mini2440驱动程序tang2440.doc

迷你2440驱动程序tang2440_buttons.c#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define DEVICE_NAME buttons/*定义中断所用的结构体*/struct button_irq_desc int irq; /按键对应的中断号 int pin; /按键所对应的 GPIO 端口 int pin_setting; /按键对应的引脚描述,实际并未用到,保留 int number; /定义键值,以传递给应用层/用户态 char *name; /每个按键的名称;/*结构体实体定义*/static struct button_irq_desc button_irqs = IRQ_EINT8 , S3C2410_GPG(0) , S3C2410_GPG0_EINT8 , 0, KEY0, IRQ_EINT11, S3C2410_GPG(3) , S3C2410_GPG3_EINT11 , 1, KEY1, IRQ_EINT13, S3C2410_GPG(5) , S3C2410_GPG5_EINT13 , 2, KEY2, IRQ_EINT14, S3C2410_GPG(6) , S3C2410_GPG6_EINT14 , 3, KEY3, IRQ_EINT15, S3C2410_GPG(7) , S3C2410_GPG7_EINT15 , 4, KEY4, IRQ_EINT19, S3C2410_GPG(11), S3C2410_GPG11_EINT19, 5, KEY5,;/*开发板上按键的状态变量,注意这里是0,对应的 ASCII 码为 30*/static volatile char key_values = 0, 0, 0, 0, 0, 0;/*因为本驱动是基于中断方式的,在此创建一个等待队列,以配合中断函数使用;当有按键按下并读取到键值时,将会唤醒此队列,并设置中断标志,以便能通过 read 函数判断和读取键值传递到用户态;当没有按键按下时,系统并不会轮询按键状态,以节省时钟资源*/static DECLARE_WAIT_QUEUE_HEAD(button_waitq);/*中断标识变量,配合上面的队列使用,中断服务程序会把它设置为 1,read 函数会把它清零*/static volatile int ev_press = 0;/*本按键驱动的中断服务程序*/static irqreturn_t buttons_interrupt(int irq, void *dev_id) struct button_irq_desc *button_irqs = (struct button_irq_desc *)dev_id; int down; /*获取被按下的按键状态*/ down = !s3c2410_gpio_getpin(button_irqs-pin); /*状态改变,按键被按下,从这句可以看出,当按键没有被按下的时候,寄存器的值为 1(上拉),但按键被按下的时候,寄存器对应的值为 0*/ if (down != (key_valuesbutton_irqs-number & 1) / Changed /*如果 key1 被按下,则 key_value0就变为1,对应的 ASCII 码为 31*/ key_valuesbutton_irqs-number = 0 + down; ev_press = 1; /*设置中断标志为 1*/ wake_up_interruptible(&button_waitq); /*唤醒等待队列*/ return IRQ_RETVAL(IRQ_HANDLED);/*在应用程序执行 open(“/dev/buttons”,.)时会调用到此函数,在这里,它的作用主要是注册 6 个按键的中断。*所用的中断类型是 IRQ_TYPE_EDGE_BOTH,也就是双沿触发,在上升沿和下降沿均会产生中断,这样做是为了更加有*效地判断按键状态*/static int s3c24xx_buttons_open(struct inode *inode, struct file *file) int i; int err = 0; for (i = 0; i sizeof(button_irqs)/sizeof(button_irqs0); i+) if (button_irqsi.irq = 0; i-) if (button_irqsi.irq 0) continue; disable_irq(button_irqsi.irq); free_irq(button_irqsi.irq, (void *)&button_irqsi); return -EBUSY; /*注册成功,则中断队列标记为 1,表示可以通过 read 读取*/ ev_press = 1; /*正常返回*/ return 0;/*此函数对应应用程序的系统调用 close(fd)函数,在此,它的主要作用是当关闭设备时释放 6 个按键的中断处理函数*/static int s3c24xx_buttons_close(struct inode *inode, struct file *file) int i; for (i = 0; i sizeof(button_irqs)/sizeof(button_irqs0); i+) if (button_irqsi.irq f_flags & O_NONBLOCK) /*当中断标识为 0 时,并且该设备是以非阻塞方式打开时,返回*/ return -EAGAIN; else /*当中断标识为 0 时,并且该设备是以阻塞方式打开时,进入休眠状态,等待被唤醒*/ wait_event_interruptible(button_waitq, ev_press); /*把中断标识清零*/ ev_press = 0; /*一组键值被传递到用户空间*/ err = copy_to_user(buff, (const void *)key_values, min(sizeof(key_values), count);return err ? -EFAULT : min(sizeof(key_values), count);static unsigned int s3c24xx_buttons_poll( struct file *file, struct poll_table_struct *wait) unsigned int mask = 0; /*把调用 poll 或者 select 的进程挂入队列,以便被驱动程序唤醒*/ poll_wait(file, &button_waitq, wait); if (ev_press) mask |= POLLIN | POLLRDNORM; return mask;/*设备操作集*/static struct file_operations dev_fops = .owner = THIS_MODULE, .open = s3c24xx_buttons_open, .release = s3c24xx_buttons_close, .read = s3c24xx_buttons_read, .poll = s3c24xx_buttons_poll,;static struct miscdevice misc = .minor = MISC_DYNAMIC_MINOR, .name = DEVICE_NAME, .fops = &dev_fops,;/*设备初始化,主要是注册设备*/static int _init dev_init(void) int ret; /*把按键设备注册为 misc 设备,其设备号是自动分配的*/ ret = misc_register(&misc); printk (DEVICE_NAMEtinitializedn); return ret;/*注销设备*/static void _exit dev_exit(void) misc_deregister(&misc);module_init(dev_init);/模块初始化,仅当使用 insmod/podprobe 命令加载时有用,如果设备不是通过模块方式加载,此处将不会被调用module_exit(dev_exit);/卸载模块,当该设备通过模块方式加载后,可以通过 rmmod 命令卸载,将调用此函数MODULE_LICENSE(GPL);/版权信息MODULE_AUTHOR(tang);/作者名字测试程序btn_test.c#include #include #include #include #include #include #include #include #include #include int main(void) int buttons_fd; char buttons6 = 0, 0, 0, 0, 0, 0; /定义按键值变量,对于驱动函数中的 key_values 数组 /*打开按键设备/dev/buttons*/ buttons_fd = open(/dev/buttons, 0); if (buttons_fd 0) /*打开失败则退出*/ perror(open device buttons); exit(1); /*永读按键并打印键值和状态*/ for (;) char current_buttons6; int count_of_changed_key; int i; /*使用 read 函数读取一组按键值(6 个)*/ if (read(buttons_fd, current_buttons, sizeof current_buttons) != sizeof current_buttons) perror(read buttons:); exit(1); /*逐个分析读取到的按键值*/ for (i = 0, count_of_changed_key = 0; i sizeof buttons / sizeof buttons0; i+) if (buttonsi != current_buttonsi) buttonsi = current_buttonsi; /*打印按键值,并标明按键按下/抬起的状态*/ printf(%skey %d is %s, count_of_changed_key? , : , i+1, buttonsi = 0 ? up :down); count_of_changed_key+; if (count_of_changed_key) printf(n); /*关闭按键设备文件*/ close(buttons_fd); return 0;arm-linux-gcc -o buttons_test buttons_test.c以下是成功加载范例jd2440_buttons.c，位于linux-2.x.xx/drivers/char下cp -f jd2440_buttons.c /linux-2.x.xx/drivers/char /把驱动源码复制到内核驱动的字符设备下#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define DEVICE_NAME buttonsstruct button_irq_desc int irq;int pin;int pin_setting;int number;char *name;static struct button_irq_desc button_irqs = IRQ_EINT11,S3C2410_GPG3, S3C2410_GPG3_EINT11, 0, KEY0,/key_rightIRQ_EINT8, S3C2410_GPG0, S3C2410_GPG0_EINT8, 1, KEY1,/key_downIRQ_EINT3, S3C2410_GPF3, S3C2410_GPF3_EINT3, 2, KEY2,/key_enterIRQ_EINT9, S3C2410_GPG1, S3C2410_GPG1_EINT9, 3, KEY3,/key_leftIRQ_EINT1, S3C2410_GPF1, S3C2410_GPF1_EINT1, 4, KEY4,/key_upIRQ_EINT5, S3C2410_GPF5, S3C2410_GPF5_EINT5, 5, KEY5,/usb wakeup -1, -1, -1, 6, KEY6,;static volatile char key_values = 0, 0, 0, 0, 0, 0;static DECLARE_WAIT_QUEUE_HEAD(button_waitq);static volatile int ev_press = 0;static irqreturn_t buttons_interrupt(int irq, void *dev_id) struct button_irq_desc *button_irqs = (struct button_irq_desc *)dev_id; int down; down = !s3c2410_gpio_getpin(button_irqs-pin); if (down != (key_valuesbutton_irqs-number & 1) key_valuesbutton_irqs-number = 0 + down;ev_press = 1;wake_up_interruptible(&button_waitq); return IRQ_RETVAL(IRQ_HANDLED);static int s3c24xx_buttons_open(struct inode *inode, struct file *file) int i; int err = 0; for (i = 0; i sizeof(button_irqs)/sizeof(button_irqs0); i+) if (button_irqsi.irq = 0; i-) if (button_irqsi.irq 0) continue; disable_irq(button_irqsi.irq); free_irq(button_irqsi.irq, (void *)&button_irqsi);return -EBUSY; ev_press = 1; return 0;static int s3c24xx_buttons_close(struct inode *inode, struct file *file)int i; for (i = 0; i sizeof(button_irqs)/sizeof(button_irqs0); i+) if (button_irqsi.irq f_flags & O_NONBLOCK) return -EAGAIN;else wait_event_interruptible(button_waitq, ev_press); ev_press = 0; err = copy_to_user(buff, (const void *)key_values, min(sizeof(key_values), count); return err ? -EFAULT : min(sizeof(key_values), count);static unsigned int s3c24xx_buttons_poll( struct file *file, struct poll_table_struct *wait) unsigned int mask = 0; poll_wait(file, &button_waitq, wait); if (ev_press) mask |= POLLIN | POLLRDNORM; return mask;static struct file_operations dev_fops = .owner = THIS_MODULE, .ope