
};
static int __init s3c_button_init(void)
{
int ret = 0;
ret = platform_device_register(&s3c_button_device);
if(ret)
{
printk(KERN_ERR "%s: Can't register platform device %d\n", __FUNCTION__, ret);
goto fail_reg_plat_dev;
}
dbg_print("Regist S3C %s Device successfully.\n", DEV_NAME);
ret = platform_driver_register(&s3c_button_driver);
if(ret)
{
printk(KERN_ERR "%s: Can't register platform driver %d\n", __FUNCTION__, ret);
goto fail_reg_plat_drv;
}
dbg_print("Regist S3C %s Driver successfully.\n", DEV_NAME);
return 0;
fail_reg_plat_drv:
platform_driver_unregister(&s3c_button_driver);
fail_reg_plat_dev:
return ret;
}
static void s3c_button_exit(void)
{
platform_driver_unregister(&s3c_button_driver);
dbg_print("S3C %s platform device removed.\n", DEV_NAME);
platform_device_unregister(&s3c_button_device);
dbg_print("S3C %s platform driver removed.\n", DEV_NAME);
}
module_init(s3c_button_init);
module_exit(s3c_button_exit);
module_param(debug, int, S_IRUGO);
module_param(dev_major, int, S_IRUGO);
module_param(dev_minor, int, S_IRUGO);
MODULE_AUTHOR(DRV_AUTHOR);
MODULE_DESCRIPTION(DRV_DESC);
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:S3C24XX_button");